drivers/cpuidle/cpuidle-psci.c - third_party/linux - Git at Google

 // 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/cpu_cooling.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/platform_device.h>
 #include <linux/psci.h>
 #include <linux/pm_domain.h>
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/syscore_ops.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;

 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,
 					  bool s2idle)
 {
 	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;

 	ret = cpu_pm_enter();
 	if (ret)
 		return -1;

 	/* Do runtime PM to manage a hierarchical CPU toplogy. */
 	ct_irq_enter_irqson();
 	if (s2idle)
 		dev_pm_genpd_suspend(pd_dev);
 	else
 		pm_runtime_put_sync_suspend(pd_dev);
 	ct_irq_exit_irqson();

 	state = psci_get_domain_state();
 	if (!state)
 		state = states[idx];

 	ret = psci_cpu_suspend_enter(state) ? -1 : idx;

 	ct_irq_enter_irqson();
 	if (s2idle)
 		dev_pm_genpd_resume(pd_dev);
 	else
 		pm_runtime_get_sync(pd_dev);
 	ct_irq_exit_irqson();

 	cpu_pm_exit();

 	/* Clear the domain state to start fresh when back from idle. */
 	psci_set_domain_state(0);
 	return ret;
 }

 static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
 					struct cpuidle_driver *drv, int idx)
 {
 	return __psci_enter_domain_idle_state(dev, drv, idx, false);
 }

 static int psci_enter_s2idle_domain_idle_state(struct cpuidle_device *dev,
 					       struct cpuidle_driver *drv,
 					       int idx)
 {
 	return __psci_enter_domain_idle_state(dev, drv, idx, true);
 }

 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 psci_idle_syscore_switch(bool suspend)
 {
 	bool cleared = false;
 	struct device *dev;
 	int cpu;

 	for_each_possible_cpu(cpu) {
 		dev = per_cpu_ptr(&psci_cpuidle_data, cpu)->dev;

 		if (dev && suspend) {
 			dev_pm_genpd_suspend(dev);
 		} else if (dev) {
 			dev_pm_genpd_resume(dev);

 			/* Account for userspace having offlined a CPU. */
 			if (pm_runtime_status_suspended(dev))
 				pm_runtime_set_active(dev);

 			/* Clear domain state to re-start fresh. */
 			if (!cleared) {
 				psci_set_domain_state(0);
 				cleared = true;
 			}
 		}
 	}
 }

 static int psci_idle_syscore_suspend(void)
 {
 	psci_idle_syscore_switch(true);
 	return 0;
 }

 static void psci_idle_syscore_resume(void)
 {
 	psci_idle_syscore_switch(false);
 }

 static struct syscore_ops psci_idle_syscore_ops = {
 	.suspend = psci_idle_syscore_suspend,
 	.resume = psci_idle_syscore_resume,
 };

 static void psci_idle_init_cpuhp(void)
 {
 	int err;

 	if (!psci_cpuidle_use_cpuhp)
 		return;

 	register_syscore_ops(&psci_idle_syscore_ops);

 	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 const struct of_device_id psci_idle_state_match[] = {
 	{ .compatible = "arm,idle-state",
 	  .data = psci_enter_idle_state },
 	{ },
 };

 int 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 psci_dt_cpu_init_topology(struct cpuidle_driver *drv,
 				     struct psci_cpuidle_data *data,
 				     unsigned int state_count, int cpu)
 {
 	/* Currently limit the hierarchical topology to be used in OSI mode. */
 	if (!psci_has_osi_support())
 		return 0;

 	data->dev = psci_dt_attach_cpu(cpu);
 	if (IS_ERR_OR_NULL(data->dev))
 		return PTR_ERR_OR_ZERO(data->dev);

 	/*
 	 * 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.
 	 */
 	drv->states[state_count - 1].enter = psci_enter_domain_idle_state;
 	drv->states[state_count - 1].enter_s2idle = psci_enter_s2idle_domain_idle_state;
 	psci_cpuidle_use_cpuhp = true;

 	return 0;
 }

 static int psci_dt_cpu_init_idle(struct device *dev, 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 = devm_kcalloc(dev, 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)
 			return ret;

 		pr_debug("psci-power-state %#x index %d\n", psci_states[i], i);
 	}

 	if (i != state_count)
 		return -ENODEV;

 	/* Initialize optional data, used for the hierarchical topology. */
 	ret = psci_dt_cpu_init_topology(drv, data, state_count, cpu);
 	if (ret < 0)
 		return ret;

