Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 816 insertions, 0 deletions

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
new file mode 100644
index 0000000000..737a026ef5
--- /dev/null
+++ b/drivers/cpuidle/cpuidle.c
@@ -0,0 +1,816 @@
+/*
+ * cpuidle.c - core cpuidle infrastructure
+ *
+ * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
+ *               Shaohua Li <shaohua.li@intel.com>
+ *               Adam Belay <abelay@novell.com>
+ *
+ * This code is licenced under the GPL.
+ */
+
+#include "linux/percpu-defs.h"
+#include <linux/clockchips.h>
+#include <linux/kernel.h>
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/sched/clock.h>
+#include <linux/sched/idle.h>
+#include <linux/notifier.h>
+#include <linux/pm_qos.h>
+#include <linux/cpu.h>
+#include <linux/cpuidle.h>
+#include <linux/ktime.h>
+#include <linux/hrtimer.h>
+#include <linux/module.h>
+#include <linux/suspend.h>
+#include <linux/tick.h>
+#include <linux/mmu_context.h>
+#include <linux/context_tracking.h>
+#include <trace/events/power.h>
+
+#include "cpuidle.h"
+
+DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
+DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
+
+DEFINE_MUTEX(cpuidle_lock);
+LIST_HEAD(cpuidle_detected_devices);
+
+static int enabled_devices;
+static int off __read_mostly;
+static int initialized __read_mostly;
+
+int cpuidle_disabled(void)
+{
+	return off;
+}
+void disable_cpuidle(void)
+{
+	off = 1;
+}
+
+bool cpuidle_not_available(struct cpuidle_driver *drv,
+			   struct cpuidle_device *dev)
+{
+	return off || !initialized || !drv || !dev || !dev->enabled;
+}
+
+/**
+ * cpuidle_play_dead - cpu off-lining
+ *
+ * Returns in case of an error or no driver
+ */
+int cpuidle_play_dead(void)
+{
+	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
+	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
+	int i;
+
+	if (!drv)
+		return -ENODEV;
+
+	/* Find lowest-power state that supports long-term idle */
+	for (i = drv->state_count - 1; i >= 0; i--)
+		if (drv->states[i].enter_dead)
+			return drv->states[i].enter_dead(dev, i);
+
+	return -ENODEV;
+}
+
+static int find_deepest_state(struct cpuidle_driver *drv,
+			      struct cpuidle_device *dev,
+			      u64 max_latency_ns,
+			      unsigned int forbidden_flags,
+			      bool s2idle)
+{
+	u64 latency_req = 0;
+	int i, ret = 0;
+
+	for (i = 1; i < drv->state_count; i++) {
+		struct cpuidle_state *s = &drv->states[i];
+
+		if (dev->states_usage[i].disable ||
+		    s->exit_latency_ns <= latency_req ||
+		    s->exit_latency_ns > max_latency_ns ||
+		    (s->flags & forbidden_flags) ||
+		    (s2idle && !s->enter_s2idle))
+			continue;
+
+		latency_req = s->exit_latency_ns;
+		ret = i;
+	}
+	return ret;
+}
+
+/**
+ * cpuidle_use_deepest_state - Set/unset governor override mode.
+ * @latency_limit_ns: Idle state exit latency limit (or no override if 0).
+ *
+ * If @latency_limit_ns is nonzero, set the current CPU to use the deepest idle
+ * state with exit latency within @latency_limit_ns (override governors going
+ * forward), or do not override governors if it is zero.
+ */
+void cpuidle_use_deepest_state(u64 latency_limit_ns)
+{
+	struct cpuidle_device *dev;
+
+	preempt_disable();
+	dev = cpuidle_get_device();
+	if (dev)
+		dev->forced_idle_latency_limit_ns = latency_limit_ns;
+	preempt_enable();
+}
+
+/**
+ * cpuidle_find_deepest_state - Find the deepest available idle state.
+ * @drv: cpuidle driver for the given CPU.
+ * @dev: cpuidle device for the given CPU.
+ * @latency_limit_ns: Idle state exit latency limit
+ *
+ * Return: the index of the deepest available idle state.
