[ARM] sa1100: add clock source support

Add generic clock source support for SA11x0 platforms.

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

2 files changed, 21 insertions, 18 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a04f507e7f2c..742527957048 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -366,6 +366,7 @@ config ARCH_SA1100
         select ARCH_DISCONTIGMEM_ENABLE
         select ARCH_MTD_XIP
         select GENERIC_GPIO
+        select GENERIC_TIME
         help
           Support for StrongARM 11x0 based boards.
 
diff --git a/arch/arm/mach-sa1100/time.c b/arch/arm/mach-sa1100/time.c
index fdf7b016e7ad..72984354a247 100644
--- a/arch/arm/mach-sa1100/time.c
+++ b/arch/arm/mach-sa1100/time.c
@@ -14,6 +14,7 @@
 #include <linux/irq.h>
 #include <linux/timex.h>
 #include <linux/signal.h>
+#include <linux/clocksource.h>
 
 #include <asm/mach/time.h>
 #include <asm/hardware.h>
@@ -35,23 +36,6 @@ static int sa1100_set_rtc(void)
         return 0;
 }
 
-/* IRQs are disabled before entering here from do_gettimeofday() */
-static unsigned long sa1100_gettimeoffset (void)
-{
-        unsigned long ticks_to_match, elapsed, usec;
-
-        /* Get ticks before next timer match */
-        ticks_to_match = OSMR0 - OSCR;
-
-        /* We need elapsed ticks since last match */
-        elapsed = LATCH - ticks_to_match;
-
-        /* Now convert them to usec */
-        usec = (unsigned long)(elapsed * (tick_nsec / 1000))/LATCH;
-
-        return usec;
-}
-
 #ifdef CONFIG_NO_IDLE_HZ
 static unsigned long initial_match;
 static int match_posponed;
@@ -96,6 +80,20 @@ static struct irqaction sa1100_timer_irq = {
         .handler        = sa1100_timer_interrupt,
 };
 
+static cycle_t sa1100_read_oscr(void)
+{
+        return OSCR;
+}
+
+static struct clocksource cksrc_sa1100_oscr = {
+        .name           = "oscr",
+        .rating         = 200,
+        .read           = sa1100_read_oscr,
+        .mask           = CLOCKSOURCE_MASK(32),
+        .shift          = 20,
+        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
 static void __init sa1100_timer_init(void)
 {
         unsigned long flags;
@@ -109,6 +107,11 @@ static void __init sa1100_timer_init(void)
         OIER = OIER_E0;         /* enable match on timer 0 to cause interrupts */
         OSMR0 = OSCR + LATCH;   /* set initial match */
         local_irq_restore(flags);
+
+        cksrc_sa1100_oscr.mult =
+                clocksource_hz2mult(CLOCK_TICK_RATE, cksrc_sa1100_oscr.shift);
+
+        clocksource_register(&cksrc_sa1100_oscr);
 }
 
 #ifdef CONFIG_NO_IDLE_HZ
@@ -182,7 +185,6 @@ struct sys_timer sa1100_timer = {
         .init           = sa1100_timer_init,
         .suspend        = sa1100_timer_suspend,
         .resume         = sa1100_timer_resume,
-        .offset         = sa1100_gettimeoffset,
 #ifdef CONFIG_NO_IDLE_HZ
         .dyn_tick       = &sa1100_dyn_tick,
 #endif