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Subject[tip:timers/core] timer: Added usleep[_range] timer
Commit-ID:  22b8f15c2f7130bb0386f548428df2ffd4e81903
Gitweb: http://git.kernel.org/tip/22b8f15c2f7130bb0386f548428df2ffd4e81903
Author: Patrick Pannuto <ppannuto@codeaurora.org>
AuthorDate: Mon, 19 Jul 2010 15:09:26 -0700
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 23 Jul 2010 15:08:12 +0200

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>
---
include/linux/delay.h | 6 ++++++
kernel/timer.c | 22 ++++++++++++++++++++++
2 files changed, 28 insertions(+), 0 deletions(-)
diff --git a/include/linux/delay.h b/include/linux/delay.h
index fd832c6..0e303d1 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 ce98685..f110f24 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);

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