Merge tag 'scmi-updates-4.17' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into next/drivers

Pull "ARM SCMI support for v4.17" from Sudeep Holla:

ARM System Control and Management Interface(SCMI)[1] is more flexible and
easily extensible than any of the existing interfaces.

Few existing as well as future ARM platforms provide micro-controllers
to abstract various power and other system management tasks which have
similar interfaces, both in terms of the functions that are provided by
them, and in terms of how requests are communicated to them.

There are quite a few protocols like ARM SCPI, TI SCI, QCOM RPM, Nvidia Tegra
BPMP, and so on already. This specification is to standardize and avoid any
further fragmentation in the design of such interface by various vendors.

The current SCMI driver implementation is very basic and initial support.
It lacks support for notifications, asynchronous/delayed response, perf/power
statistics region and sensor register region.

Mailbox is the only form of transport supported currently in the driver.
SCMI supports interrupt based mailbox communication, where, on completion
of the processing of a message, the caller receives an interrupt as well as
polling for completion.

SCMI is designed to minimize the dependency on the mailbox/transport
hardware. So in terms of SCMI, each channel in the mailbox includes
memory area, doorbell and completion interrupt.

However the doorbell and completion interrupt is highly mailbox dependent
which was bit of controversial as part of SCMI/mailbox discussions.

Arnd and me discussed about the few aspects of SCMI and the mailbox framework:

1. Use of mailbox framework for doorbell type mailbox controller:
   - Such hardware may not require any data to be sent to signal the remote
     about the presence of a message. The channel will have in-built
     information on how to trigger the signal to the remote.
     There are few mailbox controller drivers which are purely doorbell based.
     e.g.QCOM IPC, STM, Tegra, ACPI PCC,..etc

2. Supporting other mailbox controller:
   - SCMI just needs a mechanism to signal the remote firmware. Such
     controller may need fixed message to be sent to trigger a doorbell.
     In such case we may need to get that data from DT and pass the same
     to the controller. It's not covered in the current DT binding, but
     can be extended as optional property in future.

     However handling notifications may be interesting on such mailbox, but
     again there is no way to interpret what the data field(remote message)
     means, it could be a bit mask or a number or don't-care.

Arnd mentioned that he doesn't like the way the mailbox binding deals
with doorbell-type hardware, but we do have quite a few precedent drivers
already and changing the binding to add a data field would not make it any
better, but could cause other problems. So he is happy with the status quo
of SCMI implementation.

[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.den0056a/index.html

* tag 'scmi-updates-4.17' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux:
  cpufreq: scmi: add support for fast frequency switching
  cpufreq: add support for CPU DVFS based on SCMI message protocol
  hwmon: add support for sensors exported via ARM SCMI
  hwmon: (core) Add hwmon_max to hwmon_sensor_types enumeration
  clk: add support for clocks provided by SCMI
  firmware: arm_scmi: add device power domain support using genpd
  firmware: arm_scmi: add per-protocol channels support using idr objects
  firmware: arm_scmi: refactor in preparation to support per-protocol channels
  firmware: arm_scmi: add option for polling based performance domain operations
  firmware: arm_scmi: add support for polling based SCMI transfers
  firmware: arm_scmi: probe and initialise all the supported protocols
  firmware: arm_scmi: add initial support for sensor protocol
  firmware: arm_scmi: add initial support for power protocol
  firmware: arm_scmi: add initial support for clock protocol
  firmware: arm_scmi: add initial support for performance protocol
  firmware: arm_scmi: add scmi protocol bus to enumerate protocol devices
  firmware: arm_scmi: add common infrastructure and support for base protocol
  firmware: arm_scmi: add basic driver infrastructure for SCMI
  dt-bindings: arm: add support for ARM System Control and Management Interface(SCMI) protocol
  dt-bindings: mailbox: add support for mailbox client shared memory

26 files changed, 4172 insertions, 5 deletions

diff --git a/Documentation/devicetree/bindings/arm/arm,scmi.txt b/Documentation/devicetree/bindings/arm/arm,scmi.txt
new file mode 100644
index 000000000000..5f3719ab7075
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/arm,scmi.txt
@@ -0,0 +1,179 @@
+System Control and Management Interface (SCMI) Message Protocol
+----------------------------------------------------------
+
+The SCMI is intended to allow agents such as OSPM to manage various functions
+that are provided by the hardware platform it is running on, including power
+and performance functions.
+
+This binding is intended to define the interface the firmware implementing
+the SCMI as described in ARM document number ARM DUI 0922B ("ARM System Control
+and Management Interface Platform Design Document")[0] provide for OSPM in
+the device tree.
+
+Required properties:
+
+The scmi node with the following properties shall be under the /firmware/ node.
+
+- compatible : shall be "arm,scmi"
+- mboxes: List of phandle and mailbox channel specifiers. It should contain
+          exactly one or two mailboxes, one for transmitting messages("tx")
+          and another optional for receiving the notifications("rx") if
+          supported.
+- shmem : List of phandle pointing to the shared memory(SHM) area as per
+          generic mailbox client binding.
+- #address-cells : should be '1' if the device has sub-nodes, maps to
+          protocol identifier for a given sub-node.
+- #size-cells : should be '0' as 'reg' property doesn't have any size
+          associated with it.
+
+Optional properties:
+
+- mbox-names: shall be "tx" or "rx" depending on mboxes entries.
+
+See Documentation/devicetree/bindings/mailbox/mailbox.txt for more details
+about the generic mailbox controller and client driver bindings.
+
+The mailbox is the only permitted method of calling the SCMI firmware.
+Mailbox doorbell is used as a mechanism to alert the presence of a
+messages and/or notification.
+
+Each protocol supported shall have a sub-node with corresponding compatible
+as described in the following sections. If the platform supports dedicated
+communication channel for a particular protocol, the 3 properties namely:
+mboxes, mbox-names and shmem shall be present in the sub-node corresponding
+to that protocol.
+
+Clock/Performance bindings for the clocks/OPPs based on SCMI Message Protocol
+------------------------------------------------------------
+
+This binding uses the common clock binding[1].
+
+Required properties:
+- #clock-cells : Should be 1. Contains the Clock ID value used by SCMI commands.
+
+Power domain bindings for the power domains based on SCMI Message Protocol
+------------------------------------------------------------
+
+This binding for the SCMI power domain providers uses the generic power
+domain binding[2].
+
+Required properties:
+ - #power-domain-cells : Should be 1. Contains the device or the power
+                         domain ID value used by SCMI commands.
+
+Sensor bindings for the sensors based on SCMI Message Protocol
+--------------------------------------------------------------
+SCMI provides an API to access the various sensors on the SoC.
+
+Required properties:
+- #thermal-sensor-cells: should be set to 1. This property follows the
+                         thermal device tree bindings[3].
+
+                         Valid cell values are raw identifiers (Sensor ID)
+                         as used by the firmware. Refer to  platform details
+                         for your implementation for the IDs to use.
+
+SRAM and Shared Memory for SCMI
+-------------------------------
+
+A small area of SRAM is reserved for SCMI communication between application
+processors and SCP.
+
+The properties should follow the generic mmio-sram description found in [4]
+
+Each sub-node represents the reserved area for SCMI.
+
+Required sub-node properties:
+- reg : The base offset and size of the reserved area with the SRAM
+- compatible : should be "arm,scmi-shmem" for Non-secure SRAM based
+               shared memory
+
+[0] http://infocenter.arm.com/help/topic/com.arm.doc.den0056a/index.html
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+[2] Documentation/devicetree/bindings/power/power_domain.txt
+[3] Documentation/devicetree/bindings/thermal/thermal.txt
+[4] Documentation/devicetree/bindings/sram/sram.txt
+
+Example:
+
+sram@50000000 {
+        compatible = "mmio-sram";
+        reg = <0x0 0x50000000 0x0 0x10000>;
+
+        #address-cells = <1>;
+        #size-cells = <1>;
+        ranges = <0 0x0 0x50000000 0x10000>;
+
+        cpu_scp_lpri: scp-shmem@0 {
+                compatible = "arm,scmi-shmem";
+                reg = <0x0 0x200>;
+        };
+
+        cpu_scp_hpri: scp-shmem@200 {
+                compatible = "arm,scmi-shmem";
+                reg = <0x200 0x200>;
+        };
+};
+
+mailbox@40000000 {
+        ....
+        #mbox-cells = <1>;
+        reg = <0x0 0x40000000 0x0 0x10000>;
+};
+
+firmware {
+
+        ...
+
+        scmi {
+                compatible = "arm,scmi";
+                mboxes = <&mailbox 0 &mailbox 1>;
+                mbox-names = "tx", "rx";
+                shmem = <&cpu_scp_lpri &cpu_scp_hpri>;
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                scmi_devpd: protocol@11 {
+                        reg = <0x11>;
+                        #power-domain-cells = <1>;
+                };
+
+                scmi_dvfs: protocol@13 {
+                        reg = <0x13>;
+                        #clock-cells = <1>;
+                };
+
+                scmi_clk: protocol@14 {
+                        reg = <0x14>;
+                        #clock-cells = <1>;
+                };
+
+                scmi_sensors0: protocol@15 {
+                        reg = <0x15>;
+                        #thermal-sensor-cells = <1>;
+                };
+        };
+};
+
+cpu@0 {
+        ...
+        reg = <0 0>;
+        clocks = <&scmi_dvfs 0>;
+};
+
+hdlcd@7ff60000 {
+        ...
+        reg = <0 0x7ff60000 0 0x1000>;
+        clocks = <&scmi_clk 4>;
+        power-domains = <&scmi_devpd 1>;
+};
+
+thermal-zones {
+        soc_thermal {
+                polling-delay-passive = <100>;
+                polling-delay = <1000>;
+                                        /* sensor ID */
+                thermal-sensors = <&scmi_sensors0 3>;
+                ...
+        };
+};
diff --git a/Documentation/devicetree/bindings/mailbox/mailbox.txt b/Documentation/devicetree/bindings/mailbox/mailbox.txt
index be05b9746c69..af8ecee2ac68 100644
--- a/Documentation/devicetree/bindings/mailbox/mailbox.txt
+++ b/Documentation/devicetree/bindings/mailbox/mailbox.txt
@@ -23,6 +23,11 @@ Required property:
 
 Optional property:
 - mbox-names: List of identifier strings for each mailbox channel.
+- shmem : List of phandle pointing to the shared memory(SHM) area between the
+          users of these mailboxes for IPC, one for each mailbox. This shared
+          memory can be part of any memory reserved for the purpose of this
+          communication between the mailbox client and the remote.
+
 
 Example:
         pwr_cntrl: power {
@@ -30,3 +35,26 @@ Example:
                 mbox-names = "pwr-ctrl", "rpc";
                 mboxes = <&mailbox 0 &mailbox 1>;
         };
+
+Example with shared memory(shmem):
+
+        sram: sram@50000000 {
+                compatible = "mmio-sram";
+                reg = <0x50000000 0x10000>;
+
+                #address-cells = <1>;
+                #size-cells = <1>;
+                ranges = <0 0x50000000 0x10000>;
+
+                cl_shmem: shmem@0 {
+                        compatible = "client-shmem";
+                        reg = <0x0 0x200>;
+                };
+        };
+
+        client@2e000000 {
+                ...
+                mboxes = <&mailbox 0>;
+                shmem = <&cl_shmem>;
+                ..
+        };
diff --git a/MAINTAINERS b/MAINTAINERS
index 4623caf8d72d..24e19837c113 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13395,15 +13395,16 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd.git
 S:      Supported
 F:      drivers/mfd/syscon.c
 
-SYSTEM CONTROL & POWER INTERFACE (SCPI) Message Protocol drivers
+SYSTEM CONTROL & POWER/MANAGEMENT INTERFACE (SCPI/SCMI) Message Protocol drivers
 M:      Sudeep Holla <sudeep.holla@arm.com>
 L:      linux-arm-kernel@lists.infradead.org
 S:      Maintained
-F:      Documentation/devicetree/bindings/arm/arm,scpi.txt
-F:      drivers/clk/clk-scpi.c
-F:      drivers/cpufreq/scpi-cpufreq.c
+F:      Documentation/devicetree/bindings/arm/arm,sc[mp]i.txt
+F:      drivers/clk/clk-sc[mp]i.c
+F:      drivers/cpufreq/sc[mp]i-cpufreq.c
 F:      drivers/firmware/arm_scpi.c
-F:      include/linux/scpi_protocol.h
+F:      drivers/firmware/arm_scmi/
+F:      include/linux/sc[mp]i_protocol.h
 
 SYSTEM RESET/SHUTDOWN DRIVERS
 M:      Sebastian Reichel <sre@kernel.org>
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 98ce9fc6e6c0..7ae23b25b406 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -62,6 +62,16 @@ config COMMON_CLK_HI655X
           multi-function device has one fixed-rate oscillator, clocked
           at 32KHz.
 
+config COMMON_CLK_SCMI
+        tristate "Clock driver controlled via SCMI interface"
+        depends on ARM_SCMI_PROTOCOL || COMPILE_TEST
+          ---help---
+          This driver provides support for clocks that are controlled
+          by firmware that implements the SCMI interface.
+
+          This driver uses SCMI Message Protocol to interact with the
+          firmware providing all the clock controls.
+
 config COMMON_CLK_SCPI
         tristate "Clock driver controlled via SCPI interface"
         depends on ARM_SCPI_PROTOCOL || COMPILE_TEST
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 71ec41e6364f..6605513eaa94 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -41,6 +41,7 @@ obj-$(CONFIG_CLK_QORIQ)			+= clk-qoriq.o
 obj-$(CONFIG_COMMON_CLK_RK808)          += clk-rk808.o
 obj-$(CONFIG_COMMON_CLK_HI655X)         += clk-hi655x.o
 obj-$(CONFIG_COMMON_CLK_S2MPS11)        += clk-s2mps11.o
+obj-$(CONFIG_COMMON_CLK_SCMI)           += clk-scmi.o
 obj-$(CONFIG_COMMON_CLK_SCPI)           += clk-scpi.o
 obj-$(CONFIG_COMMON_CLK_SI5351)         += clk-si5351.o
 obj-$(CONFIG_COMMON_CLK_SI514)          += clk-si514.o
diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
new file mode 100644
index 000000000000..26f1476d4a79
--- /dev/null
+++ b/drivers/clk/clk-scmi.c
@@ -0,0 +1,202 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Power Interface (SCMI) Protocol based clock driver
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/module.h>
+#include <linux/scmi_protocol.h>
+#include <asm/div64.h>
+
+struct scmi_clk {
+        u32 id;
+        struct clk_hw hw;
+        const struct scmi_clock_info *info;
+        const struct scmi_handle *handle;
+};
+
+#define to_scmi_clk(clk) container_of(clk, struct scmi_clk, hw)
+
+static unsigned long scmi_clk_recalc_rate(struct clk_hw *hw,
+                                          unsigned long parent_rate)
+{
+        int ret;
+        u64 rate;
+        struct scmi_clk *clk = to_scmi_clk(hw);
+
+        ret = clk->handle->clk_ops->rate_get(clk->handle, clk->id, &rate);
+        if (ret)
+                return 0;
+        return rate;
+}
+
+static long scmi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+                                unsigned long *parent_rate)
+{
+        int step;
+        u64 fmin, fmax, ftmp;
+        struct scmi_clk *clk = to_scmi_clk(hw);
+
+        /*
+         * We can't figure out what rate it will be, so just return the
+         * rate back to the caller. scmi_clk_recalc_rate() will be called
+         * after the rate is set and we'll know what rate the clock is
+         * running at then.
+         */
+        if (clk->info->rate_discrete)
+                return rate;
+
+        fmin = clk->info->range.min_rate;
+        fmax = clk->info->range.max_rate;
+        if (rate <= fmin)
+                return fmin;
+        else if (rate >= fmax)
+                return fmax;
+
+        ftmp = rate - fmin;
+        ftmp += clk->info->range.step_size - 1; /* to round up */
+        step = do_div(ftmp, clk->info->range.step_size);
+
+        return step * clk->info->range.step_size + fmin;
+}
+
+static int scmi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+                             unsigned long parent_rate)
+{
+        struct scmi_clk *clk = to_scmi_clk(hw);
+
+        return clk->handle->clk_ops->rate_set(clk->handle, clk->id, 0, rate);
+}
+
+static int scmi_clk_enable(struct clk_hw *hw)
+{
+        struct scmi_clk *clk = to_scmi_clk(hw);
+
+        return clk->handle->clk_ops->enable(clk->handle, clk->id);
+}
+
+static void scmi_clk_disable(struct clk_hw *hw)
+{
+        struct scmi_clk *clk = to_scmi_clk(hw);
+
+        clk->handle->clk_ops->disable(clk->handle, clk->id);
+}
+
+static const struct clk_ops scmi_clk_ops = {
+        .recalc_rate = scmi_clk_recalc_rate,
+        .round_rate = scmi_clk_round_rate,
+        .set_rate = scmi_clk_set_rate,
+        /*
+         * We can't provide enable/disable callback as we can't perform the same
+         * in atomic context. Since the clock framework provides standard API
+         * clk_prepare_enable that helps cases using clk_enable in non-atomic
+         * context, it should be fine providing prepare/unprepare.
+         */
+        .prepare = scmi_clk_enable,
+        .unprepare = scmi_clk_disable,
+};
+
+static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk)
+{
+        int ret;
+        struct clk_init_data init = {
+                .flags = CLK_GET_RATE_NOCACHE,
+                .num_parents = 0,
+                .ops = &scmi_clk_ops,
+                .name = sclk->info->name,
+        };
+
+        sclk->hw.init = &init;
+        ret = devm_clk_hw_register(dev, &sclk->hw);
+        if (!ret)
+                clk_hw_set_rate_range(&sclk->hw, sclk->info->range.min_rate,
+                                      sclk->info->range.max_rate);
+        return ret;
+}
+
+static int scmi_clocks_probe(struct scmi_device *sdev)
+{
+        int idx, count, err;
+        struct clk_hw **hws;
+        struct clk_hw_onecell_data *clk_data;
+        struct device *dev = &sdev->dev;
+        struct device_node *np = dev->of_node;
+        const struct scmi_handle *handle = sdev->handle;
+
+        if (!handle || !handle->clk_ops)
+                return -ENODEV;
+
+        count = handle->clk_ops->count_get(handle);
+        if (count < 0) {
+                dev_err(dev, "%s: invalid clock output count\n", np->name);
+                return -EINVAL;
+        }
+
+        clk_data = devm_kzalloc(dev, sizeof(*clk_data) +
+                                sizeof(*clk_data->hws) * count, GFP_KERNEL);
+        if (!clk_data)
+                return -ENOMEM;
+
+        clk_data->num = count;
+        hws = clk_data->hws;
+
+        for (idx = 0; idx < count; idx++) {
+                struct scmi_clk *sclk;
+
+                sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
+                if (!sclk)
+                        return -ENOMEM;
+
+                sclk->info = handle->clk_ops->info_get(handle, idx);
+                if (!sclk->info) {
+                        dev_dbg(dev, "invalid clock info for idx %d\n", idx);
+                        continue;
+                }
+
+                sclk->id = idx;
+                sclk->handle = handle;
+
+                err = scmi_clk_ops_init(dev, sclk);
+                if (err) {
+                        dev_err(dev, "failed to register clock %d\n", idx);
+                        devm_kfree(dev, sclk);
+                        hws[idx] = NULL;
+                } else {
+                        dev_dbg(dev, "Registered clock:%s\n", sclk->info->name);
+                        hws[idx] = &sclk->hw;
+                }
+        }
+
+        return of_clk_add_hw_provider(np, of_clk_hw_onecell_get, clk_data);
+}
+
+static void scmi_clocks_remove(struct scmi_device *sdev)
+{
+        struct device *dev = &sdev->dev;
+        struct device_node *np = dev->of_node;
+
+        of_clk_del_provider(np);
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+        { SCMI_PROTOCOL_CLOCK },
+        { },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_clocks_driver = {
+        .name = "scmi-clocks",
+        .probe = scmi_clocks_probe,
+        .remove = scmi_clocks_remove,
+        .id_table = scmi_id_table,
+};
+module_scmi_driver(scmi_clocks_driver);
+
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCMI clock driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index fb586e09682d..9bbb5b39d18a 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -238,6 +238,17 @@ config ARM_SA1100_CPUFREQ
 config ARM_SA1110_CPUFREQ
         bool
 
