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  1. 24 Jun, 2013 2 commits
    • Mark Rutland's avatar
      clocksource: Add generic dummy timer driver · 06470651
      Mark Rutland authored 
      Several architectures have a dummy timer driver tightly coupled with
their broadcast code to support machines without cpu-local timers (or
where there is a lack of driver support).

Since 12ad1000: "clockevents: Add generic timer broadcast function"
it's been possible to write broadcast-capable timer drivers decoupled
from the broadcast mechanism. We can use this functionality to implement
a generic dummy timer driver that can be shared by all architectures
with generic tick broadcast (ARCH_HAS_TICK_BROADCAST).

This patch implements a generic dummy timer using this facility.

[sboyd: Make percpu data static, use __this_cpu_ptr(), move to
        early_initcall to properly register on each CPU, only
	register if more than one CPU possible]
Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>,
Cc: John Stultz <john.stultz@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1370291642-13259-3-git-send-email-sboyd@codeaurora.orgSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      06470651
    • Stephen Boyd's avatar
      clockevents: Prefer CPU local devices over global devices · 70e5975d
      Stephen Boyd authored 
      On an SMP system with only one global clockevent and a dummy
clockevent per CPU we run into problems. We want the dummy
clockevents to be registered as the per CPU tick devices, but
we can only achieve that if we register the dummy clockevents
before the global clockevent or if we artificially inflate the
rating of the dummy clockevents to be higher than the rating
of the global clockevent. Failure to do so leads to boot
hangs when the dummy timers are registered on all other CPUs
besides the CPU that accepted the global clockevent as its tick
device and there is no broadcast timer to poke the dummy
devices.

If we're registering multiple clockevents and one clockevent is
global and the other is local to a particular CPU we should
choose to use the local clockevent regardless of the rating of
the device. This way, if the clockevent is a dummy it will take
the tick device duty as long as there isn't a higher rated tick
device and any global clockevent will be bumped out into
broadcast mode, fixing the problem described above.
Reported-and-tested-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Tested-by: soren.brinkmann@xilinx.com
Cc: John Stultz <john.stultz@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20130613183950.GA32061@codeaurora.orgSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      70e5975d
  3. 18 Jun, 2013 1 commit
  5. 17 Jun, 2013 1 commit
    • Stephen Boyd's avatar
      ARM: sched_clock: Load cycle count after epoch stabilizes · 336ae118
      Stephen Boyd authored 
      There is a small race between when the cycle count is read from
the hardware and when the epoch stabilizes. Consider this
scenario:

 CPU0                           CPU1
 ----                           ----
 cyc = read_sched_clock()
 cyc_to_sched_clock()
                                 update_sched_clock()
                                  ...
                                  cd.epoch_cyc = cyc;
  epoch_cyc = cd.epoch_cyc;
  ...
  epoch_ns + cyc_to_ns((cyc - epoch_cyc)

The cyc on cpu0 was read before the epoch changed. But we
calculate the nanoseconds based on the new epoch by subtracting
the new epoch from the old cycle count. Since epoch is most likely
larger than the old cycle count we calculate a large number that
will be converted to nanoseconds and added to epoch_ns, causing
time to jump forward too much.

Fix this problem by reading the hardware after the epoch has
stabilized.

Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
      336ae118
  7. 12 Jun, 2013 4 commits
  9. 08 Jun, 2013 1 commit
  11. 06 Jun, 2013 3 commits
  13. 29 May, 2013 4 commits
    • John Stultz's avatar
      x86: Fix vrtc_get_time/set_mmss to use new timespec interface · ce0b0989
      John Stultz authored 
      The patch "x86: Increase precision of x86_platform.get/set_wallclock"
changed the x86 platform set_wallclock/get_wallclock interfaces to
use nsec granular timespecs instead of a second granular interface.

However, that patch missed converting the vrtc code, so this patch
converts those functions to use timespecs.

Many thanks to the kbuild test robot for finding this!
Reported-by: default avatarkbuild test robot <fengguang.wu@intel.com>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
      ce0b0989
    • Colin Cross's avatar
      power: Add option to log time spent in suspend · 5c83545f
      Colin Cross authored 
      Below is a patch from android kernel that maintains a histogram of
suspend times. Please review and provide feedback.

Statistices on the time spent in suspend are kept in
/sys/kernel/debug/sleep_time.

Cc: Android Kernel Team <kernel-team@android.com>
Cc: Colin Cross <ccross@android.com>
Cc: Todd Poynor <toddpoynor@google.com>
Cc: San Mehat <san@google.com>
Cc: Benoit Goby <benoit@android.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarColin Cross <ccross@android.com>
Signed-off-by: default avatarTodd Poynor <toddpoynor@google.com>
[zoran.markovic@linaro.org: Re-formatted suspend time table to better
fit expected values. Moved accounting of suspend time into timekeeping
core. Removed CONFIG_SUSPEND_TIME flag and made the feature conditional
on CONFIG_DEBUG_FS. Changed the file name to sleep_time to better fit
terminology in timekeeping core. Changed seq_printf to seq_puts. Tweaked
commit message]
Signed-off-by: default avatarZoran Markovic <zoran.markovic@linaro.org>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
      5c83545f
    • Todd Poynor's avatar
      timerfd: Add alarm timers · 11ffa9d6
      Todd Poynor authored 
      Add support for clocks CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM,
thereby enabling wakeup alarm timers via file descriptors.
Signed-off-by: default avatarTodd Poynor <toddpoynor@google.com>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
      11ffa9d6
    • Todd Poynor's avatar
      alarmtimer: Add functions for timerfd support · 6cffe00f
      Todd Poynor authored 
      Add functions needed for hooking up alarmtimer to timerfd:

* alarm_restart: Similar to hrtimer_restart, restart an alarmtimer after
  the expires time has already been updated (as with alarm_forward).

* alarm_forward_now: Similar to hrtimer_forward_now, move the expires
  time forward to an interval from the current time of the associated clock.

* alarm_start_relative: Start an alarmtimer with an expires time relative to
  the current time of the associated clock.

* alarm_expires_remaining: Similar to hrtimer_expires_remaining, return the
  amount of time remaining until alarm expiry.
Signed-off-by: default avatarTodd Poynor <toddpoynor@google.com>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
      6cffe00f
  15. 28 May, 2013 7 commits
  17. 16 May, 2013 15 commits
  19. 15 May, 2013 2 commits
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