/* * cpuidle.c - core cpuidle infrastructure * * (C) 2006-2007 Venkatesh Pallipadi * Shaohua Li * Adam Belay * * This code is licenced under the GPL. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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 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); WARN_ON(!irqs_disabled()); /* * 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, U64_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; /* * 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; } /* 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(); 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++; 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++; break; } } } else { dev->last_residency_ns = 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) { 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); } /** * 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 * */ u64 cpuidle_poll_time(struct cpuidle_driver *drv, struct cpuidle_device *dev) { int i; u64 limit_ns; if (dev->poll_limit_ns) return dev->poll_limit_ns; limit_ns = TICK_NSEC; for (i = 1; i < drv->state_count; i++) { if (dev->states_usage[i].disable) continue; limit_ns = drv->states[i].target_residency_ns; 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(cpu_subsys.dev_root); } module_param(off, int, 0444); module_param_string(governor, param_governor, CPUIDLE_NAME_LEN, 0444); core_initcall(cpuidle_init);