+config ARM_SCMI_CPUFREQ
+        tristate "SCMI based CPUfreq driver"
+        depends on ARM_SCMI_PROTOCOL || COMPILE_TEST
+        select PM_OPP
+        help
+          This adds the CPUfreq driver support for ARM platforms using SCMI
+          protocol for CPU power management.
+
+          This driver uses SCMI Message Protocol driver to interact with the
+          firmware providing the CPU DVFS functionality.
+
 config ARM_SPEAR_CPUFREQ
         bool "SPEAr CPUFreq support"
         depends on PLAT_SPEAR
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index c60c1e141d9d..4987227b67df 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -75,6 +75,7 @@ obj-$(CONFIG_ARM_S3C24XX_CPUFREQ_DEBUGFS) += s3c24xx-cpufreq-debugfs.o
 obj-$(CONFIG_ARM_S5PV210_CPUFREQ)       += s5pv210-cpufreq.o
 obj-$(CONFIG_ARM_SA1100_CPUFREQ)        += sa1100-cpufreq.o
 obj-$(CONFIG_ARM_SA1110_CPUFREQ)        += sa1110-cpufreq.o
+obj-$(CONFIG_ARM_SCMI_CPUFREQ)          += scmi-cpufreq.o
 obj-$(CONFIG_ARM_SCPI_CPUFREQ)          += scpi-cpufreq.o
 obj-$(CONFIG_ARM_SPEAR_CPUFREQ)         += spear-cpufreq.o
 obj-$(CONFIG_ARM_STI_CPUFREQ)           += sti-cpufreq.o
diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
new file mode 100644
index 000000000000..959a1dbe3835
--- /dev/null
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -0,0 +1,264 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Power Interface (SCMI) based CPUFreq Interface driver
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ * Sudeep Holla <sudeep.holla@arm.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/cpumask.h>
+#include <linux/cpu_cooling.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/pm_opp.h>
+#include <linux/slab.h>
+#include <linux/scmi_protocol.h>
+#include <linux/types.h>
+
+struct scmi_data {
+        int domain_id;
+        struct device *cpu_dev;
+        struct thermal_cooling_device *cdev;
+};
+
+static const struct scmi_handle *handle;
+
+static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
+{
+        struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
+        struct scmi_perf_ops *perf_ops = handle->perf_ops;
+        struct scmi_data *priv = policy->driver_data;
+        unsigned long rate;
+        int ret;
+
+        ret = perf_ops->freq_get(handle, priv->domain_id, &rate, false);
+        if (ret)
+                return 0;
+        return rate / 1000;
+}
+
+/*
+ * perf_ops->freq_set is not a synchronous, the actual OPP change will
+ * happen asynchronously and can get notified if the events are
+ * subscribed for by the SCMI firmware
+ */
+static int
+scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
+{
+        int ret;
+        struct scmi_data *priv = policy->driver_data;
+        struct scmi_perf_ops *perf_ops = handle->perf_ops;
+        u64 freq = policy->freq_table[index].frequency * 1000;
+
+        ret = perf_ops->freq_set(handle, priv->domain_id, freq, false);
+        if (!ret)
+                arch_set_freq_scale(policy->related_cpus, freq,
+                                    policy->cpuinfo.max_freq);
+        return ret;
+}
+
+static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
+                                             unsigned int target_freq)
+{
+        struct scmi_data *priv = policy->driver_data;
+        struct scmi_perf_ops *perf_ops = handle->perf_ops;
+
+        if (!perf_ops->freq_set(handle, priv->domain_id,
+                                target_freq * 1000, true)) {
+                arch_set_freq_scale(policy->related_cpus, target_freq,
+                                    policy->cpuinfo.max_freq);
+                return target_freq;
+        }
+
+        return 0;
+}
+
+static int
+scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
+{
+        int cpu, domain, tdomain;
+        struct device *tcpu_dev;
+
+        domain = handle->perf_ops->device_domain_id(cpu_dev);
+        if (domain < 0)
+                return domain;
+
+        for_each_possible_cpu(cpu) {
+                if (cpu == cpu_dev->id)
+                        continue;
+
+                tcpu_dev = get_cpu_device(cpu);
+                if (!tcpu_dev)
+                        continue;
+
+                tdomain = handle->perf_ops->device_domain_id(tcpu_dev);
+                if (tdomain == domain)
+                        cpumask_set_cpu(cpu, cpumask);
+        }
+
+        return 0;
+}
+
+static int scmi_cpufreq_init(struct cpufreq_policy *policy)
+{
+        int ret;
+        unsigned int latency;
+        struct device *cpu_dev;
+        struct scmi_data *priv;
+        struct cpufreq_frequency_table *freq_table;
+
+        cpu_dev = get_cpu_device(policy->cpu);
+        if (!cpu_dev) {
+                pr_err("failed to get cpu%d device\n", policy->cpu);
+                return -ENODEV;
+        }
+
+        ret = handle->perf_ops->add_opps_to_device(handle, cpu_dev);
+        if (ret) {
+                dev_warn(cpu_dev, "failed to add opps to the device\n");
+                return ret;
+        }
+
+        ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
+        if (ret) {
+                dev_warn(cpu_dev, "failed to get sharing cpumask\n");
+                return ret;
+        }
+
+        ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
+        if (ret) {
+                dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
+                        __func__, ret);
+                return ret;
+        }
+
+        ret = dev_pm_opp_get_opp_count(cpu_dev);
+        if (ret <= 0) {
+                dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
+                ret = -EPROBE_DEFER;
+                goto out_free_opp;
+        }
+
+        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+        if (!priv) {
+                ret = -ENOMEM;
+                goto out_free_opp;
+        }
+
+        ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
+        if (ret) {
+                dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
+                goto out_free_priv;
+        }
+
+        priv->cpu_dev = cpu_dev;
+        priv->domain_id = handle->perf_ops->device_domain_id(cpu_dev);
+
+        policy->driver_data = priv;
+
+        ret = cpufreq_table_validate_and_show(policy, freq_table);
+        if (ret) {
+                dev_err(cpu_dev, "%s: invalid frequency table: %d\n", __func__,
+                        ret);
+                goto out_free_cpufreq_table;
+        }
+
+        /* SCMI allows DVFS request for any domain from any CPU */
+        policy->dvfs_possible_from_any_cpu = true;
+
+        latency = handle->perf_ops->get_transition_latency(handle, cpu_dev);
+        if (!latency)
+                latency = CPUFREQ_ETERNAL;
+
+        policy->cpuinfo.transition_latency = latency;
+
+        policy->fast_switch_possible = true;
+        return 0;
+
+out_free_cpufreq_table:
+        dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
+out_free_priv:
+        kfree(priv);
+out_free_opp:
+        dev_pm_opp_cpumask_remove_table(policy->cpus);
+
+        return ret;
+}
+
+static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
+{
+        struct scmi_data *priv = policy->driver_data;
+
+        cpufreq_cooling_unregister(priv->cdev);
+        dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
+        kfree(priv);
+        dev_pm_opp_cpumask_remove_table(policy->related_cpus);
+
+        return 0;
+}
+
+static void scmi_cpufreq_ready(struct cpufreq_policy *policy)
+{
+        struct scmi_data *priv = policy->driver_data;
+
+        priv->cdev = of_cpufreq_cooling_register(policy);
+}
+
+static struct cpufreq_driver scmi_cpufreq_driver = {
+        .name   = "scmi",
+        .flags  = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
+                  CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+        .verify = cpufreq_generic_frequency_table_verify,
+        .attr   = cpufreq_generic_attr,
+        .target_index   = scmi_cpufreq_set_target,
+        .fast_switch    = scmi_cpufreq_fast_switch,
+        .get    = scmi_cpufreq_get_rate,
+        .init   = scmi_cpufreq_init,
+        .exit   = scmi_cpufreq_exit,
+        .ready  = scmi_cpufreq_ready,
+};
+
+static int scmi_cpufreq_probe(struct scmi_device *sdev)
+{
+        int ret;
+
+        handle = sdev->handle;
+
+        if (!handle || !handle->perf_ops)
+                return -ENODEV;
+
+        ret = cpufreq_register_driver(&scmi_cpufreq_driver);
+        if (ret) {
+                dev_err(&sdev->dev, "%s: registering cpufreq failed, err: %d\n",
+                        __func__, ret);
+        }
+
+        return ret;
+}
+
+static void scmi_cpufreq_remove(struct scmi_device *sdev)
+{
+        cpufreq_unregister_driver(&scmi_cpufreq_driver);
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+        { SCMI_PROTOCOL_PERF },
+        { },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_cpufreq_drv = {
+        .name           = "scmi-cpufreq",
+        .probe          = scmi_cpufreq_probe,
+        .remove         = scmi_cpufreq_remove,
+        .id_table       = scmi_id_table,
+};
+module_scmi_driver(scmi_cpufreq_drv);
+
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index b7c748248e53..6e83880046d7 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -19,6 +19,40 @@ config ARM_PSCI_CHECKER
           on and off through hotplug, so for now torture tests and PSCI checker
           are mutually exclusive.
 
+config ARM_SCMI_PROTOCOL
+        bool "ARM System Control and Management Interface (SCMI) Message Protocol"
+        depends on ARM || ARM64 || COMPILE_TEST
+        depends on MAILBOX
+        help
+          ARM System Control and Management Interface (SCMI) protocol is a
+          set of operating system-independent software interfaces that are
+          used in system management. SCMI is extensible and currently provides
+          interfaces for: Discovery and self-description of the interfaces
+          it supports, Power domain management which is the ability to place
+          a given device or domain into the various power-saving states that
+          it supports, Performance management which is the ability to control
+          the performance of a domain that is composed of compute engines
+          such as application processors and other accelerators, Clock
+          management which is the ability to set and inquire rates on platform
+          managed clocks and Sensor management which is the ability to read
+          sensor data, and be notified of sensor value.
+
+          This protocol library provides interface for all the client drivers
+          making use of the features offered by the SCMI.
+
+config ARM_SCMI_POWER_DOMAIN
+        tristate "SCMI power domain driver"
+        depends on ARM_SCMI_PROTOCOL || (COMPILE_TEST && OF)
+        default y
+        select PM_GENERIC_DOMAINS if PM
+        help
+          This enables support for the SCMI power domains which can be
+          enabled or disabled via the SCP firmware
+
+          This driver can also be built as a module.  If so, the module
+          will be called scmi_pm_domain. Note this may needed early in boot
+          before rootfs may be available.
+
 config ARM_SCPI_PROTOCOL
         tristate "ARM System Control and Power Interface (SCPI) Message Protocol"
         depends on ARM || ARM64 || COMPILE_TEST
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index b248238ddc6a..e18a041cfc53 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_QCOM_SCM_32)	+= qcom_scm-32.o
 CFLAGS_qcom_scm-32.o :=$(call as-instr,.arch armv7-a\n.arch_extension sec,-DREQUIRES_SEC=1) -march=armv7-a
 obj-$(CONFIG_TI_SCI_PROTOCOL)   += ti_sci.o
 
