diff options
author | Grant Likely <grant.likely@secretlab.ca> | 2010-05-22 00:36:56 -0600 |
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committer | Grant Likely <grant.likely@secretlab.ca> | 2010-05-22 00:36:56 -0600 |
commit | cf9b59e9d3e008591d1f54830f570982bb307a0d (patch) | |
tree | 113478ce8fd8c832ba726ffdf59b82cb46356476 /kernel/time/clocksource.c | |
parent | 44504b2bebf8b5823c59484e73096a7d6574471d (diff) | |
parent | f4b87dee923342505e1ddba8d34ce9de33e75050 (diff) |
Merge remote branch 'origin' into secretlab/next-devicetree
Merging in current state of Linus' tree to deal with merge conflicts and
build failures in vio.c after merge.
Conflicts:
drivers/i2c/busses/i2c-cpm.c
drivers/i2c/busses/i2c-mpc.c
drivers/net/gianfar.c
Also fixed up one line in arch/powerpc/kernel/vio.c to use the
correct node pointer.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Diffstat (limited to 'kernel/time/clocksource.c')
-rw-r--r-- | kernel/time/clocksource.c | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 1f5dde637457..f08e99c1d561 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -625,6 +625,54 @@ static void clocksource_enqueue(struct clocksource *cs) list_add(&cs->list, entry); } + +/* + * Maximum time we expect to go between ticks. This includes idle + * tickless time. It provides the trade off between selecting a + * mult/shift pair that is very precise but can only handle a short + * period of time, vs. a mult/shift pair that can handle long periods + * of time but isn't as precise. + * + * This is a subsystem constant, and actual hardware limitations + * may override it (ie: clocksources that wrap every 3 seconds). + */ +#define MAX_UPDATE_LENGTH 5 /* Seconds */ + +/** + * __clocksource_register_scale - Used to install new clocksources + * @t: clocksource to be registered + * @scale: Scale factor multiplied against freq to get clocksource hz + * @freq: clocksource frequency (cycles per second) divided by scale + * + * Returns -EBUSY if registration fails, zero otherwise. + * + * This *SHOULD NOT* be called directly! Please use the + * clocksource_register_hz() or clocksource_register_khz helper functions. + */ +int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) +{ + + /* + * Ideally we want to use some of the limits used in + * clocksource_max_deferment, to provide a more informed + * MAX_UPDATE_LENGTH. But for now this just gets the + * register interface working properly. + */ + clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, + NSEC_PER_SEC/scale, + MAX_UPDATE_LENGTH*scale); + cs->max_idle_ns = clocksource_max_deferment(cs); + + mutex_lock(&clocksource_mutex); + clocksource_enqueue(cs); + clocksource_select(); + clocksource_enqueue_watchdog(cs); + mutex_unlock(&clocksource_mutex); + return 0; +} +EXPORT_SYMBOL_GPL(__clocksource_register_scale); + + /** * clocksource_register - Used to install new clocksources * @t: clocksource to be registered |