PSCI: cpuidle: Refactor CPU suspend power_state parameter handling

Current PSCI code handles idle state entry through the
psci_cpu_suspend_enter() API, that takes an idle state index as a
parameter and convert the index into a previously initialized
power_state parameter before calling the PSCI.CPU_SUSPEND() with it.

This is unwieldly, since it forces the PSCI firmware layer to keep track
of power_state parameter for every idle state so that the
index->power_state conversion can be made in the PSCI firmware layer
instead of the CPUidle driver implementations.

Move the power_state handling out of drivers/firmware/psci
into the respective ACPI/DT PSCI CPUidle backends and convert
the psci_cpu_suspend_enter() API to get the power_state
parameter as input, which makes it closer to its firmware
interface PSCI.CPU_SUSPEND() API.

A notable side effect is that the PSCI ACPI/DT CPUidle backends
now can directly handle (and if needed update) power_state
parameters before handing them over to the PSCI firmware
interface to trigger PSCI.CPU_SUSPEND() calls.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Will Deacon <will@kernel.org>

1 files changed, 86 insertions, 1 deletions

diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
index ab1dea918ea3..f3c1a2396f98 100644
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -22,10 +22,15 @@
 
 #include "dt_idle_states.h"
 
+static DEFINE_PER_CPU_READ_MOSTLY(u32 *, psci_power_state);
+
 static int psci_enter_idle_state(struct cpuidle_device *dev,
 				struct cpuidle_driver *drv, int idx)
 {
-	return CPU_PM_CPU_IDLE_ENTER(psci_cpu_suspend_enter, idx);
+	u32 *state = __this_cpu_read(psci_power_state);
+
+	return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter,
+					   idx, state[idx - 1]);
 }
 
 static struct cpuidle_driver psci_idle_driver __initdata = {
@@ -51,6 +56,86 @@ static const struct of_device_id psci_idle_state_match[] __initconst = {
 	{ },
 };
 
+static int __init psci_dt_parse_state_node(struct device_node *np, u32 *state)
+{
+	int err = of_property_read_u32(np, "arm,psci-suspend-param", state);
+
+	if (err) {
+		pr_warn("%pOF missing arm,psci-suspend-param property\n", np);
+		return err;
+	}
+
+	if (!psci_power_state_is_valid(*state)) {
+		pr_warn("Invalid PSCI power state %#x\n", *state);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int __init psci_dt_cpu_init_idle(struct device_node *cpu_node, int cpu)
+{
+	int i, ret = 0, count = 0;
+	u32 *psci_states;
+	struct device_node *state_node;
+
+	/* Count idle states */
+	while ((state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
+					      count))) {
+		count++;
+		of_node_put(state_node);
+	}
+
+	if (!count)
+		return -ENODEV;
+
+	psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL);
+	if (!psci_states)
+		return -ENOMEM;
+
+	for (i = 0; i < count; i++) {
+		state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
+		ret = psci_dt_parse_state_node(state_node, &psci_states[i]);
+		of_node_put(state_node);
+
+		if (ret)
+			goto free_mem;
+
+		pr_debug("psci-power-state %#x index %d\n", psci_states[i], i);
+	}
+
+	/* Idle states parsed correctly, initialize per-cpu pointer */
+	per_cpu(psci_power_state, cpu) = psci_states;
+	return 0;
+
+free_mem:
+	kfree(psci_states);
+	return ret;
+}
+
+static __init 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;
+
+	cpu_node = of_cpu_device_node_get(cpu);
+	if (!cpu_node)
+		return -ENODEV;
+
+	ret = psci_dt_cpu_init_idle(cpu_node, cpu);
+
+	of_node_put(cpu_node);
+
+	return ret;
+}
+
 static int __init psci_idle_init_cpu(int cpu)
 {
 	struct cpuidle_driver *drv;