linux/kernel/time
Viresh Kumar bd624d75db clockevents: Introduce mode specific callbacks
It is not possible for the clockevents core to know which modes (other than
those with a corresponding feature flag) are supported by a particular
implementation. And drivers are expected to handle transition to all modes
elegantly, as ->set_mode() would be issued for them unconditionally.

Now, adding support for a new mode complicates things a bit if we want to use
the legacy ->set_mode() callback. We need to closely review all clockevents
drivers to see if they would break on addition of a new mode. And after such
reviews, it is found that we have to do non-trivial changes to most of the
drivers [1].

Introduce mode-specific set_mode_*() callbacks, some of which the drivers may or
may not implement. A missing callback would clearly convey the message that the
corresponding mode isn't supported.

A driver may still choose to keep supporting the legacy ->set_mode() callback,
but ->set_mode() wouldn't be supporting any new modes beyond RESUME. If a driver
wants to benefit from using a new mode, it would be required to migrate to
the mode specific callbacks.

The legacy ->set_mode() callback and the newly introduced mode-specific
callbacks are mutually exclusive. Only one of them should be supported by the
driver.

Sanity check is done at the time of registration to distinguish between optional
and required callbacks and to make error recovery and handling simpler. If the
legacy ->set_mode() callback is provided, all mode specific ones would be
ignored by the core but a warning is thrown if they are present.

Call sites calling ->set_mode() directly are also updated to use
__clockevents_set_mode() instead, as ->set_mode() may not be available anymore
for few drivers.

 [1] https://lkml.org/lkml/2014/12/9/605
 [2] https://lkml.org/lkml/2015/1/23/255

Suggested-by: Thomas Gleixner <tglx@linutronix.de> [2]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: linaro-kernel@lists.linaro.org
Cc: linaro-networking@linaro.org
Link: http://lkml.kernel.org/r/792d59a40423f0acffc9bb0bec9de1341a06fa02.1423788565.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-02-18 15:16:23 +01:00
..
alarmtimer.c alarmtimer: Lock k_itimer during timer callback 2014-09-12 13:59:12 -07:00
clockevents.c clockevents: Introduce mode specific callbacks 2015-02-18 15:16:23 +01:00
clocksource.c clocksource: Fix 'clcoksource' typo in comment 2014-10-29 14:48:34 +01:00
hrtimer.c hrtimer: Make __hrtimer_get_next_event() static 2015-01-24 10:53:36 +01:00
itimer.c time/timers: Move all time(r) related files into kernel/time 2014-06-23 11:22:35 +02:00
jiffies.c time: Fix overflow when HZ is smaller than 60 2014-02-06 16:01:40 +01:00
Kconfig clocksource: Move cycle_last validation to core code 2014-07-23 15:01:51 -07:00
Makefile time: Rename udelay_test.c to test_udelay.c 2014-11-21 11:59:55 -08:00
ntp_internal.h timekeeping: Convert timekeeping core to use timespec64s 2014-07-23 10:17:54 -07:00
ntp.c rtc: Convert rtc_set_ntp_time() to use timespec64 2015-01-23 17:21:57 -08:00
posix-clock.c kernel: Fix files explicitly needing EXPORT_SYMBOL infrastructure 2011-10-31 19:30:05 -04:00
posix-cpu-timers.c sched/cputime: Fix cpu_timer_sample_group() double accounting 2014-11-16 10:04:18 +01:00
posix-timers.c posix-timers: Fix stack info leak in timer_create() 2014-10-25 10:43:15 +02:00
sched_clock.c sched_clock: Avoid corrupting hrtimer tree during suspend 2014-07-24 12:02:49 +02:00
test_udelay.c time: Rename udelay_test.c to test_udelay.c 2014-11-21 11:59:55 -08:00
tick-broadcast-hrtimer.c tick: Fixup more fallout from hrtimer broadcast mode 2014-02-09 15:11:47 +01:00
tick-broadcast.c time: Replace __get_cpu_var uses 2014-08-26 13:45:44 -04:00
tick-common.c Merge branch 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2014-10-15 07:48:18 +02:00
tick-internal.h nohz: Move nohz full init call to tick init 2014-09-13 18:34:44 +02:00
tick-oneshot.c time: Replace __get_cpu_var uses 2014-08-26 13:45:44 -04:00
tick-sched.c Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-19 13:29:20 -08:00
time.c Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux 2014-12-15 15:52:01 -08:00
timeconst.bc time/timers: Move all time(r) related files into kernel/time 2014-06-23 11:22:35 +02:00
timeconv.c time: add function to convert between calendar time and broken-down time for universal use 2009-09-24 07:20:56 -07:00
timekeeping_debug.c timekeeping: Convert timekeeping core to use timespec64s 2014-07-23 10:17:54 -07:00
timekeeping_internal.h clocksource: Move cycle_last validation to core code 2014-07-23 15:01:51 -07:00
timekeeping.c time: Expose getboottime64 for in-kernel uses 2015-01-23 17:21:54 -08:00
timekeeping.h time: Consolidate the time accessor prototypes 2014-07-23 10:17:54 -07:00
timer_list.c clockevents: Introduce mode specific callbacks 2015-02-18 15:16:23 +01:00
timer_stats.c timer stats: Add a 'Collection: active/inactive' line to timer usage statistics 2013-10-10 09:59:25 +02:00
timer.c rcu: Remove "cpu" argument to rcu_check_callbacks() 2014-11-03 19:20:11 -08:00