[ARM] 4261/1: clockevent support for Versatile platform

[linux-2.6-omap-h63xx.git] / arch / arm / mach-versatile / core.c

diff --git a/arch/arm/mach-versatile/core.c b/arch/arm/mach-versatile/core.c
index bf71507c76fd91602d2513c40f19e06a8740e06b..1275aa7d2eb198249a6d4f61a74780dd82440118 100644 (file)
--- a/arch/arm/mach-versatile/core.c
+++ b/arch/arm/mach-versatile/core.c
@@ -26,6 +26,8 @@
 #include <linux/interrupt.h>
 #include <linux/amba/bus.h>
 #include <linux/amba/clcd.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
 
 #include <asm/cnt32_to_63.h>
 #include <asm/system.h>
@@ -828,59 +830,61 @@ void __init versatile_init(void)
 #define TICKS2USECS(x) ((x) / TICKS_PER_uSEC)
 #endif
 
-/*
- * Returns number of ms since last clock interrupt.  Note that interrupts
- * will have been disabled by do_gettimeoffset()
- */
-static unsigned long versatile_gettimeoffset(void)
+static void timer_set_mode(enum clock_event_mode mode,
+                          struct clock_event_device *clk)
 {
-       unsigned long ticks1, ticks2, status;
+       unsigned long ctrl;
 
-       /*
-        * Get the current number of ticks.  Note that there is a race
-        * condition between us reading the timer and checking for
-        * an interrupt.  We get around this by ensuring that the
-        * counter has not reloaded between our two reads.
-        */
-       ticks2 = readl(TIMER0_VA_BASE + TIMER_VALUE) & 0xffff;
-       do {
-               ticks1 = ticks2;
-               status = __raw_readl(VA_IC_BASE + VIC_RAW_STATUS);
-               ticks2 = readl(TIMER0_VA_BASE + TIMER_VALUE) & 0xffff;
-       } while (ticks2 > ticks1);
+       switch(mode) {
+       case CLOCK_EVT_MODE_PERIODIC:
+               writel(TIMER_RELOAD, TIMER0_VA_BASE + TIMER_LOAD);
 
-       /*
-        * Number of ticks since last interrupt.
-        */
-       ticks1 = TIMER_RELOAD - ticks2;
+               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;
+       }
 
-       /*
-        * Interrupt pending?  If so, we've reloaded once already.
-        *
-        * FIXME: Need to check this is effectively timer 0 that expires
-        */
-       if (status & IRQMASK_TIMERINT0_1)
-               ticks1 += TIMER_RELOAD;
+       writel(ctrl, TIMER0_VA_BASE + TIMER_CTRL);
+}
 
-       /*
-        * Convert the ticks to usecs
-        */
-       return TICKS2USECS(ticks1);
+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,
+};
+
 /*
  * IRQ handler for the timer
  */
 static irqreturn_t versatile_timer_interrupt(int irq, void *dev_id)
 {
-       write_seqlock(&xtime_lock);
+       struct clock_event_device *evt = &timer0_clockevent;
 
-       // ...clear the interrupt
        writel(1, TIMER0_VA_BASE + TIMER_INTCLR);
 
-       timer_tick();
-
-       write_sequnlock(&xtime_lock);
+       evt->event_handler(evt);
 
        return IRQ_HANDLED;
 }
@@ -891,6 +895,36 @@ static struct irqaction versatile_timer_irq = {
        .handler        = versatile_timer_interrupt,
 };
 
+static cycle_t versatile_get_cycles(void)
+{
+       return ~readl(TIMER3_VA_BASE + TIMER_VALUE);
+}
+
+static struct clocksource clocksource_versatile = {
+       .name           = "timer3",
+       .rating         = 200,
+       .read           = versatile_get_cycles,
+       .mask           = CLOCKSOURCE_MASK(32),
+       .shift          = 20,
+       .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int __init versatile_clocksource_init(void)
+{
+       /* setup timer3 as free-running clocksource */
+       writel(0, TIMER3_VA_BASE + TIMER_CTRL);
+       writel(0xffffffff, TIMER3_VA_BASE + TIMER_LOAD);
+       writel(0xffffffff, TIMER3_VA_BASE + TIMER_VALUE);
+       writel(TIMER_CTRL_32BIT | TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC,
+              TIMER3_VA_BASE + TIMER_CTRL);
+
+       clocksource_versatile.mult =
+               clocksource_khz2mult(1000, clocksource_versatile.shift);
+       clocksource_register(&clocksource_versatile);
+
+       return 0;
+}
+
 /*
  * Set up timer interrupt, and return the current time in seconds.
  */
@@ -918,18 +952,25 @@ static void __init versatile_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, &versatile_timer_irq);
+
+       versatile_clocksource_init();
+
+       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);
+
+       timer0_clockevent.cpumask = cpumask_of_cpu(0);
+       clockevents_register_device(&timer0_clockevent);
 }
 
 struct sys_timer versatile_timer = {
        .init           = versatile_timer_init,
-       .offset         = versatile_gettimeoffset,
 };
+