Commit | Line | Data |
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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> | |
d7b90689 | 17 | #include <linux/interrupt.h> |
79bf2bb3 TG |
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 | /** | |
7205656a | 26 | * tick_program_event internal worker function |
79bf2bb3 | 27 | */ |
1fb9b7d2 TG |
28 | int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires, |
29 | int force) | |
79bf2bb3 | 30 | { |
79bf2bb3 | 31 | ktime_t now = ktime_get(); |
1fb9b7d2 | 32 | int i; |
79bf2bb3 | 33 | |
1fb9b7d2 | 34 | for (i = 0;;) { |
79bf2bb3 TG |
35 | int ret = clockevents_program_event(dev, expires, now); |
36 | ||
37 | if (!ret || !force) | |
38 | return ret; | |
1fb9b7d2 TG |
39 | |
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) { | |
61c22c34 | 46 | /* Increase the min. delta and try again */ |
1fb9b7d2 TG |
47 | if (!dev->min_delta_ns) |
48 | dev->min_delta_ns = 5000; | |
49 | else | |
61c22c34 TG |
50 | 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 | ||
1fb9b7d2 TG |
57 | i = 0; |
58 | } | |
59 | ||
79bf2bb3 | 60 | now = ktime_get(); |
1fb9b7d2 | 61 | expires = ktime_add_ns(now, dev->min_delta_ns); |
79bf2bb3 TG |
62 | } |
63 | } | |
64 | ||
7205656a TG |
65 | /** |
66 | * tick_program_event | |
67 | */ | |
68 | int tick_program_event(ktime_t expires, int force) | |
69 | { | |
70 | struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev; | |
71 | ||
1fb9b7d2 | 72 | return tick_dev_program_event(dev, expires, force); |
7205656a TG |
73 | } |
74 | ||
cd05a1f8 TG |
75 | /** |
76 | * tick_resume_onshot - resume oneshot mode | |
77 | */ | |
78 | void 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 | ||
79bf2bb3 TG |
87 | /** |
88 | * tick_setup_oneshot - setup the event device for oneshot mode (hres or nohz) | |
89 | */ | |
90 | void 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); | |
1fb9b7d2 | 96 | tick_dev_program_event(newdev, next_event, 1); |
79bf2bb3 TG |
97 | } |
98 | ||
99 | /** | |
100 | * tick_switch_to_oneshot - switch to oneshot mode | |
101 | */ | |
102 | int 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) || | |
820de5c3 IM |
108 | !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 | } | |
79bf2bb3 | 121 | return -EINVAL; |
820de5c3 | 122 | } |
79bf2bb3 TG |
123 | |
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 | ||
131 | #ifdef CONFIG_HIGH_RES_TIMERS | |
132 | /** | |
133 | * tick_init_highres - switch to high resolution mode | |
134 | * | |
135 | * Called with interrupts disabled. | |
136 | */ | |
137 | int tick_init_highres(void) | |
138 | { | |
139 | return tick_switch_to_oneshot(hrtimer_interrupt); | |
140 | } | |
141 | #endif |