[ARM] 3856/1: Add clocksource for Intel IXP4xx platforms

Enables the ixp4xx platforms to use Generic time-of-day.

Signed-off-by: Kevin Hilman <khilman@mvista.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 27 insertions, 11 deletions

diff --git a/arch/arm/mach-ixp4xx/common.c b/arch/arm/mach-ixp4xx/common.c
index 7c25dbd5a181..35dd8b3824b0 100644
--- a/arch/arm/mach-ixp4xx/common.c
+++ b/arch/arm/mach-ixp4xx/common.c
@@ -26,6 +26,7 @@
 #include <linux/bitops.h>
 #include <linux/time.h>
 #include <linux/timex.h>
+#include <linux/clocksource.h>
 
 #include <asm/hardware.h>
 #include <asm/uaccess.h>
@@ -255,16 +256,6 @@ static unsigned volatile last_jiffy_time;
 
 #define CLOCK_TICKS_PER_USEC    ((CLOCK_TICK_RATE + USEC_PER_SEC/2) / USEC_PER_SEC)
 
-/* IRQs are disabled before entering here from do_gettimeofday() */
-static unsigned long ixp4xx_gettimeoffset(void)
-{
-        u32 elapsed;
-
-        elapsed = *IXP4XX_OSTS - last_jiffy_time;
-
-        return elapsed / CLOCK_TICKS_PER_USEC;
-}
-
 static irqreturn_t ixp4xx_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 {
         write_seqlock(&xtime_lock);
@@ -309,7 +300,6 @@ static void __init ixp4xx_timer_init(void)
 
 struct sys_timer ixp4xx_timer = {
         .init           = ixp4xx_timer_init,
-        .offset         = ixp4xx_gettimeoffset,
 };
 
 static struct resource ixp46x_i2c_resources[] = {
@@ -365,3 +355,29 @@ void __init ixp4xx_sys_init(void)
                         ixp4xx_exp_bus_size >> 20);
 }
 
+cycle_t ixp4xx_get_cycles(void)
+{
+        return *IXP4XX_OSTS;
+}
+
+static struct clocksource clocksource_ixp4xx = {
+        .name           = "OSTS",
+        .rating         = 200,
+        .read           = ixp4xx_get_cycles,
+        .mask           = CLOCKSOURCE_MASK(32),
+        .shift          = 20,
+        .is_continuous  = 1,
+};
+
+unsigned long ixp4xx_timer_freq = FREQ;
+static int __init ixp4xx_clocksource_init(void)
+{
+        clocksource_ixp4xx.mult =
+                clocksource_hz2mult(ixp4xx_timer_freq,
+                                    clocksource_ixp4xx.shift);
+        clocksource_register(&clocksource_ixp4xx);
+
+        return 0;
+}
+
+device_initcall(ixp4xx_clocksource_init);