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.rutl...@arm.com>
---
include/linux/clockchips.h | 5 +++++
kernel/time/Kconfig | 4 ++++
kernel/time/tick-broadcast.c | 15 +++++++++++++++
3 files changed, 24 insertions(+), 0 deletions(-)
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 c2dd022..ec22a80 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 +87,12 @@ 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("Attempted to broadcast tick, but no broadcast mechanism "
+ "present. Some CPUs may be unresponsive.");
+}
+
/*
* Check, if the device is disfunctional and a place holder, which
* needs to be handled by the broadcast device.
@@ -105,6 +112,14 @@ 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;
--
1.7.0.4
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