+ */
+int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
+			       struct cpuidle_device *dev,
+			       u64 latency_limit_ns)
+{
+	return find_deepest_state(drv, dev, latency_limit_ns, 0, false);
+}
+
+#ifdef CONFIG_SUSPEND
+static noinstr void enter_s2idle_proper(struct cpuidle_driver *drv,
+					 struct cpuidle_device *dev, int index)
+{
+	struct cpuidle_state *target_state = &drv->states[index];
+	ktime_t time_start, time_end;
+
+	instrumentation_begin();
+
+	time_start = ns_to_ktime(local_clock_noinstr());
+
+	tick_freeze();
+	/*
+	 * The state used here cannot be a "coupled" one, because the "coupled"
+	 * cpuidle mechanism enables interrupts and doing that with timekeeping
+	 * suspended is generally unsafe.
+	 */
+	stop_critical_timings();
+	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) {
+		ct_cpuidle_enter();
+		/* Annotate away the indirect call */
+		instrumentation_begin();
+	}
+	target_state->enter_s2idle(dev, drv, index);
+	if (WARN_ON_ONCE(!irqs_disabled()))
+		raw_local_irq_disable();
+	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) {
+		instrumentation_end();
+		ct_cpuidle_exit();
+	}
+	tick_unfreeze();
+	start_critical_timings();
+
+	time_end = ns_to_ktime(local_clock_noinstr());
+
+	dev->states_usage[index].s2idle_time += ktime_us_delta(time_end, time_start);
+	dev->states_usage[index].s2idle_usage++;
+	instrumentation_end();
+}
+
+/**
+ * cpuidle_enter_s2idle - Enter an idle state suitable for suspend-to-idle.
+ * @drv: cpuidle driver for the given CPU.
+ * @dev: cpuidle device for the given CPU.
+ *
+ * If there are states with the ->enter_s2idle callback, find the deepest of
+ * them and enter it with frozen tick.
+ */
+int cpuidle_enter_s2idle(struct cpuidle_driver *drv, struct cpuidle_device *dev)
+{
+	int index;
+
+	/*
+	 * Find the deepest state with ->enter_s2idle present, which guarantees
+	 * that interrupts won't be enabled when it exits and allows the tick to
+	 * be frozen safely.
+	 */
+	index = find_deepest_state(drv, dev, U64_MAX, 0, true);
+	if (index > 0) {
+		enter_s2idle_proper(drv, dev, index);
+		local_irq_enable();
+	}
+	return index;
+}
+#endif /* CONFIG_SUSPEND */
+
+/**
+ * cpuidle_enter_state - enter the state and update stats
+ * @dev: cpuidle device for this cpu
+ * @drv: cpuidle driver for this cpu
+ * @index: index into the states table in @drv of the state to enter
+ */
+noinstr int cpuidle_enter_state(struct cpuidle_device *dev,
+				 struct cpuidle_driver *drv,
+				 int index)
+{
+	int entered_state;
+
+	struct cpuidle_state *target_state = &drv->states[index];
+	bool broadcast = !!(target_state->flags & CPUIDLE_FLAG_TIMER_STOP);
+	ktime_t time_start, time_end;
+
+	instrumentation_begin();
+
+	/*
+	 * Tell the time framework to switch to a broadcast timer because our
+	 * local timer will be shut down.  If a local timer is used from another
+	 * CPU as a broadcast timer, this call may fail if it is not available.
+	 */
+	if (broadcast && tick_broadcast_enter()) {
+		index = find_deepest_state(drv, dev, target_state->exit_latency_ns,
+					   CPUIDLE_FLAG_TIMER_STOP, false);
+		if (index < 0) {
+			default_idle_call();
+			return -EBUSY;
+		}
+		target_state = &drv->states[index];
+		broadcast = false;
+	}
+
+	if (target_state->flags & CPUIDLE_FLAG_TLB_FLUSHED)
+		leave_mm(dev->cpu);
+
+	/* Take note of the planned idle state. */
+	sched_idle_set_state(target_state);
+
+	trace_cpu_idle(index, dev->cpu);
+	time_start = ns_to_ktime(local_clock_noinstr());
+
+	stop_critical_timings();
+	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) {
+		ct_cpuidle_enter();
+		/* Annotate away the indirect call */
+		instrumentation_begin();
+	}
+
+	/*
+	 * NOTE!!
