5 files changed, 432 insertions, 3 deletions

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 9fd9c6717e0c..c04fed9eb15d 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -33,4 +33,16 @@ config OMAP_MBOX_KFIFO_SIZE
           Specify the default size of mailbox's kfifo buffers (bytes).
           This can also be changed at runtime (via the mbox_kfifo_size
           module parameter).
+
+config PCC
+        bool "Platform Communication Channel Driver"
+        depends on ACPI
+        help
+          ACPI 5.0+ spec defines a generic mode of communication
+          between the OS and a platform such as the BMC. This medium
+          (PCC) is typically used by CPPC (ACPI CPU Performance management),
+          RAS (ACPI reliability protocol) and MPST (ACPI Memory power
+          states). Select this driver if your platform implements the
+          PCC clients mentioned above.
+
 endif
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index 94ed7cefb14d..dd412c22208b 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -5,3 +5,5 @@ obj-$(CONFIG_MAILBOX)		+= mailbox.o
 obj-$(CONFIG_PL320_MBOX)        += pl320-ipc.o
 
 obj-$(CONFIG_OMAP2PLUS_MBOX)    += omap-mailbox.o
+
+obj-$(CONFIG_PCC)               += pcc.o
diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index 58789b027708..59aad4d5da53 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -21,9 +21,7 @@
 #include <linux/mailbox_client.h>
 #include <linux/mailbox_controller.h>
 
-#define TXDONE_BY_IRQ   BIT(0) /* controller has remote RTR irq */
-#define TXDONE_BY_POLL  BIT(1) /* controller can read status of last TX */
-#define TXDONE_BY_ACK   BIT(2) /* S/W ACK recevied by Client ticks the TX */
+#include "mailbox.h"
 
 static LIST_HEAD(mbox_cons);
 static DEFINE_MUTEX(con_mutex);
diff --git a/drivers/mailbox/mailbox.h b/drivers/mailbox/mailbox.h
new file mode 100644
index 000000000000..456ba68513bb
--- /dev/null
+++ b/drivers/mailbox/mailbox.h
@@ -0,0 +1,14 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __MAILBOX_H
+#define __MAILBOX_H
+
+#define TXDONE_BY_IRQ   BIT(0) /* controller has remote RTR irq */
+#define TXDONE_BY_POLL  BIT(1) /* controller can read status of last TX */
+#define TXDONE_BY_ACK   BIT(2) /* S/W ACK recevied by Client ticks the TX */
+
+#endif /* __MAILBOX_H */
diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
new file mode 100644
index 000000000000..6dbf6fcbdfaf
--- /dev/null
+++ b/drivers/mailbox/pcc.c
@@ -0,0 +1,403 @@
+/*
+ *      Copyright (C) 2014 Linaro Ltd.
+ *      Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  PCC (Platform Communication Channel) is defined in the ACPI 5.0+
+ *  specification. It is a mailbox like mechanism to allow clients
+ *  such as CPPC (Collaborative Processor Performance Control), RAS
+ *  (Reliability, Availability and Serviceability) and MPST (Memory
+ *  Node Power State Table) to talk to the platform (e.g. BMC) through
+ *  shared memory regions as defined in the PCC table entries. The PCC
+ *  specification supports a Doorbell mechanism for the PCC clients
+ *  to notify the platform about new data. This Doorbell information
+ *  is also specified in each PCC table entry. See pcc_send_data()
+ *  and pcc_tx_done() for basic mode of operation.
+ *
+ *  For more details about PCC, please see the ACPI specification from
+ *  http://www.uefi.org/ACPIv5.1 Section 14.
+ *
+ *  This file implements PCC as a Mailbox controller and allows for PCC
+ *  clients to be implemented as its Mailbox Client Channels.
