[ARM] sa1100: add clock event support

d142b6e77d394a4fcc0a42381b03852bd9c4e263 added clock source support,
now it's time for the clock event support.

Tested-by: Thomas Kunze <thommycheck@gmx.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 67 insertions, 94 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 1f7c728f5ce5..63cc733fdb32 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -425,6 +425,8 @@ config ARCH_SA1100
         select ARCH_MTD_XIP
         select GENERIC_GPIO
         select GENERIC_TIME
+        select GENERIC_CLOCKEVENTS
+        select TICK_ONESHOT
         select HAVE_IDE
         select HAVE_GPIO_LIB
         help
diff --git a/arch/arm/mach-sa1100/time.c b/arch/arm/mach-sa1100/time.c
index c2677368d6af..a9799cb35b74 100644
--- a/arch/arm/mach-sa1100/time.c
+++ b/arch/arm/mach-sa1100/time.c
@@ -13,67 +13,69 @@
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/timex.h>
-#include <linux/signal.h>
-#include <linux/clocksource.h>
+#include <linux/clockchips.h>
 
 #include <asm/mach/time.h>
 #include <asm/hardware.h>
 
-#define RTC_DEF_DIVIDER         (32768 - 1)
-#define RTC_DEF_TRIM            0
+#define MIN_OSCR_DELTA 2
 
-static int sa1100_set_rtc(void)
+static irqreturn_t sa1100_ost0_interrupt(int irq, void *dev_id)
 {
-        unsigned long current_time = xtime.tv_sec;
+        struct clock_event_device *c = dev_id;
 
-        if (RTSR & RTSR_ALE) {
-                /* make sure not to forward the clock over an alarm */
-                unsigned long alarm = RTAR;
-                if (current_time >= alarm && alarm >= RCNR)
-                        return -ERESTARTSYS;
-        }
-        RCNR = current_time;
-        return 0;
-}
+        /* Disarm the compare/match, signal the event. */
+        OIER &= ~OIER_E0;
+        OSSR = OSSR_M0;
+        c->event_handler(c);
 
-#ifdef CONFIG_NO_IDLE_HZ
-static unsigned long initial_match;
-static int match_posponed;
-#endif
+        return IRQ_HANDLED;
+}
 
-static irqreturn_t
-sa1100_timer_interrupt(int irq, void *dev_id)
+static int
+sa1100_osmr0_set_next_event(unsigned long delta, struct clock_event_device *c)
 {
-        unsigned int next_match;
+        unsigned long flags, next, oscr;
 
-#ifdef CONFIG_NO_IDLE_HZ
-        if (match_posponed) {
-                match_posponed = 0;
-                OSMR0 = initial_match;
-        }
-#endif
+        raw_local_irq_save(flags);
+        OIER |= OIER_E0;
+        next = OSCR + delta;
+        OSMR0 = next;
+        oscr = OSCR;
+        raw_local_irq_restore(flags);
 
-        /*
-         * Loop until we get ahead of the free running timer.
-         * This ensures an exact clock tick count and time accuracy.
-         * Since IRQs are disabled at this point, coherence between
-         * lost_ticks(updated in do_timer()) and the match reg value is
-         * ensured, hence we can use do_gettimeofday() from interrupt
-         * handlers.
-         */
-        do {
-                timer_tick();
-                OSSR = OSSR_M0;  /* Clear match on timer 0 */
-                next_match = (OSMR0 += LATCH);
-        } while ((signed long)(next_match - OSCR) <= 0);
+        return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
+}
 
-        return IRQ_HANDLED;
+static void
+sa1100_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *c)
+{
+        unsigned long flags;
+
+        switch (mode) {
+        case CLOCK_EVT_MODE_ONESHOT:
+        case CLOCK_EVT_MODE_UNUSED:
+        case CLOCK_EVT_MODE_SHUTDOWN:
+                raw_local_irq_save(flags);
+                OIER &= ~OIER_E0;
+                OSSR = OSSR_M0;
+                raw_local_irq_restore(flags);
+                break;
+
+        case CLOCK_EVT_MODE_RESUME:
+        case CLOCK_EVT_MODE_PERIODIC:
+                break;
+        }
 }
 
