[RFC PATCH 3/3] arm: psci: add cpuidle_ops support

[Jisheng Zhang]

This patch implement cpuidle_ops using psci, the code is stolen from
arm64. Now we can use cpuidle-arm.c for both arm and arm64.

Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxxx>
---
 arch/arm/kernel/psci.c | 116 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 116 insertions(+)

diff --git a/arch/arm/kernel/psci.c b/arch/arm/kernel/psci.c
index 7f6ff02..7bf744d 100644
--- a/arch/arm/kernel/psci.c
+++ b/arch/arm/kernel/psci.c
@@ -13,16 +13,132 @@
  * Author: Will Deacon <will.deacon@xxxxxxx>
  */
 
+#include <linux/cpuidle.h>
 #include <linux/init.h>
 #include <linux/smp.h>
 #include <linux/of.h>
 #include <linux/delay.h>
 #include <linux/psci.h>
+#include <linux/slab.h>
 
 #include <uapi/linux/psci.h>
 
+#include <asm/cpuidle.h>
 #include <asm/psci.h>
 #include <asm/smp_plat.h>
+#include <asm/suspend.h>
+
+#ifdef CONFIG_CPU_IDLE
+static bool psci_power_state_loses_context(u32 state)
+{
+	return state & PSCI_0_2_POWER_STATE_TYPE_MASK;
+}
+
+static bool psci_power_state_is_valid(u32 state)
+{
+	const u32 valid_mask = PSCI_0_2_POWER_STATE_ID_MASK |
+			       PSCI_0_2_POWER_STATE_TYPE_MASK |
+			       PSCI_0_2_POWER_STATE_AFFL_MASK;
+
+	return !(state & ~valid_mask);
+}
+
+static DEFINE_PER_CPU_READ_MOSTLY(u32 *, psci_power_state);
+
+static int __init cpu_psci_cpu_init_idle(struct device_node *cpu_node,
+					 int cpu)
+{
+	int i, ret, count = 0;
+	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))) {
+		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++) {
+		u32 state;
+
+		state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
+
+		ret = of_property_read_u32(state_node,
+					   "arm,psci-suspend-param",
+					   &state);
+		if (ret) {
+			pr_warn(" * %s missing arm,psci-suspend-param property\n",
+				state_node->full_name);
+			of_node_put(state_node);
+			goto free_mem;
+		}
+
+		of_node_put(state_node);
+		pr_warn("psci-power-state %#x index %d\n", state, i);
+		if (!psci_power_state_is_valid(state)) {
+			pr_warn("Invalid PSCI power state %#x\n", state);
+			ret = -EINVAL;
+			goto free_mem;
+		}
+		psci_states[i] = state;
+	}
+	/* 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 int psci_suspend_finisher(unsigned long index)
+{
+	u32 *state = __this_cpu_read(psci_power_state);
+
+	return psci_ops.cpu_suspend(state[index - 1],
+				    virt_to_phys(cpu_resume));
+}
+
+static int cpu_psci_cpu_suspend(int cpu, unsigned long index)
+{
+	int ret;
+	u32 *state = __this_cpu_read(psci_power_state);
+	/*
+	 * idle state index 0 corresponds to wfi, should never be called
+	 * from the cpu_suspend operations
+	 */
+	if (WARN_ON_ONCE(!index))
+		return -EINVAL;
+
+	if (!psci_power_state_loses_context(state[index - 1]))
+		ret = psci_ops.cpu_suspend(state[index - 1], 0);
+	else
+		ret = cpu_suspend(index, psci_suspend_finisher);
+
+	return ret;
+}
+
+static struct cpuidle_ops psci_cpuidle_ops __initdata = {
+	.suspend = cpu_psci_cpu_suspend,
+	.init = cpu_psci_cpu_init_idle,
+};
+CPUIDLE_METHOD_OF_DECLARE(psci_idle, "psci", &psci_cpuidle_ops);
+#endif
 
 /*
  * psci_smp assumes that the following is true about PSCI:
-- 
2.1.4

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