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>

3 files changed, 22 insertions, 0 deletions

diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index e1089aa7816d..66346521cb65 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 8601f0db1261..b69692250af4 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 7cc81c57eb31..f726537d24eb 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;