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Subject[PATCH 1/4] android-alarm: Convert ALARM_ELAPSED_REALTIME to use CLOCK_BOOTTIME
Date
The ALARM_ELAPSED_REALTIME clock domain in Android pointed
to the need for something similar in linux system-wide
(instead of limited to just the alarm interface).

Thus CLOCK_BOOTTIME was introduced into the upstream kernel
in 2.6.39.

This patch attempts to convert the android alarm timer to utilize
the kernel's CLOCK_BOOTTIME clockid for ALARM_ELAPSED_REALTIME,
instead of managing it itself.

CC: Colin Cross <ccross@android.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Greg KH <gregkh@linuxfoundation.org>
CC: Android Kernel Team <kernel-team@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
drivers/staging/android/alarm-dev.c | 3 +-
drivers/staging/android/alarm.c | 70 +++++++------------------------
drivers/staging/android/android_alarm.h | 7 +++-
3 files changed, 22 insertions(+), 58 deletions(-)

diff --git a/drivers/staging/android/alarm-dev.c b/drivers/staging/android/alarm-dev.c
index 03efb34..bc57568 100644
--- a/drivers/staging/android/alarm-dev.c
+++ b/drivers/staging/android/alarm-dev.c
@@ -179,8 +179,7 @@ from_old_alarm_set:
break;
case ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP:
case ANDROID_ALARM_ELAPSED_REALTIME:
- tmp_time =
- ktime_to_timespec(alarm_get_elapsed_realtime());
+ get_monotonic_boottime(&tmp_time);
break;
case ANDROID_ALARM_TYPE_COUNT:
case ANDROID_ALARM_SYSTEMTIME:
diff --git a/drivers/staging/android/alarm.c b/drivers/staging/android/alarm.c
index c68950b..9ac4f7b 100644
--- a/drivers/staging/android/alarm.c
+++ b/drivers/staging/android/alarm.c
@@ -65,7 +65,6 @@ struct alarm_queue {
struct rb_root alarms;
struct rb_node *first;
struct hrtimer timer;
- ktime_t delta;
bool stopped;
ktime_t stopped_time;
};
@@ -107,8 +106,8 @@ static void update_timer_locked(struct alarm_queue *base, bool head_removed)
}

hrtimer_try_to_cancel(&base->timer);
- base->timer.node.expires = ktime_add(base->delta, alarm->expires);
- base->timer._softexpires = ktime_add(base->delta, alarm->softexpires);
+ base->timer.node.expires = alarm->expires;
+ base->timer._softexpires = alarm->softexpires;
hrtimer_start_expires(&base->timer, HRTIMER_MODE_ABS);
}

@@ -279,10 +278,6 @@ int android_alarm_set_rtc(struct timespec new_time)
alarms[i].stopped = true;
alarms[i].stopped_time = timespec_to_ktime(tmp_time);
}
- alarms[ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP].delta =
- alarms[ANDROID_ALARM_ELAPSED_REALTIME].delta =
- ktime_sub(alarms[ANDROID_ALARM_ELAPSED_REALTIME].delta,
- timespec_to_ktime(timespec_sub(tmp_time, new_time)));
spin_unlock_irqrestore(&alarm_slock, flags);
ret = do_settimeofday(&new_time);
spin_lock_irqsave(&alarm_slock, flags);
@@ -310,24 +305,6 @@ err:
return ret;
}

-/**
- * alarm_get_elapsed_realtime - get the elapsed real time in ktime_t format
- *
- * returns the time in ktime_t format
- */
-ktime_t alarm_get_elapsed_realtime(void)
-{
- ktime_t now;
- unsigned long flags;
- struct alarm_queue *base = &alarms[ANDROID_ALARM_ELAPSED_REALTIME];
-
- spin_lock_irqsave(&alarm_slock, flags);
- now = base->stopped ? base->stopped_time : ktime_get_real();
- now = ktime_sub(now, base->delta);
- spin_unlock_irqrestore(&alarm_slock, flags);
- return now;
-}
-
static enum hrtimer_restart alarm_timer_triggered(struct hrtimer *timer)
{
struct alarm_queue *base;
@@ -339,7 +316,6 @@ static enum hrtimer_restart alarm_timer_triggered(struct hrtimer *timer)

base = container_of(timer, struct alarm_queue, timer);
now = base->stopped ? base->stopped_time : hrtimer_cb_get_time(timer);
- now = ktime_sub(now, base->delta);

pr_alarm(INT, "alarm_timer_triggered type %ld at %lld\n",
base - alarms, ktime_to_ns(now));
@@ -536,40 +512,25 @@ static struct platform_driver alarm_driver = {
}
};

