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79bf2bb3 TG |
1 | /* |
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> | |
17 | #include <linux/irq.h> | |
18 | #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 | /** | |
26 | * tick_program_event | |
27 | */ | |
28 | int tick_program_event(ktime_t expires, int force) | |
29 | { | |
30 | struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev; | |
31 | ktime_t now = ktime_get(); | |
32 | ||
33 | while (1) { | |
34 | int ret = clockevents_program_event(dev, expires, now); | |
35 | ||
36 | if (!ret || !force) | |
37 | return ret; | |
38 | now = ktime_get(); | |
39 | expires = ktime_add(now, ktime_set(0, dev->min_delta_ns)); | |
40 | } | |
41 | } | |
42 | ||
43 | /** | |
44 | * tick_setup_oneshot - setup the event device for oneshot mode (hres or nohz) | |
45 | */ | |
46 | void tick_setup_oneshot(struct clock_event_device *newdev, | |
47 | void (*handler)(struct clock_event_device *), | |
48 | ktime_t next_event) | |
49 | { | |
50 | newdev->event_handler = handler; | |
51 | clockevents_set_mode(newdev, CLOCK_EVT_MODE_ONESHOT); | |
52 | clockevents_program_event(newdev, next_event, ktime_get()); | |
53 | } | |
54 | ||
55 | /** | |
56 | * tick_switch_to_oneshot - switch to oneshot mode | |
57 | */ | |
58 | int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *)) | |
59 | { | |
60 | struct tick_device *td = &__get_cpu_var(tick_cpu_device); | |
61 | struct clock_event_device *dev = td->evtdev; | |
62 | ||
63 | if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT) || | |
64 | !tick_device_is_functional(dev)) | |
65 | return -EINVAL; | |
66 | ||
67 | td->mode = TICKDEV_MODE_ONESHOT; | |
68 | dev->event_handler = handler; | |
69 | clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT); | |
70 | tick_broadcast_switch_to_oneshot(); | |
71 | return 0; | |
72 | } | |
73 | ||
74 | #ifdef CONFIG_HIGH_RES_TIMERS | |
75 | /** | |
76 | * tick_init_highres - switch to high resolution mode | |
77 | * | |
78 | * Called with interrupts disabled. | |
79 | */ | |
80 | int tick_init_highres(void) | |
81 | { | |
82 | return tick_switch_to_oneshot(hrtimer_interrupt); | |
83 | } | |
84 | #endif |