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    Subject[tip:timers/core] clockevents: Add generic timer broadcast function
    Commit-ID:  12ad10004645d38356b14d1fbba379c523a61916
    Gitweb: http://git.kernel.org/tip/12ad10004645d38356b14d1fbba379c523a61916
    Author: Mark Rutland <mark.rutland@arm.com>
    AuthorDate: Mon, 14 Jan 2013 17:05:22 +0000
    Committer: Thomas Gleixner <tglx@linutronix.de>
    CommitDate: Thu, 31 Jan 2013 22:15:36 +0100

    clockevents: Add generic timer broadcast function

    Currently, the timer broadcast mechanism is defined by a function
    pointer on struct clock_event_device. As the fundamental mechanism for
    broadcast is architecture-specific, this means that clock_event_device
    drivers cannot be shared across multiple architectures.

    This patch adds an (optional) architecture-specific function for timer
    tick broadcast, allowing drivers which may require broadcast
    functionality to be shared across multiple architectures.

    Signed-off-by: Mark Rutland <mark.rutland@arm.com>
    Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
    Cc: linux-arm-kernel@lists.infradead.org
    Cc: nico@linaro.org
    Cc: Will.Deacon@arm.com
    Cc: Marc.Zyngier@arm.com
    Cc: john.stultz@linaro.org
    Link: http://lkml.kernel.org/r/1358183124-28461-3-git-send-email-mark.rutland@arm.com
    Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
    Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    ---
    include/linux/clockchips.h | 5 +++++
    kernel/time/Kconfig | 4 ++++
    kernel/time/tick-broadcast.c | 13 +++++++++++++
    3 files changed, 22 insertions(+)

    diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
    index e1089aa..6634652 100644
    --- a/include/linux/clockchips.h
    +++ b/include/linux/clockchips.h
    @@ -162,6 +162,11 @@ extern void clockevents_suspend(void);
    extern void clockevents_resume(void);

    #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
    +#ifdef CONFIG_ARCH_HAS_TICK_BROADCAST
    +extern void tick_broadcast(const struct cpumask *mask);
    +#else
    +#define tick_broadcast NULL
    +#endif
    extern int tick_receive_broadcast(void);
    #endif

    diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
    index 8601f0d..b696922 100644
    --- a/kernel/time/Kconfig
    +++ b/kernel/time/Kconfig
    @@ -38,6 +38,10 @@ config GENERIC_CLOCKEVENTS_BUILD
    default y
    depends on GENERIC_CLOCKEVENTS

    +# Architecture can handle broadcast in a driver-agnostic way
    +config ARCH_HAS_TICK_BROADCAST
    + bool
    +
    # Clockevents broadcasting infrastructure
    config GENERIC_CLOCKEVENTS_BROADCAST
    bool
    diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
    index 7cc81c5..f726537 100644
    --- a/kernel/time/tick-broadcast.c
    +++ b/kernel/time/tick-broadcast.c
    @@ -18,6 +18,7 @@
    #include <linux/percpu.h>
    #include <linux/profile.h>
    #include <linux/sched.h>
    +#include <linux/smp.h>

    #include "tick-internal.h"

    @@ -86,6 +87,11 @@ int tick_is_broadcast_device(struct clock_event_device *dev)
    return (dev && tick_broadcast_device.evtdev == dev);
    }

    +static void err_broadcast(const struct cpumask *mask)
    +{
    + pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
    +}
    +
    /*
    * Check, if the device is disfunctional and a place holder, which
    * needs to be handled by the broadcast device.
    @@ -105,6 +111,13 @@ int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
    */
    if (!tick_device_is_functional(dev)) {
    dev->event_handler = tick_handle_periodic;
    + if (!dev->broadcast)
    + dev->broadcast = tick_broadcast;
    + if (!dev->broadcast) {
    + pr_warn_once("%s depends on broadcast, but no broadcast function available\n",
    + dev->name);
    + dev->broadcast = err_broadcast;
    + }
    cpumask_set_cpu(cpu, tick_get_broadcast_mask());
    tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
    ret = 1;

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