RealView: clockevents support for the RealView platforms

The patch updates the RealView code to the clockevents infrastructure.
The SMP support is implemented in subsequent patches. Based on the
Versatile implementation by Kevin Hilman.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm/Kconfig

@@ -164,6 +164,7 @@ config ARCH_REALVIEW
 	select ARM_AMBA
 	select ICST307
 	select GENERIC_TIME
+	select GENERIC_CLOCKEVENTS
 	help
 	  This enables support for ARM Ltd RealView boards.
 

arch/arm/mach-realview/core.c

@@ -26,6 +26,7 @@
 #include <linux/amba/bus.h>
 #include <linux/amba/clcd.h>
 #include <linux/clocksource.h>
+#include <linux/clockchips.h>
 
 #include <asm/system.h>
 #include <asm/hardware.h>
@@ -485,24 +486,77 @@ void realview_leds_event(led_event_t ledevt)
 #define TICKS2USECS(x)	((x) / TICKS_PER_uSEC)
 #endif
 
+static void timer_set_mode(enum clock_event_mode mode,
+			   struct clock_event_device *clk)
+{
+	unsigned long ctrl;
+
+	switch(mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+		writel(TIMER_RELOAD, TIMER0_VA_BASE + TIMER_LOAD);
+
+		ctrl = TIMER_CTRL_PERIODIC;
+		ctrl |= TIMER_CTRL_32BIT | TIMER_CTRL_IE | TIMER_CTRL_ENABLE;
+		break;
+	case CLOCK_EVT_MODE_ONESHOT:
+		/* period set, and timer enabled in 'next_event' hook */
+		ctrl = TIMER_CTRL_ONESHOT;
+		ctrl |= TIMER_CTRL_32BIT | TIMER_CTRL_IE;
+		break;
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+	default:
+		ctrl = 0;
+	}
+
+	writel(ctrl, TIMER0_VA_BASE + TIMER_CTRL);
+}
+
+static int timer_set_next_event(unsigned long evt,
+				struct clock_event_device *unused)
+{
+	unsigned long ctrl = readl(TIMER0_VA_BASE + TIMER_CTRL);
+
+	writel(evt, TIMER0_VA_BASE + TIMER_LOAD);
+	writel(ctrl | TIMER_CTRL_ENABLE, TIMER0_VA_BASE + TIMER_CTRL);
+
+	return 0;
+}
+
+static struct clock_event_device timer0_clockevent =	 {
+	.name		= "timer0",
+	.shift		= 32,
+	.features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+	.set_mode	= timer_set_mode,
+	.set_next_event	= timer_set_next_event,
+	.rating		= 300,
+	.irq		= IRQ_TIMERINT0_1,
+	.cpumask	= CPU_MASK_ALL,
+};
+
+static void __init realview_clockevents_init(void)
+{
+	timer0_clockevent.mult =
+		div_sc(1000000, NSEC_PER_SEC, timer0_clockevent.shift);
+	timer0_clockevent.max_delta_ns =
+		clockevent_delta2ns(0xffffffff, &timer0_clockevent);
+	timer0_clockevent.min_delta_ns =
+		clockevent_delta2ns(0xf, &timer0_clockevent);
+
+	clockevents_register_device(&timer0_clockevent);
+}
+
 /*
  * IRQ handler for the timer
  */
 static irqreturn_t realview_timer_interrupt(int irq, void *dev_id)
 {
-	write_seqlock(&xtime_lock);
+	struct clock_event_device *evt = &timer0_clockevent;
 
-	// ...clear the interrupt
+	/* clear the interrupt */
 	writel(1, TIMER0_VA_BASE + TIMER_INTCLR);
 
-	timer_tick();
-
-#if defined(CONFIG_SMP) && !defined(CONFIG_LOCAL_TIMERS)
-	smp_send_timer();
-	update_process_times(user_mode(get_irq_regs()));
-#endif
-
-	write_sequnlock(&xtime_lock);
+	evt->event_handler(evt);
 
 	return IRQ_HANDLED;
 }
@@ -568,17 +622,13 @@ static void __init realview_timer_init(void)
 	writel(0, TIMER2_VA_BASE + TIMER_CTRL);
 	writel(0, TIMER3_VA_BASE + TIMER_CTRL);
 
-	writel(TIMER_RELOAD, TIMER0_VA_BASE + TIMER_LOAD);
-	writel(TIMER_RELOAD, TIMER0_VA_BASE + TIMER_VALUE);
-	writel(TIMER_DIVISOR | TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC |
-	       TIMER_CTRL_IE, TIMER0_VA_BASE + TIMER_CTRL);
-
 	/* 
 	 * Make irqs happen for the system timer
 	 */
 	setup_irq(IRQ_TIMERINT0_1, &realview_timer_irq);
 
 	realview_clocksource_init();
+	realview_clockevents_init();
 }
 
 struct sys_timer realview_timer = {