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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>
This commit is contained in:
Patrick Pannuto 2010-07-19 15:09:26 -07:00 committed by Thomas Gleixner
parent 866e26115c
commit 22b8f15c2f
2 changed files with 28 additions and 0 deletions
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6
include/linux/delay.h
View File

@ -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)
{

22
kernel/timer.c
View File

@ -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);