clocksource: samsung_pwm_timer: Cache clocksource register address

Instead of calculating register every time the timer should be read,
we can just do it one time at initialization and store the address in
driver data.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Mark Brown <broonie@linaro.org>
Tested-by: Sylwester Nawrocki <sylvester.nawrocki@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

drivers/clocksource/samsung_pwm_timer.c

@@ -65,6 +65,7 @@ EXPORT_SYMBOL(samsung_pwm_lock);
 
 struct samsung_pwm_clocksource {
 	void __iomem *base;
+	void __iomem *source_reg;
 	unsigned int irq[SAMSUNG_PWM_NUM];
 	struct samsung_pwm_variant variant;
 
@@ -297,23 +298,6 @@ static void __init samsung_clockevent_init(void)
 	}
 }
 
-static void __iomem *samsung_timer_reg(void)
-{
-	switch (pwm.source_id) {
-	case 0:
-	case 1:
-	case 2:
-	case 3:
-		return pwm.base + pwm.source_id * 0x0c + 0x14;
-
-	case 4:
-		return pwm.base + 0x40;
-
-	default:
-		BUG();
-	}
-}
-
 /*
  * Override the global weak sched_clock symbol with this
  * local implementation which uses the clocksource to get some
@@ -323,17 +307,11 @@ static void __iomem *samsung_timer_reg(void)
  */
 static u32 notrace samsung_read_sched_clock(void)
 {
-	void __iomem *reg = samsung_timer_reg();
-
-	if (!reg)
-		return 0;
-
-	return ~__raw_readl(reg);
+	return ~__raw_readl(pwm.source_reg);
 }
 
 static void __init samsung_clocksource_init(void)
 {
-	void __iomem *reg = samsung_timer_reg();
 	unsigned long pclk;
 	unsigned long clock_rate;
 	int ret;
@@ -348,10 +326,15 @@ static void __init samsung_clocksource_init(void)
 	samsung_time_setup(pwm.source_id, pwm.tcnt_max);
 	samsung_time_start(pwm.source_id, true);
 
+	if (pwm.source_id == 4)
+		pwm.source_reg = pwm.base + 0x40;
+	else
+		pwm.source_reg = pwm.base + pwm.source_id * 0x0c + 0x14;
+
 	setup_sched_clock(samsung_read_sched_clock,
 						pwm.variant.bits, clock_rate);
 
-	ret = clocksource_mmio_init(reg, "samsung_clocksource_timer",
+	ret = clocksource_mmio_init(pwm.source_reg, "samsung_clocksource_timer",
 					clock_rate, 250, pwm.variant.bits,
 					clocksource_mmio_readl_down);
 	if (ret)