1 files changed, 347 insertions, 0 deletions
diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
new file mode 100644
index 000000000000..edd7a54ef0d3
--- /dev/null
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -0,0 +1,347 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * PSCI CPU idle driver.
+ *
+ * Copyright (C) 2019 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+ */
+
+#define pr_fmt(fmt) "CPUidle PSCI: " fmt
+
+#include <linux/cpuhotplug.h>
+#include <linux/cpuidle.h>
+#include <linux/cpumask.h>
+#include <linux/cpu_pm.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/psci.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+
+#include <asm/cpuidle.h>
+
+#include "cpuidle-psci.h"
+#include "dt_idle_states.h"
+
+struct psci_cpuidle_data {
+	u32 *psci_states;
+	struct device *dev;
+};
+
+static DEFINE_PER_CPU_READ_MOSTLY(struct psci_cpuidle_data, psci_cpuidle_data);
+static DEFINE_PER_CPU(u32, domain_state);
+static bool psci_cpuidle_use_cpuhp __initdata;
+
+void psci_set_domain_state(u32 state)
+{
+	__this_cpu_write(domain_state, state);
+}
+
+static inline u32 psci_get_domain_state(void)
+{
+	return __this_cpu_read(domain_state);
+}
+
+static inline int psci_enter_state(int idx, u32 state)
+{
+	return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter, idx, state);
+}
+
+static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
+					struct cpuidle_driver *drv, int idx)
+{
+	struct psci_cpuidle_data *data = this_cpu_ptr(&psci_cpuidle_data);
+	u32 *states = data->psci_states;
+	struct device *pd_dev = data->dev;
+	u32 state;
+	int ret;
+
+	/* Do runtime PM to manage a hierarchical CPU toplogy. */
+	pm_runtime_put_sync_suspend(pd_dev);
+
+	state = psci_get_domain_state();
+	if (!state)
+		state = states[idx];
+
+	ret = psci_enter_state(idx, state);
+
+	pm_runtime_get_sync(pd_dev);
+
+	/* Clear the domain state to start fresh when back from idle. */
+	psci_set_domain_state(0);
+	return ret;
+}
+
+static int psci_idle_cpuhp_up(unsigned int cpu)
+{
+	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
+
+	if (pd_dev)
+		pm_runtime_get_sync(pd_dev);
+
+	return 0;
+}
+
+static int psci_idle_cpuhp_down(unsigned int cpu)
+{
+	struct device *pd_dev = __this_cpu_read(psci_cpuidle_data.dev);
+
+	if (pd_dev) {
+		pm_runtime_put_sync(pd_dev);
+		/* Clear domain state to start fresh at next online. */
+		psci_set_domain_state(0);
+	}
+
+	return 0;
+}
+
+static void __init psci_idle_init_cpuhp(void)
+{
+	int err;
+
+	if (!psci_cpuidle_use_cpuhp)
+		return;
+
+	err = cpuhp_setup_state_nocalls(CPUHP_AP_CPU_PM_STARTING,
+					"cpuidle/psci:online",
+					psci_idle_cpuhp_up,
+					psci_idle_cpuhp_down);
+	if (err)
+		pr_warn("Failed %d while setup cpuhp state\n", err);
+}
+
+static int psci_enter_idle_state(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv, int idx)
+{
+	u32 *state = __this_cpu_read(psci_cpuidle_data.psci_states);
+
+	return psci_enter_state(idx, state[idx]);
+}
+
+static struct cpuidle_driver psci_idle_driver __initdata = {
+	.name = "psci_idle",
+	.owner = THIS_MODULE,
+	/*
+	 * PSCI idle states relies on architectural WFI to
+	 * be represented as state index 0.
+	 */
+	.states[0] = {
+		.enter                  = psci_enter_idle_state,
+		.exit_latency           = 1,
+		.target_residency       = 1,
+		.power_usage		= UINT_MAX,
+		.name                   = "WFI",
+		.desc                   = "ARM WFI",
+	}
+};
+
+static const struct of_device_id psci_idle_state_match[] __initconst = {
+	{ .compatible = "arm,idle-state",
+	  .data = psci_enter_idle_state },
+	{ },
+};
+
+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 cpuidle_driver *drv,
+					struct device_node *cpu_node,
+					unsigned int state_count, int cpu)
+{
+	int i, ret = 0;
+	u32 *psci_states;
+	struct device_node *state_node;
+	struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);
+
+	state_count++; /* Add WFI state too */
+	psci_states = kcalloc(state_count, sizeof(*psci_states), GFP_KERNEL);
+	if (!psci_states)
+		return -ENOMEM;
+
+	for (i = 1; i < state_count; i++) {
+		state_node = of_get_cpu_state_node(cpu_node, i - 1);
+		if (!state_node)
+			break;
+
+		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);
+	}
+
+	if (i != state_count) {
+		ret = -ENODEV;
+		goto free_mem;
+	}
+
+	/* Currently limit the hierarchical topology to be used in OSI mode. */
+	if (psci_has_osi_support()) {
+		data->dev = psci_dt_attach_cpu(cpu);
+		if (IS_ERR(data->dev)) {
+			ret = PTR_ERR(data->dev);
+			goto free_mem;
+		}
+
+		/*
+		 * Using the deepest state for the CPU to trigger a potential
+		 * selection of a shared state for the domain, assumes the
+		 * domain states are all deeper states.