+ */
+
+#include <linux/acpi.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/platform_device.h>
+#include <linux/mailbox_controller.h>
+#include <linux/mailbox_client.h>
+
+#include "mailbox.h"
+
+#define MAX_PCC_SUBSPACES       256
+#define PCCS_SS_SIG_MAGIC       0x50434300
+#define PCC_CMD_COMPLETE        0x1
+
+static struct mbox_chan *pcc_mbox_channels;
+
+static struct mbox_controller pcc_mbox_ctrl = {};
+/**
+ * get_pcc_channel - Given a PCC subspace idx, get
+ *      the respective mbox_channel.
+ * @id: PCC subspace index.
+ *
+ * Return: ERR_PTR(errno) if error, else pointer
+ *      to mbox channel.
+ */
+static struct mbox_chan *get_pcc_channel(int id)
+{
+        struct mbox_chan *pcc_chan;
+
+        if (id < 0 || id > pcc_mbox_ctrl.num_chans)
+                return ERR_PTR(-ENOENT);
+
+        pcc_chan = (struct mbox_chan *)
+                (unsigned long) pcc_mbox_channels +
+                (id * sizeof(*pcc_chan));
+
+        return pcc_chan;
+}
+
+/**
+ * get_subspace_id - Given a Mailbox channel, find out the
+ *              PCC subspace id.
+ * @chan: Pointer to Mailbox Channel from which we want
+ *              the index.
+ * Return: Errno if not found, else positive index number.
+ */
+static int get_subspace_id(struct mbox_chan *chan)
+{
+        unsigned int id = chan - pcc_mbox_channels;
+
+        if (id < 0 || id > pcc_mbox_ctrl.num_chans)
+                return -ENOENT;
+
+        return id;
+}
+
+/**
+ * pcc_mbox_request_channel - PCC clients call this function to
+ *              request a pointer to their PCC subspace, from which they
+ *              can get the details of communicating with the remote.
+ * @cl: Pointer to Mailbox client, so we know where to bind the
+ *              Channel.
+ * @subspace_id: The PCC Subspace index as parsed in the PCC client
+ *              ACPI package. This is used to lookup the array of PCC
+ *              subspaces as parsed by the PCC Mailbox controller.
+ *
+ * Return: Pointer to the Mailbox Channel if successful or
+ *              ERR_PTR.
+ */
+struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
+                int subspace_id)
+{
+        struct device *dev = pcc_mbox_ctrl.dev;
+        struct mbox_chan *chan;
+        unsigned long flags;
+
+        /*
+         * Each PCC Subspace is a Mailbox Channel.
+         * The PCC Clients get their PCC Subspace ID
+         * from their own tables and pass it here.
+         * This returns a pointer to the PCC subspace
+         * for the Client to operate on.
+         */
+        chan = get_pcc_channel(subspace_id);
+
+        if (!chan || chan->cl) {
+                dev_err(dev, "%s: PCC mailbox not free\n", __func__);
+                return ERR_PTR(-EBUSY);
+        }
+
+        spin_lock_irqsave(&chan->lock, flags);
+        chan->msg_free = 0;
+        chan->msg_count = 0;
+        chan->active_req = NULL;
+        chan->cl = cl;
+        init_completion(&chan->tx_complete);
+
+        if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
+                chan->txdone_method |= TXDONE_BY_ACK;
+
+        spin_unlock_irqrestore(&chan->lock, flags);
+
+        return chan;
+}
+EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
+
+/**
+ * pcc_mbox_free_channel - Clients call this to free their Channel.
+ *
+ * @chan: Pointer to the mailbox channel as returned by
+ *              pcc_mbox_request_channel()
+ */
+void pcc_mbox_free_channel(struct mbox_chan *chan)
+{
+        unsigned long flags;
+
+        if (!chan || !chan->cl)
+                return;
+
+        spin_lock_irqsave(&chan->lock, flags);
+        chan->cl = NULL;
+        chan->active_req = NULL;
+        if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
+                chan->txdone_method = TXDONE_BY_POLL;
+
+        spin_unlock_irqrestore(&chan->lock, flags);
+}
+EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
+
+/**
+ * pcc_tx_done - Callback from Mailbox controller code to
+ *              check if PCC message transmission completed.
