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-rw-r--r--kernel/time/tick-oneshot.c128
1 files changed, 128 insertions, 0 deletions
diff --git a/kernel/time/tick-oneshot.c b/kernel/time/tick-oneshot.c
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index 0000000000..5e2c2c26b3
--- /dev/null
+++ b/kernel/time/tick-oneshot.c
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+// 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