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Merge branch 'timers/core' into sched/idle
Avoid heavy conflicts caused by WIP patches in drivers/cpuidle/cpuidle.c, by merging these into a single base. Signed-off-by: Ingo Molnar <mingo@kernel.org>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,106 @@ | ||
| /* | ||
| * linux/kernel/time/tick-broadcast-hrtimer.c | ||
| * This file emulates a local clock event device | ||
| * via a pseudo clock device. | ||
| */ | ||
| #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/clockchips.h> | ||
| #include <linux/sched.h> | ||
| #include <linux/smp.h> | ||
| #include <linux/module.h> | ||
|
|
||
| #include "tick-internal.h" | ||
|
|
||
| static struct hrtimer bctimer; | ||
|
|
||
| static void bc_set_mode(enum clock_event_mode mode, | ||
| struct clock_event_device *bc) | ||
| { | ||
| switch (mode) { | ||
| case CLOCK_EVT_MODE_SHUTDOWN: | ||
| /* | ||
| * Note, we cannot cancel the timer here as we might | ||
| * run into the following live lock scenario: | ||
| * | ||
| * cpu 0 cpu1 | ||
| * lock(broadcast_lock); | ||
| * hrtimer_interrupt() | ||
| * bc_handler() | ||
| * tick_handle_oneshot_broadcast(); | ||
| * lock(broadcast_lock); | ||
| * hrtimer_cancel() | ||
| * wait_for_callback() | ||
| */ | ||
| hrtimer_try_to_cancel(&bctimer); | ||
| break; | ||
| default: | ||
| break; | ||
| } | ||
| } | ||
|
|
||
| /* | ||
| * This is called from the guts of the broadcast code when the cpu | ||
| * which is about to enter idle has the earliest broadcast timer event. | ||
| */ | ||
| static int bc_set_next(ktime_t expires, struct clock_event_device *bc) | ||
| { | ||
| /* | ||
| * We try to cancel the timer first. If the callback is on | ||
| * flight on some other cpu then we let it handle it. If we | ||
| * were able to cancel the timer nothing can rearm it as we | ||
| * own broadcast_lock. | ||
| * | ||
| * However we can also be called from the event handler of | ||
| * ce_broadcast_hrtimer itself when it expires. We cannot | ||
| * restart the timer because we are in the callback, but we | ||
| * can set the expiry time and let the callback return | ||
| * HRTIMER_RESTART. | ||
| */ | ||
| if (hrtimer_try_to_cancel(&bctimer) >= 0) { | ||
| hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED); | ||
| /* Bind the "device" to the cpu */ | ||
| bc->bound_on = smp_processor_id(); | ||
| } else if (bc->bound_on == smp_processor_id()) { | ||
| hrtimer_set_expires(&bctimer, expires); | ||
| } | ||
| return 0; | ||
| } | ||
|
|
||
| static struct clock_event_device ce_broadcast_hrtimer = { | ||
| .set_mode = bc_set_mode, | ||
| .set_next_ktime = bc_set_next, | ||
| .features = CLOCK_EVT_FEAT_ONESHOT | | ||
| CLOCK_EVT_FEAT_KTIME | | ||
| CLOCK_EVT_FEAT_HRTIMER, | ||
| .rating = 0, | ||
| .bound_on = -1, | ||
| .min_delta_ns = 1, | ||
| .max_delta_ns = KTIME_MAX, | ||
| .min_delta_ticks = 1, | ||
| .max_delta_ticks = ULONG_MAX, | ||
| .mult = 1, | ||
| .shift = 0, | ||
| .cpumask = cpu_all_mask, | ||
| }; | ||
|
|
||
| static enum hrtimer_restart bc_handler(struct hrtimer *t) | ||
| { | ||
| ce_broadcast_hrtimer.event_handler(&ce_broadcast_hrtimer); | ||
|
|
||
| if (ce_broadcast_hrtimer.next_event.tv64 == KTIME_MAX) | ||
| return HRTIMER_NORESTART; | ||
|
|
||
| return HRTIMER_RESTART; | ||
| } | ||
|
|
||
| void tick_setup_hrtimer_broadcast(void) | ||
| { | ||
| hrtimer_init(&bctimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); | ||
| bctimer.function = bc_handler; | ||
| clockevents_register_device(&ce_broadcast_hrtimer); | ||
| } |
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