+obj-$(CONFIG_ARM_SCMI_PROTOCOL) += arm_scmi/
 obj-y                           += broadcom/
 obj-y                           += meson/
 obj-$(CONFIG_GOOGLE_FIRMWARE)   += google/
diff --git a/drivers/firmware/arm_scmi/Makefile b/drivers/firmware/arm_scmi/Makefile
new file mode 100644
index 000000000000..99e36c580fbc
--- /dev/null
+++ b/drivers/firmware/arm_scmi/Makefile
@@ -0,0 +1,5 @@
+obj-y   = scmi-bus.o scmi-driver.o scmi-protocols.o
+scmi-bus-y = bus.o
+scmi-driver-y = driver.o
+scmi-protocols-y = base.o clock.o perf.o power.o sensors.o
+obj-$(CONFIG_ARM_SCMI_POWER_DOMAIN) += scmi_pm_domain.o
diff --git a/drivers/firmware/arm_scmi/base.c b/drivers/firmware/arm_scmi/base.c
new file mode 100644
index 000000000000..0d3806c0d432
--- /dev/null
+++ b/drivers/firmware/arm_scmi/base.c
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Base Protocol
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ */
+
+#include "common.h"
+
+enum scmi_base_protocol_cmd {
+        BASE_DISCOVER_VENDOR = 0x3,
+        BASE_DISCOVER_SUB_VENDOR = 0x4,
+        BASE_DISCOVER_IMPLEMENT_VERSION = 0x5,
+        BASE_DISCOVER_LIST_PROTOCOLS = 0x6,
+        BASE_DISCOVER_AGENT = 0x7,
+        BASE_NOTIFY_ERRORS = 0x8,
+};
+
+struct scmi_msg_resp_base_attributes {
+        u8 num_protocols;
+        u8 num_agents;
+        __le16 reserved;
+};
+
+/**
+ * scmi_base_attributes_get() - gets the implementation details
+ *      that are associated with the base protocol.
+ *
+ * @handle - SCMI entity handle
+ *
+ * Return: 0 on success, else appropriate SCMI error.
+ */
+static int scmi_base_attributes_get(const struct scmi_handle *handle)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_msg_resp_base_attributes *attr_info;
+        struct scmi_revision_info *rev = handle->version;
+
+        ret = scmi_one_xfer_init(handle, PROTOCOL_ATTRIBUTES,
+                                 SCMI_PROTOCOL_BASE, 0, sizeof(*attr_info), &t);
+        if (ret)
+                return ret;
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret) {
+                attr_info = t->rx.buf;
+                rev->num_protocols = attr_info->num_protocols;
+                rev->num_agents = attr_info->num_agents;
+        }
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+/**
+ * scmi_base_vendor_id_get() - gets vendor/subvendor identifier ASCII string.
+ *
+ * @handle - SCMI entity handle
+ * @sub_vendor - specify true if sub-vendor ID is needed
+ *
+ * Return: 0 on success, else appropriate SCMI error.
+ */
+static int
+scmi_base_vendor_id_get(const struct scmi_handle *handle, bool sub_vendor)
+{
+        u8 cmd;
+        int ret, size;
+        char *vendor_id;
+        struct scmi_xfer *t;
+        struct scmi_revision_info *rev = handle->version;
+
+        if (sub_vendor) {
+                cmd = BASE_DISCOVER_SUB_VENDOR;
+                vendor_id = rev->sub_vendor_id;
+                size = ARRAY_SIZE(rev->sub_vendor_id);
+        } else {
+                cmd = BASE_DISCOVER_VENDOR;
+                vendor_id = rev->vendor_id;
+                size = ARRAY_SIZE(rev->vendor_id);
+        }
+
+        ret = scmi_one_xfer_init(handle, cmd, SCMI_PROTOCOL_BASE, 0, size, &t);
+        if (ret)
+                return ret;
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret)
+                memcpy(vendor_id, t->rx.buf, size);
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+/**
+ * scmi_base_implementation_version_get() - gets a vendor-specific
+ *      implementation 32-bit version. The format of the version number is
+ *      vendor-specific
+ *
+ * @handle - SCMI entity handle
+ *
+ * Return: 0 on success, else appropriate SCMI error.
+ */
+static int
+scmi_base_implementation_version_get(const struct scmi_handle *handle)
+{
+        int ret;
+        __le32 *impl_ver;
+        struct scmi_xfer *t;
+        struct scmi_revision_info *rev = handle->version;
+
+        ret = scmi_one_xfer_init(handle, BASE_DISCOVER_IMPLEMENT_VERSION,
+                                 SCMI_PROTOCOL_BASE, 0, sizeof(*impl_ver), &t);
+        if (ret)
+                return ret;
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret) {
+                impl_ver = t->rx.buf;
+                rev->impl_ver = le32_to_cpu(*impl_ver);
+        }
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+/**
+ * scmi_base_implementation_list_get() - gets the list of protocols it is
+ *      OSPM is allowed to access
+ *
+ * @handle - SCMI entity handle
+ * @protocols_imp - pointer to hold the list of protocol identifiers
+ *
+ * Return: 0 on success, else appropriate SCMI error.
+ */
+static int scmi_base_implementation_list_get(const struct scmi_handle *handle,
+                                             u8 *protocols_imp)
+{
+        u8 *list;
+        int ret, loop;
+        struct scmi_xfer *t;
+        __le32 *num_skip, *num_ret;
+        u32 tot_num_ret = 0, loop_num_ret;
+        struct device *dev = handle->dev;
+
+        ret = scmi_one_xfer_init(handle, BASE_DISCOVER_LIST_PROTOCOLS,
+                                 SCMI_PROTOCOL_BASE, sizeof(*num_skip), 0, &t);
+        if (ret)
+                return ret;
+
+        num_skip = t->tx.buf;
+        num_ret = t->rx.buf;
+        list = t->rx.buf + sizeof(*num_ret);
+
+        do {
+                /* Set the number of protocols to be skipped/already read */
+                *num_skip = cpu_to_le32(tot_num_ret);
+
+                ret = scmi_do_xfer(handle, t);
+                if (ret)
+                        break;
+
+                loop_num_ret = le32_to_cpu(*num_ret);
+                if (tot_num_ret + loop_num_ret > MAX_PROTOCOLS_IMP) {
+                        dev_err(dev, "No. of Protocol > MAX_PROTOCOLS_IMP");
+                        break;
+                }
+
+                for (loop = 0; loop < loop_num_ret; loop++)
+                        protocols_imp[tot_num_ret + loop] = *(list + loop);
+
+                tot_num_ret += loop_num_ret;
+        } while (loop_num_ret);
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+/**
+ * scmi_base_discover_agent_get() - discover the name of an agent
+ *
+ * @handle - SCMI entity handle
+ * @id - Agent identifier
+ * @name - Agent identifier ASCII string
+ *
+ * An agent id of 0 is reserved to identify the platform itself.
+ * Generally operating system is represented as "OSPM"
+ *
+ * Return: 0 on success, else appropriate SCMI error.
+ */
+static int scmi_base_discover_agent_get(const struct scmi_handle *handle,
+                                        int id, char *name)
+{
+        int ret;
+        struct scmi_xfer *t;
+
+        ret = scmi_one_xfer_init(handle, BASE_DISCOVER_AGENT,
+                                 SCMI_PROTOCOL_BASE, sizeof(__le32),
+                                 SCMI_MAX_STR_SIZE, &t);
+        if (ret)
+                return ret;
+
+        *(__le32 *)t->tx.buf = cpu_to_le32(id);
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret)
+                memcpy(name, t->rx.buf, SCMI_MAX_STR_SIZE);
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+int scmi_base_protocol_init(struct scmi_handle *h)
+{
+        int id, ret;
+        u8 *prot_imp;
+        u32 version;
+        char name[SCMI_MAX_STR_SIZE];
+        const struct scmi_handle *handle = h;
+        struct device *dev = handle->dev;
+        struct scmi_revision_info *rev = handle->version;
+
+        ret = scmi_version_get(handle, SCMI_PROTOCOL_BASE, &version);
+        if (ret)
+                return ret;
+
+        prot_imp = devm_kcalloc(dev, MAX_PROTOCOLS_IMP, sizeof(u8), GFP_KERNEL);
+        if (!prot_imp)
+                return -ENOMEM;
+
+        rev->major_ver = PROTOCOL_REV_MAJOR(version),
+        rev->minor_ver = PROTOCOL_REV_MINOR(version);
+
+        scmi_base_attributes_get(handle);
+        scmi_base_vendor_id_get(handle, false);
+        scmi_base_vendor_id_get(handle, true);
+        scmi_base_implementation_version_get(handle);
+        scmi_base_implementation_list_get(handle, prot_imp);
+        scmi_setup_protocol_implemented(handle, prot_imp);
+
+        dev_info(dev, "SCMI Protocol v%d.%d '%s:%s' Firmware version 0x%x\n",
+                 rev->major_ver, rev->minor_ver, rev->vendor_id,
+                 rev->sub_vendor_id, rev->impl_ver);
+        dev_dbg(dev, "Found %d protocol(s) %d agent(s)\n", rev->num_protocols,
+                rev->num_agents);
+
+        for (id = 0; id < rev->num_agents; id++) {
+                scmi_base_discover_agent_get(handle, id, name);
+                dev_dbg(dev, "Agent %d: %s\n", id, name);
+        }
+
+        return 0;
+}
diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
new file mode 100644
index 000000000000..f2760a596c28
--- /dev/null
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Message Protocol bus layer
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+
+#include "common.h"
+
+static DEFINE_IDA(scmi_bus_id);
+static DEFINE_IDR(scmi_protocols);
+static DEFINE_SPINLOCK(protocol_lock);
+
+static const struct scmi_device_id *
+scmi_dev_match_id(struct scmi_device *scmi_dev, struct scmi_driver *scmi_drv)
+{
+        const struct scmi_device_id *id = scmi_drv->id_table;
+
+        if (!id)
+                return NULL;
+
+        for (; id->protocol_id; id++)
+                if (id->protocol_id == scmi_dev->protocol_id)
+                        return id;
+
+        return NULL;
+}
+
+static int scmi_dev_match(struct device *dev, struct device_driver *drv)
+{
+        struct scmi_driver *scmi_drv = to_scmi_driver(drv);
+        struct scmi_device *scmi_dev = to_scmi_dev(dev);
+        const struct scmi_device_id *id;
+
+        id = scmi_dev_match_id(scmi_dev, scmi_drv);
+        if (id)
+                return 1;
+
+        return 0;
+}
+
+static int scmi_protocol_init(int protocol_id, struct scmi_handle *handle)
+{
+        scmi_prot_init_fn_t fn = idr_find(&scmi_protocols, protocol_id);
+
+        if (unlikely(!fn))
+                return -EINVAL;
+        return fn(handle);
+}
+
+static int scmi_dev_probe(struct device *dev)
+{
+        struct scmi_driver *scmi_drv = to_scmi_driver(dev->driver);
+        struct scmi_device *scmi_dev = to_scmi_dev(dev);
+        const struct scmi_device_id *id;
+        int ret;
+
+        id = scmi_dev_match_id(scmi_dev, scmi_drv);
+        if (!id)
+                return -ENODEV;
+
+        if (!scmi_dev->handle)
+                return -EPROBE_DEFER;
+
+        ret = scmi_protocol_init(scmi_dev->protocol_id, scmi_dev->handle);
+        if (ret)
+                return ret;
+
+        return scmi_drv->probe(scmi_dev);
+}
+
+static int scmi_dev_remove(struct device *dev)
+{
+        struct scmi_driver *scmi_drv = to_scmi_driver(dev->driver);
+        struct scmi_device *scmi_dev = to_scmi_dev(dev);
+
+        if (scmi_drv->remove)
+                scmi_drv->remove(scmi_dev);
+
+        return 0;
+}
+
+static struct bus_type scmi_bus_type = {
+        .name = "scmi_protocol",
+        .match = scmi_dev_match,
+        .probe = scmi_dev_probe,
+        .remove = scmi_dev_remove,
+};
+
+int scmi_driver_register(struct scmi_driver *driver, struct module *owner,
+                         const char *mod_name)
+{
+        int retval;
+
+        driver->driver.bus = &scmi_bus_type;
+        driver->driver.name = driver->name;
+        driver->driver.owner = owner;
+        driver->driver.mod_name = mod_name;
+
+        retval = driver_register(&driver->driver);
+        if (!retval)
+                pr_debug("registered new scmi driver %s\n", driver->name);
+
+        return retval;
+}
+EXPORT_SYMBOL_GPL(scmi_driver_register);
+
+void scmi_driver_unregister(struct scmi_driver *driver)
+{
+        driver_unregister(&driver->driver);
+}
+EXPORT_SYMBOL_GPL(scmi_driver_unregister);
+
+struct scmi_device *
+scmi_device_create(struct device_node *np, struct device *parent, int protocol)
+{
+        int id, retval;
+        struct scmi_device *scmi_dev;
+
+        id = ida_simple_get(&scmi_bus_id, 1, 0, GFP_KERNEL);
+        if (id < 0)
+                return NULL;
+
+        scmi_dev = kzalloc(sizeof(*scmi_dev), GFP_KERNEL);
+        if (!scmi_dev)
+                goto no_mem;
+
+        scmi_dev->id = id;
+        scmi_dev->protocol_id = protocol;
+        scmi_dev->dev.parent = parent;
+        scmi_dev->dev.of_node = np;
+        scmi_dev->dev.bus = &scmi_bus_type;
+        dev_set_name(&scmi_dev->dev, "scmi_dev.%d", id);
+
+        retval = device_register(&scmi_dev->dev);
+        if (!retval)
+                return scmi_dev;
+
+        put_device(&scmi_dev->dev);
+        kfree(scmi_dev);
+no_mem:
+        ida_simple_remove(&scmi_bus_id, id);
+        return NULL;
+}
+
+void scmi_device_destroy(struct scmi_device *scmi_dev)
+{
+        scmi_handle_put(scmi_dev->handle);
+        device_unregister(&scmi_dev->dev);
+        ida_simple_remove(&scmi_bus_id, scmi_dev->id);
+        kfree(scmi_dev);
+}
+
+void scmi_set_handle(struct scmi_device *scmi_dev)
+{
+        scmi_dev->handle = scmi_handle_get(&scmi_dev->dev);
+}
+
+int scmi_protocol_register(int protocol_id, scmi_prot_init_fn_t fn)
+{
+        int ret;
+
+        spin_lock(&protocol_lock);
+        ret = idr_alloc(&scmi_protocols, fn, protocol_id, protocol_id + 1,
+                        GFP_ATOMIC);
+        if (ret != protocol_id)
+                pr_err("unable to allocate SCMI idr slot, err %d\n", ret);
+        spin_unlock(&protocol_lock);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(scmi_protocol_register);
+
+void scmi_protocol_unregister(int protocol_id)
+{
+        spin_lock(&protocol_lock);
+        idr_remove(&scmi_protocols, protocol_id);
+        spin_unlock(&protocol_lock);
+}
+EXPORT_SYMBOL_GPL(scmi_protocol_unregister);
+
+static int __scmi_devices_unregister(struct device *dev, void *data)
+{
+        struct scmi_device *scmi_dev = to_scmi_dev(dev);
+
+        scmi_device_destroy(scmi_dev);
+        return 0;
+}
+
+static void scmi_devices_unregister(void)
+{
+        bus_for_each_dev(&scmi_bus_type, NULL, NULL, __scmi_devices_unregister);
+}
+
+static int __init scmi_bus_init(void)
+{
+        int retval;
+
+        retval = bus_register(&scmi_bus_type);
+        if (retval)
+                pr_err("scmi protocol bus register failed (%d)\n", retval);
+
+        return retval;
+}
+subsys_initcall(scmi_bus_init);
+
+static void __exit scmi_bus_exit(void)
+{
+        scmi_devices_unregister();
+        bus_unregister(&scmi_bus_type);
+        ida_destroy(&scmi_bus_id);
+}
+module_exit(scmi_bus_exit);
diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
new file mode 100644
index 000000000000..e8ffad33a0ff
--- /dev/null
+++ b/drivers/firmware/arm_scmi/clock.c
@@ -0,0 +1,342 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Clock Protocol
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ */
+
+#include "common.h"
+
+enum scmi_clock_protocol_cmd {
+        CLOCK_ATTRIBUTES = 0x3,
+        CLOCK_DESCRIBE_RATES = 0x4,
+        CLOCK_RATE_SET = 0x5,
+        CLOCK_RATE_GET = 0x6,
+        CLOCK_CONFIG_SET = 0x7,
+};
+
+struct scmi_msg_resp_clock_protocol_attributes {
+        __le16 num_clocks;
+        u8 max_async_req;
+        u8 reserved;
+};
+
+struct scmi_msg_resp_clock_attributes {
+        __le32 attributes;
+#define CLOCK_ENABLE    BIT(0)
+            u8 name[SCMI_MAX_STR_SIZE];
+};
+
+struct scmi_clock_set_config {
+        __le32 id;
+        __le32 attributes;
+};
+
+struct scmi_msg_clock_describe_rates {
+        __le32 id;
+        __le32 rate_index;
+};
+
+struct scmi_msg_resp_clock_describe_rates {
+        __le32 num_rates_flags;
+#define NUM_RETURNED(x)         ((x) & 0xfff)
+#define RATE_DISCRETE(x)        !((x) & BIT(12))
+#define NUM_REMAINING(x)        ((x) >> 16)
+        struct {
+                __le32 value_low;
+                __le32 value_high;
+        } rate[0];
+#define RATE_TO_U64(X)          \
+({                              \
+        typeof(X) x = (X);      \
+        le32_to_cpu((x).value_low) | (u64)le32_to_cpu((x).value_high) << 32; \
+})
+};
+
+struct scmi_clock_set_rate {
+        __le32 flags;
+#define CLOCK_SET_ASYNC         BIT(0)
+#define CLOCK_SET_DELAYED       BIT(1)
+#define CLOCK_SET_ROUND_UP      BIT(2)
+#define CLOCK_SET_ROUND_AUTO    BIT(3)
+        __le32 id;
+        __le32 value_low;
+        __le32 value_high;
+};
+
+struct clock_info {
+        int num_clocks;
+        int max_async_req;
+        struct scmi_clock_info *clk;
+};
+
+static int scmi_clock_protocol_attributes_get(const struct scmi_handle *handle,
+                                              struct clock_info *ci)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_msg_resp_clock_protocol_attributes *attr;
+
+        ret = scmi_one_xfer_init(handle, PROTOCOL_ATTRIBUTES,
+                                 SCMI_PROTOCOL_CLOCK, 0, sizeof(*attr), &t);
+        if (ret)
+                return ret;
+
+        attr = t->rx.buf;
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret) {
+                ci->num_clocks = le16_to_cpu(attr->num_clocks);
+                ci->max_async_req = attr->max_async_req;
+        }
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int scmi_clock_attributes_get(const struct scmi_handle *handle,
+                                     u32 clk_id, struct scmi_clock_info *clk)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_msg_resp_clock_attributes *attr;
+
+        ret = scmi_one_xfer_init(handle, CLOCK_ATTRIBUTES, SCMI_PROTOCOL_CLOCK,
+                                 sizeof(clk_id), sizeof(*attr), &t);
+        if (ret)
+                return ret;
+
+        *(__le32 *)t->tx.buf = cpu_to_le32(clk_id);
+        attr = t->rx.buf;
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret)
+                memcpy(clk->name, attr->name, SCMI_MAX_STR_SIZE);
+        else
+                clk->name[0] = '\0';
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int
+scmi_clock_describe_rates_get(const struct scmi_handle *handle, u32 clk_id,
+                              struct scmi_clock_info *clk)
+{
+        u64 *rate;
+        int ret, cnt;
+        bool rate_discrete;
+        u32 tot_rate_cnt = 0, rates_flag;
+        u16 num_returned, num_remaining;
+        struct scmi_xfer *t;
+        struct scmi_msg_clock_describe_rates *clk_desc;
+        struct scmi_msg_resp_clock_describe_rates *rlist;
+
+        ret = scmi_one_xfer_init(handle, CLOCK_DESCRIBE_RATES,
+                                 SCMI_PROTOCOL_CLOCK, sizeof(*clk_desc), 0, &t);
+        if (ret)
+                return ret;
+
+        clk_desc = t->tx.buf;
+        rlist = t->rx.buf;
+
+        do {
+                clk_desc->id = cpu_to_le32(clk_id);
+                /* Set the number of rates to be skipped/already read */
+                clk_desc->rate_index = cpu_to_le32(tot_rate_cnt);
+
+                ret = scmi_do_xfer(handle, t);
+                if (ret)
+                        break;
+
+                rates_flag = le32_to_cpu(rlist->num_rates_flags);
+                num_remaining = NUM_REMAINING(rates_flag);
+                rate_discrete = RATE_DISCRETE(rates_flag);
+                num_returned = NUM_RETURNED(rates_flag);
+
+                if (tot_rate_cnt + num_returned > SCMI_MAX_NUM_RATES) {
+                        dev_err(handle->dev, "No. of rates > MAX_NUM_RATES");
+                        break;
+                }
+
+                if (!rate_discrete) {
+                        clk->range.min_rate = RATE_TO_U64(rlist->rate[0]);
+                        clk->range.max_rate = RATE_TO_U64(rlist->rate[1]);
+                        clk->range.step_size = RATE_TO_U64(rlist->rate[2]);
+                        dev_dbg(handle->dev, "Min %llu Max %llu Step %llu Hz\n",
+                                clk->range.min_rate, clk->range.max_rate,
+                                clk->range.step_size);
+                        break;
+                }
+
+                rate = &clk->list.rates[tot_rate_cnt];
+                for (cnt = 0; cnt < num_returned; cnt++, rate++) {
+                        *rate = RATE_TO_U64(rlist->rate[cnt]);
+                        dev_dbg(handle->dev, "Rate %llu Hz\n", *rate);
+                }
+
+                tot_rate_cnt += num_returned;
+                /*
+                 * check for both returned and remaining to avoid infinite
+                 * loop due to buggy firmware
+                 */
+        } while (num_returned && num_remaining);
+
+        if (rate_discrete)
+                clk->list.num_rates = tot_rate_cnt;
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int
+scmi_clock_rate_get(const struct scmi_handle *handle, u32 clk_id, u64 *value)
+{
+        int ret;
+        struct scmi_xfer *t;
+
+        ret = scmi_one_xfer_init(handle, CLOCK_RATE_GET, SCMI_PROTOCOL_CLOCK,
+                                 sizeof(__le32), sizeof(u64), &t);
+        if (ret)
+                return ret;
+
+        *(__le32 *)t->tx.buf = cpu_to_le32(clk_id);
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret) {
+                __le32 *pval = t->rx.buf;
+
+                *value = le32_to_cpu(*pval);
+                *value |= (u64)le32_to_cpu(*(pval + 1)) << 32;
+        }
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int scmi_clock_rate_set(const struct scmi_handle *handle, u32 clk_id,
+                               u32 config, u64 rate)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_clock_set_rate *cfg;
+
+        ret = scmi_one_xfer_init(handle, CLOCK_RATE_SET, SCMI_PROTOCOL_CLOCK,
+                                 sizeof(*cfg), 0, &t);
+        if (ret)
+                return ret;
+
+        cfg = t->tx.buf;
+        cfg->flags = cpu_to_le32(config);
+        cfg->id = cpu_to_le32(clk_id);
+        cfg->value_low = cpu_to_le32(rate & 0xffffffff);
+        cfg->value_high = cpu_to_le32(rate >> 32);
+
+        ret = scmi_do_xfer(handle, t);
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int
+scmi_clock_config_set(const struct scmi_handle *handle, u32 clk_id, u32 config)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_clock_set_config *cfg;
+
+        ret = scmi_one_xfer_init(handle, CLOCK_CONFIG_SET, SCMI_PROTOCOL_CLOCK,
+                                 sizeof(*cfg), 0, &t);
+        if (ret)
+                return ret;
+
+        cfg = t->tx.buf;
+        cfg->id = cpu_to_le32(clk_id);
+        cfg->attributes = cpu_to_le32(config);
+
+        ret = scmi_do_xfer(handle, t);
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int scmi_clock_enable(const struct scmi_handle *handle, u32 clk_id)
+{
+        return scmi_clock_config_set(handle, clk_id, CLOCK_ENABLE);
+}
+
+static int scmi_clock_disable(const struct scmi_handle *handle, u32 clk_id)
+{
+        return scmi_clock_config_set(handle, clk_id, 0);
+}
+
+static int scmi_clock_count_get(const struct scmi_handle *handle)
+{
+        struct clock_info *ci = handle->clk_priv;
+
+        return ci->num_clocks;
+}
+
+static const struct scmi_clock_info *
+scmi_clock_info_get(const struct scmi_handle *handle, u32 clk_id)
+{
+        struct clock_info *ci = handle->clk_priv;
+        struct scmi_clock_info *clk = ci->clk + clk_id;
+
