clocksource: convert 32-bit down counting clocksource on S5PV210/S5P64X0

Convert the S5PV210/S5P64X0 32-bit down-counting clocksource to
the generic mmio clocksource infrastructure

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/Kconfig

@@ -726,6 +726,7 @@ config ARCH_S5P64X0
 	select GENERIC_GPIO
 	select HAVE_CLK
 	select CLKDEV_LOOKUP
+	select CLKSRC_MMIO
 	select HAVE_S3C2410_WATCHDOG if WATCHDOG
 	select GENERIC_CLOCKEVENTS
 	select HAVE_SCHED_CLOCK
@@ -756,6 +757,7 @@ config ARCH_S5PV210
 	select GENERIC_GPIO
 	select HAVE_CLK
 	select CLKDEV_LOOKUP
+	select CLKSRC_MMIO
 	select ARM_L1_CACHE_SHIFT_6
 	select ARCH_HAS_CPUFREQ
 	select GENERIC_CLOCKEVENTS

arch/arm/plat-s5p/s5p-time.c

@@ -314,13 +314,6 @@ static void __iomem *s5p_timer_reg(void)
 	return S3C_TIMERREG(offset);
 }
 
-static cycle_t s5p_timer_read(struct clocksource *cs)
-{
-	void __iomem *reg = s5p_timer_reg();
-
-	return (cycle_t) (reg ? ~__raw_readl(reg) : 0);
-}
-
 /*
  * Override the global weak sched_clock symbol with this
  * local implementation which uses the clocksource to get some
@@ -350,14 +343,6 @@ static void notrace s5p_update_sched_clock(void)
 	update_sched_clock(&cd, ~__raw_readl(reg), (u32)~0);
 }
 
-struct clocksource time_clocksource = {
-	.name		= "s5p_clocksource_timer",
-	.rating		= 250,
-	.read		= s5p_timer_read,
-	.mask		= CLOCKSOURCE_MASK(32),
-	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
-};
-
 static void __init s5p_clocksource_init(void)
 {
 	unsigned long pclk;
@@ -375,8 +360,9 @@ static void __init s5p_clocksource_init(void)
 
 	init_sched_clock(&cd, s5p_update_sched_clock, 32, clock_rate);
 
-	if (clocksource_register_hz(&time_clocksource, clock_rate))
-		panic("%s: can't register clocksource\n", time_clocksource.name);
+	if (clocksource_mmio_init(s5p_timer_reg(), "s5p_clocksource_timer",
+			clock_rate, 250, 32, clocksource_mmio_readl_down))
+		panic("s5p_clocksource_timer: can't register clocksource\n");
 }
 
 static void __init s5p_timer_resources(void)