ARM: OMAP: Add clocksource driver for OMAP

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Index: linux-2.6.20-rc1/arch/arm/plat-omap/timer32k.c
===================================================================
@@ -42,6 +42,7 @@
 #include <linux/spinlock.h>
 #include <linux/err.h>
 #include <linux/clk.h>
+#include <linux/clocksource.h>
 
 #include <asm/system.h>
 #include <asm/hardware.h>

@@ -171,15 +172,6 @@ omap_32k_ticks_to_nsecs(unsigned long ti
 static unsigned long omap_32k_last_tick = 0;
 
 /*
- * Returns elapsed usecs since last 32k timer interrupt
- */
-static unsigned long omap_32k_timer_gettimeoffset(void)
-{
-	unsigned long now = omap_32k_sync_timer_read();
-	return omap_32k_ticks_to_usecs(now - omap_32k_last_tick);
-}
-
-/*
  * Returns current time from boot in nsecs. It's OK for this to wrap
  * around for now, as it's just a relative time stamp.
  */

@@ -217,11 +209,6 @@ static inline irqreturn_t _omap_32k_time
 	return IRQ_HANDLED;
 }
 
-static irqreturn_t omap_32k_timer_handler(int irq, void *dev_id)
-{
-	return _omap_32k_timer_interrupt(irq, dev_id);
-}
-
 static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id)
 {
 	unsigned long flags;

@@ -234,6 +221,7 @@ static irqreturn_t omap_32k_timer_interr
 }
 
 #ifdef CONFIG_NO_IDLE_HZ
+
 /*
  * Programs the next timer interrupt needed. Called when dynamic tick is
  * enabled, and to reprogram the ticks to skip from pm_idle. Note that

@@ -269,6 +257,22 @@ static int omap_32k_timer_disable_dyn_ti
 	return 0;
 }
 
+static irqreturn_t omap_32k_timer_handler(int irq, void *dev_id)
+{
+	unsigned long now;
+
+	now = omap_32k_sync_timer_read();
+
+	/* Don't bother reprogramming timer if last tick was before next
+	 * jiffie. We will get another interrupt when previously programmed
+	 * timer expires. This cuts down interrupt load quite a bit.
+	 */
+	if (now - omap_32k_last_tick < OMAP_32K_TICKS_PER_HZ)
+		return IRQ_HANDLED;
+
+	return _omap_32k_timer_interrupt(irq, dev_id);
+}
+
 static struct dyn_tick_timer omap_dyn_tick_timer = {
 	.enable		= omap_32k_timer_enable_dyn_tick,
 	.disable	= omap_32k_timer_disable_dyn_tick,

@@ -291,7 +295,6 @@ static __init void omap_init_32k_timer(v
 
 	if (cpu_class_is_omap1())
 		setup_irq(INT_OS_TIMER, &omap_32k_timer_irq);
-	omap_timer.offset  = omap_32k_timer_gettimeoffset;
 	omap_32k_last_tick = omap_32k_sync_timer_read();
 
 #ifdef CONFIG_ARCH_OMAP2

@@ -326,5 +329,4 @@ static void __init omap_timer_init(void)
 
 struct sys_timer omap_timer = {
 	.init		= omap_timer_init,
-	.offset		= NULL,		/* Initialized later */
 };

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