+        if (!clk->name || !clk->name[0])
+                return NULL;
+
+        return clk;
+}
+
+static struct scmi_clk_ops clk_ops = {
+        .count_get = scmi_clock_count_get,
+        .info_get = scmi_clock_info_get,
+        .rate_get = scmi_clock_rate_get,
+        .rate_set = scmi_clock_rate_set,
+        .enable = scmi_clock_enable,
+        .disable = scmi_clock_disable,
+};
+
+static int scmi_clock_protocol_init(struct scmi_handle *handle)
+{
+        u32 version;
+        int clkid, ret;
+        struct clock_info *cinfo;
+
+        scmi_version_get(handle, SCMI_PROTOCOL_CLOCK, &version);
+
+        dev_dbg(handle->dev, "Clock Version %d.%d\n",
+                PROTOCOL_REV_MAJOR(version), PROTOCOL_REV_MINOR(version));
+
+        cinfo = devm_kzalloc(handle->dev, sizeof(*cinfo), GFP_KERNEL);
+        if (!cinfo)
+                return -ENOMEM;
+
+        scmi_clock_protocol_attributes_get(handle, cinfo);
+
+        cinfo->clk = devm_kcalloc(handle->dev, cinfo->num_clocks,
+                                  sizeof(*cinfo->clk), GFP_KERNEL);
+        if (!cinfo->clk)
+                return -ENOMEM;
+
+        for (clkid = 0; clkid < cinfo->num_clocks; clkid++) {
+                struct scmi_clock_info *clk = cinfo->clk + clkid;
+
+                ret = scmi_clock_attributes_get(handle, clkid, clk);
+                if (!ret)
+                        scmi_clock_describe_rates_get(handle, clkid, clk);
+        }
+
+        handle->clk_ops = &clk_ops;
+        handle->clk_priv = cinfo;
+
+        return 0;
+}
+
+static int __init scmi_clock_init(void)
+{
+        return scmi_protocol_register(SCMI_PROTOCOL_CLOCK,
+                                      &scmi_clock_protocol_init);
+}
+subsys_initcall(scmi_clock_init);
diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
new file mode 100644
index 000000000000..0c30234f9098
--- /dev/null
+++ b/drivers/firmware/arm_scmi/common.h
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Message Protocol
+ * driver common header file containing some definitions, structures
+ * and function prototypes used in all the different SCMI protocols.
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ */
+
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/scmi_protocol.h>
+#include <linux/types.h>
+
+#define PROTOCOL_REV_MINOR_BITS 16
+#define PROTOCOL_REV_MINOR_MASK ((1U << PROTOCOL_REV_MINOR_BITS) - 1)
+#define PROTOCOL_REV_MAJOR(x)   ((x) >> PROTOCOL_REV_MINOR_BITS)
+#define PROTOCOL_REV_MINOR(x)   ((x) & PROTOCOL_REV_MINOR_MASK)
+#define MAX_PROTOCOLS_IMP       16
+#define MAX_OPPS                16
+
+enum scmi_common_cmd {
+        PROTOCOL_VERSION = 0x0,
+        PROTOCOL_ATTRIBUTES = 0x1,
+        PROTOCOL_MESSAGE_ATTRIBUTES = 0x2,
+};
+
+/**
+ * struct scmi_msg_resp_prot_version - Response for a message
+ *
+ * @major_version: Major version of the ABI that firmware supports
+ * @minor_version: Minor version of the ABI that firmware supports
+ *
+ * In general, ABI version changes follow the rule that minor version increments
+ * are backward compatible. Major revision changes in ABI may not be
+ * backward compatible.
+ *
+ * Response to a generic message with message type SCMI_MSG_VERSION
+ */
+struct scmi_msg_resp_prot_version {
+        __le16 minor_version;
+        __le16 major_version;
+};
+
+/**
+ * struct scmi_msg_hdr - Message(Tx/Rx) header
+ *
+ * @id: The identifier of the command being sent
+ * @protocol_id: The identifier of the protocol used to send @id command
+ * @seq: The token to identify the message. when a message/command returns,
+ *       the platform returns the whole message header unmodified including
+ *       the token.
+ */
+struct scmi_msg_hdr {
+        u8 id;
+        u8 protocol_id;
+        u16 seq;
+        u32 status;
+        bool poll_completion;
+};
+
+/**
+ * struct scmi_msg - Message(Tx/Rx) structure
+ *
+ * @buf: Buffer pointer
+ * @len: Length of data in the Buffer
+ */
+struct scmi_msg {
+        void *buf;
+        size_t len;
+};
+
+/**
+ * struct scmi_xfer - Structure representing a message flow
+ *
+ * @hdr: Transmit message header
+ * @tx: Transmit message
+ * @rx: Receive message, the buffer should be pre-allocated to store
+ *      message. If request-ACK protocol is used, we can reuse the same
+ *      buffer for the rx path as we use for the tx path.
+ * @done: completion event
+ */
+
+struct scmi_xfer {
+        void *con_priv;
+        struct scmi_msg_hdr hdr;
+        struct scmi_msg tx;
+        struct scmi_msg rx;
+        struct completion done;
+};
+
+void scmi_one_xfer_put(const struct scmi_handle *h, struct scmi_xfer *xfer);
+int scmi_do_xfer(const struct scmi_handle *h, struct scmi_xfer *xfer);
+int scmi_one_xfer_init(const struct scmi_handle *h, u8 msg_id, u8 prot_id,
+                       size_t tx_size, size_t rx_size, struct scmi_xfer **p);
+int scmi_handle_put(const struct scmi_handle *handle);
+struct scmi_handle *scmi_handle_get(struct device *dev);
+void scmi_set_handle(struct scmi_device *scmi_dev);
+int scmi_version_get(const struct scmi_handle *h, u8 protocol, u32 *version);
+void scmi_setup_protocol_implemented(const struct scmi_handle *handle,
+                                     u8 *prot_imp);
+
+int scmi_base_protocol_init(struct scmi_handle *h);
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
new file mode 100644
index 000000000000..14b147135a0c
--- /dev/null
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -0,0 +1,871 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Message Protocol driver
+ *
+ * SCMI Message Protocol is used between the System Control Processor(SCP)
+ * and the Application Processors(AP). The Message Handling Unit(MHU)
+ * provides a mechanism for inter-processor communication between SCP's
+ * Cortex M3 and AP.
+ *
+ * SCP offers control and management of the core/cluster power states,
+ * various power domain DVFS including the core/cluster, certain system
+ * clocks configuration, thermal sensors and many others.
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ */
+
+#include <linux/bitmap.h>
+#include <linux/export.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/ktime.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/processor.h>
+#include <linux/semaphore.h>
+#include <linux/slab.h>
+
+#include "common.h"
+
+#define MSG_ID_SHIFT            0
+#define MSG_ID_MASK             0xff
+#define MSG_TYPE_SHIFT          8
+#define MSG_TYPE_MASK           0x3
+#define MSG_PROTOCOL_ID_SHIFT   10
+#define MSG_PROTOCOL_ID_MASK    0xff
+#define MSG_TOKEN_ID_SHIFT      18
+#define MSG_TOKEN_ID_MASK       0x3ff
+#define MSG_XTRACT_TOKEN(header)        \
+        (((header) >> MSG_TOKEN_ID_SHIFT) & MSG_TOKEN_ID_MASK)
+
+enum scmi_error_codes {
+        SCMI_SUCCESS = 0,       /* Success */
+        SCMI_ERR_SUPPORT = -1,  /* Not supported */
+        SCMI_ERR_PARAMS = -2,   /* Invalid Parameters */
+        SCMI_ERR_ACCESS = -3,   /* Invalid access/permission denied */
+        SCMI_ERR_ENTRY = -4,    /* Not found */
+        SCMI_ERR_RANGE = -5,    /* Value out of range */
+        SCMI_ERR_BUSY = -6,     /* Device busy */
+        SCMI_ERR_COMMS = -7,    /* Communication Error */
+        SCMI_ERR_GENERIC = -8,  /* Generic Error */
+        SCMI_ERR_HARDWARE = -9, /* Hardware Error */
+        SCMI_ERR_PROTOCOL = -10,/* Protocol Error */
+        SCMI_ERR_MAX
+};
+
+/* List of all  SCMI devices active in system */
+static LIST_HEAD(scmi_list);
+/* Protection for the entire list */
+static DEFINE_MUTEX(scmi_list_mutex);
+
+/**
+ * struct scmi_xfers_info - Structure to manage transfer information
+ *
+ * @xfer_block: Preallocated Message array
+ * @xfer_alloc_table: Bitmap table for allocated messages.
+ *      Index of this bitmap table is also used for message
+ *      sequence identifier.
+ * @xfer_lock: Protection for message allocation
+ */
+struct scmi_xfers_info {
+        struct scmi_xfer *xfer_block;
+        unsigned long *xfer_alloc_table;
+        /* protect transfer allocation */
+        spinlock_t xfer_lock;
+};
+
+/**
+ * struct scmi_desc - Description of SoC integration
+ *
+ * @max_rx_timeout_ms: Timeout for communication with SoC (in Milliseconds)
+ * @max_msg: Maximum number of messages that can be pending
+ *      simultaneously in the system
+ * @max_msg_size: Maximum size of data per message that can be handled.
+ */
+struct scmi_desc {
+        int max_rx_timeout_ms;
+        int max_msg;
+        int max_msg_size;
+};
+
+/**
+ * struct scmi_chan_info - Structure representing a SCMI channel informfation
+ *
+ * @cl: Mailbox Client
+ * @chan: Transmit/Receive mailbox channel
+ * @payload: Transmit/Receive mailbox channel payload area
+ * @dev: Reference to device in the SCMI hierarchy corresponding to this
+ *       channel
+ */
+struct scmi_chan_info {
+        struct mbox_client cl;
+        struct mbox_chan *chan;
+        void __iomem *payload;
+        struct device *dev;
+        struct scmi_handle *handle;
+};
+
+/**
+ * struct scmi_info - Structure representing a  SCMI instance
+ *
+ * @dev: Device pointer
+ * @desc: SoC description for this instance
+ * @handle: Instance of SCMI handle to send to clients
+ * @version: SCMI revision information containing protocol version,
+ *      implementation version and (sub-)vendor identification.
+ * @minfo: Message info
+ * @tx_idr: IDR object to map protocol id to channel info pointer
+ * @protocols_imp: list of protocols implemented, currently maximum of
+ *      MAX_PROTOCOLS_IMP elements allocated by the base protocol
+ * @node: list head
+ * @users: Number of users of this instance
+ */
+struct scmi_info {
+        struct device *dev;
+        const struct scmi_desc *desc;
+        struct scmi_revision_info version;
+        struct scmi_handle handle;
+        struct scmi_xfers_info minfo;
+        struct idr tx_idr;
+        u8 *protocols_imp;
+        struct list_head node;
+        int users;
+};
+
+#define client_to_scmi_chan_info(c) container_of(c, struct scmi_chan_info, cl)
+#define handle_to_scmi_info(h)  container_of(h, struct scmi_info, handle)
+
+/*
+ * SCMI specification requires all parameters, message headers, return
+ * arguments or any protocol data to be expressed in little endian
+ * format only.
+ */
+struct scmi_shared_mem {
+        __le32 reserved;
+        __le32 channel_status;
+#define SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR      BIT(1)
+#define SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE       BIT(0)
+        __le32 reserved1[2];
+        __le32 flags;
+#define SCMI_SHMEM_FLAG_INTR_ENABLED    BIT(0)
+        __le32 length;
+        __le32 msg_header;
+        u8 msg_payload[0];
+};
+
+static const int scmi_linux_errmap[] = {
+        /* better than switch case as long as return value is continuous */
+        0,                      /* SCMI_SUCCESS */
+        -EOPNOTSUPP,            /* SCMI_ERR_SUPPORT */
+        -EINVAL,                /* SCMI_ERR_PARAM */
+        -EACCES,                /* SCMI_ERR_ACCESS */
+        -ENOENT,                /* SCMI_ERR_ENTRY */
+        -ERANGE,                /* SCMI_ERR_RANGE */
+        -EBUSY,                 /* SCMI_ERR_BUSY */
+        -ECOMM,                 /* SCMI_ERR_COMMS */
+        -EIO,                   /* SCMI_ERR_GENERIC */
+        -EREMOTEIO,             /* SCMI_ERR_HARDWARE */
+        -EPROTO,                /* SCMI_ERR_PROTOCOL */
+};
+
+static inline int scmi_to_linux_errno(int errno)
+{
+        if (errno < SCMI_SUCCESS && errno > SCMI_ERR_MAX)
+                return scmi_linux_errmap[-errno];
+        return -EIO;
+}
+
+/**
+ * scmi_dump_header_dbg() - Helper to dump a message header.
+ *
+ * @dev: Device pointer corresponding to the SCMI entity
+ * @hdr: pointer to header.
+ */
+static inline void scmi_dump_header_dbg(struct device *dev,
+                                        struct scmi_msg_hdr *hdr)
+{
+        dev_dbg(dev, "Command ID: %x Sequence ID: %x Protocol: %x\n",
+                hdr->id, hdr->seq, hdr->protocol_id);
+}
+
+static void scmi_fetch_response(struct scmi_xfer *xfer,
+                                struct scmi_shared_mem __iomem *mem)
+{
+        xfer->hdr.status = ioread32(mem->msg_payload);
+        /* Skip the length of header and statues in payload area i.e 8 bytes*/
+        xfer->rx.len = min_t(size_t, xfer->rx.len, ioread32(&mem->length) - 8);
+
+        /* Take a copy to the rx buffer.. */
+        memcpy_fromio(xfer->rx.buf, mem->msg_payload + 4, xfer->rx.len);
+}
+
+/**
+ * scmi_rx_callback() - mailbox client callback for receive messages
+ *
+ * @cl: client pointer
+ * @m: mailbox message
+ *
+ * Processes one received message to appropriate transfer information and
+ * signals completion of the transfer.
+ *
+ * NOTE: This function will be invoked in IRQ context, hence should be
+ * as optimal as possible.
+ */
+static void scmi_rx_callback(struct mbox_client *cl, void *m)
+{
+        u16 xfer_id;
+        struct scmi_xfer *xfer;
+        struct scmi_chan_info *cinfo = client_to_scmi_chan_info(cl);
+        struct device *dev = cinfo->dev;
+        struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
+        struct scmi_xfers_info *minfo = &info->minfo;
+        struct scmi_shared_mem __iomem *mem = cinfo->payload;
+
+        xfer_id = MSG_XTRACT_TOKEN(ioread32(&mem->msg_header));
+
+        /*
+         * Are we even expecting this?
+         */
+        if (!test_bit(xfer_id, minfo->xfer_alloc_table)) {
+                dev_err(dev, "message for %d is not expected!\n", xfer_id);
+                return;
+        }
+
+        xfer = &minfo->xfer_block[xfer_id];
+
+        scmi_dump_header_dbg(dev, &xfer->hdr);
+        /* Is the message of valid length? */
+        if (xfer->rx.len > info->desc->max_msg_size) {
+                dev_err(dev, "unable to handle %zu xfer(max %d)\n",
+                        xfer->rx.len, info->desc->max_msg_size);
+                return;
+        }
+
+        scmi_fetch_response(xfer, mem);
+        complete(&xfer->done);
+}
+
+/**
+ * pack_scmi_header() - packs and returns 32-bit header
+ *
+ * @hdr: pointer to header containing all the information on message id,
+ *      protocol id and sequence id.
+ */
+static inline u32 pack_scmi_header(struct scmi_msg_hdr *hdr)
+{
+        return ((hdr->id & MSG_ID_MASK) << MSG_ID_SHIFT) |
+           ((hdr->seq & MSG_TOKEN_ID_MASK) << MSG_TOKEN_ID_SHIFT) |
+           ((hdr->protocol_id & MSG_PROTOCOL_ID_MASK) << MSG_PROTOCOL_ID_SHIFT);
+}
+
+/**
+ * scmi_tx_prepare() - mailbox client callback to prepare for the transfer
+ *
+ * @cl: client pointer
+ * @m: mailbox message
+ *
+ * This function prepares the shared memory which contains the header and the
+ * payload.
+ */
+static void scmi_tx_prepare(struct mbox_client *cl, void *m)
+{
+        struct scmi_xfer *t = m;
+        struct scmi_chan_info *cinfo = client_to_scmi_chan_info(cl);
+        struct scmi_shared_mem __iomem *mem = cinfo->payload;
+
+        /* Mark channel busy + clear error */
+        iowrite32(0x0, &mem->channel_status);
+        iowrite32(t->hdr.poll_completion ? 0 : SCMI_SHMEM_FLAG_INTR_ENABLED,
+                  &mem->flags);
+        iowrite32(sizeof(mem->msg_header) + t->tx.len, &mem->length);
+        iowrite32(pack_scmi_header(&t->hdr), &mem->msg_header);
+        if (t->tx.buf)
+                memcpy_toio(mem->msg_payload, t->tx.buf, t->tx.len);
+}
+
+/**
+ * scmi_one_xfer_get() - Allocate one message
+ *
+ * @handle: SCMI entity handle
+ *
+ * Helper function which is used by various command functions that are
+ * exposed to clients of this driver for allocating a message traffic event.
+ *
+ * This function can sleep depending on pending requests already in the system
+ * for the SCMI entity. Further, this also holds a spinlock to maintain
+ * integrity of internal data structures.
+ *
+ * Return: 0 if all went fine, else corresponding error.
+ */
+static struct scmi_xfer *scmi_one_xfer_get(const struct scmi_handle *handle)
+{
+        u16 xfer_id;
+        struct scmi_xfer *xfer;
+        unsigned long flags, bit_pos;
+        struct scmi_info *info = handle_to_scmi_info(handle);
+        struct scmi_xfers_info *minfo = &info->minfo;
+
+        /* Keep the locked section as small as possible */
+        spin_lock_irqsave(&minfo->xfer_lock, flags);
+        bit_pos = find_first_zero_bit(minfo->xfer_alloc_table,
+                                      info->desc->max_msg);
+        if (bit_pos == info->desc->max_msg) {
+                spin_unlock_irqrestore(&minfo->xfer_lock, flags);
+                return ERR_PTR(-ENOMEM);
+        }
+        set_bit(bit_pos, minfo->xfer_alloc_table);
+        spin_unlock_irqrestore(&minfo->xfer_lock, flags);
+
+        xfer_id = bit_pos;
+
+        xfer = &minfo->xfer_block[xfer_id];
+        xfer->hdr.seq = xfer_id;
+        reinit_completion(&xfer->done);
+
+        return xfer;
+}
+
+/**
+ * scmi_one_xfer_put() - Release a message
+ *
+ * @minfo: transfer info pointer
+ * @xfer: message that was reserved by scmi_one_xfer_get
+ *
+ * This holds a spinlock to maintain integrity of internal data structures.
+ */
+void scmi_one_xfer_put(const struct scmi_handle *handle, struct scmi_xfer *xfer)
+{
+        unsigned long flags;
+        struct scmi_info *info = handle_to_scmi_info(handle);
+        struct scmi_xfers_info *minfo = &info->minfo;
+
+        /*
+         * Keep the locked section as small as possible
+         * NOTE: we might escape with smp_mb and no lock here..
+         * but just be conservative and symmetric.
+         */
+        spin_lock_irqsave(&minfo->xfer_lock, flags);
+        clear_bit(xfer->hdr.seq, minfo->xfer_alloc_table);
+        spin_unlock_irqrestore(&minfo->xfer_lock, flags);
+}
+
+static bool
+scmi_xfer_poll_done(const struct scmi_chan_info *cinfo, struct scmi_xfer *xfer)
+{
+        struct scmi_shared_mem __iomem *mem = cinfo->payload;
+        u16 xfer_id = MSG_XTRACT_TOKEN(ioread32(&mem->msg_header));
+
+        if (xfer->hdr.seq != xfer_id)
+                return false;
+
+        return ioread32(&mem->channel_status) &
+                (SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR |
+                SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE);
+}
+
+#define SCMI_MAX_POLL_TO_NS     (100 * NSEC_PER_USEC)
+
+static bool scmi_xfer_done_no_timeout(const struct scmi_chan_info *cinfo,
+                                      struct scmi_xfer *xfer, ktime_t stop)
+{
+        ktime_t __cur = ktime_get();
+
+        return scmi_xfer_poll_done(cinfo, xfer) || ktime_after(__cur, stop);
+}
+
+/**
+ * scmi_do_xfer() - Do one transfer
+ *
+ * @info: Pointer to SCMI entity information
+ * @xfer: Transfer to initiate and wait for response
+ *
+ * Return: -ETIMEDOUT in case of no response, if transmit error,
+ *   return corresponding error, else if all goes well,
+ *   return 0.
+ */
+int scmi_do_xfer(const struct scmi_handle *handle, struct scmi_xfer *xfer)
+{
+        int ret;
+        int timeout;
+        struct scmi_info *info = handle_to_scmi_info(handle);
+        struct device *dev = info->dev;
+        struct scmi_chan_info *cinfo;
+
+        cinfo = idr_find(&info->tx_idr, xfer->hdr.protocol_id);
+        if (unlikely(!cinfo))
+                return -EINVAL;
+
+        ret = mbox_send_message(cinfo->chan, xfer);
+        if (ret < 0) {
+                dev_dbg(dev, "mbox send fail %d\n", ret);
+                return ret;
+        }
+
+        /* mbox_send_message returns non-negative value on success, so reset */
+        ret = 0;
+
+        if (xfer->hdr.poll_completion) {
+                ktime_t stop = ktime_add_ns(ktime_get(), SCMI_MAX_POLL_TO_NS);
+
+                spin_until_cond(scmi_xfer_done_no_timeout(cinfo, xfer, stop));
+
+                if (ktime_before(ktime_get(), stop))
+                        scmi_fetch_response(xfer, cinfo->payload);
+                else
+                        ret = -ETIMEDOUT;
+        } else {
+                /* And we wait for the response. */
+                timeout = msecs_to_jiffies(info->desc->max_rx_timeout_ms);
+                if (!wait_for_completion_timeout(&xfer->done, timeout)) {
+                        dev_err(dev, "mbox timed out in resp(caller: %pS)\n",
+                                (void *)_RET_IP_);
+                        ret = -ETIMEDOUT;
+                }
+        }
+
+        if (!ret && xfer->hdr.status)
+                ret = scmi_to_linux_errno(xfer->hdr.status);
+
+        /*
+         * NOTE: we might prefer not to need the mailbox ticker to manage the
+         * transfer queueing since the protocol layer queues things by itself.
+         * Unfortunately, we have to kick the mailbox framework after we have
+         * received our message.
+         */
+        mbox_client_txdone(cinfo->chan, ret);
+
+        return ret;
+}
+
+/**
+ * scmi_one_xfer_init() - Allocate and initialise one message
+ *
+ * @handle: SCMI entity handle
+ * @msg_id: Message identifier
+ * @msg_prot_id: Protocol identifier for the message
+ * @tx_size: transmit message size
+ * @rx_size: receive message size
+ * @p: pointer to the allocated and initialised message
+ *
+ * This function allocates the message using @scmi_one_xfer_get and
+ * initialise the header.
+ *
+ * Return: 0 if all went fine with @p pointing to message, else
+ *      corresponding error.
+ */
+int scmi_one_xfer_init(const struct scmi_handle *handle, u8 msg_id, u8 prot_id,
+                       size_t tx_size, size_t rx_size, struct scmi_xfer **p)
+{
+        int ret;
+        struct scmi_xfer *xfer;
+        struct scmi_info *info = handle_to_scmi_info(handle);
+        struct device *dev = info->dev;
+
+        /* Ensure we have sane transfer sizes */
+        if (rx_size > info->desc->max_msg_size ||
+            tx_size > info->desc->max_msg_size)
+                return -ERANGE;
+
+        xfer = scmi_one_xfer_get(handle);
+        if (IS_ERR(xfer)) {
+                ret = PTR_ERR(xfer);
+                dev_err(dev, "failed to get free message slot(%d)\n", ret);
+                return ret;
+        }
+
+        xfer->tx.len = tx_size;
+        xfer->rx.len = rx_size ? : info->desc->max_msg_size;
+        xfer->hdr.id = msg_id;
+        xfer->hdr.protocol_id = prot_id;
+        xfer->hdr.poll_completion = false;
+
+        *p = xfer;
+        return 0;
+}
+
+/**
+ * scmi_version_get() - command to get the revision of the SCMI entity
+ *
+ * @handle: Handle to SCMI entity information
+ *
+ * Updates the SCMI information in the internal data structure.
+ *
+ * Return: 0 if all went fine, else return appropriate error.
+ */
+int scmi_version_get(const struct scmi_handle *handle, u8 protocol,
+                     u32 *version)
+{
+        int ret;
+        __le32 *rev_info;
+        struct scmi_xfer *t;
+
+        ret = scmi_one_xfer_init(handle, PROTOCOL_VERSION, protocol, 0,
+                                 sizeof(*version), &t);
+        if (ret)
+                return ret;
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret) {
+                rev_info = t->rx.buf;
+                *version = le32_to_cpu(*rev_info);
+        }