-static struct irqaction sa1100_timer_irq = {
-        .name           = "SA11xx Timer Tick",
-        .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
-        .handler        = sa1100_timer_interrupt,
+static struct clock_event_device ckevt_sa1100_osmr0 = {
+        .name           = "osmr0",
+        .features       = CLOCK_EVT_FEAT_ONESHOT,
+        .shift          = 32,
+        .rating         = 200,
+        .cpumask        = CPU_MASK_CPU0,
+        .set_next_event = sa1100_osmr0_set_next_event,
+        .set_mode       = sa1100_osmr0_set_mode,
 };
 
 static cycle_t sa1100_read_oscr(void)
@@ -90,62 +92,34 @@ static struct clocksource cksrc_sa1100_oscr = {
         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
+static struct irqaction sa1100_timer_irq = {
+        .name           = "ost0",
+        .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
+        .handler        = sa1100_ost0_interrupt,
+        .dev_id         = &ckevt_sa1100_osmr0,
+};
+
 static void __init sa1100_timer_init(void)
 {
-        unsigned long flags;
-
-        set_rtc = sa1100_set_rtc;
-
         OIER = 0;               /* disable any timer interrupts */
         OSSR = 0xf;             /* clear status on all timers */
-        setup_irq(IRQ_OST0, &sa1100_timer_irq);
-        local_irq_save(flags);
-        OIER = OIER_E0;         /* enable match on timer 0 to cause interrupts */
-        OSMR0 = OSCR + LATCH;   /* set initial match */
-        local_irq_restore(flags);
+
+        ckevt_sa1100_osmr0.mult =
+                div_sc(3686400, NSEC_PER_SEC, ckevt_sa1100_osmr0.shift);
+        ckevt_sa1100_osmr0.max_delta_ns =
+                clockevent_delta2ns(0x7fffffff, &ckevt_sa1100_osmr0);
+        ckevt_sa1100_osmr0.min_delta_ns =
+                clockevent_delta2ns(MIN_OSCR_DELTA * 2, &ckevt_sa1100_osmr0) + 1;
 
         cksrc_sa1100_oscr.mult =
                 clocksource_hz2mult(CLOCK_TICK_RATE, cksrc_sa1100_oscr.shift);
 
-        clocksource_register(&cksrc_sa1100_oscr);
-}
-
-#ifdef CONFIG_NO_IDLE_HZ
-static int sa1100_dyn_tick_enable_disable(void)
-{
-        /* nothing to do */
-        return 0;
-}
-
-static void sa1100_dyn_tick_reprogram(unsigned long ticks)
-{
-        if (ticks > 1) {
-                initial_match = OSMR0;
-                OSMR0 = initial_match + ticks * LATCH;
-                match_posponed = 1;
-        }
-}
+        setup_irq(IRQ_OST0, &sa1100_timer_irq);
 
-static irqreturn_t
-sa1100_dyn_tick_handler(int irq, void *dev_id)
-{
-        if (match_posponed) {
-                match_posponed = 0;
-                OSMR0 = initial_match;
-                if ((signed long)(initial_match - OSCR) <= 0)
-                        return sa1100_timer_interrupt(irq, dev_id);
-        }
-        return IRQ_NONE;
+        clocksource_register(&cksrc_sa1100_oscr);
+        clockevents_register_device(&ckevt_sa1100_osmr0);
 }
 
-static struct dyn_tick_timer sa1100_dyn_tick = {
-        .enable         = sa1100_dyn_tick_enable_disable,
-        .disable        = sa1100_dyn_tick_enable_disable,
-        .reprogram      = sa1100_dyn_tick_reprogram,
-        .handler        = sa1100_dyn_tick_handler,
-};
-#endif
-
 #ifdef CONFIG_PM
 unsigned long osmr[4], oier;
 
@@ -181,7 +155,4 @@ struct sys_timer sa1100_timer = {
         .init           = sa1100_timer_init,
         .suspend        = sa1100_timer_suspend,
         .resume         = sa1100_timer_resume,
-#ifdef CONFIG_NO_IDLE_HZ
-        .dyn_tick       = &sa1100_dyn_tick,
-#endif
 };