diff options
| author | Patrick Pannuto <ppannuto@codeaurora.org> | 2010-07-19 15:09:26 -0700 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2010-07-23 15:08:12 +0200 |
| commit | 22b8f15c2f7130bb0386f548428df2ffd4e81903 (patch) | |
| tree | 4ed7ac08115afdce20d21bd923cd1071c2249dda | |
| parent | 866e26115cba6b59cec669b6307599e3e4440491 (diff) | |
| download | lwn-22b8f15c2f7130bb0386f548428df2ffd4e81903.tar.gz lwn-22b8f15c2f7130bb0386f548428df2ffd4e81903.zip | |
timer: Added usleep[_range] timer
usleep[_range] are finer precision implementations of msleep
and are designed to be drop-in replacements for udelay where
a precise sleep / busy-wait is unnecessary. They also allow
an easy interface to specify slack when a precise (ish)
wakeup is unnecessary to help minimize wakeups
Signed-off-by: Patrick Pannuto <ppannuto@codeaurora.org>
Cc: akinobu.mita@gmail.com
Cc: sboyd@codeaurora.org
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <4C44CDD2.1070708@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| -rw-r--r-- | include/linux/delay.h | 6 | ||||
| -rw-r--r-- | kernel/timer.c | 22 |
2 files changed, 28 insertions, 0 deletions
diff --git a/include/linux/delay.h b/include/linux/delay.h index fd832c6d419e..0e303d1aacd8 100644 --- a/include/linux/delay.h +++ b/include/linux/delay.h @@ -45,6 +45,12 @@ extern unsigned long lpj_fine; void calibrate_delay(void); void msleep(unsigned int msecs); unsigned long msleep_interruptible(unsigned int msecs); +void usleep_range(unsigned long min, unsigned long max); + +static inline void usleep(unsigned long usecs) +{ + usleep_range(usecs, usecs); +} static inline void ssleep(unsigned int seconds) { diff --git a/kernel/timer.c b/kernel/timer.c index ce98685cd1cb..f110f241ab66 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1755,3 +1755,25 @@ unsigned long msleep_interruptible(unsigned int msecs) } EXPORT_SYMBOL(msleep_interruptible); + +static int __sched do_usleep_range(unsigned long min, unsigned long max) +{ + ktime_t kmin; + unsigned long delta; + + kmin = ktime_set(0, min * NSEC_PER_USEC); + delta = max - min; + return schedule_hrtimeout_range(&kmin, delta, HRTIMER_MODE_REL); +} + +/** + * usleep_range - Drop in replacement for udelay where wakeup is flexible + * @min: Minimum time in usecs to sleep + * @max: Maximum time in usecs to sleep + */ +void usleep_range(unsigned long min, unsigned long max) +{ + __set_current_state(TASK_UNINTERRUPTIBLE); + do_usleep_range(min, max); +} +EXPORT_SYMBOL(usleep_range); |