+	 *
+	 * For cpuidle_state::enter() methods that do *NOT* set
+	 * CPUIDLE_FLAG_RCU_IDLE RCU will be disabled here and these functions
+	 * must be marked either noinstr or __cpuidle.
+	 *
+	 * For cpuidle_state::enter() methods that *DO* set
+	 * CPUIDLE_FLAG_RCU_IDLE this isn't required, but they must mark the
+	 * function calling ct_cpuidle_enter() as noinstr/__cpuidle and all
+	 * functions called within the RCU-idle region.
+	 */
+	entered_state = target_state->enter(dev, drv, index);
+
+	if (WARN_ONCE(!irqs_disabled(), "%ps leaked IRQ state", target_state->enter))
+		raw_local_irq_disable();
+
+	if (!(target_state->flags & CPUIDLE_FLAG_RCU_IDLE)) {
+		instrumentation_end();
+		ct_cpuidle_exit();
+	}
+	start_critical_timings();
+
+	sched_clock_idle_wakeup_event();
+	time_end = ns_to_ktime(local_clock_noinstr());
+	trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu);
+
+	/* The cpu is no longer idle or about to enter idle. */
+	sched_idle_set_state(NULL);
+
+	if (broadcast)
+		tick_broadcast_exit();
+
+	if (!cpuidle_state_is_coupled(drv, index))
+		local_irq_enable();
+
+	if (entered_state >= 0) {
+		s64 diff, delay = drv->states[entered_state].exit_latency_ns;
+		int i;
+
+		/*
+		 * Update cpuidle counters
+		 * This can be moved to within driver enter routine,
+		 * but that results in multiple copies of same code.
+		 */
+		diff = ktime_sub(time_end, time_start);
+
+		dev->last_residency_ns = diff;
+		dev->states_usage[entered_state].time_ns += diff;
+		dev->states_usage[entered_state].usage++;
+
+		if (diff < drv->states[entered_state].target_residency_ns) {
+			for (i = entered_state - 1; i >= 0; i--) {
+				if (dev->states_usage[i].disable)
+					continue;
+
+				/* Shallower states are enabled, so update. */
+				dev->states_usage[entered_state].above++;
+				trace_cpu_idle_miss(dev->cpu, entered_state, false);
+				break;
+			}
+		} else if (diff > delay) {
+			for (i = entered_state + 1; i < drv->state_count; i++) {
+				if (dev->states_usage[i].disable)
+					continue;
+
+				/*
+				 * Update if a deeper state would have been a
+				 * better match for the observed idle duration.
+				 */
+				if (diff - delay >= drv->states[i].target_residency_ns) {
+					dev->states_usage[entered_state].below++;
+					trace_cpu_idle_miss(dev->cpu, entered_state, true);
+				}
+
+				break;
+			}
+		}
+	} else {
+		dev->last_residency_ns = 0;
+		dev->states_usage[index].rejected++;
+	}
+
+	instrumentation_end();
+
+	return entered_state;
+}
+
+/**
+ * cpuidle_select - ask the cpuidle framework to choose an idle state
+ *
+ * @drv: the cpuidle driver
+ * @dev: the cpuidle device
+ * @stop_tick: indication on whether or not to stop the tick
+ *
+ * Returns the index of the idle state.  The return value must not be negative.
+ *
+ * The memory location pointed to by @stop_tick is expected to be written the
+ * 'false' boolean value if the scheduler tick should not be stopped before
+ * entering the returned state.
+ */
+int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
+		   bool *stop_tick)
+{
+	return cpuidle_curr_governor->select(drv, dev, stop_tick);
+}
+
+/**
+ * cpuidle_enter - enter into the specified idle state
+ *
+ * @drv:   the cpuidle driver tied with the cpu
+ * @dev:   the cpuidle device
+ * @index: the index in the idle state table
+ *
+ * Returns the index in the idle state, < 0 in case of error.
+ * The error code depends on the backend driver
+ */
+int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
+		  int index)
+{
+	int ret = 0;
+
+	/*
+	 * Store the next hrtimer, which becomes either next tick or the next
+	 * timer event, whatever expires first. Additionally, to make this data
+	 * useful for consumers outside cpuidle, we rely on that the governor's
+	 * ->select() callback have decided, whether to stop the tick or not.
