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| author | Magnus Damm <damm@igel.co.jp> | 2009-04-21 12:24:02 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-21 13:41:47 -0700 |
| commit | 4614e6adafa2c5e6c3a9c245af2807fa7bc5117a (patch) | |
| tree | e4bb5eeaa252ede053abc6b3c4d15c4127ce7a32 /include | |
| parent | 8e19608e8b5c001e4a66ce482edc474f05fb7355 (diff) | |
| download | linux-stable-4614e6adafa2c5e6c3a9c245af2807fa7bc5117a.tar.gz linux-stable-4614e6adafa2c5e6c3a9c245af2807fa7bc5117a.tar.bz2 linux-stable-4614e6adafa2c5e6c3a9c245af2807fa7bc5117a.zip | |
clocksource: add enable() and disable() callbacks
Add enable() and disable() callbacks for clocksources.
This allows us to put unused clocksources in power save mode. The
functions clocksource_enable() and clocksource_disable() wrap the
callbacks and are inserted in the timekeeping code to enable before use
and disable after switching to a new clocksource.
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/clocksource.h | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index 0d96cde9ee5d..5a40d14daa9f 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -144,6 +144,8 @@ extern u64 timecounter_cyc2time(struct timecounter *tc, * The ideal clocksource. A must-use where * available. * @read: returns a cycle value, passes clocksource as argument + * @enable: optional function to enable the clocksource + * @disable: optional function to disable the clocksource * @mask: bitmask for two's complement * subtraction of non 64 bit counters * @mult: cycle to nanosecond multiplier (adjusted by NTP) @@ -163,6 +165,8 @@ struct clocksource { struct list_head list; int rating; cycle_t (*read)(struct clocksource *cs); + int (*enable)(struct clocksource *cs); + void (*disable)(struct clocksource *cs); cycle_t mask; u32 mult; u32 mult_orig; @@ -275,6 +279,33 @@ static inline cycle_t clocksource_read(struct clocksource *cs) } /** + * clocksource_enable: - enable clocksource + * @cs: pointer to clocksource + * + * Enables the specified clocksource. The clocksource callback + * function should start up the hardware and setup mult and field + * members of struct clocksource to reflect hardware capabilities. + */ +static inline int clocksource_enable(struct clocksource *cs) +{ + return cs->enable ? cs->enable(cs) : 0; +} + +/** + * clocksource_disable: - disable clocksource + * @cs: pointer to clocksource + * + * Disables the specified clocksource. The clocksource callback + * function should power down the now unused hardware block to + * save power. + */ +static inline void clocksource_disable(struct clocksource *cs) +{ + if (cs->disable) + cs->disable(cs); +} + +/** * cyc2ns - converts clocksource cycles to nanoseconds * @cs: Pointer to clocksource * @cycles: Cycles |