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authorMagnus Damm <damm@igel.co.jp>2009-04-21 15:24:02 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-21 16:41:47 -0400
commit4614e6adafa2c5e6c3a9c245af2807fa7bc5117a (patch)
treee4bb5eeaa252ede053abc6b3c4d15c4127ce7a32 /include
parent8e19608e8b5c001e4a66ce482edc474f05fb7355 (diff)
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.h31
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,
144 * The ideal clocksource. A must-use where 144 * The ideal clocksource. A must-use where
145 * available. 145 * available.
146 * @read: returns a cycle value, passes clocksource as argument 146 * @read: returns a cycle value, passes clocksource as argument
147 * @enable: optional function to enable the clocksource
148 * @disable: optional function to disable the clocksource
147 * @mask: bitmask for two's complement 149 * @mask: bitmask for two's complement
148 * subtraction of non 64 bit counters 150 * subtraction of non 64 bit counters
149 * @mult: cycle to nanosecond multiplier (adjusted by NTP) 151 * @mult: cycle to nanosecond multiplier (adjusted by NTP)
@@ -163,6 +165,8 @@ struct clocksource {
163 struct list_head list; 165 struct list_head list;
164 int rating; 166 int rating;
165 cycle_t (*read)(struct clocksource *cs); 167 cycle_t (*read)(struct clocksource *cs);
168 int (*enable)(struct clocksource *cs);
169 void (*disable)(struct clocksource *cs);
166 cycle_t mask; 170 cycle_t mask;
167 u32 mult; 171 u32 mult;
168 u32 mult_orig; 172 u32 mult_orig;
@@ -275,6 +279,33 @@ static inline cycle_t clocksource_read(struct clocksource *cs)
275} 279}
276 280
277/** 281/**
282 * clocksource_enable: - enable clocksource
283 * @cs: pointer to clocksource
284 *
285 * Enables the specified clocksource. The clocksource callback
286 * function should start up the hardware and setup mult and field
287 * members of struct clocksource to reflect hardware capabilities.
288 */
289static inline int clocksource_enable(struct clocksource *cs)
290{
291 return cs->enable ? cs->enable(cs) : 0;
292}
293
294/**
295 * clocksource_disable: - disable clocksource
296 * @cs: pointer to clocksource
297 *
298 * Disables the specified clocksource. The clocksource callback
299 * function should power down the now unused hardware block to
300 * save power.
301 */
302static inline void clocksource_disable(struct clocksource *cs)
303{
304 if (cs->disable)
305 cs->disable(cs);
306}
307
308/**
278 * cyc2ns - converts clocksource cycles to nanoseconds 309 * cyc2ns - converts clocksource cycles to nanoseconds
279 * @cs: Pointer to clocksource 310 * @cs: Pointer to clocksource
280 * @cycles: Cycles 311 * @cycles: Cycles