-static int __init alarm_late_init(void)
-{
- unsigned long flags;
- struct timespec tmp_time, system_time;
-
- /* this needs to run after the rtc is read at boot */
- spin_lock_irqsave(&alarm_slock, flags);
- /* We read the current rtc and system time so we can later calulate
- * elasped realtime to be (boot_systemtime + rtc - boot_rtc) ==
- * (rtc - (boot_rtc - boot_systemtime))
- */
- getnstimeofday(&tmp_time);
- ktime_get_ts(&system_time);
- alarms[ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP].delta =
- alarms[ANDROID_ALARM_ELAPSED_REALTIME].delta =
- timespec_to_ktime(timespec_sub(tmp_time, system_time));
-
- spin_unlock_irqrestore(&alarm_slock, flags);
- return 0;
-}
-
static int __init alarm_driver_init(void)
{
int err;
int i;

- for (i = 0; i < ANDROID_ALARM_SYSTEMTIME; i++) {
- hrtimer_init(&alarms[i].timer,
- CLOCK_REALTIME, HRTIMER_MODE_ABS);
- alarms[i].timer.function = alarm_timer_triggered;
- }
+ hrtimer_init(&alarms[ANDROID_ALARM_RTC_WAKEUP].timer,
+ CLOCK_REALTIME, HRTIMER_MODE_ABS);
+ hrtimer_init(&alarms[ANDROID_ALARM_RTC].timer,
+ CLOCK_REALTIME, HRTIMER_MODE_ABS);
+ hrtimer_init(&alarms[ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP].timer,
+ CLOCK_BOOTTIME, HRTIMER_MODE_ABS);
+ hrtimer_init(&alarms[ANDROID_ALARM_ELAPSED_REALTIME].timer,
+ CLOCK_BOOTTIME, HRTIMER_MODE_ABS);
hrtimer_init(&alarms[ANDROID_ALARM_SYSTEMTIME].timer,
- CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
- alarms[ANDROID_ALARM_SYSTEMTIME].timer.function = alarm_timer_triggered;
+ CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+
+ for (i = 0; i < ANDROID_ALARM_TYPE_COUNT; i++)
+ alarms[i].timer.function = alarm_timer_triggered;
+
err = platform_driver_register(&alarm_driver);
if (err < 0)
goto err1;
@@ -595,7 +556,6 @@ static void __exit alarm_exit(void)
platform_driver_unregister(&alarm_driver);
}

-late_initcall(alarm_late_init);
module_init(alarm_driver_init);
module_exit(alarm_exit);

diff --git a/drivers/staging/android/android_alarm.h b/drivers/staging/android/android_alarm.h
index 6eecbde..011be19 100644
--- a/drivers/staging/android/android_alarm.h
+++ b/drivers/staging/android/android_alarm.h
@@ -37,6 +37,7 @@ enum android_alarm_type {

#include <linux/ktime.h>
#include <linux/rbtree.h>
+#include <linux/hrtimer.h>

/*
* The alarm interface is similar to the hrtimer interface but adds support
@@ -71,7 +72,11 @@ void android_alarm_start_range(struct android_alarm *alarm, ktime_t start,
ktime_t end);
int android_alarm_try_to_cancel(struct android_alarm *alarm);
int android_alarm_cancel(struct android_alarm *alarm);
-ktime_t alarm_get_elapsed_realtime(void);
+
+static inline ktime_t alarm_get_elapsed_realtime(void)
+{
+ return ktime_get_boottime();
+}

/* set rtc while preserving elapsed realtime */
int android_alarm_set_rtc(const struct timespec ts);
--
1.7.3.2.146.gca209


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