blob: a96c0e2b89cf82b574de560971256dc7f2bf0931 [file] [log] [blame]
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -08001/*
2 * linux/kernel/time/tick-oneshot.c
3 *
4 * This file contains functions which manage high resolution tick
5 * related events.
6 *
7 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
8 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
9 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
10 *
11 * This code is licenced under the GPL version 2. For details see
12 * kernel-base/COPYING.
13 */
14#include <linux/cpu.h>
15#include <linux/err.h>
16#include <linux/hrtimer.h>
Russell Kingd7b90682008-04-17 07:46:24 +020017#include <linux/interrupt.h>
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080018#include <linux/percpu.h>
19#include <linux/profile.h>
20#include <linux/sched.h>
21#include <linux/tick.h>
22
23#include "tick-internal.h"
24
25/**
Thomas Gleixner72056562008-09-03 21:37:03 +000026 * tick_program_event internal worker function
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080027 */
Thomas Gleixner1fb9b7d2008-09-03 21:37:14 +000028int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
29 int force)
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080030{
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080031 ktime_t now = ktime_get();
Thomas Gleixner1fb9b7d2008-09-03 21:37:14 +000032 int i;
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080033
Thomas Gleixner1fb9b7d2008-09-03 21:37:14 +000034 for (i = 0;;) {
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080035 int ret = clockevents_program_event(dev, expires, now);
36
37 if (!ret || !force)
38 return ret;
Thomas Gleixner1fb9b7d2008-09-03 21:37:14 +000039
40 /*
41 * We tried 2 times to program the device with the given
42 * min_delta_ns. If that's not working then we double it
43 * and emit a warning.
44 */
45 if (++i > 2) {
Thomas Gleixner61c22c32008-09-09 21:38:57 +020046 /* Increase the min. delta and try again */
Thomas Gleixner1fb9b7d2008-09-03 21:37:14 +000047 if (!dev->min_delta_ns)
48 dev->min_delta_ns = 5000;
49 else
Thomas Gleixner61c22c32008-09-09 21:38:57 +020050 dev->min_delta_ns += dev->min_delta_ns >> 1;
51
52 printk(KERN_WARNING
53 "CE: %s increasing min_delta_ns to %lu nsec\n",
54 dev->name ? dev->name : "?",
55 dev->min_delta_ns << 1);
56
Thomas Gleixner1fb9b7d2008-09-03 21:37:14 +000057 i = 0;
58 }
59
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080060 now = ktime_get();
Thomas Gleixner1fb9b7d2008-09-03 21:37:14 +000061 expires = ktime_add_ns(now, dev->min_delta_ns);
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080062 }
63}
64
65/**
Thomas Gleixner72056562008-09-03 21:37:03 +000066 * tick_program_event
67 */
68int tick_program_event(ktime_t expires, int force)
69{
70 struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
71
Thomas Gleixner1fb9b7d2008-09-03 21:37:14 +000072 return tick_dev_program_event(dev, expires, force);
Thomas Gleixner72056562008-09-03 21:37:03 +000073}
74
75/**
Thomas Gleixnercd05a1f2007-03-17 00:25:52 +010076 * tick_resume_onshot - resume oneshot mode
77 */
78void tick_resume_oneshot(void)
79{
80 struct tick_device *td = &__get_cpu_var(tick_cpu_device);
81 struct clock_event_device *dev = td->evtdev;
82
83 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
84 tick_program_event(ktime_get(), 1);
85}
86
87/**
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080088 * tick_setup_oneshot - setup the event device for oneshot mode (hres or nohz)
89 */
90void tick_setup_oneshot(struct clock_event_device *newdev,
91 void (*handler)(struct clock_event_device *),
92 ktime_t next_event)
93{
94 newdev->event_handler = handler;
95 clockevents_set_mode(newdev, CLOCK_EVT_MODE_ONESHOT);
Thomas Gleixner1fb9b7d2008-09-03 21:37:14 +000096 tick_dev_program_event(newdev, next_event, 1);
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -080097}
98
99/**
100 * tick_switch_to_oneshot - switch to oneshot mode
101 */
102int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *))
103{
104 struct tick_device *td = &__get_cpu_var(tick_cpu_device);
105 struct clock_event_device *dev = td->evtdev;
106
107 if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT) ||
Ingo Molnar820de5c2007-07-21 04:37:36 -0700108 !tick_device_is_functional(dev)) {
109
110 printk(KERN_INFO "Clockevents: "
111 "could not switch to one-shot mode:");
112 if (!dev) {
113 printk(" no tick device\n");
114 } else {
115 if (!tick_device_is_functional(dev))
116 printk(" %s is not functional.\n", dev->name);
117 else
118 printk(" %s does not support one-shot mode.\n",
119 dev->name);
120 }
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800121 return -EINVAL;
Ingo Molnar820de5c2007-07-21 04:37:36 -0700122 }
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800123
124 td->mode = TICKDEV_MODE_ONESHOT;
125 dev->event_handler = handler;
126 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
127 tick_broadcast_switch_to_oneshot();
128 return 0;
129}
130
Thomas Gleixnercd6d95d2009-06-12 11:29:27 +0200131/**
132 * tick_check_oneshot_mode - check whether the system is in oneshot mode
133 *
134 * returns 1 when either nohz or highres are enabled. otherwise 0.
135 */
136int tick_oneshot_mode_active(void)
137{
138 unsigned long flags;
139 int ret;
140
141 local_irq_save(flags);
142 ret = __get_cpu_var(tick_cpu_device).mode == TICKDEV_MODE_ONESHOT;
143 local_irq_restore(flags);
144
145 return ret;
146}
147
Thomas Gleixner79bf2bb2007-02-16 01:28:03 -0800148#ifdef CONFIG_HIGH_RES_TIMERS
149/**
150 * tick_init_highres - switch to high resolution mode
151 *
152 * Called with interrupts disabled.
153 */
154int tick_init_highres(void)
155{
156 return tick_switch_to_oneshot(hrtimer_interrupt);
157}
158#endif