ARM: set arch_gettimeoffset directly

remove ARM's struct sys_timer .offset function pointer, and instead
directly set the arch_gettimeoffset function pointer when the timer
driver is initialized. This requires multiplying all function results
by 1000, since the removed arm_gettimeoffset() did this. Also,
s/unsigned long/u32/ just to make the function prototypes exactly
match that of arch_gettimeoffset.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: Andrew Victor <linux@maxim.org.za>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Cc: Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ryan Mallon <rmallon@gmail.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>

1 files changed, 18 insertions, 11 deletions

diff --git a/arch/arm/mach-ep93xx/core.c b/arch/arm/mach-ep93xx/core.c
index e85bf17f2d2..6f48b87a1ac 100644
--- a/arch/arm/mach-ep93xx/core.c
+++ b/arch/arm/mach-ep93xx/core.c
@@ -140,11 +140,29 @@ static struct irqaction ep93xx_timer_irq = {
 	.handler	= ep93xx_timer_interrupt,
 };
 
+static u32 ep93xx_gettimeoffset(void)
+{
+	int offset;
+
+	offset = __raw_readl(EP93XX_TIMER4_VALUE_LOW) - last_jiffy_time;
+
+	/*
+	 * Timer 4 is based on a 983.04 kHz reference clock,
+	 * so dividing by 983040 gives the fraction of a second,
+	 * so dividing by 0.983040 converts to uS.
+	 * Refactor the calculation to avoid overflow.
+	 * Finally, multiply by 1000 to give nS.
+	 */
+	return (offset + (53 * offset / 3072)) * 1000;
+}
+
 static void __init ep93xx_timer_init(void)
 {
 	u32 tmode = EP93XX_TIMER123_CONTROL_MODE |
 		    EP93XX_TIMER123_CONTROL_CLKSEL;
 
+	arch_gettimeoffset = ep93xx_gettimeoffset;
+
 	/* Enable periodic HZ timer.  */
 	__raw_writel(tmode, EP93XX_TIMER1_CONTROL);
 	__raw_writel(TIMER1_RELOAD, EP93XX_TIMER1_LOAD);
@@ -158,19 +176,8 @@ static void __init ep93xx_timer_init(void)
 	setup_irq(IRQ_EP93XX_TIMER1, &ep93xx_timer_irq);
 }
 
-static unsigned long ep93xx_gettimeoffset(void)
-{
-	int offset;
-
-	offset = __raw_readl(EP93XX_TIMER4_VALUE_LOW) - last_jiffy_time;
-
-	/* Calculate (1000000 / 983040) * offset.  */
-	return offset + (53 * offset / 3072);
-}
-
 struct sys_timer ep93xx_timer = {
 	.init		= ep93xx_timer_init,
-	.offset		= ep93xx_gettimeoffset,
 };