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+void scmi_setup_protocol_implemented(const struct scmi_handle *handle,
+                                     u8 *prot_imp)
+{
+        struct scmi_info *info = handle_to_scmi_info(handle);
+
+        info->protocols_imp = prot_imp;
+}
+
+static bool
+scmi_is_protocol_implemented(const struct scmi_handle *handle, u8 prot_id)
+{
+        int i;
+        struct scmi_info *info = handle_to_scmi_info(handle);
+
+        if (!info->protocols_imp)
+                return false;
+
+        for (i = 0; i < MAX_PROTOCOLS_IMP; i++)
+                if (info->protocols_imp[i] == prot_id)
+                        return true;
+        return false;
+}
+
+/**
+ * scmi_handle_get() - Get the  SCMI handle for a device
+ *
+ * @dev: pointer to device for which we want SCMI handle
+ *
+ * NOTE: The function does not track individual clients of the framework
+ * and is expected to be maintained by caller of  SCMI protocol library.
+ * scmi_handle_put must be balanced with successful scmi_handle_get
+ *
+ * Return: pointer to handle if successful, NULL on error
+ */
+struct scmi_handle *scmi_handle_get(struct device *dev)
+{
+        struct list_head *p;
+        struct scmi_info *info;
+        struct scmi_handle *handle = NULL;
+
+        mutex_lock(&scmi_list_mutex);
+        list_for_each(p, &scmi_list) {
+                info = list_entry(p, struct scmi_info, node);
+                if (dev->parent == info->dev) {
+                        handle = &info->handle;
+                        info->users++;
+                        break;
+                }
+        }
+        mutex_unlock(&scmi_list_mutex);
+
+        return handle;
+}
+
+/**
+ * scmi_handle_put() - Release the handle acquired by scmi_handle_get
+ *
+ * @handle: handle acquired by scmi_handle_get
+ *
+ * NOTE: The function does not track individual clients of the framework
+ * and is expected to be maintained by caller of  SCMI protocol library.
+ * scmi_handle_put must be balanced with successful scmi_handle_get
+ *
+ * Return: 0 is successfully released
+ *      if null was passed, it returns -EINVAL;
+ */
+int scmi_handle_put(const struct scmi_handle *handle)
+{
+        struct scmi_info *info;
+
+        if (!handle)
+                return -EINVAL;
+
+        info = handle_to_scmi_info(handle);
+        mutex_lock(&scmi_list_mutex);
+        if (!WARN_ON(!info->users))
+                info->users--;
+        mutex_unlock(&scmi_list_mutex);
+
+        return 0;
+}
+
+static const struct scmi_desc scmi_generic_desc = {
+        .max_rx_timeout_ms = 30,        /* we may increase this if required */
+        .max_msg = 20,          /* Limited by MBOX_TX_QUEUE_LEN */
+        .max_msg_size = 128,
+};
+
+/* Each compatible listed below must have descriptor associated with it */
+static const struct of_device_id scmi_of_match[] = {
+        { .compatible = "arm,scmi", .data = &scmi_generic_desc },
+        { /* Sentinel */ },
+};
+
+MODULE_DEVICE_TABLE(of, scmi_of_match);
+
+static int scmi_xfer_info_init(struct scmi_info *sinfo)
+{
+        int i;
+        struct scmi_xfer *xfer;
+        struct device *dev = sinfo->dev;
+        const struct scmi_desc *desc = sinfo->desc;
+        struct scmi_xfers_info *info = &sinfo->minfo;
+
+        /* Pre-allocated messages, no more than what hdr.seq can support */
+        if (WARN_ON(desc->max_msg >= (MSG_TOKEN_ID_MASK + 1))) {
+                dev_err(dev, "Maximum message of %d exceeds supported %d\n",
+                        desc->max_msg, MSG_TOKEN_ID_MASK + 1);
+                return -EINVAL;
+        }
+
+        info->xfer_block = devm_kcalloc(dev, desc->max_msg,
+                                        sizeof(*info->xfer_block), GFP_KERNEL);
+        if (!info->xfer_block)
+                return -ENOMEM;
+
+        info->xfer_alloc_table = devm_kcalloc(dev, BITS_TO_LONGS(desc->max_msg),
+                                              sizeof(long), GFP_KERNEL);
+        if (!info->xfer_alloc_table)
+                return -ENOMEM;
+
+        bitmap_zero(info->xfer_alloc_table, desc->max_msg);
+
+        /* Pre-initialize the buffer pointer to pre-allocated buffers */
+        for (i = 0, xfer = info->xfer_block; i < desc->max_msg; i++, xfer++) {
+                xfer->rx.buf = devm_kcalloc(dev, sizeof(u8), desc->max_msg_size,
+                                            GFP_KERNEL);
+                if (!xfer->rx.buf)
+                        return -ENOMEM;
+
+                xfer->tx.buf = xfer->rx.buf;
+                init_completion(&xfer->done);
+        }
+
+        spin_lock_init(&info->xfer_lock);
+
+        return 0;
+}
+
+static int scmi_mailbox_check(struct device_node *np)
+{
+        struct of_phandle_args arg;
+
+        return of_parse_phandle_with_args(np, "mboxes", "#mbox-cells", 0, &arg);
+}
+
+static int scmi_mbox_free_channel(int id, void *p, void *data)
+{
+        struct scmi_chan_info *cinfo = p;
+        struct idr *idr = data;
+
+        if (!IS_ERR_OR_NULL(cinfo->chan)) {
+                mbox_free_channel(cinfo->chan);
+                cinfo->chan = NULL;
+        }
+
+        idr_remove(idr, id);
+
+        return 0;
+}
+
+static int scmi_remove(struct platform_device *pdev)
+{
+        int ret = 0;
+        struct scmi_info *info = platform_get_drvdata(pdev);
+        struct idr *idr = &info->tx_idr;
+
+        mutex_lock(&scmi_list_mutex);
+        if (info->users)
+                ret = -EBUSY;
+        else
+                list_del(&info->node);
+        mutex_unlock(&scmi_list_mutex);
+
+        if (!ret) {
+                /* Safe to free channels since no more users */
+                ret = idr_for_each(idr, scmi_mbox_free_channel, idr);
+                idr_destroy(&info->tx_idr);
+        }
+
+        return ret;
+}
+
+static inline int
+scmi_mbox_chan_setup(struct scmi_info *info, struct device *dev, int prot_id)
+{
+        int ret;
+        struct resource res;
+        resource_size_t size;
+        struct device_node *shmem, *np = dev->of_node;
+        struct scmi_chan_info *cinfo;
+        struct mbox_client *cl;
+
+        if (scmi_mailbox_check(np)) {
+                cinfo = idr_find(&info->tx_idr, SCMI_PROTOCOL_BASE);
+                goto idr_alloc;
+        }
+
+        cinfo = devm_kzalloc(info->dev, sizeof(*cinfo), GFP_KERNEL);
+        if (!cinfo)
+                return -ENOMEM;
+
+        cinfo->dev = dev;
+
+        cl = &cinfo->cl;
+        cl->dev = dev;
+        cl->rx_callback = scmi_rx_callback;
+        cl->tx_prepare = scmi_tx_prepare;
+        cl->tx_block = false;
+        cl->knows_txdone = true;
+
+        shmem = of_parse_phandle(np, "shmem", 0);
+        ret = of_address_to_resource(shmem, 0, &res);
+        of_node_put(shmem);
+        if (ret) {
+                dev_err(dev, "failed to get SCMI Tx payload mem resource\n");
+                return ret;
+        }
+
+        size = resource_size(&res);
+        cinfo->payload = devm_ioremap(info->dev, res.start, size);
+        if (!cinfo->payload) {
+                dev_err(dev, "failed to ioremap SCMI Tx payload\n");
+                return -EADDRNOTAVAIL;
+        }
+
+        /* Transmit channel is first entry i.e. index 0 */
+        cinfo->chan = mbox_request_channel(cl, 0);
+        if (IS_ERR(cinfo->chan)) {
+                ret = PTR_ERR(cinfo->chan);
+                if (ret != -EPROBE_DEFER)
+                        dev_err(dev, "failed to request SCMI Tx mailbox\n");
+                return ret;
+        }
+
+idr_alloc:
+        ret = idr_alloc(&info->tx_idr, cinfo, prot_id, prot_id + 1, GFP_KERNEL);
+        if (ret != prot_id) {
+                dev_err(dev, "unable to allocate SCMI idr slot err %d\n", ret);
+                return ret;
+        }
+
+        cinfo->handle = &info->handle;
+        return 0;
+}
+
+static inline void
+scmi_create_protocol_device(struct device_node *np, struct scmi_info *info,
+                            int prot_id)
+{
+        struct scmi_device *sdev;
+
+        sdev = scmi_device_create(np, info->dev, prot_id);
+        if (!sdev) {
+                dev_err(info->dev, "failed to create %d protocol device\n",
+                        prot_id);
+                return;
+        }
+
+        if (scmi_mbox_chan_setup(info, &sdev->dev, prot_id)) {
+                dev_err(&sdev->dev, "failed to setup transport\n");
+                scmi_device_destroy(sdev);
+        }
+
+        /* setup handle now as the transport is ready */
+        scmi_set_handle(sdev);
+}
+
+static int scmi_probe(struct platform_device *pdev)
+{
+        int ret;
+        struct scmi_handle *handle;
+        const struct scmi_desc *desc;
+        struct scmi_info *info;
+        struct device *dev = &pdev->dev;
+        struct device_node *child, *np = dev->of_node;
+
+        /* Only mailbox method supported, check for the presence of one */
+        if (scmi_mailbox_check(np)) {
+                dev_err(dev, "no mailbox found in %pOF\n", np);
+                return -EINVAL;
+        }
+
+        desc = of_match_device(scmi_of_match, dev)->data;
+
+        info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
+        if (!info)
+                return -ENOMEM;
+
+        info->dev = dev;
+        info->desc = desc;
+        INIT_LIST_HEAD(&info->node);
+
+        ret = scmi_xfer_info_init(info);
+        if (ret)
+                return ret;
+
+        platform_set_drvdata(pdev, info);
+        idr_init(&info->tx_idr);
+
+        handle = &info->handle;
+        handle->dev = info->dev;
+        handle->version = &info->version;
+
+        ret = scmi_mbox_chan_setup(info, dev, SCMI_PROTOCOL_BASE);
+        if (ret)
+                return ret;
+
+        ret = scmi_base_protocol_init(handle);
+        if (ret) {
+                dev_err(dev, "unable to communicate with SCMI(%d)\n", ret);
+                return ret;
+        }
+
+        mutex_lock(&scmi_list_mutex);
+        list_add_tail(&info->node, &scmi_list);
+        mutex_unlock(&scmi_list_mutex);
+
+        for_each_available_child_of_node(np, child) {
+                u32 prot_id;
+
+                if (of_property_read_u32(child, "reg", &prot_id))
+                        continue;
+
+                prot_id &= MSG_PROTOCOL_ID_MASK;
+
+                if (!scmi_is_protocol_implemented(handle, prot_id)) {
+                        dev_err(dev, "SCMI protocol %d not implemented\n",
+                                prot_id);
+                        continue;
+                }
+
+                scmi_create_protocol_device(child, info, prot_id);
+        }
+
+        return 0;
+}
+
+static struct platform_driver scmi_driver = {
+        .driver = {
+                   .name = "arm-scmi",
+                   .of_match_table = scmi_of_match,
+                   },
+        .probe = scmi_probe,
+        .remove = scmi_remove,
+};
+
+module_platform_driver(scmi_driver);
+
+MODULE_ALIAS("platform: arm-scmi");
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCMI protocol driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
new file mode 100644
index 000000000000..987c64d19801
--- /dev/null
+++ b/drivers/firmware/arm_scmi/perf.c
@@ -0,0 +1,481 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Performance Protocol
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ */
+
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/sort.h>
+
+#include "common.h"
+
+enum scmi_performance_protocol_cmd {
+        PERF_DOMAIN_ATTRIBUTES = 0x3,
+        PERF_DESCRIBE_LEVELS = 0x4,
+        PERF_LIMITS_SET = 0x5,
+        PERF_LIMITS_GET = 0x6,
+        PERF_LEVEL_SET = 0x7,
+        PERF_LEVEL_GET = 0x8,
+        PERF_NOTIFY_LIMITS = 0x9,
+        PERF_NOTIFY_LEVEL = 0xa,
+};
+
+struct scmi_opp {
+        u32 perf;
+        u32 power;
+        u32 trans_latency_us;
+};
+
+struct scmi_msg_resp_perf_attributes {
+        __le16 num_domains;
+        __le16 flags;
+#define POWER_SCALE_IN_MILLIWATT(x)     ((x) & BIT(0))
+        __le32 stats_addr_low;
+        __le32 stats_addr_high;
+        __le32 stats_size;
+};
+
+struct scmi_msg_resp_perf_domain_attributes {
+        __le32 flags;
+#define SUPPORTS_SET_LIMITS(x)          ((x) & BIT(31))
+#define SUPPORTS_SET_PERF_LVL(x)        ((x) & BIT(30))
+#define SUPPORTS_PERF_LIMIT_NOTIFY(x)   ((x) & BIT(29))
+#define SUPPORTS_PERF_LEVEL_NOTIFY(x)   ((x) & BIT(28))
+        __le32 rate_limit_us;
+        __le32 sustained_freq_khz;
+        __le32 sustained_perf_level;
+            u8 name[SCMI_MAX_STR_SIZE];
+};
+
+struct scmi_msg_perf_describe_levels {
+        __le32 domain;
+        __le32 level_index;
+};
+
+struct scmi_perf_set_limits {
+        __le32 domain;
+        __le32 max_level;
+        __le32 min_level;
+};
+
+struct scmi_perf_get_limits {
+        __le32 max_level;
+        __le32 min_level;
+};
+
+struct scmi_perf_set_level {
+        __le32 domain;
+        __le32 level;
+};
+
+struct scmi_perf_notify_level_or_limits {
+        __le32 domain;
+        __le32 notify_enable;
+};
+
+struct scmi_msg_resp_perf_describe_levels {
+        __le16 num_returned;
+        __le16 num_remaining;
+        struct {
+                __le32 perf_val;
+                __le32 power;
+                __le16 transition_latency_us;
+                __le16 reserved;
+        } opp[0];
+};
+
+struct perf_dom_info {
+        bool set_limits;
+        bool set_perf;
+        bool perf_limit_notify;
+        bool perf_level_notify;
+        u32 opp_count;
+        u32 sustained_freq_khz;
+        u32 sustained_perf_level;
+        u32 mult_factor;
+        char name[SCMI_MAX_STR_SIZE];
+        struct scmi_opp opp[MAX_OPPS];
+};
+
+struct scmi_perf_info {
+        int num_domains;
+        bool power_scale_mw;
+        u64 stats_addr;
+        u32 stats_size;
+        struct perf_dom_info *dom_info;
+};
+
+static int scmi_perf_attributes_get(const struct scmi_handle *handle,
+                                    struct scmi_perf_info *pi)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_msg_resp_perf_attributes *attr;
+
+        ret = scmi_one_xfer_init(handle, PROTOCOL_ATTRIBUTES,
+                                 SCMI_PROTOCOL_PERF, 0, sizeof(*attr), &t);
+        if (ret)
+                return ret;
+
+        attr = t->rx.buf;
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret) {
+                u16 flags = le16_to_cpu(attr->flags);
+
+                pi->num_domains = le16_to_cpu(attr->num_domains);
+                pi->power_scale_mw = POWER_SCALE_IN_MILLIWATT(flags);
+                pi->stats_addr = le32_to_cpu(attr->stats_addr_low) |
+                                (u64)le32_to_cpu(attr->stats_addr_high) << 32;
+                pi->stats_size = le32_to_cpu(attr->stats_size);
+        }
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int
+scmi_perf_domain_attributes_get(const struct scmi_handle *handle, u32 domain,
+                                struct perf_dom_info *dom_info)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_msg_resp_perf_domain_attributes *attr;
+
+        ret = scmi_one_xfer_init(handle, PERF_DOMAIN_ATTRIBUTES,
+                                 SCMI_PROTOCOL_PERF, sizeof(domain),
+                                 sizeof(*attr), &t);
+        if (ret)
+                return ret;
+
+        *(__le32 *)t->tx.buf = cpu_to_le32(domain);
+        attr = t->rx.buf;
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret) {
+                u32 flags = le32_to_cpu(attr->flags);
+
+                dom_info->set_limits = SUPPORTS_SET_LIMITS(flags);
+                dom_info->set_perf = SUPPORTS_SET_PERF_LVL(flags);
+                dom_info->perf_limit_notify = SUPPORTS_PERF_LIMIT_NOTIFY(flags);
+                dom_info->perf_level_notify = SUPPORTS_PERF_LEVEL_NOTIFY(flags);
+                dom_info->sustained_freq_khz =
+                                        le32_to_cpu(attr->sustained_freq_khz);
+                dom_info->sustained_perf_level =
+                                        le32_to_cpu(attr->sustained_perf_level);
+                dom_info->mult_factor = (dom_info->sustained_freq_khz * 1000) /
+                                        dom_info->sustained_perf_level;
+                memcpy(dom_info->name, attr->name, SCMI_MAX_STR_SIZE);
+        }
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int opp_cmp_func(const void *opp1, const void *opp2)
+{
+        const struct scmi_opp *t1 = opp1, *t2 = opp2;
+
+        return t1->perf - t2->perf;
+}
+
+static int
+scmi_perf_describe_levels_get(const struct scmi_handle *handle, u32 domain,
+                              struct perf_dom_info *perf_dom)
+{
+        int ret, cnt;
+        u32 tot_opp_cnt = 0;
+        u16 num_returned, num_remaining;
+        struct scmi_xfer *t;
+        struct scmi_opp *opp;
+        struct scmi_msg_perf_describe_levels *dom_info;
+        struct scmi_msg_resp_perf_describe_levels *level_info;
+
+        ret = scmi_one_xfer_init(handle, PERF_DESCRIBE_LEVELS,
+                                 SCMI_PROTOCOL_PERF, sizeof(*dom_info), 0, &t);
+        if (ret)
+                return ret;
+
+        dom_info = t->tx.buf;
+        level_info = t->rx.buf;
+
+        do {
+                dom_info->domain = cpu_to_le32(domain);
+                /* Set the number of OPPs to be skipped/already read */
+                dom_info->level_index = cpu_to_le32(tot_opp_cnt);
+
+                ret = scmi_do_xfer(handle, t);
+                if (ret)
+                        break;
+
+                num_returned = le16_to_cpu(level_info->num_returned);
+                num_remaining = le16_to_cpu(level_info->num_remaining);
+                if (tot_opp_cnt + num_returned > MAX_OPPS) {
+                        dev_err(handle->dev, "No. of OPPs exceeded MAX_OPPS");
+                        break;
+                }
+
+                opp = &perf_dom->opp[tot_opp_cnt];
+                for (cnt = 0; cnt < num_returned; cnt++, opp++) {
+                        opp->perf = le32_to_cpu(level_info->opp[cnt].perf_val);
+                        opp->power = le32_to_cpu(level_info->opp[cnt].power);
+                        opp->trans_latency_us = le16_to_cpu
+                                (level_info->opp[cnt].transition_latency_us);
+
+                        dev_dbg(handle->dev, "Level %d Power %d Latency %dus\n",
+                                opp->perf, opp->power, opp->trans_latency_us);
+                }
+
+                tot_opp_cnt += num_returned;
+                /*
+                 * check for both returned and remaining to avoid infinite
+                 * loop due to buggy firmware
+                 */
+        } while (num_returned && num_remaining);
+
+        perf_dom->opp_count = tot_opp_cnt;
+        scmi_one_xfer_put(handle, t);
+
+        sort(perf_dom->opp, tot_opp_cnt, sizeof(*opp), opp_cmp_func, NULL);
+        return ret;
+}
+
+static int scmi_perf_limits_set(const struct scmi_handle *handle, u32 domain,
+                                u32 max_perf, u32 min_perf)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_perf_set_limits *limits;
+
+        ret = scmi_one_xfer_init(handle, PERF_LIMITS_SET, SCMI_PROTOCOL_PERF,
+                                 sizeof(*limits), 0, &t);
+        if (ret)
+                return ret;
+
+        limits = t->tx.buf;
+        limits->domain = cpu_to_le32(domain);
+        limits->max_level = cpu_to_le32(max_perf);
+        limits->min_level = cpu_to_le32(min_perf);
+
+        ret = scmi_do_xfer(handle, t);
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int scmi_perf_limits_get(const struct scmi_handle *handle, u32 domain,
+                                u32 *max_perf, u32 *min_perf)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_perf_get_limits *limits;
+
+        ret = scmi_one_xfer_init(handle, PERF_LIMITS_GET, SCMI_PROTOCOL_PERF,
+                                 sizeof(__le32), 0, &t);
+        if (ret)
+                return ret;
+
+        *(__le32 *)t->tx.buf = cpu_to_le32(domain);
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret) {
+                limits = t->rx.buf;
+
+                *max_perf = le32_to_cpu(limits->max_level);
+                *min_perf = le32_to_cpu(limits->min_level);
+        }
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int scmi_perf_level_set(const struct scmi_handle *handle, u32 domain,
+                               u32 level, bool poll)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_perf_set_level *lvl;
+
+        ret = scmi_one_xfer_init(handle, PERF_LEVEL_SET, SCMI_PROTOCOL_PERF,
+                                 sizeof(*lvl), 0, &t);
+        if (ret)
+                return ret;
+
+        t->hdr.poll_completion = poll;
+        lvl = t->tx.buf;
+        lvl->domain = cpu_to_le32(domain);
+        lvl->level = cpu_to_le32(level);
+
+        ret = scmi_do_xfer(handle, t);
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int scmi_perf_level_get(const struct scmi_handle *handle, u32 domain,
+                               u32 *level, bool poll)
+{
+        int ret;
+        struct scmi_xfer *t;
+
+        ret = scmi_one_xfer_init(handle, PERF_LEVEL_GET, SCMI_PROTOCOL_PERF,
+                                 sizeof(u32), sizeof(u32), &t);
+        if (ret)
+                return ret;
+
+        t->hdr.poll_completion = poll;
+        *(__le32 *)t->tx.buf = cpu_to_le32(domain);
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret)
+                *level = le32_to_cpu(*(__le32 *)t->rx.buf);
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+/* Device specific ops */
+static int scmi_dev_domain_id(struct device *dev)
+{
+        struct of_phandle_args clkspec;
+
+        if (of_parse_phandle_with_args(dev->of_node, "clocks", "#clock-cells",
+                                       0, &clkspec))
+                return -EINVAL;
+
+        return clkspec.args[0];
+}
+
+static int scmi_dvfs_add_opps_to_device(const struct scmi_handle *handle,
+                                        struct device *dev)
+{
+        int idx, ret, domain;
+        unsigned long freq;
+        struct scmi_opp *opp;
+        struct perf_dom_info *dom;
+        struct scmi_perf_info *pi = handle->perf_priv;
+
+        domain = scmi_dev_domain_id(dev);
+        if (domain < 0)
+                return domain;
+
+        dom = pi->dom_info + domain;
+        if (!dom)
+                return -EIO;
+
+        for (opp = dom->opp, idx = 0; idx < dom->opp_count; idx++, opp++) {
+                freq = opp->perf * dom->mult_factor;
+
+                ret = dev_pm_opp_add(dev, freq, 0);
+                if (ret) {
+                        dev_warn(dev, "failed to add opp %luHz\n", freq);
+
+                        while (idx-- > 0) {
+                                freq = (--opp)->perf * dom->mult_factor;
+                                dev_pm_opp_remove(dev, freq);
+                        }
+                        return ret;
+                }
+        }
+        return 0;
+}
+
+static int scmi_dvfs_get_transition_latency(const struct scmi_handle *handle,
+                                            struct device *dev)
+{
+        struct perf_dom_info *dom;