+		 */
+		if (data->dev) {
+			drv->states[state_count - 1].enter =
+				psci_enter_domain_idle_state;
+			psci_cpuidle_use_cpuhp = true;
+		}
+	}
+
+	/* Idle states parsed correctly, store them in the per-cpu struct. */
+	data->psci_states = psci_states;
+	return 0;
+
+free_mem:
+	kfree(psci_states);
+	return ret;
+}
+
+static __init int psci_cpu_init_idle(struct cpuidle_driver *drv,
+				     unsigned int cpu, unsigned int state_count)
+{
+	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(drv, cpu_node, state_count, cpu);
+
+	of_node_put(cpu_node);
+
+	return ret;
+}
+
+static int __init psci_idle_init_cpu(int cpu)
+{
+	struct cpuidle_driver *drv;
+	struct device_node *cpu_node;
+	const char *enable_method;
+	int ret = 0;
+
+	cpu_node = of_cpu_device_node_get(cpu);
+	if (!cpu_node)
+		return -ENODEV;
+
+	/*
+	 * Check whether the enable-method for the cpu is PSCI, fail
+	 * if it is not.
+	 */
+	enable_method = of_get_property(cpu_node, "enable-method", NULL);
+	if (!enable_method || (strcmp(enable_method, "psci")))
+		ret = -ENODEV;
+
+	of_node_put(cpu_node);
+	if (ret)
+		return ret;
+
+	drv = kmemdup(&psci_idle_driver, sizeof(*drv), GFP_KERNEL);
+	if (!drv)
+		return -ENOMEM;
+
+	drv->cpumask = (struct cpumask *)cpumask_of(cpu);
+
+	/*
+	 * Initialize idle states data, starting at index 1, since
+	 * by default idle state 0 is the quiescent state reached
+	 * by the cpu by executing the wfi instruction.
+	 *
+	 * If no DT idle states are detected (ret == 0) let the driver
+	 * initialization fail accordingly since there is no reason to
+	 * initialize the idle driver if only wfi is supported, the
+	 * default archictectural back-end already executes wfi
+	 * on idle entry.
+	 */
+	ret = dt_init_idle_driver(drv, psci_idle_state_match, 1);
+	if (ret <= 0) {
+		ret = ret ? : -ENODEV;
+		goto out_kfree_drv;
+	}
+
+	/*
+	 * Initialize PSCI idle states.
+	 */
+	ret = psci_cpu_init_idle(drv, cpu, ret);
+	if (ret) {
+		pr_err("CPU %d failed to PSCI idle\n", cpu);
+		goto out_kfree_drv;
+	}
+
+	ret = cpuidle_register(drv, NULL);
+	if (ret)
+		goto out_kfree_drv;
+
+	return 0;
+
+out_kfree_drv:
+	kfree(drv);
+	return ret;
+}
+
+/*
+ * psci_idle_init - Initializes PSCI cpuidle driver
+ *
+ * Initializes PSCI cpuidle driver for all CPUs, if any CPU fails
+ * to register cpuidle driver then rollback to cancel all CPUs
+ * registration.
+ */
+static int __init psci_idle_init(void)
+{
+	int cpu, ret;
+	struct cpuidle_driver *drv;
+	struct cpuidle_device *dev;
+
+	for_each_possible_cpu(cpu) {
+		ret = psci_idle_init_cpu(cpu);
+		if (ret)
+			goto out_fail;
+	}
+
+	psci_idle_init_cpuhp();
+	return 0;
+
+out_fail:
+	while (--cpu >= 0) {
+		dev = per_cpu(cpuidle_devices, cpu);
+		drv = cpuidle_get_cpu_driver(dev);
+		cpuidle_unregister(drv);
+		kfree(drv);
+	}
+
+	return ret;
+}
+device_initcall(psci_idle_init);