+	 */
+	WRITE_ONCE(dev->next_hrtimer, tick_nohz_get_next_hrtimer());
+
+	if (cpuidle_state_is_coupled(drv, index))
+		ret = cpuidle_enter_state_coupled(dev, drv, index);
+	else
+		ret = cpuidle_enter_state(dev, drv, index);
+
+	WRITE_ONCE(dev->next_hrtimer, 0);
+	return ret;
+}
+
+/**
+ * cpuidle_reflect - tell the underlying governor what was the state
+ * we were in
+ *
+ * @dev  : the cpuidle device
+ * @index: the index in the idle state table
+ *
+ */
+void cpuidle_reflect(struct cpuidle_device *dev, int index)
+{
+	if (cpuidle_curr_governor->reflect && index >= 0)
+		cpuidle_curr_governor->reflect(dev, index);
+}
+
+/*
+ * Min polling interval of 10usec is a guess. It is assuming that
+ * for most users, the time for a single ping-pong workload like
+ * perf bench pipe would generally complete within 10usec but
+ * this is hardware dependant. Actual time can be estimated with
+ *
+ * perf bench sched pipe -l 10000
+ *
+ * Run multiple times to avoid cpufreq effects.
+ */
+#define CPUIDLE_POLL_MIN 10000
+#define CPUIDLE_POLL_MAX (TICK_NSEC / 16)
+
+/**
+ * cpuidle_poll_time - return amount of time to poll for,
+ * governors can override dev->poll_limit_ns if necessary
+ *
+ * @drv:   the cpuidle driver tied with the cpu
+ * @dev:   the cpuidle device
+ *
+ */
+__cpuidle u64 cpuidle_poll_time(struct cpuidle_driver *drv,
+		      struct cpuidle_device *dev)
+{
+	int i;
+	u64 limit_ns;
+
+	BUILD_BUG_ON(CPUIDLE_POLL_MIN > CPUIDLE_POLL_MAX);
+
+	if (dev->poll_limit_ns)
+		return dev->poll_limit_ns;
+
+	limit_ns = CPUIDLE_POLL_MAX;
+	for (i = 1; i < drv->state_count; i++) {
+		u64 state_limit;
+
+		if (dev->states_usage[i].disable)
+			continue;
+
+		state_limit = drv->states[i].target_residency_ns;
+		if (state_limit < CPUIDLE_POLL_MIN)
+			continue;
+
+		limit_ns = min_t(u64, state_limit, CPUIDLE_POLL_MAX);
+		break;
+	}
+
+	dev->poll_limit_ns = limit_ns;
+
+	return dev->poll_limit_ns;
+}
+
+/**
+ * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
+ */
+void cpuidle_install_idle_handler(void)
+{
+	if (enabled_devices) {
+		/* Make sure all changes finished before we switch to new idle */
+		smp_wmb();
+		initialized = 1;
+	}
+}
+
+/**
+ * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
+ */
+void cpuidle_uninstall_idle_handler(void)
+{
+	if (enabled_devices) {
+		initialized = 0;
+		wake_up_all_idle_cpus();
+	}
+
+	/*
+	 * Make sure external observers (such as the scheduler)
+	 * are done looking at pointed idle states.
+	 */
+	synchronize_rcu();
+}
+
+/**
+ * cpuidle_pause_and_lock - temporarily disables CPUIDLE
+ */
+void cpuidle_pause_and_lock(void)
+{
+	mutex_lock(&cpuidle_lock);
+	cpuidle_uninstall_idle_handler();
+}
+
+EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
+
+/**
+ * cpuidle_resume_and_unlock - resumes CPUIDLE operation
+ */
+void cpuidle_resume_and_unlock(void)
+{
+	cpuidle_install_idle_handler();
+	mutex_unlock(&cpuidle_lock);
+}
+
+EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
+
+/* Currently used in suspend/resume path to suspend cpuidle */
+void cpuidle_pause(void)
+{
+	mutex_lock(&cpuidle_lock);
+	cpuidle_uninstall_idle_handler();
+	mutex_unlock(&cpuidle_lock);
+}
+
+/* Currently used in suspend/resume path to resume cpuidle */
+void cpuidle_resume(void)
+{
+	mutex_lock(&cpuidle_lock);
+	cpuidle_install_idle_handler();
+	mutex_unlock(&cpuidle_lock);
+}
+
+/**
+ * cpuidle_enable_device - enables idle PM for a CPU
+ * @dev: the CPU
+ *
+ * This function must be called between cpuidle_pause_and_lock and
+ * cpuidle_resume_and_unlock when used externally.