+        struct scmi_perf_info *pi = handle->perf_priv;
+        int domain = scmi_dev_domain_id(dev);
+
+        if (domain < 0)
+                return domain;
+
+        dom = pi->dom_info + domain;
+        if (!dom)
+                return -EIO;
+
+        /* uS to nS */
+        return dom->opp[dom->opp_count - 1].trans_latency_us * 1000;
+}
+
+static int scmi_dvfs_freq_set(const struct scmi_handle *handle, u32 domain,
+                              unsigned long freq, bool poll)
+{
+        struct scmi_perf_info *pi = handle->perf_priv;
+        struct perf_dom_info *dom = pi->dom_info + domain;
+
+        return scmi_perf_level_set(handle, domain, freq / dom->mult_factor,
+                                   poll);
+}
+
+static int scmi_dvfs_freq_get(const struct scmi_handle *handle, u32 domain,
+                              unsigned long *freq, bool poll)
+{
+        int ret;
+        u32 level;
+        struct scmi_perf_info *pi = handle->perf_priv;
+        struct perf_dom_info *dom = pi->dom_info + domain;
+
+        ret = scmi_perf_level_get(handle, domain, &level, poll);
+        if (!ret)
+                *freq = level * dom->mult_factor;
+
+        return ret;
+}
+
+static struct scmi_perf_ops perf_ops = {
+        .limits_set = scmi_perf_limits_set,
+        .limits_get = scmi_perf_limits_get,
+        .level_set = scmi_perf_level_set,
+        .level_get = scmi_perf_level_get,
+        .device_domain_id = scmi_dev_domain_id,
+        .get_transition_latency = scmi_dvfs_get_transition_latency,
+        .add_opps_to_device = scmi_dvfs_add_opps_to_device,
+        .freq_set = scmi_dvfs_freq_set,
+        .freq_get = scmi_dvfs_freq_get,
+};
+
+static int scmi_perf_protocol_init(struct scmi_handle *handle)
+{
+        int domain;
+        u32 version;
+        struct scmi_perf_info *pinfo;
+
+        scmi_version_get(handle, SCMI_PROTOCOL_PERF, &version);
+
+        dev_dbg(handle->dev, "Performance Version %d.%d\n",
+                PROTOCOL_REV_MAJOR(version), PROTOCOL_REV_MINOR(version));
+
+        pinfo = devm_kzalloc(handle->dev, sizeof(*pinfo), GFP_KERNEL);
+        if (!pinfo)
+                return -ENOMEM;
+
+        scmi_perf_attributes_get(handle, pinfo);
+
+        pinfo->dom_info = devm_kcalloc(handle->dev, pinfo->num_domains,
+                                       sizeof(*pinfo->dom_info), GFP_KERNEL);
+        if (!pinfo->dom_info)
+                return -ENOMEM;
+
+        for (domain = 0; domain < pinfo->num_domains; domain++) {
+                struct perf_dom_info *dom = pinfo->dom_info + domain;
+
+                scmi_perf_domain_attributes_get(handle, domain, dom);
+                scmi_perf_describe_levels_get(handle, domain, dom);
+        }
+
+        handle->perf_ops = &perf_ops;
+        handle->perf_priv = pinfo;
+
+        return 0;
+}
+
+static int __init scmi_perf_init(void)
+{
+        return scmi_protocol_register(SCMI_PROTOCOL_PERF,
+                                      &scmi_perf_protocol_init);
+}
+subsys_initcall(scmi_perf_init);
diff --git a/drivers/firmware/arm_scmi/power.c b/drivers/firmware/arm_scmi/power.c
new file mode 100644
index 000000000000..087c2876cdf2
--- /dev/null
+++ b/drivers/firmware/arm_scmi/power.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Power Protocol
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ */
+
+#include "common.h"
+
+enum scmi_power_protocol_cmd {
+        POWER_DOMAIN_ATTRIBUTES = 0x3,
+        POWER_STATE_SET = 0x4,
+        POWER_STATE_GET = 0x5,
+        POWER_STATE_NOTIFY = 0x6,
+};
+
+struct scmi_msg_resp_power_attributes {
+        __le16 num_domains;
+        __le16 reserved;
+        __le32 stats_addr_low;
+        __le32 stats_addr_high;
+        __le32 stats_size;
+};
+
+struct scmi_msg_resp_power_domain_attributes {
+        __le32 flags;
+#define SUPPORTS_STATE_SET_NOTIFY(x)    ((x) & BIT(31))
+#define SUPPORTS_STATE_SET_ASYNC(x)     ((x) & BIT(30))
+#define SUPPORTS_STATE_SET_SYNC(x)      ((x) & BIT(29))
+            u8 name[SCMI_MAX_STR_SIZE];
+};
+
+struct scmi_power_set_state {
+        __le32 flags;
+#define STATE_SET_ASYNC         BIT(0)
+        __le32 domain;
+        __le32 state;
+};
+
+struct scmi_power_state_notify {
+        __le32 domain;
+        __le32 notify_enable;
+};
+
+struct power_dom_info {
+        bool state_set_sync;
+        bool state_set_async;
+        bool state_set_notify;
+        char name[SCMI_MAX_STR_SIZE];
+};
+
+struct scmi_power_info {
+        int num_domains;
+        u64 stats_addr;
+        u32 stats_size;
+        struct power_dom_info *dom_info;
+};
+
+static int scmi_power_attributes_get(const struct scmi_handle *handle,
+                                     struct scmi_power_info *pi)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_msg_resp_power_attributes *attr;
+
+        ret = scmi_one_xfer_init(handle, PROTOCOL_ATTRIBUTES,
+                                 SCMI_PROTOCOL_POWER, 0, sizeof(*attr), &t);
+        if (ret)
+                return ret;
+
+        attr = t->rx.buf;
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret) {
+                pi->num_domains = le16_to_cpu(attr->num_domains);
+                pi->stats_addr = le32_to_cpu(attr->stats_addr_low) |
+                                (u64)le32_to_cpu(attr->stats_addr_high) << 32;
+                pi->stats_size = le32_to_cpu(attr->stats_size);
+        }
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int
+scmi_power_domain_attributes_get(const struct scmi_handle *handle, u32 domain,
+                                 struct power_dom_info *dom_info)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_msg_resp_power_domain_attributes *attr;
+
+        ret = scmi_one_xfer_init(handle, POWER_DOMAIN_ATTRIBUTES,
+                                 SCMI_PROTOCOL_POWER, sizeof(domain),
+                                 sizeof(*attr), &t);
+        if (ret)
+                return ret;
+
+        *(__le32 *)t->tx.buf = cpu_to_le32(domain);
+        attr = t->rx.buf;
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret) {
+                u32 flags = le32_to_cpu(attr->flags);
+
+                dom_info->state_set_notify = SUPPORTS_STATE_SET_NOTIFY(flags);
+                dom_info->state_set_async = SUPPORTS_STATE_SET_ASYNC(flags);
+                dom_info->state_set_sync = SUPPORTS_STATE_SET_SYNC(flags);
+                memcpy(dom_info->name, attr->name, SCMI_MAX_STR_SIZE);
+        }
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int
+scmi_power_state_set(const struct scmi_handle *handle, u32 domain, u32 state)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_power_set_state *st;
+
+        ret = scmi_one_xfer_init(handle, POWER_STATE_SET, SCMI_PROTOCOL_POWER,
+                                 sizeof(*st), 0, &t);
+        if (ret)
+                return ret;
+
+        st = t->tx.buf;
+        st->flags = cpu_to_le32(0);
+        st->domain = cpu_to_le32(domain);
+        st->state = cpu_to_le32(state);
+
+        ret = scmi_do_xfer(handle, t);
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int
+scmi_power_state_get(const struct scmi_handle *handle, u32 domain, u32 *state)
+{
+        int ret;
+        struct scmi_xfer *t;
+
+        ret = scmi_one_xfer_init(handle, POWER_STATE_GET, SCMI_PROTOCOL_POWER,
+                                 sizeof(u32), sizeof(u32), &t);
+        if (ret)
+                return ret;
+
+        *(__le32 *)t->tx.buf = cpu_to_le32(domain);
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret)
+                *state = le32_to_cpu(*(__le32 *)t->rx.buf);
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int scmi_power_num_domains_get(const struct scmi_handle *handle)
+{
+        struct scmi_power_info *pi = handle->power_priv;
+
+        return pi->num_domains;
+}
+
+static char *scmi_power_name_get(const struct scmi_handle *handle, u32 domain)
+{
+        struct scmi_power_info *pi = handle->power_priv;
+        struct power_dom_info *dom = pi->dom_info + domain;
+
+        return dom->name;
+}
+
+static struct scmi_power_ops power_ops = {
+        .num_domains_get = scmi_power_num_domains_get,
+        .name_get = scmi_power_name_get,
+        .state_set = scmi_power_state_set,
+        .state_get = scmi_power_state_get,
+};
+
+static int scmi_power_protocol_init(struct scmi_handle *handle)
+{
+        int domain;
+        u32 version;
+        struct scmi_power_info *pinfo;
+
+        scmi_version_get(handle, SCMI_PROTOCOL_POWER, &version);
+
+        dev_dbg(handle->dev, "Power Version %d.%d\n",
+                PROTOCOL_REV_MAJOR(version), PROTOCOL_REV_MINOR(version));
+
+        pinfo = devm_kzalloc(handle->dev, sizeof(*pinfo), GFP_KERNEL);
+        if (!pinfo)
+                return -ENOMEM;
+
+        scmi_power_attributes_get(handle, pinfo);
+
+        pinfo->dom_info = devm_kcalloc(handle->dev, pinfo->num_domains,
+                                       sizeof(*pinfo->dom_info), GFP_KERNEL);
+        if (!pinfo->dom_info)
+                return -ENOMEM;
+
+        for (domain = 0; domain < pinfo->num_domains; domain++) {
+                struct power_dom_info *dom = pinfo->dom_info + domain;
+
+                scmi_power_domain_attributes_get(handle, domain, dom);
+        }
+
+        handle->power_ops = &power_ops;
+        handle->power_priv = pinfo;
+
+        return 0;
+}
+
+static int __init scmi_power_init(void)
+{
+        return scmi_protocol_register(SCMI_PROTOCOL_POWER,
+                                      &scmi_power_protocol_init);
+}
+subsys_initcall(scmi_power_init);
diff --git a/drivers/firmware/arm_scmi/scmi_pm_domain.c b/drivers/firmware/arm_scmi/scmi_pm_domain.c
new file mode 100644
index 000000000000..87f737e01473
--- /dev/null
+++ b/drivers/firmware/arm_scmi/scmi_pm_domain.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SCMI Generic power domain support.
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/pm_domain.h>
+#include <linux/scmi_protocol.h>
+
+struct scmi_pm_domain {
+        struct generic_pm_domain genpd;
+        const struct scmi_handle *handle;
+        const char *name;
+        u32 domain;
+};
+
+#define to_scmi_pd(gpd) container_of(gpd, struct scmi_pm_domain, genpd)
+
+static int scmi_pd_power(struct generic_pm_domain *domain, bool power_on)
+{
+        int ret;
+        u32 state, ret_state;
+        struct scmi_pm_domain *pd = to_scmi_pd(domain);
+        const struct scmi_power_ops *ops = pd->handle->power_ops;
+
+        if (power_on)
+                state = SCMI_POWER_STATE_GENERIC_ON;
+        else
+                state = SCMI_POWER_STATE_GENERIC_OFF;
+
+        ret = ops->state_set(pd->handle, pd->domain, state);
+        if (!ret)
+                ret = ops->state_get(pd->handle, pd->domain, &ret_state);
+        if (!ret && state != ret_state)
+                return -EIO;
+
+        return ret;
+}
+
+static int scmi_pd_power_on(struct generic_pm_domain *domain)
+{
+        return scmi_pd_power(domain, true);
+}
+
+static int scmi_pd_power_off(struct generic_pm_domain *domain)
+{
+        return scmi_pd_power(domain, false);
+}
+
+static int scmi_pm_domain_probe(struct scmi_device *sdev)
+{
+        int num_domains, i;
+        struct device *dev = &sdev->dev;
+        struct device_node *np = dev->of_node;
+        struct scmi_pm_domain *scmi_pd;
+        struct genpd_onecell_data *scmi_pd_data;
+        struct generic_pm_domain **domains;
+        const struct scmi_handle *handle = sdev->handle;
+
+        if (!handle || !handle->power_ops)
+                return -ENODEV;
+
+        num_domains = handle->power_ops->num_domains_get(handle);
+        if (num_domains < 0) {
+                dev_err(dev, "number of domains not found\n");
+                return num_domains;
+        }
+
+        scmi_pd = devm_kcalloc(dev, num_domains, sizeof(*scmi_pd), GFP_KERNEL);
+        if (!scmi_pd)
+                return -ENOMEM;
+
+        scmi_pd_data = devm_kzalloc(dev, sizeof(*scmi_pd_data), GFP_KERNEL);
+        if (!scmi_pd_data)
+                return -ENOMEM;
+
+        domains = devm_kcalloc(dev, num_domains, sizeof(*domains), GFP_KERNEL);
+        if (!domains)
+                return -ENOMEM;
+
+        for (i = 0; i < num_domains; i++, scmi_pd++) {
+                u32 state;
+
+                domains[i] = &scmi_pd->genpd;
+
+                scmi_pd->domain = i;
+                scmi_pd->handle = handle;
+                scmi_pd->name = handle->power_ops->name_get(handle, i);
+                scmi_pd->genpd.name = scmi_pd->name;
+                scmi_pd->genpd.power_off = scmi_pd_power_off;
+                scmi_pd->genpd.power_on = scmi_pd_power_on;
+
+                if (handle->power_ops->state_get(handle, i, &state)) {
+                        dev_warn(dev, "failed to get state for domain %d\n", i);
+                        continue;
+                }
+
+                pm_genpd_init(&scmi_pd->genpd, NULL,
+                              state == SCMI_POWER_STATE_GENERIC_OFF);
+        }
+
+        scmi_pd_data->domains = domains;
+        scmi_pd_data->num_domains = num_domains;
+
+        of_genpd_add_provider_onecell(np, scmi_pd_data);
+
+        return 0;
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+        { SCMI_PROTOCOL_POWER },
+        { },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_power_domain_driver = {
+        .name = "scmi-power-domain",
+        .probe = scmi_pm_domain_probe,
+        .id_table = scmi_id_table,
+};
+module_scmi_driver(scmi_power_domain_driver);
+
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCMI power domain driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/firmware/arm_scmi/sensors.c b/drivers/firmware/arm_scmi/sensors.c
new file mode 100644
index 000000000000..bbb469fea0ed
--- /dev/null
+++ b/drivers/firmware/arm_scmi/sensors.c
@@ -0,0 +1,291 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Sensor Protocol
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ */
+
+#include "common.h"
+
+enum scmi_sensor_protocol_cmd {
+        SENSOR_DESCRIPTION_GET = 0x3,
+        SENSOR_CONFIG_SET = 0x4,
+        SENSOR_TRIP_POINT_SET = 0x5,
+        SENSOR_READING_GET = 0x6,
+};
+
+struct scmi_msg_resp_sensor_attributes {
+        __le16 num_sensors;
+        u8 max_requests;
+        u8 reserved;
+        __le32 reg_addr_low;
+        __le32 reg_addr_high;
+        __le32 reg_size;
+};
+
+struct scmi_msg_resp_sensor_description {
+        __le16 num_returned;
+        __le16 num_remaining;
+        struct {
+                __le32 id;
+                __le32 attributes_low;
+#define SUPPORTS_ASYNC_READ(x)  ((x) & BIT(31))
+#define NUM_TRIP_POINTS(x)      (((x) >> 4) & 0xff)
+                __le32 attributes_high;
+#define SENSOR_TYPE(x)          ((x) & 0xff)
+#define SENSOR_SCALE(x)         (((x) >> 11) & 0x3f)
+#define SENSOR_UPDATE_SCALE(x)  (((x) >> 22) & 0x1f)
+#define SENSOR_UPDATE_BASE(x)   (((x) >> 27) & 0x1f)
+                    u8 name[SCMI_MAX_STR_SIZE];
+        } desc[0];
+};
+
+struct scmi_msg_set_sensor_config {
+        __le32 id;
+        __le32 event_control;
+};
+
+struct scmi_msg_set_sensor_trip_point {
+        __le32 id;
+        __le32 event_control;
+#define SENSOR_TP_EVENT_MASK    (0x3)
+#define SENSOR_TP_DISABLED      0x0
+#define SENSOR_TP_POSITIVE      0x1
+#define SENSOR_TP_NEGATIVE      0x2
+#define SENSOR_TP_BOTH          0x3
+#define SENSOR_TP_ID(x)         (((x) & 0xff) << 4)
+        __le32 value_low;
+        __le32 value_high;
+};
+
+struct scmi_msg_sensor_reading_get {
+        __le32 id;
+        __le32 flags;
+#define SENSOR_READ_ASYNC       BIT(0)
+};
+
+struct sensors_info {
+        int num_sensors;
+        int max_requests;
+        u64 reg_addr;
+        u32 reg_size;
+        struct scmi_sensor_info *sensors;
+};
+
+static int scmi_sensor_attributes_get(const struct scmi_handle *handle,
+                                      struct sensors_info *si)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_msg_resp_sensor_attributes *attr;
+
+        ret = scmi_one_xfer_init(handle, PROTOCOL_ATTRIBUTES,
+                                 SCMI_PROTOCOL_SENSOR, 0, sizeof(*attr), &t);
+        if (ret)
+                return ret;
+
+        attr = t->rx.buf;
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret) {
+                si->num_sensors = le16_to_cpu(attr->num_sensors);
+                si->max_requests = attr->max_requests;
+                si->reg_addr = le32_to_cpu(attr->reg_addr_low) |
+                                (u64)le32_to_cpu(attr->reg_addr_high) << 32;
+                si->reg_size = le32_to_cpu(attr->reg_size);
+        }
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int scmi_sensor_description_get(const struct scmi_handle *handle,
+                                       struct sensors_info *si)
+{
+        int ret, cnt;
+        u32 desc_index = 0;
+        u16 num_returned, num_remaining;
+        struct scmi_xfer *t;
+        struct scmi_msg_resp_sensor_description *buf;
+
+        ret = scmi_one_xfer_init(handle, SENSOR_DESCRIPTION_GET,
+                                 SCMI_PROTOCOL_SENSOR, sizeof(__le32), 0, &t);
+        if (ret)
+                return ret;
+
+        buf = t->rx.buf;
+
+        do {
+                /* Set the number of sensors to be skipped/already read */
+                *(__le32 *)t->tx.buf = cpu_to_le32(desc_index);
+
+                ret = scmi_do_xfer(handle, t);
+                if (ret)
+                        break;
+
+                num_returned = le16_to_cpu(buf->num_returned);
+                num_remaining = le16_to_cpu(buf->num_remaining);
+
+                if (desc_index + num_returned > si->num_sensors) {
+                        dev_err(handle->dev, "No. of sensors can't exceed %d",
+                                si->num_sensors);
+                        break;
+                }
+
+                for (cnt = 0; cnt < num_returned; cnt++) {
+                        u32 attrh;
+                        struct scmi_sensor_info *s;
+
+                        attrh = le32_to_cpu(buf->desc[cnt].attributes_high);
+                        s = &si->sensors[desc_index + cnt];
+                        s->id = le32_to_cpu(buf->desc[cnt].id);
+                        s->type = SENSOR_TYPE(attrh);
+                        memcpy(s->name, buf->desc[cnt].name, SCMI_MAX_STR_SIZE);
+                }
+
+                desc_index += num_returned;
+                /*
+                 * check for both returned and remaining to avoid infinite
+                 * loop due to buggy firmware
+                 */
+        } while (num_returned && num_remaining);
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int
+scmi_sensor_configuration_set(const struct scmi_handle *handle, u32 sensor_id)
+{
+        int ret;
+        u32 evt_cntl = BIT(0);
+        struct scmi_xfer *t;
+        struct scmi_msg_set_sensor_config *cfg;
+
+        ret = scmi_one_xfer_init(handle, SENSOR_CONFIG_SET,
+                                 SCMI_PROTOCOL_SENSOR, sizeof(*cfg), 0, &t);
+        if (ret)
+                return ret;
+
+        cfg = t->tx.buf;
+        cfg->id = cpu_to_le32(sensor_id);
+        cfg->event_control = cpu_to_le32(evt_cntl);
+
+        ret = scmi_do_xfer(handle, t);
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int scmi_sensor_trip_point_set(const struct scmi_handle *handle,
+                                      u32 sensor_id, u8 trip_id, u64 trip_value)
+{
+        int ret;
+        u32 evt_cntl = SENSOR_TP_BOTH;
+        struct scmi_xfer *t;
+        struct scmi_msg_set_sensor_trip_point *trip;
+
+        ret = scmi_one_xfer_init(handle, SENSOR_TRIP_POINT_SET,
+                                 SCMI_PROTOCOL_SENSOR, sizeof(*trip), 0, &t);
+        if (ret)
+                return ret;
+
+        trip = t->tx.buf;
+        trip->id = cpu_to_le32(sensor_id);
+        trip->event_control = cpu_to_le32(evt_cntl | SENSOR_TP_ID(trip_id));
+        trip->value_low = cpu_to_le32(trip_value & 0xffffffff);
+        trip->value_high = cpu_to_le32(trip_value >> 32);
+
+        ret = scmi_do_xfer(handle, t);
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static int scmi_sensor_reading_get(const struct scmi_handle *handle,
+                                   u32 sensor_id, bool async, u64 *value)
+{
+        int ret;
+        struct scmi_xfer *t;
+        struct scmi_msg_sensor_reading_get *sensor;
+
+        ret = scmi_one_xfer_init(handle, SENSOR_READING_GET,
+                                 SCMI_PROTOCOL_SENSOR, sizeof(*sensor),
+                                 sizeof(u64), &t);
+        if (ret)
+                return ret;
+
+        sensor = t->tx.buf;
+        sensor->id = cpu_to_le32(sensor_id);
+        sensor->flags = cpu_to_le32(async ? SENSOR_READ_ASYNC : 0);
+
+        ret = scmi_do_xfer(handle, t);
+        if (!ret) {
+                __le32 *pval = t->rx.buf;
+
+                *value = le32_to_cpu(*pval);
+                *value |= (u64)le32_to_cpu(*(pval + 1)) << 32;
+        }
+
+        scmi_one_xfer_put(handle, t);
+        return ret;
+}
+
+static const struct scmi_sensor_info *
+scmi_sensor_info_get(const struct scmi_handle *handle, u32 sensor_id)
+{
+        struct sensors_info *si = handle->sensor_priv;
+
+        return si->sensors + sensor_id;
+}
+
+static int scmi_sensor_count_get(const struct scmi_handle *handle)
+{
+        struct sensors_info *si = handle->sensor_priv;
+
+        return si->num_sensors;
+}
+
+static struct scmi_sensor_ops sensor_ops = {
+        .count_get = scmi_sensor_count_get,
+        .info_get = scmi_sensor_info_get,
+        .configuration_set = scmi_sensor_configuration_set,
+        .trip_point_set = scmi_sensor_trip_point_set,
+        .reading_get = scmi_sensor_reading_get,
+};
+
+static int scmi_sensors_protocol_init(struct scmi_handle *handle)
+{
+        u32 version;
+        struct sensors_info *sinfo;
+
+        scmi_version_get(handle, SCMI_PROTOCOL_SENSOR, &version);
+
+        dev_dbg(handle->dev, "Sensor Version %d.%d\n",
+                PROTOCOL_REV_MAJOR(version), PROTOCOL_REV_MINOR(version));
+
+        sinfo = devm_kzalloc(handle->dev, sizeof(*sinfo), GFP_KERNEL);
+        if (!sinfo)
+                return -ENOMEM;
+
+        scmi_sensor_attributes_get(handle, sinfo);
+
+        sinfo->sensors = devm_kcalloc(handle->dev, sinfo->num_sensors,
+                                      sizeof(*sinfo->sensors), GFP_KERNEL);
+        if (!sinfo->sensors)
+                return -ENOMEM;
+
+        scmi_sensor_description_get(handle, sinfo);
+
+        handle->sensor_ops = &sensor_ops;
+        handle->sensor_priv = sinfo;
+
+        return 0;
+}
+
+static int __init scmi_sensors_init(void)
+{
+        return scmi_protocol_register(SCMI_PROTOCOL_SENSOR,
+                                      &scmi_sensors_protocol_init);
+}
+subsys_initcall(scmi_sensors_init);
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index ef23553ff5cb..033e57366d56 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -317,6 +317,18 @@ config SENSORS_APPLESMC
           Say Y here if you have an applicable laptop and want to experience
           the awesome power of applesmc.
 
