ARM: prima2: convert to common sched_clock() implementation

Prima2 has its own sched_clock() implementation, which gets in the
way of a single zImage. Moving to the common sched_clock framework
makes the code slightly cleaner (the mapping hack in sched_clock()
goes away...).

Acked-by: Barry Song <baohua.song@csr.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm/Kconfig

@@ -388,6 +388,7 @@ config ARCH_PRIMA2
 	select GENERIC_CLOCKEVENTS
 	select CLKDEV_LOOKUP
 	select GENERIC_IRQ_CHIP
+	select HAVE_SCHED_CLOCK
 	select MIGHT_HAVE_CACHE_L2X0
 	select USE_OF
 	select ZONE_DMA

arch/arm/mach-prima2/timer.c

@@ -18,6 +18,7 @@
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <mach/map.h>
+#include <asm/sched_clock.h>
 #include <asm/mach/time.h>
 
 #define SIRFSOC_TIMER_COUNTER_LO	0x0000
@@ -165,21 +166,9 @@ static struct irqaction sirfsoc_timer_irq = {
 };
 
 /* Overwrite weak default sched_clock with more precise one */
-unsigned long long notrace sched_clock(void)
+static u32 notrace sirfsoc_read_sched_clock(void)
 {
-	static int is_mapped;
-
-	/*
-	 * sched_clock is called earlier than .init of sys_timer
-	 * if we map timer memory in .init of sys_timer, system
-	 * will panic due to illegal memory access
-	 */
-	if (!is_mapped) {
-		sirfsoc_of_timer_map();
-		is_mapped = 1;
-	}
-
-	return sirfsoc_timer_read(NULL) * (NSEC_PER_SEC / CLOCK_TICK_RATE);
+	return (u32)(sirfsoc_timer_read(NULL) & 0xffffffff);
 }
 
 static void __init sirfsoc_clockevent_init(void)
@@ -210,13 +199,17 @@ static void __init sirfsoc_timer_init(void)
 	BUG_ON(rate < CLOCK_TICK_RATE);
 	BUG_ON(rate % CLOCK_TICK_RATE);
 
+	sirfsoc_of_timer_map();
+
 	writel_relaxed(rate / CLOCK_TICK_RATE / 2 - 1, sirfsoc_timer_base + SIRFSOC_TIMER_DIV);
 	writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_LO);
 	writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_HI);
 	writel_relaxed(BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_STATUS);
 
 	BUG_ON(clocksource_register_hz(&sirfsoc_clocksource, CLOCK_TICK_RATE));
 
+	setup_sched_clock(sirfsoc_read_sched_clock, 32, CLOCK_TICK_RATE);
+
 	BUG_ON(setup_irq(sirfsoc_timer_irq.irq, &sirfsoc_timer_irq));
 
 	sirfsoc_clockevent_init();