diff options
author | John Stultz <john.stultz@linaro.org> | 2011-01-11 20:42:13 +0300 |
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committer | John Stultz <john.stultz@linaro.org> | 2011-04-27 01:01:44 +0400 |
commit | ff3ead96d17f47ee70c294a5cc2cce9b61e82f0f (patch) | |
tree | e87fc16e1fc4a80b9591c2b1d02c99459254aa95 /kernel/time | |
parent | 88d19cf37952a7e1e38b2bf87a00f0e857e63180 (diff) | |
download | linux-ff3ead96d17f47ee70c294a5cc2cce9b61e82f0f.tar.xz |
timers: Introduce in-kernel alarm-timer interface
This provides the in kernel interface and infrastructure for
alarm-timers.
Alarm-timers are a hybrid style timer, similar to hrtimers,
but when the system is suspended, the RTC device is set to
fire and wake the system for when the soonest alarm-timer
expires.
The concept for Alarm-timers was inspired by the Android Alarm
driver (by Arve Hjønnevåg) found in the Android kernel tree.
See: http://android.git.kernel.org/?p=kernel/common.git;a=blob;f=drivers/rtc/alarm.c;h=1250edfbdf3302f5e4ea6194847c6ef4bb7beb1c;hb=android-2.6.36
This in-kernel interface should be fairly compatible with the
Android alarm driver in-kernel interface, but has the advantage
of utilizing the new RTC timerqueue code instead of doing direct
RTC manipulation.
CC: Arve Hjønnevåg <arve@android.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Alessandro Zummo <a.zummo@towertech.it>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'kernel/time')
-rw-r--r-- | kernel/time/Makefile | 2 | ||||
-rw-r--r-- | kernel/time/alarmtimer.c | 375 |
2 files changed, 376 insertions, 1 deletions
diff --git a/kernel/time/Makefile b/kernel/time/Makefile index b0425991e9ac..e2fd74b8e8c2 100644 --- a/kernel/time/Makefile +++ b/kernel/time/Makefile @@ -1,5 +1,5 @@ obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o timecompare.o -obj-y += timeconv.o posix-clock.o +obj-y += timeconv.o posix-clock.o alarmtimer.o obj-$(CONFIG_GENERIC_CLOCKEVENTS_BUILD) += clockevents.o obj-$(CONFIG_GENERIC_CLOCKEVENTS) += tick-common.o diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c new file mode 100644 index 000000000000..48c2ee949e61 --- /dev/null +++ b/kernel/time/alarmtimer.c @@ -0,0 +1,375 @@ +/* + * Alarmtimer interface + * + * This interface provides a timer which is similarto hrtimers, + * but triggers a RTC alarm if the box is suspend. + * + * This interface is influenced by the Android RTC Alarm timer + * interface. + * + * Copyright (C) 2010 IBM Corperation + * + * Author: John Stultz <john.stultz@linaro.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#include <linux/time.h> +#include <linux/hrtimer.h> +#include <linux/timerqueue.h> +#include <linux/rtc.h> +#include <linux/alarmtimer.h> +#include <linux/mutex.h> +#include <linux/platform_device.h> +#include <linux/posix-timers.h> +#include <linux/workqueue.h> +#include <linux/freezer.h> + + +static struct alarm_base { + spinlock_t lock; + struct timerqueue_head timerqueue; + struct hrtimer timer; + ktime_t (*gettime)(void); + clockid_t base_clockid; + struct work_struct irqwork; +} alarm_bases[ALARM_NUMTYPE]; + +static struct rtc_timer rtctimer; +static struct rtc_device *rtcdev; + +static ktime_t freezer_delta; +static DEFINE_SPINLOCK(freezer_delta_lock); + + +/************************************************************************** + * alarmtimer management code + */ + +/* + * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue + * @base: pointer to the base where the timer is being run + * @alarm: pointer to alarm being enqueued. + * + * Adds alarm to a alarm_base timerqueue and if necessary sets + * an hrtimer to run. + * + * Must hold base->lock when calling. + */ +static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm) +{ + timerqueue_add(&base->timerqueue, &alarm->node); + if (&alarm->node == timerqueue_getnext(&base->timerqueue)) { + hrtimer_try_to_cancel(&base->timer); + hrtimer_start(&base->timer, alarm->node.expires, + HRTIMER_MODE_ABS); + } +} + +/* + * alarmtimer_remove - Removes an alarm timer from an alarm_base timerqueue + * @base: pointer