[ARM] 4259/1: clockevent support for ixp4xx platform

Update ixp4xx timer support to use new clockevent infrastructure.

Signed-off-by: Kevin Hilman <khilman@mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 75 insertions, 19 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 2d13b016612..2aadd0e1e58 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -266,6 +266,7 @@ config ARCH_IXP4XX
         bool "IXP4xx-based"
         depends on MMU
         select GENERIC_TIME
+        select GENERIC_CLOCKEVENTS
         help
           Support for Intel's IXP4XX (XScale) family of processors.
 
diff --git a/arch/arm/mach-ixp4xx/common.c b/arch/arm/mach-ixp4xx/common.c
index 45068c3d8dc..09edea9779e 100644
--- a/arch/arm/mach-ixp4xx/common.c
+++ b/arch/arm/mach-ixp4xx/common.c
@@ -27,6 +27,7 @@
 #include <linux/time.h>
 #include <linux/timex.h>
 #include <linux/clocksource.h>
+#include <linux/clockchips.h>
 
 #include <asm/arch/udc.h>
 #include <asm/hardware.h>
@@ -41,6 +42,8 @@
 #include <asm/mach/time.h>
 
 static int __init ixp4xx_clocksource_init(void);
+static int __init ixp4xx_clockevent_init(void);
+static struct clock_event_device clockevent_ixp4xx;
 
 /*************************************************************************
  * IXP4xx chipset I/O mapping
@@ -239,52 +242,40 @@ void __init ixp4xx_init_irq(void)
  * counter as a source of real clock ticks to account for missed jiffies.
  *************************************************************************/
 
-static unsigned volatile last_jiffy_time;
-
-#define CLOCK_TICKS_PER_USEC    ((CLOCK_TICK_RATE + USEC_PER_SEC/2) / USEC_PER_SEC)
-
 static irqreturn_t ixp4xx_timer_interrupt(int irq, void *dev_id)
 {
-        write_seqlock(&xtime_lock);
+        struct clock_event_device *evt = &clockevent_ixp4xx;
 
         /* Clear Pending Interrupt by writing '1' to it */
         *IXP4XX_OSST = IXP4XX_OSST_TIMER_1_PEND;
 
-        /*
-         * Catch up with the real idea of time
-         */
-        while ((signed long)(*IXP4XX_OSTS - last_jiffy_time) >= LATCH) {
-                timer_tick();
-                last_jiffy_time += LATCH;
-        }
-
-        write_sequnlock(&xtime_lock);
+        evt->event_handler(evt);
 
         return IRQ_HANDLED;
 }
 
 static struct irqaction ixp4xx_timer_irq = {
-        .name           = "IXP4xx Timer Tick",
+        .name           = "timer1",
         .flags          = IRQF_DISABLED | IRQF_TIMER,
         .handler        = ixp4xx_timer_interrupt,
 };
 
 static void __init ixp4xx_timer_init(void)
 {
+        /* Reset/disable counter */
+        *IXP4XX_OSRT1 = 0;
+
         /* Clear Pending Interrupt by writing '1' to it */
         *IXP4XX_OSST = IXP4XX_OSST_TIMER_1_PEND;
 
-        /* Setup the Timer counter value */
-        *IXP4XX_OSRT1 = (LATCH & ~IXP4XX_OST_RELOAD_MASK) | IXP4XX_OST_ENABLE;
-
         /* Reset time-stamp counter */
         *IXP4XX_OSTS = 0;
-        last_jiffy_time = 0;
 
         /* Connect the interrupt handler and enable the interrupt */
         setup_irq(IRQ_IXP4XX_TIMER1, &ixp4xx_timer_irq);
 
         ixp4xx_clocksource_init();
+        ixp4xx_clockevent_init();
 }
 
 struct sys_timer ixp4xx_timer = {
@@ -384,6 +375,9 @@ void __init ixp4xx_sys_init(void)
                         ixp4xx_exp_bus_size >> 20);
 }
 
+/*
+ * clocksource
+ */
 cycle_t ixp4xx_get_cycles(void)
 {
         return *IXP4XX_OSTS;
@@ -408,3 +402,64 @@ static int __init ixp4xx_clocksource_init(void)
 
         return 0;
 }
+
+/*
+ * clockevents
+ */
+static int ixp4xx_set_next_event(unsigned long evt,
+                                 struct clock_event_device *unused)
+{
+        unsigned long opts = *IXP4XX_OSRT1 & IXP4XX_OST_RELOAD_MASK;
+
+        *IXP4XX_OSRT1 = (evt & ~IXP4XX_OST_RELOAD_MASK) | opts;
+
+        return 0;
+}
+
+static void ixp4xx_set_mode(enum clock_event_mode mode,
+                            struct clock_event_device *evt)
+{
+        unsigned long opts, osrt = *IXP4XX_OSRT1 & ~IXP4XX_OST_RELOAD_MASK;
+
+        switch (mode) {
+        case CLOCK_EVT_MODE_PERIODIC:
+                osrt = LATCH & ~IXP4XX_OST_RELOAD_MASK;
+                opts = IXP4XX_OST_ENABLE;
+                break;
+        case CLOCK_EVT_MODE_ONESHOT:
+                /* period set by 'set next_event' */
+                osrt = 0;
+                opts = IXP4XX_OST_ENABLE | IXP4XX_OST_ONE_SHOT;
+                break;
+        case CLOCK_EVT_MODE_SHUTDOWN:
+        case CLOCK_EVT_MODE_UNUSED:
+        default:
+                osrt = opts = 0;
+                break;
+        }
+
+        *IXP4XX_OSRT1 = osrt | opts;
+}
+
+static struct clock_event_device clockevent_ixp4xx = {
+        .name           = "ixp4xx timer1",
+        .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+        .rating         = 200,
+        .shift          = 24,
+        .set_mode       = ixp4xx_set_mode,
+        .set_next_event = ixp4xx_set_next_event,
+};
+
+static int __init ixp4xx_clockevent_init(void)
+{
+        clockevent_ixp4xx.mult = div_sc(FREQ, NSEC_PER_SEC,
+                                        clockevent_ixp4xx.shift);
+        clockevent_ixp4xx.max_delta_ns =
+                clockevent_delta2ns(0xfffffffe, &clockevent_ixp4xx);
+        clockevent_ixp4xx.min_delta_ns =
+                clockevent_delta2ns(0xf, &clockevent_ixp4xx);
+        clockevent_ixp4xx.cpumask = cpumask_of_cpu(0);
+
+        clockevents_register_device(&clockevent_ixp4xx);
+        return 0;
+}