 	/* Idle states parsed correctly, store them in the per-cpu struct. */
 	data->psci_states = psci_states;
 	return 0;
 }

 static int psci_cpu_init_idle(struct device *dev, 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(dev, drv, cpu_node, state_count, cpu);

 	of_node_put(cpu_node);

 	return ret;
 }

 static void psci_cpu_deinit_idle(int cpu)
 {
 	struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);

 	psci_dt_detach_cpu(data->dev);
 	psci_cpuidle_use_cpuhp = false;
 }

 static int psci_idle_init_cpu(struct device *dev, 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 = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
 	if (!drv)
 		return -ENOMEM;

 	drv->name = "psci_idle";
 	drv->owner = THIS_MODULE;
 	drv->cpumask = (struct cpumask *)cpumask_of(cpu);

 	/*
 	 * PSCI idle states relies on architectural WFI to be represented as
 	 * state index 0.
 	 */
 	drv->states[0].enter = psci_enter_idle_state;
 	drv->states[0].exit_latency = 1;
 	drv->states[0].target_residency = 1;
 	drv->states[0].power_usage = UINT_MAX;
 	strcpy(drv->states[0].name, "WFI");
 	strcpy(drv->states[0].desc, "ARM WFI");

 	/*
 	 * 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)
 		return ret ? : -ENODEV;

 	/*
 	 * Initialize PSCI idle states.
 	 */
 	ret = psci_cpu_init_idle(dev, drv, cpu, ret);
 	if (ret) {
 		pr_err("CPU %d failed to PSCI idle\n", cpu);
 		return ret;
 	}

 	ret = cpuidle_register(drv, NULL);
 	if (ret)
 		goto deinit;

 	cpuidle_cooling_register(drv);

 	return 0;
 deinit:
 	psci_cpu_deinit_idle(cpu);
 	return ret;
 }

 /*
  * psci_idle_probe - 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 psci_cpuidle_probe(struct platform_device *pdev)
 {
 	int cpu, ret;
 	struct cpuidle_driver *drv;
 	struct cpuidle_device *dev;

 	for_each_possible_cpu(cpu) {
 		ret = psci_idle_init_cpu(&pdev->dev, 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);
 		psci_cpu_deinit_idle(cpu);
 	}

 	return ret;
 }

 static struct platform_driver psci_cpuidle_driver = {
 	.probe = psci_cpuidle_probe,
 	.driver = {
 		.name = "psci-cpuidle",
 	},
 };

 static int __init psci_idle_init(void)
 {
 	struct platform_device *pdev;
 	int ret;

 	ret = platform_driver_register(&psci_cpuidle_driver);
 	if (ret)
 		return ret;

 	pdev = platform_device_register_simple("psci-cpuidle", -1, NULL, 0);
 	if (IS_ERR(pdev)) {
 		platform_driver_unregister(&psci_cpuidle_driver);
 		return PTR_ERR(pdev);
 	}

 	return 0;
 }
 device_initcall(psci_idle_init);
	// 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/cpu_cooling.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/platform_device.h>
	#include <linux/psci.h>
	#include <linux/pm_domain.h>
	#include <linux/pm_runtime.h>
	#include <linux/slab.h>
	#include <linux/string.h>
	#include <linux/syscore_ops.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;

	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,
	bool s2idle)
	{
	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;

	ret = cpu_pm_enter();
	if (ret)
	return -1;

	/* Do runtime PM to manage a hierarchical CPU toplogy. */
	ct_irq_enter_irqson();
	if (s2idle)
	dev_pm_genpd_suspend(pd_dev);
	else
	pm_runtime_put_sync_suspend(pd_dev);
	ct_irq_exit_irqson();

	state = psci_get_domain_state();
	if (!state)
	state = states[idx];

	ret = psci_cpu_suspend_enter(state) ? -1 : idx;

	ct_irq_enter_irqson();
	if (s2idle)
	dev_pm_genpd_resume(pd_dev);
	else
	pm_runtime_get_sync(pd_dev);
	ct_irq_exit_irqson();

	cpu_pm_exit();

	/* Clear the domain state to start fresh when back from idle. */
	psci_set_domain_state(0);
	return ret;
	}

	static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
	struct cpuidle_driver *drv, int idx)
	{
	return __psci_enter_domain_idle_state(dev, drv, idx, false);
	}

	static int psci_enter_s2idle_domain_idle_state(struct cpuidle_device *dev,
	struct cpuidle_driver *drv,
	int idx)
	{
	return __psci_enter_domain_idle_state(dev, drv, idx, true);
	}

	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 psci_idle_syscore_switch(bool suspend)
	{
	bool cleared = false;
	struct device *dev;
	int cpu;

	for_each_possible_cpu(cpu) {
	dev = per_cpu_ptr(&psci_cpuidle_data, cpu)->dev;

	if (dev && suspend) {
	dev_pm_genpd_suspend(dev);
	} else if (dev) {
	dev_pm_genpd_resume(dev);

	/* Account for userspace having offlined a CPU. */
	if (pm_runtime_status_suspended(dev))
	pm_runtime_set_active(dev);

