ARM: architected timers: add support for UP timer

If CONFIG_LOCAL_TIMERS is not defined, let the architected timer
driver register a single clock_event_device that is used as a
global timer.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c
index 1a34eeebc26e..154f0a1756b1 100644
--- a/arch/arm/kernel/arch_timer.c
+++ b/arch/arm/kernel/arch_timer.c
@@ -246,6 +246,8 @@ static struct local_timer_ops arch_timer_ops __cpuinitdata = {
         .stop   = arch_timer_stop,
 };
 
+static struct clock_event_device arch_timer_global_evt;
+
 static int __init arch_timer_common_register(void)
 {
         int err;
@@ -280,6 +282,17 @@ static int __init arch_timer_common_register(void)
         }
 
         err = local_timer_register(&arch_timer_ops);
+        if (err) {
+                /*
+                 * We couldn't register as a local timer (could be
+                 * because we're on a UP platform, or because some
+                 * other local timer is already present...). Try as a
+                 * global timer instead.
+                 */
+                arch_timer_global_evt.cpumask = cpumask_of(0);
+                err = arch_timer_setup(&arch_timer_global_evt);
+        }
+
         if (err)
                 goto out_free_irq;