+config SENSORS_ARM_SCMI
+        tristate "ARM SCMI Sensors"
+        depends on ARM_SCMI_PROTOCOL
+        depends on THERMAL || !THERMAL_OF
+        help
+          This driver provides support for temperature, voltage, current
+          and power sensors available on SCMI based platforms. The actual
+          number and type of sensors exported depend on the platform.
+
+          This driver can also be built as a module.  If so, the module
+          will be called scmi-hwmon.
+
 config SENSORS_ARM_SCPI
         tristate "ARM SCPI Sensors"
         depends on ARM_SCPI_PROTOCOL
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index f814b4ace138..e7d52a36e6c4 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -46,6 +46,7 @@ obj-$(CONFIG_SENSORS_ADT7462)	+= adt7462.o
 obj-$(CONFIG_SENSORS_ADT7470)   += adt7470.o
 obj-$(CONFIG_SENSORS_ADT7475)   += adt7475.o
 obj-$(CONFIG_SENSORS_APPLESMC)  += applesmc.o
+obj-$(CONFIG_SENSORS_ARM_SCMI)  += scmi-hwmon.o
 obj-$(CONFIG_SENSORS_ARM_SCPI)  += scpi-hwmon.o
 obj-$(CONFIG_SENSORS_ASC7621)   += asc7621.o
 obj-$(CONFIG_SENSORS_ASPEED)    += aspeed-pwm-tacho.o
diff --git a/drivers/hwmon/scmi-hwmon.c b/drivers/hwmon/scmi-hwmon.c
new file mode 100644
index 000000000000..32e750373ced
--- /dev/null
+++ b/drivers/hwmon/scmi-hwmon.c
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface(SCMI) based hwmon sensor driver
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ * Sudeep Holla <sudeep.holla@arm.com>
+ */
+
+#include <linux/hwmon.h>
+#include <linux/module.h>
+#include <linux/scmi_protocol.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/thermal.h>
+
+struct scmi_sensors {
+        const struct scmi_handle *handle;
+        const struct scmi_sensor_info **info[hwmon_max];
+};
+
+static int scmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+                           u32 attr, int channel, long *val)
+{
+        int ret;
+        u64 value;
+        const struct scmi_sensor_info *sensor;
+        struct scmi_sensors *scmi_sensors = dev_get_drvdata(dev);
+        const struct scmi_handle *h = scmi_sensors->handle;
+
+        sensor = *(scmi_sensors->info[type] + channel);
+        ret = h->sensor_ops->reading_get(h, sensor->id, false, &value);
+        if (!ret)
+                *val = value;
+
+        return ret;
+}
+
+static int
+scmi_hwmon_read_string(struct device *dev, enum hwmon_sensor_types type,
+                       u32 attr, int channel, const char **str)
+{
+        const struct scmi_sensor_info *sensor;
+        struct scmi_sensors *scmi_sensors = dev_get_drvdata(dev);
+
+        sensor = *(scmi_sensors->info[type] + channel);
+        *str = sensor->name;
+
+        return 0;
+}
+
+static umode_t
+scmi_hwmon_is_visible(const void *drvdata, enum hwmon_sensor_types type,
+                      u32 attr, int channel)
+{
+        const struct scmi_sensor_info *sensor;
+        const struct scmi_sensors *scmi_sensors = drvdata;
+
+        sensor = *(scmi_sensors->info[type] + channel);
+        if (sensor && sensor->name)
+                return S_IRUGO;
+
+        return 0;
+}
+
+static const struct hwmon_ops scmi_hwmon_ops = {
+        .is_visible = scmi_hwmon_is_visible,
+        .read = scmi_hwmon_read,
+        .read_string = scmi_hwmon_read_string,
+};
+
+static struct hwmon_chip_info scmi_chip_info = {
+        .ops = &scmi_hwmon_ops,
+        .info = NULL,
+};
+
+static int scmi_hwmon_add_chan_info(struct hwmon_channel_info *scmi_hwmon_chan,
+                                    struct device *dev, int num,
+                                    enum hwmon_sensor_types type, u32 config)
+{
+        int i;
+        u32 *cfg = devm_kcalloc(dev, num + 1, sizeof(*cfg), GFP_KERNEL);
+
+        if (!cfg)
+                return -ENOMEM;
+
+        scmi_hwmon_chan->type = type;
+        scmi_hwmon_chan->config = cfg;
+        for (i = 0; i < num; i++, cfg++)
+                *cfg = config;
+
+        return 0;
+}
+
+static enum hwmon_sensor_types scmi_types[] = {
+        [TEMPERATURE_C] = hwmon_temp,
+        [VOLTAGE] = hwmon_in,
+        [CURRENT] = hwmon_curr,
+        [POWER] = hwmon_power,
+        [ENERGY] = hwmon_energy,
+};
+
+static u32 hwmon_attributes[] = {
+        [hwmon_chip] = HWMON_C_REGISTER_TZ,
+        [hwmon_temp] = HWMON_T_INPUT | HWMON_T_LABEL,
+        [hwmon_in] = HWMON_I_INPUT | HWMON_I_LABEL,
+        [hwmon_curr] = HWMON_C_INPUT | HWMON_C_LABEL,
+        [hwmon_power] = HWMON_P_INPUT | HWMON_P_LABEL,
+        [hwmon_energy] = HWMON_E_INPUT | HWMON_E_LABEL,
+};
+
+static int scmi_hwmon_probe(struct scmi_device *sdev)
+{
+        int i, idx;
+        u16 nr_sensors;
+        enum hwmon_sensor_types type;
+        struct scmi_sensors *scmi_sensors;
+        const struct scmi_sensor_info *sensor;
+        int nr_count[hwmon_max] = {0}, nr_types = 0;
+        const struct hwmon_chip_info *chip_info;
+        struct device *hwdev, *dev = &sdev->dev;
+        struct hwmon_channel_info *scmi_hwmon_chan;
+        const struct hwmon_channel_info **ptr_scmi_ci;
+        const struct scmi_handle *handle = sdev->handle;
+
+        if (!handle || !handle->sensor_ops)
+                return -ENODEV;
+
+        nr_sensors = handle->sensor_ops->count_get(handle);
+        if (!nr_sensors)
+                return -EIO;
+
+        scmi_sensors = devm_kzalloc(dev, sizeof(*scmi_sensors), GFP_KERNEL);
+        if (!scmi_sensors)
+                return -ENOMEM;
+
+        scmi_sensors->handle = handle;
+
+        for (i = 0; i < nr_sensors; i++) {
+                sensor = handle->sensor_ops->info_get(handle, i);
+                if (!sensor)
+                        return PTR_ERR(sensor);
+
+                switch (sensor->type) {
+                case TEMPERATURE_C:
+                case VOLTAGE:
+                case CURRENT:
+                case POWER:
+                case ENERGY:
+                        type = scmi_types[sensor->type];
+                        if (!nr_count[type])
+                                nr_types++;
+                        nr_count[type]++;
+                        break;
+                }
+        }
+
+        if (nr_count[hwmon_temp])
+                nr_count[hwmon_chip]++, nr_types++;
+
+        scmi_hwmon_chan = devm_kcalloc(dev, nr_types, sizeof(*scmi_hwmon_chan),
+                                       GFP_KERNEL);
+        if (!scmi_hwmon_chan)
+                return -ENOMEM;
+
+        ptr_scmi_ci = devm_kcalloc(dev, nr_types + 1, sizeof(*ptr_scmi_ci),
+                                   GFP_KERNEL);
+        if (!ptr_scmi_ci)
+                return -ENOMEM;
+
+        scmi_chip_info.info = ptr_scmi_ci;
+        chip_info = &scmi_chip_info;
+
+        for (type = 0; type < hwmon_max && nr_count[type]; type++) {
+                scmi_hwmon_add_chan_info(scmi_hwmon_chan, dev, nr_count[type],
+                                         type, hwmon_attributes[type]);
+                *ptr_scmi_ci++ = scmi_hwmon_chan++;
+
+                scmi_sensors->info[type] =
+                        devm_kcalloc(dev, nr_count[type],
+                                     sizeof(*scmi_sensors->info), GFP_KERNEL);
+                if (!scmi_sensors->info[type])
+                        return -ENOMEM;
+        }
+
+        for (i = nr_sensors - 1; i >= 0 ; i--) {
+                sensor = handle->sensor_ops->info_get(handle, i);
+                if (!sensor)
+                        continue;
+
+                switch (sensor->type) {
+                case TEMPERATURE_C:
+                case VOLTAGE:
+                case CURRENT:
+                case POWER:
+                case ENERGY:
+                        type = scmi_types[sensor->type];
+                        idx = --nr_count[type];
+                        *(scmi_sensors->info[type] + idx) = sensor;
+                        break;
+                }
+        }
+
+        hwdev = devm_hwmon_device_register_with_info(dev, "scmi_sensors",
+                                                     scmi_sensors, chip_info,
+                                                     NULL);
+
+        return PTR_ERR_OR_ZERO(hwdev);
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+        { SCMI_PROTOCOL_SENSOR },
+        { },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_hwmon_drv = {
+        .name           = "scmi-hwmon",
+        .probe          = scmi_hwmon_probe,
+        .id_table       = scmi_id_table,
+};
+module_scmi_driver(scmi_hwmon_drv);
+
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCMI HWMON interface driver");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/hwmon.h b/include/linux/hwmon.h
index ceb751987c40..e5fd2707b6df 100644
--- a/include/linux/hwmon.h
+++ b/include/linux/hwmon.h
@@ -29,6 +29,7 @@ enum hwmon_sensor_types {
         hwmon_humidity,
         hwmon_fan,
         hwmon_pwm,
+        hwmon_max,
 };
 