+ * @chan: Pointer to Mailbox channel on which previous
+ *              transmission occurred.
+ *
+ * Return: TRUE if succeeded.
+ */
+static bool pcc_tx_done(struct mbox_chan *chan)
+{
+        struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
+        struct acpi_pcct_shared_memory *generic_comm_base =
+                (struct acpi_pcct_shared_memory *) pcct_ss->base_address;
+        u16 cmd_delay = pcct_ss->latency;
+        unsigned int retries = 0;
+
+        /* Try a few times while waiting for platform to consume */
+        while (!(readw_relaxed(&generic_comm_base->status)
+                    & PCC_CMD_COMPLETE)) {
+
+                if (retries++ < 5)
+                        udelay(cmd_delay);
+                else {
+                        /*
+                         * If the remote is dead, this will cause the Mbox
+                         * controller to timeout after mbox client.tx_tout
+                         * msecs.
+                         */
+                        pr_err("PCC platform did not respond.\n");
+                        return false;
+                }
+        }
+        return true;
+}
+
+/**
+ * pcc_send_data - Called from Mailbox Controller code to finally
+ *      transmit data over channel.
+ * @chan: Pointer to Mailbox channel over which to send data.
+ * @data: Actual data to be written over channel.
+ *
+ * Return: Err if something failed else 0 for success.
+ */
+static int pcc_send_data(struct mbox_chan *chan, void *data)
+{
+        struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
+        struct acpi_pcct_shared_memory *generic_comm_base =
+                (struct acpi_pcct_shared_memory *) pcct_ss->base_address;
+        struct acpi_generic_address doorbell;
+        u64 doorbell_preserve;
+        u64 doorbell_val;
+        u64 doorbell_write;
+        u16 cmd = *(u16 *) data;
+        u16 ss_idx = -1;
+
+        ss_idx = get_subspace_id(chan);
+
+        if (ss_idx < 0) {
+                pr_err("Invalid Subspace ID from PCC client\n");
+                return -EINVAL;
+        }
+
+        doorbell = pcct_ss->doorbell_register;
+        doorbell_preserve = pcct_ss->preserve_mask;
+        doorbell_write = pcct_ss->write_mask;
+
+        /* Write to the shared comm region. */
+        writew(cmd, &generic_comm_base->command);
+
+        /* Write Subspace MAGIC value so platform can identify destination. */
+        writel((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature);
+
+        /* Flip CMD COMPLETE bit */
+        writew(0, &generic_comm_base->status);
+
+        /* Sync notification from OSPM to Platform. */
+        acpi_read(&doorbell_val, &doorbell);
+        acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
+                        &doorbell);
+
+        return 0;
+}
+
+static struct mbox_chan_ops pcc_chan_ops = {
+        .send_data = pcc_send_data,
+        .last_tx_done = pcc_tx_done,
+};
+
+/**
+ * parse_pcc_subspace - Parse the PCC table and verify PCC subspace
+ *              entries. There should be one entry per PCC client.
+ * @header: Pointer to the ACPI subtable header under the PCCT.
+ * @end: End of subtable entry.
+ *
+ * Return: 0 for Success, else errno.
+ *
+ * This gets called for each entry in the PCC table.
+ */
+static int parse_pcc_subspace(struct acpi_subtable_header *header,
+                const unsigned long end)
+{
+        struct acpi_pcct_hw_reduced *pcct_ss;
+
+        if (pcc_mbox_ctrl.num_chans <= MAX_PCC_SUBSPACES) {
+                pcct_ss = (struct acpi_pcct_hw_reduced *) header;
+
+                if (pcct_ss->header.type !=
+                                ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE) {
+                        pr_err("Incorrect PCC Subspace type detected\n");
+                        return -EINVAL;
+                }
+        }
+
+        return 0;
+}
+
+/**
+ * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
+ *
+ * Return: 0 for Success, else errno.
