user/sven/linux.git/include/linux/time.h, branch v3.3.5

timers: Posix interface for alarm-timers

2011-04-26T21:01:46Z

This patch exposes alarm-timers to userland via the posix clock and timers interface, using two new clockids: CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. Both clockids behave identically to CLOCK_REALTIME and CLOCK_BOOTTIME, respectively, but timers set against the _ALARM suffixed clockids will wake the system if it is suspended. Some background can be found here: https://lwn.net/Articles/429925/ The concept for Alarm-timers was inspired by the Android Alarm driver (by Arve Hjønnevåg) found in the Android kernel tree. See: http://android.git.kernel.org/?p=kernel/common.git;a=blob;f=drivers/rtc/alarm.c;h=1250edfbdf3302f5e4ea6194847c6ef4bb7beb1c;hb=android-2.6.36 While the in-kernel interface is pretty similar between alarm-timers and Android alarm driver, the user-space interface for the Android alarm driver is via ioctls to a new char device. As mentioned above, I've instead chosen to export this functionality via the posix interface, as it seemed a little simpler and avoids creating duplicate interfaces to things like CLOCK_REALTIME and CLOCK_MONOTONIC under alternate names (ie:ANDROID_ALARM_RTC and ANDROID_ALARM_SYSTEMTIME). The semantics of the Android alarm driver are different from what this posix interface provides. For instance, threads other then the thread waiting on the Android alarm driver are able to modify the alarm being waited on. Also this interface does not allow the same wakelock semantics that the Android driver provides (ie: kernel takes a wakelock on RTC alarm-interupt, and holds it through process wakeup, and while the process runs, until the process either closes the char device or calls back in to wait on a new alarm). One potential way to implement similar semantics may be via the timerfd infrastructure, but this needs more research. There may also need to be some sort of sysfs system level policy hooks that allow alarm timers to be disabled to keep them from firing at inappropriate times (ie: laptop in a well insulated bag, mid-flight). CC: Arve Hjønnevåg CC: Thomas Gleixner CC: Alessandro Zummo Acked-by: Arnd Bergmann Signed-off-by: John Stultz

time: Add timekeeping_inject_sleeptime

2011-04-26T21:01:41Z

Some platforms cannot implement read_persistent_clock, as their RTC devices are only accessible when interrupts are enabled. This keeps them from being used by the timekeeping code on resume to measure the time in suspend. The RTC layer tries to work around this, by calling do_settimeofday on resume after irqs are reenabled to set the time properly. However, this only corrects CLOCK_REALTIME, and does not properly adjust the sleep time value. This causes btime in /proc/stat to be incorrect as well as making the new CLOCK_BOTTTIME inaccurate. This patch resolves the issue by introducing a new timekeeping hook to allow the RTC layer to inject the sleep time on resume. The code also checks to make sure that read_persistent_clock is nonfunctional before setting the sleep time, so that should the RTC's HCTOSYS option be configured in on a system that does support read_persistent_clock we will not increase the total_sleep_time twice. CC: Arve Hjønnevåg CC: Thomas Gleixner Acked-by: Arnd Bergmann Signed-off-by: John Stultz

timers: Add CLOCK_BOOTTIME hrtimer base

2011-02-21T20:53:08Z

CLOCK_MONOTONIC stops while the system is in suspend. This is because to applications system suspend is invisible. However, there is a growing set of applications that are wanting to be suspend-aware, but do not want to deal with the complications of CLOCK_REALTIME (which might jump around if settimeofday is called). For these applications, I propose a new clockid: CLOCK_BOOTTIME. CLOCK_BOOTTIME is idential to CLOCK_MONOTONIC, except it also includes any time spent in suspend. This patch add hrtimer base for CLOCK_BOOTTIME, using get_monotonic_boottime/ktime_get_boottime, to allow in kernel users to set timers against. CC: Jamie Lokier CC: Thomas Gleixner CC: Alexander Shishkin CC: Arve Hjønnevåg Signed-off-by: John Stultz

time: Extend get_xtime_and_monotonic_offset() to also return sleep

2011-02-21T20:53:07Z

Extend get_xtime_and_monotonic_offset to get_xtime_and_monotonic_and_sleep_offset(). CC: Jamie Lokier CC: Thomas Gleixner CC: Alexander Shishkin CC: Arve Hjønnevåg Signed-off-by: John Stultz

time: Introduce get_monotonic_boottime and ktime_get_boottime

2011-02-21T20:53:05Z

This adds new functions that return the monotonic time since boot (in other words, CLOCK_MONOTONIC + suspend time). CC: Jamie Lokier CC: Thomas Gleixner CC: Alexander Shishkin CC: Arve Hjønnevåg Signed-off-by: John Stultz

time: Introduce timekeeping_inject_offset

2011-02-02T14:28:18Z

This adds a kernel-internal timekeeping interface to add or subtract a fixed amount from CLOCK_REALTIME. This makes it so kernel users or interfaces trying to do so do not have to read the time, then add an offset and then call settimeofday(), which adds some extra error in comparision to just simply adding the offset in the kernel timekeeping core. Signed-off-by: John Stultz Signed-off-by: Richard Cochran LKML-Reference: <20110201134419.584311693@linutronix.de> Signed-off-by: Thomas Gleixner

time: Correct the settime parameters

2011-02-02T14:28:11Z

Both settimeofday() and clock_settime() promise with a 'const' attribute not to alter the arguments passed in. This patch adds the missing 'const' attribute into the various kernel functions implementing these calls. Signed-off-by: Richard Cochran Acked-by: John Stultz LKML-Reference: <20110201134417.545698637@linutronix.de> Signed-off-by: Thomas Gleixner

time: Make do_timer() and xtime_lock local to kernel/time/

2011-01-31T18:26:50Z

All callers of do_timer() are converted to xtime_update(). The only users of xtime_lock are in kernel/time/. Make both local to kernel/time/ and remove them from the global header files. [ tglx: Reuse tick-internal.h instead of creating another local header file. Massaged changelog ] Signed-off-by: Torben Hohn Cc: Peter Zijlstra Cc: johnstul@us.ibm.com Cc: yong.zhang0@gmail.com Cc: hch@infradead.org Signed-off-by: Thomas Gleixner

time: Remove unused __get_wall_to_monotonic()

2011-01-31T13:55:43Z

No users left. Remove it. Signed-off-by: Thomas Gleixner

time: Provide get_xtime_and_monotonic_offset()

2011-01-31T13:55:42Z

The hrtimer code accesses timekeeping variables under xtime_lock. Provide a sensible accessor function and use it. [ tglx: Removed the conditionals, unused variable, fixed codingstyle and massaged changelog ] Signed-off-by: Torben Hohn Cc: Peter Zijlstra Cc: johnstul@us.ibm.com Cc: yong.zhang0@gmail.com Cc: hch@infradead.org LKML-Reference: <20110127145905.23248.30458.stgit@localhost> Signed-off-by: Thomas Gleixner