// SPDX-License-Identifier: GPL-2.0 /* * This file contains functions which manage high resolution tick * related events. * * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de> * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner */ #include <linux/cpu.h> #include <linux/err.h> #include <linux/hrtimer.h> #include <linux/interrupt.h> #include <linux/percpu.h> #include <linux/profile.h> #include <linux/sched.h> #include "tick-internal.h" /** * tick_program_event - program the CPU local timer device for the next event */ int tick_program_event(ktime_t expires, int force) { struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); if (unlikely(expires == KTIME_MAX)) { /* * We don't need the clock event device any more, stop it. */ clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT_STOPPED); dev->next_event = KTIME_MAX; return 0; } if (unlikely(clockevent_state_oneshot_stopped(dev))) { /* * We need the clock event again, configure it in ONESHOT mode * before using it. */ clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT); } return clockevents_program_event(dev, expires, force); } /** * tick_resume_oneshot - resume oneshot mode */ void tick_resume_oneshot(void) { struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT); clockevents_program_event(dev, ktime_get(), true); } /** * tick_setup_oneshot - setup the event device for oneshot mode (hres or nohz) */ void tick_setup_oneshot(struct clock_event_device *newdev, void (*handler)(struct clock_event_device *), ktime_t next_event) { newdev->event_handler = handler; clockevents_switch_state(newdev, CLOCK_EVT_STATE_ONESHOT); clockevents_program_event(newdev, next_event, true); } /** * tick_switch_to_oneshot - switch to oneshot mode */ int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *)) { struct tick_device *td = this_cpu_ptr(&tick_cpu_device); struct clock_event_device *dev = td->evtdev; if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT) || !tick_device_is_functional(dev)) { pr_info("Clockevents: could not switch to one-shot mode:"); if (!dev) { pr_cont(" no tick device\n"); } else { if (!tick_device_is_functional(dev)) pr_cont(" %s is not functional.\n", dev->name); else pr_cont(" %s does not support one-shot mode.\n", dev->name); } return -EINVAL; } td->mode = TICKDEV_MODE_ONESHOT; dev->event_handler = handler; clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT); tick_broadcast_switch_to_oneshot(); return 0; } /** * tick_oneshot_mode_active - check whether the system is in oneshot mode * * returns 1 when either nohz or highres are enabled. otherwise 0. */ int tick_oneshot_mode_active(void) { unsigned long flags; int ret; local_irq_save(flags); ret = __this_cpu_read(tick_cpu_device.mode) == TICKDEV_MODE_ONESHOT; local_irq_restore(flags); return ret; } #ifdef CONFIG_HIGH_RES_TIMERS /** * tick_init_highres - switch to high resolution mode * * Called with interrupts disabled. */ int tick_init_highres(void) { return tick_switch_to_oneshot(hrtimer_interrupt); } #endif