+ */
+static int __init acpi_pcc_probe(void)
+{
+        acpi_size pcct_tbl_header_size;
+        struct acpi_table_header *pcct_tbl;
+        struct acpi_subtable_header *pcct_entry;
+        int count, i;
+        acpi_status status = AE_OK;
+
+        /* Search for PCCT */
+        status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0,
+                        &pcct_tbl,
+                        &pcct_tbl_header_size);
+
+        if (ACPI_FAILURE(status) || !pcct_tbl) {
+                pr_warn("PCCT header not found.\n");
+                return -ENODEV;
+        }
+
+        count = acpi_table_parse_entries(ACPI_SIG_PCCT,
+                        sizeof(struct acpi_table_pcct),
+                        ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE,
+                        parse_pcc_subspace, MAX_PCC_SUBSPACES);
+
+        if (count <= 0) {
+                pr_err("Error parsing PCC subspaces from PCCT\n");
+                return -EINVAL;
+        }
+
+        pcc_mbox_channels = kzalloc(sizeof(struct mbox_chan) *
+                        count, GFP_KERNEL);
+
+        if (!pcc_mbox_channels) {
+                pr_err("Could not allocate space for PCC mbox channels\n");
+                return -ENOMEM;
+        }
+
+        /* Point to the first PCC subspace entry */
+        pcct_entry = (struct acpi_subtable_header *) (
+                (unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
+
+        for (i = 0; i < count; i++) {
+                pcc_mbox_channels[i].con_priv = pcct_entry;
+                pcct_entry = (struct acpi_subtable_header *)
+                        ((unsigned long) pcct_entry + pcct_entry->length);
+        }
+
+        pcc_mbox_ctrl.num_chans = count;
+
+        pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
+
+        return 0;
+}
+
+/**
+ * pcc_mbox_probe - Called when we find a match for the
+ *      PCCT platform device. This is purely used to represent
+ *      the PCCT as a virtual device for registering with the
+ *      generic Mailbox framework.
+ *
+ * @pdev: Pointer to platform device returned when a match
+ *      is found.
+ *
+ *      Return: 0 for Success, else errno.
+ */
+static int pcc_mbox_probe(struct platform_device *pdev)
+{
+        int ret = 0;
+
+        pcc_mbox_ctrl.chans = pcc_mbox_channels;
+        pcc_mbox_ctrl.ops = &pcc_chan_ops;
+        pcc_mbox_ctrl.txdone_poll = true;
+        pcc_mbox_ctrl.txpoll_period = 10;
+        pcc_mbox_ctrl.dev = &pdev->dev;
+
+        pr_info("Registering PCC driver as Mailbox controller\n");
+        ret = mbox_controller_register(&pcc_mbox_ctrl);
+
+        if (ret) {
+                pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
+                ret = -ENODEV;
+        }
+
+        return ret;
+}
+
+struct platform_driver pcc_mbox_driver = {
+        .probe = pcc_mbox_probe,
+        .driver = {
+                .name = "PCCT",
+                .owner = THIS_MODULE,
+        },
+};
+
+static int __init pcc_init(void)
+{
+        int ret;
+        struct platform_device *pcc_pdev;
+
+        if (acpi_disabled)
+                return -ENODEV;
+
+        /* Check if PCC support is available. */
+        ret = acpi_pcc_probe();
+
+        if (ret) {
+                pr_err("ACPI PCC probe failed.\n");
+                return -ENODEV;
+        }
+
+        pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
+                        pcc_mbox_probe, NULL, 0, NULL, 0);
+
+        if (!pcc_pdev) {
+                pr_err("Err creating PCC platform bundle\n");
+                return -ENODEV;
+        }
+
+        return 0;
+}
+device_initcall(pcc_init);