 enum hwmon_chip_attributes {
diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
new file mode 100644
index 000000000000..b458c87b866c
--- /dev/null
+++ b/include/linux/scmi_protocol.h
@@ -0,0 +1,277 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SCMI Message Protocol driver header
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ */
+#include <linux/device.h>
+#include <linux/types.h>
+
+#define SCMI_MAX_STR_SIZE       16
+#define SCMI_MAX_NUM_RATES      16
+
+/**
+ * struct scmi_revision_info - version information structure
+ *
+ * @major_ver: Major ABI version. Change here implies risk of backward
+ *      compatibility break.
+ * @minor_ver: Minor ABI version. Change here implies new feature addition,
+ *      or compatible change in ABI.
+ * @num_protocols: Number of protocols that are implemented, excluding the
+ *      base protocol.
+ * @num_agents: Number of agents in the system.
+ * @impl_ver: A vendor-specific implementation version.
+ * @vendor_id: A vendor identifier(Null terminated ASCII string)
+ * @sub_vendor_id: A sub-vendor identifier(Null terminated ASCII string)
+ */
+struct scmi_revision_info {
+        u16 major_ver;
+        u16 minor_ver;
+        u8 num_protocols;
+        u8 num_agents;
+        u32 impl_ver;
+        char vendor_id[SCMI_MAX_STR_SIZE];
+        char sub_vendor_id[SCMI_MAX_STR_SIZE];
+};
+
+struct scmi_clock_info {
+        char name[SCMI_MAX_STR_SIZE];
+        bool rate_discrete;
+        union {
+                struct {
+                        int num_rates;
+                        u64 rates[SCMI_MAX_NUM_RATES];
+                } list;
+                struct {
+                        u64 min_rate;
+                        u64 max_rate;
+                        u64 step_size;
+                } range;
+        };
+};
+
+struct scmi_handle;
+
+/**
+ * struct scmi_clk_ops - represents the various operations provided
+ *      by SCMI Clock Protocol
+ *
+ * @count_get: get the count of clocks provided by SCMI
+ * @info_get: get the information of the specified clock
+ * @rate_get: request the current clock rate of a clock
+ * @rate_set: set the clock rate of a clock
+ * @enable: enables the specified clock
+ * @disable: disables the specified clock
+ */
+struct scmi_clk_ops {
+        int (*count_get)(const struct scmi_handle *handle);
+
+        const struct scmi_clock_info *(*info_get)
+                (const struct scmi_handle *handle, u32 clk_id);
+        int (*rate_get)(const struct scmi_handle *handle, u32 clk_id,
+                        u64 *rate);
+        int (*rate_set)(const struct scmi_handle *handle, u32 clk_id,
+                        u32 config, u64 rate);
+        int (*enable)(const struct scmi_handle *handle, u32 clk_id);
+        int (*disable)(const struct scmi_handle *handle, u32 clk_id);
+};
+
+/**
+ * struct scmi_perf_ops - represents the various operations provided
+ *      by SCMI Performance Protocol
+ *
+ * @limits_set: sets limits on the performance level of a domain
+ * @limits_get: gets limits on the performance level of a domain
+ * @level_set: sets the performance level of a domain
+ * @level_get: gets the performance level of a domain
+ * @device_domain_id: gets the scmi domain id for a given device
+ * @get_transition_latency: gets the DVFS transition latency for a given device
+ * @add_opps_to_device: adds all the OPPs for a given device
+ * @freq_set: sets the frequency for a given device using sustained frequency
+ *      to sustained performance level mapping
+ * @freq_get: gets the frequency for a given device using sustained frequency
+ *      to sustained performance level mapping
+ */
+struct scmi_perf_ops {
+        int (*limits_set)(const struct scmi_handle *handle, u32 domain,
+                          u32 max_perf, u32 min_perf);
+        int (*limits_get)(const struct scmi_handle *handle, u32 domain,
+                          u32 *max_perf, u32 *min_perf);
+        int (*level_set)(const struct scmi_handle *handle, u32 domain,
+                         u32 level, bool poll);
+        int (*level_get)(const struct scmi_handle *handle, u32 domain,
+                         u32 *level, bool poll);
+        int (*device_domain_id)(struct device *dev);
+        int (*get_transition_latency)(const struct scmi_handle *handle,
+                                      struct device *dev);
+        int (*add_opps_to_device)(const struct scmi_handle *handle,
+                                  struct device *dev);
+        int (*freq_set)(const struct scmi_handle *handle, u32 domain,
+                        unsigned long rate, bool poll);
+        int (*freq_get)(const struct scmi_handle *handle, u32 domain,
+                        unsigned long *rate, bool poll);
+};
+
+/**
+ * struct scmi_power_ops - represents the various operations provided
+ *      by SCMI Power Protocol
+ *
+ * @num_domains_get: get the count of power domains provided by SCMI
+ * @name_get: gets the name of a power domain
+ * @state_set: sets the power state of a power domain
+ * @state_get: gets the power state of a power domain
+ */
+struct scmi_power_ops {
+        int (*num_domains_get)(const struct scmi_handle *handle);
+        char *(*name_get)(const struct scmi_handle *handle, u32 domain);
+#define SCMI_POWER_STATE_TYPE_SHIFT     30
+#define SCMI_POWER_STATE_ID_MASK        (BIT(28) - 1)
+#define SCMI_POWER_STATE_PARAM(type, id) \
+        ((((type) & BIT(0)) << SCMI_POWER_STATE_TYPE_SHIFT) | \
+                ((id) & SCMI_POWER_STATE_ID_MASK))
+#define SCMI_POWER_STATE_GENERIC_ON     SCMI_POWER_STATE_PARAM(0, 0)
+#define SCMI_POWER_STATE_GENERIC_OFF    SCMI_POWER_STATE_PARAM(1, 0)
+        int (*state_set)(const struct scmi_handle *handle, u32 domain,
+                         u32 state);
+        int (*state_get)(const struct scmi_handle *handle, u32 domain,
+                         u32 *state);
+};
+
+struct scmi_sensor_info {
+        u32 id;
+        u8 type;
+        char name[SCMI_MAX_STR_SIZE];
+};
+
+/*
+ * Partial list from Distributed Management Task Force (DMTF) specification:
+ * DSP0249 (Platform Level Data Model specification)
+ */
+enum scmi_sensor_class {
+        NONE = 0x0,
+        TEMPERATURE_C = 0x2,
+        VOLTAGE = 0x5,
+        CURRENT = 0x6,
+        POWER = 0x7,
+        ENERGY = 0x8,
+};
+
+/**
+ * struct scmi_sensor_ops - represents the various operations provided
+ *      by SCMI Sensor Protocol
+ *
+ * @count_get: get the count of sensors provided by SCMI
+ * @info_get: get the information of the specified sensor
+ * @configuration_set: control notifications on cross-over events for
+ *      the trip-points
+ * @trip_point_set: selects and configures a trip-point of interest
+ * @reading_get: gets the current value of the sensor
+ */
+struct scmi_sensor_ops {
+        int (*count_get)(const struct scmi_handle *handle);
+
+        const struct scmi_sensor_info *(*info_get)
+                (const struct scmi_handle *handle, u32 sensor_id);
+        int (*configuration_set)(const struct scmi_handle *handle,
+                                 u32 sensor_id);
+        int (*trip_point_set)(const struct scmi_handle *handle, u32 sensor_id,
+                              u8 trip_id, u64 trip_value);
+        int (*reading_get)(const struct scmi_handle *handle, u32 sensor_id,
+                           bool async, u64 *value);
+};
+
+/**
+ * struct scmi_handle - Handle returned to ARM SCMI clients for usage.
+ *
+ * @dev: pointer to the SCMI device
+ * @version: pointer to the structure containing SCMI version information
+ * @power_ops: pointer to set of power protocol operations
+ * @perf_ops: pointer to set of performance protocol operations
+ * @clk_ops: pointer to set of clock protocol operations
+ * @sensor_ops: pointer to set of sensor protocol operations
+ */
+struct scmi_handle {
+        struct device *dev;
+        struct scmi_revision_info *version;
+        struct scmi_perf_ops *perf_ops;
+        struct scmi_clk_ops *clk_ops;
+        struct scmi_power_ops *power_ops;
+        struct scmi_sensor_ops *sensor_ops;
+        /* for protocol internal use */
+        void *perf_priv;
+        void *clk_priv;
+        void *power_priv;
+        void *sensor_priv;
+};
+
+enum scmi_std_protocol {
+        SCMI_PROTOCOL_BASE = 0x10,
+        SCMI_PROTOCOL_POWER = 0x11,
+        SCMI_PROTOCOL_SYSTEM = 0x12,
+        SCMI_PROTOCOL_PERF = 0x13,
+        SCMI_PROTOCOL_CLOCK = 0x14,
+        SCMI_PROTOCOL_SENSOR = 0x15,
+};
+
+struct scmi_device {
+        u32 id;
+        u8 protocol_id;
+        struct device dev;
+        struct scmi_handle *handle;
+};
+
+#define to_scmi_dev(d) container_of(d, struct scmi_device, dev)
+
+struct scmi_device *
+scmi_device_create(struct device_node *np, struct device *parent, int protocol);
+void scmi_device_destroy(struct scmi_device *scmi_dev);
+
+struct scmi_device_id {
+        u8 protocol_id;
+};
+
+struct scmi_driver {
+        const char *name;
+        int (*probe)(struct scmi_device *sdev);
+        void (*remove)(struct scmi_device *sdev);
+        const struct scmi_device_id *id_table;
+
+        struct device_driver driver;
+};
+
+#define to_scmi_driver(d) container_of(d, struct scmi_driver, driver)
+
+#ifdef CONFIG_ARM_SCMI_PROTOCOL
+int scmi_driver_register(struct scmi_driver *driver,
+                         struct module *owner, const char *mod_name);
+void scmi_driver_unregister(struct scmi_driver *driver);
+#else
+static inline int
+scmi_driver_register(struct scmi_driver *driver, struct module *owner,
+                     const char *mod_name)
+{
+        return -EINVAL;
+}
+
+static inline void scmi_driver_unregister(struct scmi_driver *driver) {}
+#endif /* CONFIG_ARM_SCMI_PROTOCOL */
+
+#define scmi_register(driver) \
+        scmi_driver_register(driver, THIS_MODULE, KBUILD_MODNAME)
+#define scmi_unregister(driver) \
+        scmi_driver_unregister(driver)
+
+/**
+ * module_scmi_driver() - Helper macro for registering a scmi driver
+ * @__scmi_driver: scmi_driver structure
+ *
+ * Helper macro for scmi drivers to set up proper module init / exit
+ * functions.  Replaces module_init() and module_exit() and keeps people from
+ * printing pointless things to the kernel log when their driver is loaded.
+ */
+#define module_scmi_driver(__scmi_driver)       \
+        module_driver(__scmi_driver, scmi_register, scmi_unregister)
+
+typedef int (*scmi_prot_init_fn_t)(struct scmi_handle *);
+int scmi_protocol_register(int protocol_id, scmi_prot_init_fn_t fn);
+void scmi_protocol_unregister(int protocol_id);