+ */
+int cpuidle_enable_device(struct cpuidle_device *dev)
+{
+	int ret;
+	struct cpuidle_driver *drv;
+
+	if (!dev)
+		return -EINVAL;
+
+	if (dev->enabled)
+		return 0;
+
+	if (!cpuidle_curr_governor)
+		return -EIO;
+
+	drv = cpuidle_get_cpu_driver(dev);
+
+	if (!drv)
+		return -EIO;
+
+	if (!dev->registered)
+		return -EINVAL;
+
+	ret = cpuidle_add_device_sysfs(dev);
+	if (ret)
+		return ret;
+
+	if (cpuidle_curr_governor->enable) {
+		ret = cpuidle_curr_governor->enable(drv, dev);
+		if (ret)
+			goto fail_sysfs;
+	}
+
+	smp_wmb();
+
+	dev->enabled = 1;
+
+	enabled_devices++;
+	return 0;
+
+fail_sysfs:
+	cpuidle_remove_device_sysfs(dev);
+
+	return ret;
+}
+
+EXPORT_SYMBOL_GPL(cpuidle_enable_device);
+
+/**
+ * cpuidle_disable_device - disables idle PM for a CPU
+ * @dev: the CPU
+ *
+ * This function must be called between cpuidle_pause_and_lock and
+ * cpuidle_resume_and_unlock when used externally.
+ */
+void cpuidle_disable_device(struct cpuidle_device *dev)
+{
+	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
+
+	if (!dev || !dev->enabled)
+		return;
+
+	if (!drv || !cpuidle_curr_governor)
+		return;
+
+	dev->enabled = 0;
+
+	if (cpuidle_curr_governor->disable)
+		cpuidle_curr_governor->disable(drv, dev);
+
+	cpuidle_remove_device_sysfs(dev);
+	enabled_devices--;
+}
+
+EXPORT_SYMBOL_GPL(cpuidle_disable_device);
+
+static void __cpuidle_unregister_device(struct cpuidle_device *dev)
+{
+	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
+
+	list_del(&dev->device_list);
+	per_cpu(cpuidle_devices, dev->cpu) = NULL;
+	module_put(drv->owner);
+
+	dev->registered = 0;
+}
+
+static void __cpuidle_device_init(struct cpuidle_device *dev)
+{
+	memset(dev->states_usage, 0, sizeof(dev->states_usage));
+	dev->last_residency_ns = 0;
+	dev->next_hrtimer = 0;
+}
+
+/**
+ * __cpuidle_register_device - internal register function called before register
+ * and enable routines
+ * @dev: the cpu
+ *
+ * cpuidle_lock mutex must be held before this is called
+ */
+static int __cpuidle_register_device(struct cpuidle_device *dev)
+{
+	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
+	int i, ret;
+
+	if (!try_module_get(drv->owner))
+		return -EINVAL;
+
+	for (i = 0; i < drv->state_count; i++) {
+		if (drv->states[i].flags & CPUIDLE_FLAG_UNUSABLE)
+			dev->states_usage[i].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER;
+
+		if (drv->states[i].flags & CPUIDLE_FLAG_OFF)
+			dev->states_usage[i].disable |= CPUIDLE_STATE_DISABLED_BY_USER;
+	}
+
+	per_cpu(cpuidle_devices, dev->cpu) = dev;
+	list_add(&dev->device_list, &cpuidle_detected_devices);
+
+	ret = cpuidle_coupled_register_device(dev);
+	if (ret)
+		__cpuidle_unregister_device(dev);
+	else
+		dev->registered = 1;
+
+	return ret;
+}
+
+/**
+ * cpuidle_register_device - registers a CPU's idle PM feature
+ * @dev: the cpu
+ */
+int cpuidle_register_device(struct cpuidle_device *dev)
+{
+	int ret = -EBUSY;
+
+	if (!dev)
+		return -EINVAL;
+
+	mutex_lock(&cpuidle_lock);
+
+	if (dev->registered)
+		goto out_unlock;
+
+	__cpuidle_device_init(dev);
+
+	ret = __cpuidle_register_device(dev);
+	if (ret)
+		goto out_unlock;
