Commit-ID: 7aca0c07207385cca76025cc85231519935722b9
Gitweb: http://git.kernel.org/tip/7aca0c07207385cca76025cc85231519935722b9
Author: Alexander Kuleshov <kuleshovmail@xxxxxxxxx>
AuthorDate: Fri, 26 Feb 2016 19:14:13 -0800
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Sat, 27 Feb 2016 08:55:30 +0100
clocksource: Introduce clocksource_freq2mult()
The clocksource_khz2mult() and clocksource_hz2mult() share similar
code wihch calculates a mult from the given frequency. Both implementations
in differ only in value of a frequency. This patch introduces the
clocksource_freq2mult() helper with generic implementation of
mult calculation to prevent code duplication.
Signed-off-by: Alexander Kuleshov <kuleshovmail@xxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Prarit Bhargava <prarit@xxxxxxxxxx>
Cc: Richard Cochran <richardcochran@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1456542854-22104-2-git-send-email-john.stultz@xxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
include/linux/clocksource.h | 45 +++++++++++++++++++--------------------------
1 file changed, 19 insertions(+), 26 deletions(-)
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 6013021..a307bf6 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -118,6 +118,23 @@ struct clocksource {
/* simplify initialization of mask field */
#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
+static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from)
+{
+ /* freq = cyc/from
+ * mult/2^shift = ns/cyc
+ * mult = ns/cyc * 2^shift
+ * mult = from/freq * 2^shift
+ * mult = from * 2^shift / freq
+ * mult = (from<<shift) / freq
+ */
+ u64 tmp = ((u64)from) << shift_constant;
+
+ tmp += freq/2; /* round for do_div */
+ do_div(tmp, freq);
+
+ return (u32)tmp;
+}
+
/**
* clocksource_khz2mult - calculates mult from khz and shift
* @khz: Clocksource frequency in KHz
@@ -128,19 +145,7 @@ struct clocksource {
*/
static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)
{
- /* khz = cyc/(Million ns)
- * mult/2^shift = ns/cyc
- * mult = ns/cyc * 2^shift
- * mult = 1Million/khz * 2^shift
- * mult = 1000000 * 2^shift / khz
- * mult = (1000000<<shift) / khz
- */
- u64 tmp = ((u64)1000000) << shift_constant;
-
- tmp += khz/2; /* round for do_div */
- do_div(tmp, khz);
-
- return (u32)tmp;
+ return clocksource_freq2mult(khz, shift_constant, NSEC_PER_MSEC);
}
/**
@@ -154,19 +159,7 @@ static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)
*/
static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant)
{
- /* hz = cyc/(Billion ns)
- * mult/2^shift = ns/cyc
- * mult = ns/cyc * 2^shift
- * mult = 1Billion/hz * 2^shift
- * mult = 1000000000 * 2^shift / hz
- * mult = (1000000000<<shift) / hz
- */
- u64 tmp = ((u64)1000000000) << shift_constant;
-
- tmp += hz/2; /* round for do_div */
- do_div(tmp, hz);
-
- return (u32)tmp;
+ return clocksource_freq2mult(hz, shift_constant, NSEC_PER_SEC);
}
/**
--
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