	/* Clear domain state to re-start fresh. */
	if (!cleared) {
	psci_set_domain_state(0);
	cleared = true;
	}
	}
	}
	}

	static int psci_idle_syscore_suspend(void)
	{
	psci_idle_syscore_switch(true);
	return 0;
	}

	static void psci_idle_syscore_resume(void)
	{
	psci_idle_syscore_switch(false);
	}

	static struct syscore_ops psci_idle_syscore_ops = {
	.suspend = psci_idle_syscore_suspend,
	.resume = psci_idle_syscore_resume,
	};

	static void psci_idle_init_cpuhp(void)
	{
	int err;

	if (!psci_cpuidle_use_cpuhp)
	return;

	register_syscore_ops(&psci_idle_syscore_ops);

	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 const struct of_device_id psci_idle_state_match[] = {
	{ .compatible = "arm,idle-state",
	.data = psci_enter_idle_state },
	{ },
	};

	int 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 psci_dt_cpu_init_topology(struct cpuidle_driver *drv,
	struct psci_cpuidle_data *data,
	unsigned int state_count, int cpu)
	{
	/* Currently limit the hierarchical topology to be used in OSI mode. */
	if (!psci_has_osi_support())
	return 0;

	data->dev = psci_dt_attach_cpu(cpu);
	if (IS_ERR_OR_NULL(data->dev))
	return PTR_ERR_OR_ZERO(data->dev);

	/*
	* 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.
	*/
	drv->states[state_count - 1].enter = psci_enter_domain_idle_state;
	drv->states[state_count - 1].enter_s2idle = psci_enter_s2idle_domain_idle_state;
	psci_cpuidle_use_cpuhp = true;

	return 0;
	}

	static int psci_dt_cpu_init_idle(struct device dev, 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 = devm_kcalloc(dev, 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)
	return ret;

	pr_debug("psci-power-state %#x index %d\n", psci_states[i], i);
	}

	if (i != state_count)
	return -ENODEV;

	/* Initialize optional data, used for the hierarchical topology. */
	ret = psci_dt_cpu_init_topology(drv, data, state_count, cpu);
	if (ret < 0)
	return ret;

	/* Idle states parsed correctly, store them in the per-cpu struct. */
	data->psci_states = psci_states;
	return 0;
	}

	static int psci_cpu_init_idle(struct device dev, 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(dev, drv, cpu_node, state_count, cpu);

	of_node_put(cpu_node);

	return ret;
	}

	static void psci_cpu_deinit_idle(int cpu)
	{
	struct psci_cpuidle_data *data = per_cpu_ptr(&psci_cpuidle_data, cpu);

	psci_dt_detach_cpu(data->dev);
	psci_cpuidle_use_cpuhp = false;
	}

	static int psci_idle_init_cpu(struct device *dev, 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 = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
	if (!drv)
	return -ENOMEM;

	drv->name = "psci_idle";
	drv->owner = THIS_MODULE;
	drv->cpumask = (struct cpumask *)cpumask_of(cpu);

	/*
	* PSCI idle states relies on architectural WFI to be represented as
	* state index 0.
	*/
	drv->states[0].enter = psci_enter_idle_state;
	drv->states[0].exit_latency = 1;
	drv->states[0].target_residency = 1;
	drv->states[0].power_usage = UINT_MAX;
	strcpy(drv->states[0].name, "WFI");
	strcpy(drv->states[0].desc, "ARM WFI");

	/*
	* 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)
	return ret ? : -ENODEV;

	/*
	* Initialize PSCI idle states.
	*/
	ret = psci_cpu_init_idle(dev, drv, cpu, ret);
	if (ret) {
	pr_err("CPU %d failed to PSCI idle\n", cpu);
	return ret;
	}

	ret = cpuidle_register(drv, NULL);
	if (ret)
	goto deinit;

	cpuidle_cooling_register(drv);

	return 0;
	deinit:
	psci_cpu_deinit_idle(cpu);
	return ret;
	}

	/*
	* psci_idle_probe - 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 psci_cpuidle_probe(struct platform_device *pdev)
	{
	int cpu, ret;
	struct cpuidle_driver *drv;
	struct cpuidle_device *dev;

	for_each_possible_cpu(cpu) {
	ret = psci_idle_init_cpu(&pdev->dev, 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);
	psci_cpu_deinit_idle(cpu);
	}

	return ret;
	}

	static struct platform_driver psci_cpuidle_driver = {
	.probe = psci_cpuidle_probe,
	.driver = {
	.name = "psci-cpuidle",
	},
	};

	static int __init psci_idle_init(void)
	{
	struct platform_device *pdev;
	int ret;

	ret = platform_driver_register(&psci_cpuidle_driver);
	if (ret)
	return ret;

	pdev = platform_device_register_simple("psci-cpuidle", -1, NULL, 0);
	if (IS_ERR(pdev)) {
	platform_driver_unregister(&psci_cpuidle_driver);
	return PTR_ERR(pdev);
	}

	return 0;
	}
	device_initcall(psci_idle_init);