diff options
Diffstat (limited to 'drivers/cpuidle/cpuidle.c')
| -rw-r--r-- | drivers/cpuidle/cpuidle.c | 706 |
1 files changed, 706 insertions, 0 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c new file mode 100644 index 000000000..2d182dc1b --- /dev/null +++ b/drivers/cpuidle/cpuidle.c @@ -0,0 +1,706 @@ +/* + * 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/clockchips.h> +#include <linux/kernel.h> +#include <linux/mutex.h> +#include <linux/sched.h> +#include <linux/sched/clock.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 <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, + unsigned int max_latency, + unsigned int forbidden_flags, + bool s2idle) +{ + unsigned int latency_req = 0; + int i, ret = 0; + + for (i = 1; i < drv->state_count; i++) { + struct cpuidle_state *s = &drv->states[i]; + struct cpuidle_state_usage *su = &dev->states_usage[i]; + + if (s->disabled || su->disable || s->exit_latency <= latency_req + || s->exit_latency > max_latency + || (s->flags & forbidden_flags) + || (s2idle && !s->enter_s2idle)) + continue; + + latency_req = s->exit_latency; + ret = i; + } + return ret; +} + +/** + * cpuidle_use_deepest_state - Set/clear governor override flag. + * @enable: New value of the flag. + * + * Set/unset the current CPU to use the deepest idle state (override governors + * going forward if set). + */ +void cpuidle_use_deepest_state(bool enable) +{ + struct cpuidle_device *dev; + + preempt_disable(); + dev = cpuidle_get_device(); + if (dev) + dev->use_deepest_state = enable; + 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. + */ +int cpuidle_find_deepest_state(struct cpuidle_driver *drv, + struct cpuidle_device *dev) +{ + return find_deepest_state(drv, dev, UINT_MAX, 0, false); +} + +#ifdef CONFIG_SUSPEND +static void enter_s2idle_proper(struct cpuidle_driver *drv, + struct cpuidle_device *dev, int index) +{ + ktime_t time_start, time_end; + + time_start = ns_to_ktime(local_clock()); + + /* + * trace_suspend_resume() called by tick_freeze() for the last CPU + * executing it contains RCU usage regarded as invalid in the idle + * context, so tell RCU about that. + */ + RCU_NONIDLE(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(); + drv->states[index].enter_s2idle(dev, drv, index); + if (WARN_ON_ONCE(!irqs_disabled())) + local_irq_disable(); + /* + * timekeeping_resume() that will be called by tick_unfreeze() for the + * first CPU executing it calls functions containing RCU read-side + * critical sections, so tell RCU about that. + */ + RCU_NONIDLE(tick_unfreeze()); + start_critical_timings(); + + time_end = ns_to_ktime(local_clock()); + + dev->states_usage[index].s2idle_time += ktime_us_delta(time_end, time_start); + dev->states_usage[index].s2idle_usage++; +} + +/** + * 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, UINT_MAX, 0, true); + if (index > 0) + enter_s2idle_proper(drv, dev, index); + + 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 + */ +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; + s64 diff; + + /* + * 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, + CPUIDLE_FLAG_TIMER_STOP, false); + if (index < 0) { + default_idle_call(); + return -EBUSY; + } + target_state = &drv->states[index]; + broadcast = false; + } + + /* Take note of the planned idle state. */ + sched_idle_set_state(target_state); + + trace_cpu_idle_rcuidle(index, dev->cpu); + time_start = ns_to_ktime(local_clock()); + + stop_critical_timings(); + entered_state = target_state->enter(dev, drv, index); + start_critical_timings(); + + sched_clock_idle_wakeup_event(); + time_end = ns_to_ktime(local_clock()); + trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); + + /* The cpu is no longer idle or about to enter idle. */ + sched_idle_set_state(NULL); + + if (broadcast) { + if (WARN_ON_ONCE(!irqs_disabled())) + local_irq_disable(); + + tick_broadcast_exit(); + } + + if (!cpuidle_state_is_coupled(drv, index)) + local_irq_enable(); + + diff = ktime_us_delta(time_end, time_start); + if (diff > INT_MAX) + diff = INT_MAX; + + dev->last_residency = (int) diff; + + if (entered_state >= 0) { + /* Update cpuidle counters */ + /* This can be moved to within driver enter routine + * but that results in multiple copies of same code. + */ + dev->states_usage[entered_state].time += dev->last_residency; + dev->states_usage[entered_state].usage++; + } else { + dev->last_residency = 0; + } + + 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) +{ + if (cpuidle_state_is_coupled(drv, index)) + return cpuidle_enter_state_coupled(dev, drv, index); + return cpuidle_enter_state(dev, drv, index); +} + +/** + * 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); +} + +/** + * 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 = 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) +{ + int ret; + struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); + + if (!try_module_get(drv->owner)) + return -EINVAL; + + 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); + +#ifdef CONFIG_SMP + +/* + * This function gets called when a part of the kernel has a new latency + * requirement. This means we need to get all processors out of their C-state, + * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that + * wakes them all right up. + */ +static int cpuidle_latency_notify(struct notifier_block *b, + unsigned long l, void *v) +{ + wake_up_all_idle_cpus(); + return NOTIFY_OK; +} + +static struct notifier_block cpuidle_latency_notifier = { + .notifier_call = cpuidle_latency_notify, +}; + +static inline void latency_notifier_init(struct notifier_block *n) +{ + pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n); +} + +#else /* CONFIG_SMP */ + +#define latency_notifier_init(x) do { } while (0) + +#endif /* CONFIG_SMP */ + +/** + * cpuidle_init - core initializer + */ +static int __init cpuidle_init(void) +{ + int ret; + + if (cpuidle_disabled()) + return -ENODEV; + + ret = cpuidle_add_interface(cpu_subsys.dev_root); + if (ret) + return ret; + + latency_notifier_init(&cpuidle_latency_notifier); + + return 0; +} + +module_param(off, int, 0444); +core_initcall(cpuidle_init); |