[ARM] 4262/1: OMAP: clocksource and clockevent support

Update OMAP1 to enable support for hrtimers and dynticks by using new clocksource and clockevent infrastructure.

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

3 files changed, 90 insertions, 100 deletions

diff --git a/arch/arm/plat-omap/Kconfig b/arch/arm/plat-omap/Kconfig
index f2dc363de66b..9e8d21eca4ec 100644
--- a/arch/arm/plat-omap/Kconfig
+++ b/arch/arm/plat-omap/Kconfig
@@ -11,6 +11,7 @@ choice
 
 config ARCH_OMAP1
         bool "TI OMAP1"
+        select GENERIC_CLOCKEVENTS
 
 config ARCH_OMAP2
         bool "TI OMAP2"
diff --git a/arch/arm/plat-omap/common.c b/arch/arm/plat-omap/common.c
index 57b7b93674a4..fecd3d625995 100644
--- a/arch/arm/plat-omap/common.c
+++ b/arch/arm/plat-omap/common.c
@@ -156,3 +156,53 @@ static int __init omap_add_serial_console(void)
         return add_preferred_console("ttyS", line, opt);
 }
 console_initcall(omap_add_serial_console);
+
+
+/*
+ * 32KHz clocksource ... always available, on pretty most chips except
+ * OMAP 730 and 1510.  Other timers could be used as clocksources, with
+ * higher resolution in free-running counter modes (e.g. 12 MHz xtal),
+ * but systems won't necessarily want to spend resources that way.
+ */
+
+#if defined(CONFIG_ARCH_OMAP16XX)
+#define TIMER_32K_SYNCHRONIZED          0xfffbc410
+#elif defined(CONFIG_ARCH_OMAP24XX)
+#define TIMER_32K_SYNCHRONIZED          0x48004010
+#endif
+
+#ifdef  TIMER_32K_SYNCHRONIZED
+
+#include <linux/clocksource.h>
+
+static cycle_t omap_32k_read(void)
+{
+        return omap_readl(TIMER_32K_SYNCHRONIZED);
+}
+
+static struct clocksource clocksource_32k = {
+        .name           = "32k_counter",
+        .rating         = 250,
+        .read           = omap_32k_read,
+        .mask           = CLOCKSOURCE_MASK(32),
+        .shift          = 10,
+        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int __init omap_init_clocksource_32k(void)
+{
+        static char err[] __initdata = KERN_ERR
+                        "%s: can't register clocksource!\n";
+
+        if (cpu_is_omap16xx() || cpu_is_omap24xx()) {
+                clocksource_32k.mult = clocksource_hz2mult(32768,
+                                            clocksource_32k.shift);
+
+                if (clocksource_register(&clocksource_32k))
+                        printk(err, clocksource_32k.name);
+        }
+        return 0;
+}
+arch_initcall(omap_init_clocksource_32k);
+
+#endif  /* TIMER_32K_SYNCHRONIZED */
diff --git a/arch/arm/plat-omap/timer32k.c b/arch/arm/plat-omap/timer32k.c
index 265310601161..114f87151d60 100644
--- a/arch/arm/plat-omap/timer32k.c
+++ b/arch/arm/plat-omap/timer32k.c
@@ -42,6 +42,8 @@
 #include <linux/spinlock.h>
 #include <linux/err.h>
 #include <linux/clk.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
 
 #include <asm/system.h>
 #include <asm/hardware.h>
@@ -80,13 +82,13 @@ struct sys_timer omap_timer;
 #define OMAP1_32K_TIMER_TVR             0x00
 #define OMAP1_32K_TIMER_TCR             0x04
 
-#define OMAP_32K_TICKS_PER_HZ           (32768 / HZ)
+#define OMAP_32K_TICKS_PER_SEC          (32768)
 
 /*
  * TRM says 1 / HZ = ( TVR + 1) / 32768, so TRV = (32768 / HZ) - 1
  * so with HZ = 128, TVR = 255.
  */
-#define OMAP_32K_TIMER_TICK_PERIOD      ((32768 / HZ) - 1)
+#define OMAP_32K_TIMER_TICK_PERIOD      ((OMAP_32K_TICKS_PER_SEC / HZ) - 1)
 
 #define JIFFIES_TO_HW_TICKS(nr_jiffies, clock_rate)                     \
                                 (((nr_jiffies) * (clock_rate)) / HZ)
@@ -142,6 +144,28 @@ static inline void omap_32k_timer_ack_irq(void)
 
