Commit 22b8f15c authored by Patrick Pannuto's avatar Patrick Pannuto Committed by Thomas Gleixner
Browse files

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: default avatarPatrick Pannuto <ppannuto@codeaurora.org>
Cc: akinobu.mita@gmail.com
Cc: sboyd@codeaurora.org
Acked-by: default avatarArjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <4C44CDD2.1070708@codeaurora.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 866e2611

include/linux/delay.h

+6 −0
Original line number Diff line number Diff line
@@ -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)

{

kernel/timer.c

+22 −0
Original line number Diff line number Diff line
@@ -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);

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