+
+	ret = cpuidle_add_sysfs(dev);
+	if (ret)
+		goto out_unregister;
+
+	ret = cpuidle_enable_device(dev);
+	if (ret)
+		goto out_sysfs;
+
+	cpuidle_install_idle_handler();
+
+out_unlock:
+	mutex_unlock(&cpuidle_lock);
+
+	return ret;
+
+out_sysfs:
+	cpuidle_remove_sysfs(dev);
+out_unregister:
+	__cpuidle_unregister_device(dev);
+	goto out_unlock;
+}
+
+EXPORT_SYMBOL_GPL(cpuidle_register_device);
+
+/**
+ * cpuidle_unregister_device - unregisters a CPU's idle PM feature
+ * @dev: the cpu
+ */
+void cpuidle_unregister_device(struct cpuidle_device *dev)
+{
+	if (!dev || dev->registered == 0)
+		return;
+
+	cpuidle_pause_and_lock();
+
+	cpuidle_disable_device(dev);
+
+	cpuidle_remove_sysfs(dev);
+
+	__cpuidle_unregister_device(dev);
+
+	cpuidle_coupled_unregister_device(dev);
+
+	cpuidle_resume_and_unlock();
+}
+
+EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
+
+/**
+ * cpuidle_unregister: unregister a driver and the devices. This function
+ * can be used only if the driver has been previously registered through
+ * the cpuidle_register function.
+ *
+ * @drv: a valid pointer to a struct cpuidle_driver
+ */
+void cpuidle_unregister(struct cpuidle_driver *drv)
+{
+	int cpu;
+	struct cpuidle_device *device;
+
+	for_each_cpu(cpu, drv->cpumask) {
+		device = &per_cpu(cpuidle_dev, cpu);
+		cpuidle_unregister_device(device);
+	}
+
+	cpuidle_unregister_driver(drv);
+}
+EXPORT_SYMBOL_GPL(cpuidle_unregister);
+
+/**
+ * cpuidle_register: registers the driver and the cpu devices with the
+ * coupled_cpus passed as parameter. This function is used for all common
+ * initialization pattern there are in the arch specific drivers. The
+ * devices is globally defined in this file.
+ *
+ * @drv         : a valid pointer to a struct cpuidle_driver
+ * @coupled_cpus: a cpumask for the coupled states
+ *
+ * Returns 0 on success, < 0 otherwise
+ */
+int cpuidle_register(struct cpuidle_driver *drv,
+		     const struct cpumask *const coupled_cpus)
+{
+	int ret, cpu;
+	struct cpuidle_device *device;
+
+	ret = cpuidle_register_driver(drv);
+	if (ret) {
+		pr_err("failed to register cpuidle driver\n");
+		return ret;
+	}
+
+	for_each_cpu(cpu, drv->cpumask) {
+		device = &per_cpu(cpuidle_dev, cpu);
+		device->cpu = cpu;
+
+#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
+		/*
+		 * On multiplatform for ARM, the coupled idle states could be
+		 * enabled in the kernel even if the cpuidle driver does not
+		 * use it. Note, coupled_cpus is a struct copy.
+		 */
+		if (coupled_cpus)
+			device->coupled_cpus = *coupled_cpus;
+#endif
+		ret = cpuidle_register_device(device);
+		if (!ret)
+			continue;
+
+		pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
+
+		cpuidle_unregister(drv);
+		break;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cpuidle_register);
+
+/**
+ * cpuidle_init - core initializer
+ */
+static int __init cpuidle_init(void)
+{
+	if (cpuidle_disabled())
+		return -ENODEV;
+
+	return cpuidle_add_interface();
+}
+
+module_param(off, int, 0444);
+module_param_string(governor, param_governor, CPUIDLE_NAME_LEN, 0444);
+core_initcall(cpuidle_init);