drivers: firmware: psci: initialise idle states using ACPI LPI

This patch adds support for initialisation of PSCI CPUIdle states
from Low Power Idle(_LPI) entries in the ACPI tables when acpi is
enabled.

Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 59 insertions, 7 deletions

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index 03e04582791c..8263429e21b8 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -13,6 +13,7 @@
 
 #define pr_fmt(fmt) "psci: " fmt
 
+#include <linux/acpi.h>
 #include <linux/arm-smccc.h>
 #include <linux/cpuidle.h>
 #include <linux/errno.h>
@@ -256,13 +257,6 @@ static int psci_dt_cpu_init_idle(struct device_node *cpu_node, int cpu)
         u32 *psci_states;
         struct device_node *state_node;
 
-        /*
-         * If the PSCI cpu_suspend function hook has not been initialized
-         * idle states must not be enabled, so bail out
-         */
-        if (!psci_ops.cpu_suspend)
-                return -EOPNOTSUPP;
-
         /* Count idle states */
         while ((state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
                                               count))) {
@@ -310,11 +304,69 @@ free_mem:
         return ret;
 }
 
+#ifdef CONFIG_ACPI
+#include <acpi/processor.h>
+
+static int __maybe_unused psci_acpi_cpu_init_idle(unsigned int cpu)
+{
+        int i, count;
+        u32 *psci_states;
+        struct acpi_lpi_state *lpi;
+        struct acpi_processor *pr = per_cpu(processors, cpu);
+
+        if (unlikely(!pr || !pr->flags.has_lpi))
+                return -EINVAL;
+
+        count = pr->power.count - 1;
+        if (count <= 0)
+                return -ENODEV;
+
+        psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL);
+        if (!psci_states)
+                return -ENOMEM;
+
+        for (i = 0; i < count; i++) {
+                u32 state;
+
+                lpi = &pr->power.lpi_states[i + 1];
+                /*
+                 * Only bits[31:0] represent a PSCI power_state while
+                 * bits[63:32] must be 0x0 as per ARM ACPI FFH Specification
+                 */
+                state = lpi->address;
+                if (!psci_power_state_is_valid(state)) {
+                        pr_warn("Invalid PSCI power state %#x\n", state);
+                        kfree(psci_states);
+                        return -EINVAL;
+                }
+                psci_states[i] = state;
+        }
+        /* Idle states parsed correctly, initialize per-cpu pointer */
+        per_cpu(psci_power_state, cpu) = psci_states;
+        return 0;
+}
+#else
+static int __maybe_unused psci_acpi_cpu_init_idle(unsigned int cpu)
+{
+        return -EINVAL;
+}
+#endif
+
 int psci_cpu_init_idle(unsigned int cpu)
 {
         struct device_node *cpu_node;
         int ret;
 
+        /*
+         * If the PSCI cpu_suspend function hook has not been initialized
+         * idle states must not be enabled, so bail out
+         */
+        if (!psci_ops.cpu_suspend)
+                return -EOPNOTSUPP;
+
+        if (!acpi_disabled)
+                return psci_acpi_cpu_init_idle(cpu);
+
         cpu_node = of_get_cpu_node(cpu, NULL);
         if (!cpu_node)
                 return -ENODEV;