[ARM] 3135/1: harden SA11x0 and PXA2xx timer init code

Patch from Nicolas Pitre

Make it completely deterministic and leave nothing to chance
(even if it had at worst 0.001% probability of failing).

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 10 insertions, 6 deletions

diff --git a/arch/arm/mach-pxa/time.c b/arch/arm/mach-pxa/time.c
index 7dad3f1465e0..b9b2057349eb 100644
--- a/arch/arm/mach-pxa/time.c
+++ b/arch/arm/mach-pxa/time.c
@@ -132,11 +132,13 @@ static void __init pxa_timer_init(void)
         tv.tv_sec = pxa_get_rtc_time();
         do_settimeofday(&tv);
 
-        OSMR0 = 0;              /* set initial match at 0 */
+        OIER = 0;               /* disable any timer interrupts */
+        OSCR = LATCH*2;         /* push OSCR out of the way */
+        OSMR0 = LATCH;          /* set initial match */
         OSSR = 0xf;             /* clear status on all timers */
         setup_irq(IRQ_OST0, &pxa_timer_irq);
-        OIER |= OIER_E0;        /* enable match on timer 0 to cause interrupts */
-        OSCR = 0;               /* initialize free-running timer, force first match */
+        OIER = OIER_E0;         /* enable match on timer 0 to cause interrupts */
+        OSCR = 0;               /* initialize free-running timer */
 }
 
 #ifdef CONFIG_NO_IDLE_HZ
diff --git a/arch/arm/mach-sa1100/time.c b/arch/arm/mach-sa1100/time.c
index 47e0420623fc..e4b435e634e4 100644
--- a/arch/arm/mach-sa1100/time.c
+++ b/arch/arm/mach-sa1100/time.c
@@ -124,11 +124,13 @@ static void __init sa1100_timer_init(void)
         tv.tv_sec = sa1100_get_rtc_time();
         do_settimeofday(&tv);
 
-        OSMR0 = 0;              /* set initial match at 0 */
+        OIER = 0;               /* disable any timer interrupts */
+        OSCR = LATCH*2;         /* push OSCR out of the way */
+        OSMR0 = LATCH;          /* set initial match */
         OSSR = 0xf;             /* clear status on all timers */
         setup_irq(IRQ_OST0, &sa1100_timer_irq);
-        OIER |= OIER_E0;        /* enable match on timer 0 to cause interrupts */
-        OSCR = 0;               /* initialize free-running timer, force first match */
+        OIER = OIER_E0;         /* enable match on timer 0 to cause interrupts */
+        OSCR = 0;               /* initialize free-running timer */
 }
 
 #ifdef CONFIG_NO_IDLE_HZ