to the base where the timer is running + * @alarm: pointer to alarm being removed + * + * Removes alarm to a alarm_base timerqueue and if necessary sets + * a new timer to run. + * + * Must hold base->lock when calling. + */ +static void alarmtimer_remove(struct alarm_base *base, struct alarm *alarm) +{ + struct timerqueue_node *next = timerqueue_getnext(&base->timerqueue); + + timerqueue_del(&base->timerqueue, &alarm->node); + if (next == &alarm->node) { + hrtimer_try_to_cancel(&base->timer); + next = timerqueue_getnext(&base->timerqueue); + if (!next) + return; + hrtimer_start(&base->timer, next->expires, HRTIMER_MODE_ABS); + } +} + +/* + * alarmtimer_do_work - Handles alarm being fired. + * @work: pointer to workqueue being run + * + * When a timer fires, this runs through the timerqueue to see + * which alarm timers, and run those that expired. If there are + * more alarm timers queued, we set the hrtimer to fire in the + * future. + */ +void alarmtimer_do_work(struct work_struct *work) +{ + struct alarm_base *base = container_of(work, struct alarm_base, + irqwork); + struct timerqueue_node *next; + unsigned long flags; + ktime_t now; + + spin_lock_irqsave(&base->lock, flags); + now = base->gettime(); + while ((next = timerqueue_getnext(&base->timerqueue))) { + struct alarm *alarm; + ktime_t expired = next->expires; + + if (expired.tv64 >= now.tv64) + break; + + alarm = container_of(next, struct alarm, node); + + timerqueue_del(&base->timerqueue, &alarm->node); + alarm->enabled = 0; + /* Re-add periodic timers */ + if (alarm->period.tv64) { + alarm->node.expires = ktime_add(expired, alarm->period); + timerqueue_add(&base->timerqueue, &alarm->node); + alarm->enabled = 1; + } + spin_unlock_irqrestore(&base->lock, flags); + if (alarm->function) + alarm->function(alarm); + spin_lock_irqsave(&base->lock, flags); + } + + if (next) { + hrtimer_start(&base->timer, next->expires, + HRTIMER_MODE_ABS); + } + spin_unlock_irqrestore(&base->lock, flags); +} + + +/* + * alarmtimer_fired - Handles alarm hrtimer being fired. + * @timer: pointer to hrtimer being run + * + * When a timer fires, this schedules the do_work function to + * be run. + */ +static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer) +{ + struct alarm_base *base = container_of(timer, struct alarm_base, timer); + schedule_work(&base->irqwork); + return HRTIMER_NORESTART; +} + + +/* + * alarmtimer_suspend - Suspend time callback + * @dev: unused + * @state: unused + * + * When we are going into suspend, we look through the bases + * to see which is the soonest timer to expire. We then + * set an rtc timer to fire that far into the future, which + * will wake us from suspend. + */ +static int alarmtimer_suspend(struct device *dev) +{ + struct rtc_time tm; + ktime_t min, now; + unsigned long flags; + int i; + + spin_lock_irqsave(&freezer_delta_lock, flags); + min = freezer_delta; + freezer_delta = ktime_set(0, 0); + spin_unlock_irqrestore(&freezer_delta_lock, flags); + + /* If we have no rtcdev, just return */ + if (!rtcdev) + return 0; + + /* Find the soonest timer to expire*/ + for (i = 0; i < ALARM_NUMTYPE; i++) { + struct alarm_base *base = &alarm_bases[i]; + struct timerqueue_node *next; + ktime_t delta; + + spin_lock_irqsave(&base->lock, flags); + next = timerqueue_getnext(&base->timerqueue); + spin_unlock_irqrestore(&base->lock, flags); + if (!next) + continue; + delta = ktime_sub(next->expires, base->gettime()); + if (!min.tv64 || (delta.tv64 < min.tv64)) + min = delta; + } + if (min.tv64 == 0) + return 0; + + /* XXX - Should we enforce a minimum sleep time? */ + WARN_ON(min.tv64 < NSEC_PER_SEC); + + /* Setup an rtc timer to fire that far in the future */ + rtc_timer_cancel(rtcdev, &rtctimer); + rtc_read_time(rtcdev, &tm); + now = rtc_tm_to_ktime(tm); + now = ktime_add(now, min); + + rtc_timer_start(rtcdev, &rtctimer, now, ktime_set(0, 0)); + + return 0; +} + + +/************************************************************************** + * alarm kernel interface code + */ + +/* + * alarm_init - Initialize an alarm structure + * @alarm: ptr to alarm to be initialized + * @type: the type of the alarm + * @function: callback that is run when the alarm fires + * + * In-kernel interface to initializes the alarm structure. + */ +void alarm_init(struct alarm *alarm, enum alarmtimer_type type, + void (*function)(struct alarm *)) +{ + timerqueue_init(&alarm->node); + alarm->period = ktime_set(0, 0); + alarm->function = function; + alarm->type = type; + alarm->enabled = 0; +} + +/* + * alarm_start - Sets an alarm to fire + * @alarm: ptr to alarm to set + * @start: time to run the alarm + * @period: period at which the alarm will recur + * + * In-kernel interface set an alarm timer. + */ +void alarm_start(struct alarm *alarm, ktime_t start, ktime_t period) +{ + struct alarm_base *base = &alarm_bases[alarm->type]; + unsigned long flags; + + spin_lock_irqsave(&base->lock, flags); + if (alarm->enabled) + alarmtimer_remove(base, alarm); + alarm->node.expires = start; + alarm->period = period; + alarmtimer_enqueue(base, alarm); + alarm->enabled = 1; + spin_unlock_irqrestore(&base->lock, flags); +} + +/* + * alarm_cancel - Tries to cancel an alarm timer + * @alarm: ptr to alarm to be canceled + * + * In-kernel interface to cancel an alarm timer. + */ +void alarm_cancel(struct alarm *alarm) +{ + struct alarm_base *base = &alarm_bases[alarm->type]; + unsigned long flags; + + spin_lock_irqsave(&base->lock, flags); + if (alarm->enabled) + alarmtimer_remove(base, alarm); + alarm->enabled = 0; + spin_unlock_irqrestore(&base->lock, flags); +} + + + +/************************************************************************** + * alarmtimer initialization code + */ + +/* Suspend hook structures */ +static const struct dev_pm_ops alarmtimer_pm_ops = { + .suspend = alarmtimer_suspend, +}; + +static struct platform_driver alarmtimer_driver = { + .driver = { + .name = "alarmtimer", + .pm = &alarmtimer_pm_ops, + } +}; + +/** + * alarmtimer_init - Initialize alarm timer code + * + * This function initializes the alarm bases and registers + * the posix clock ids. + */ +static int __init alarmtimer_init(void) +{ + int error = 0; + int i; + + /* Initialize alarm bases */ + alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME; + alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real; + alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME; + alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime; + for (i = 0; i < ALARM_NUMTYPE; i++) { + timerqueue_init_head(&alarm_bases[i].timerqueue); + spin_lock_init(&alarm_bases[i].lock); + hrtimer_init(&alarm_bases[i].timer, + alarm_bases[i].base_clockid, + HRTIMER_MODE_ABS); + alarm_bases[i].timer.function = alarmtimer_fired; + INIT_WORK(&alarm_bases[i].irqwork, alarmtimer_do_work); + } + error = platform_driver_register(&alarmtimer_driver); + platform_device_register_simple("alarmtimer", -1, NULL, 0); + + return error; +} +device_initcall(alarmtimer_init); + +/** + * has_wakealarm - check rtc device has wakealarm ability + * @dev: current device + * @name_ptr: name to be returned + * + * This helper function checks to see if the rtc device can wake + * from suspend. + */ +static int __init has_wakealarm(struct device *dev, void *name_ptr) +{ + struct rtc_device *candidate = to_rtc_device(dev); + + if (!candidate->ops->set_alarm) + return 0; + if (!device_may_wakeup(candidate->dev.parent)) + return 0; + + *(const char **)name_ptr = dev_name(dev); + return 1; +} + +/** + * alarmtimer_init_late - Late initializing of alarmtimer code + * + * This function locates a rtc device to use for wakealarms. + * Run as late_initcall to make sure rtc devices have been + * registered. + */ +static int __init alarmtimer_init_late(void) +{ + char *str; + + /* Find an rtc device and init the rtc_timer */ + class_find_device(rtc_class, NULL, &str, has_wakealarm); + if (str) + rtcdev = rtc_class_open(str); + if (!rtcdev) { + printk(KERN_WARNING "No RTC device found, ALARM timers will" + " not wake from suspend"); + } + rtc_timer_init(&rtctimer, NULL, NULL); + + return 0; +} +late_initcall(alarmtimer_init_late); |