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>

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index 03e0458..8263429 100644 (file)
--- 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;