 #endif
 
+static void omap_32k_timer_set_mode(enum clock_event_mode mode,
+                                    struct clock_event_device *evt)
+{
+        switch (mode) {
+        case CLOCK_EVT_MODE_ONESHOT:
+        case CLOCK_EVT_MODE_PERIODIC:
+                omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
+                break;
+        case CLOCK_EVT_MODE_UNUSED:
+        case CLOCK_EVT_MODE_SHUTDOWN:
+                omap_32k_timer_stop();
+                break;
+        }
+}
+
+static struct clock_event_device clockevent_32k_timer = {
+        .name           = "32k-timer",
+        .features       = CLOCK_EVT_FEAT_PERIODIC,
+        .shift          = 32,
+        .set_mode       = omap_32k_timer_set_mode,
+};
+
 /*
  * The 32KHz synchronized timer is an additional timer on 16xx.
  * It is always running.
@@ -171,15 +195,6 @@ omap_32k_ticks_to_nsecs(unsigned long ticks_32k)
 static unsigned long omap_32k_last_tick = 0;
 
 /*
- * Returns elapsed usecs since last 32k timer interrupt
- */
-static unsigned long omap_32k_timer_gettimeoffset(void)
-{
-        unsigned long now = omap_32k_sync_timer_read();
-        return omap_32k_ticks_to_usecs(now - omap_32k_last_tick);
-}
-
-/*
  * Returns current time from boot in nsecs. It's OK for this to wrap
  * around for now, as it's just a relative time stamp.
  */
@@ -188,95 +203,16 @@ unsigned long long sched_clock(void)
         return omap_32k_ticks_to_nsecs(omap_32k_sync_timer_read());
 }
 
-/*
- * Timer interrupt for 32KHz timer. When dynamic tick is enabled, this
- * function is also called from other interrupts to remove latency
- * issues with dynamic tick. In the dynamic tick case, we need to lock
- * with irqsave.
- */
-static inline irqreturn_t _omap_32k_timer_interrupt(int irq, void *dev_id)
-{
-        unsigned long now;
-
-        omap_32k_timer_ack_irq();
-        now = omap_32k_sync_timer_read();
-
-        while ((signed long)(now - omap_32k_last_tick)
-                                                >= OMAP_32K_TICKS_PER_HZ) {
-                omap_32k_last_tick += OMAP_32K_TICKS_PER_HZ;
-                timer_tick();
-        }
-
-        /* Restart timer so we don't drift off due to modulo or dynamic tick.
-         * By default we program the next timer to be continuous to avoid
-         * latencies during high system load. During dynamic tick operation the
-         * continuous timer can be overridden from pm_idle to be longer.
-         */
-        omap_32k_timer_start(omap_32k_last_tick + OMAP_32K_TICKS_PER_HZ - now);
-
-        return IRQ_HANDLED;
-}
-
-static irqreturn_t omap_32k_timer_handler(int irq, void *dev_id)
-{
-        return _omap_32k_timer_interrupt(irq, dev_id);
-}
-
 static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id)
 {
-        unsigned long flags;
+        struct clock_event_device *evt = &clockevent_32k_timer;
+        omap_32k_timer_ack_irq();
 
-        write_seqlock_irqsave(&xtime_lock, flags);
-        _omap_32k_timer_interrupt(irq, dev_id);
-        write_sequnlock_irqrestore(&xtime_lock, flags);
+        evt->event_handler(evt);
 
         return IRQ_HANDLED;
 }
 
-#ifdef CONFIG_NO_IDLE_HZ
-/*
- * Programs the next timer interrupt needed. Called when dynamic tick is
- * enabled, and to reprogram the ticks to skip from pm_idle. Note that
- * we can keep the timer continuous, and don't need to set it to run in
- * one-shot mode. This is because the timer will get reprogrammed again
- * after next interrupt.
- */
-void omap_32k_timer_reprogram(unsigned long next_tick)
-{
-        unsigned long ticks = JIFFIES_TO_HW_TICKS(next_tick, 32768) + 1;
-        unsigned long now = omap_32k_sync_timer_read();
-        unsigned long idled = now - omap_32k_last_tick;
-
-        if (idled + 1 < ticks)
-                ticks -= idled;
-        else
-                ticks = 1;
-        omap_32k_timer_start(ticks);
-}
-
-static struct irqaction omap_32k_timer_irq;
-extern struct timer_update_handler timer_update;
-
-static int omap_32k_timer_enable_dyn_tick(void)
-{
-        /* No need to reprogram timer, just use the next interrupt */
-        return 0;
-}
-
-static int omap_32k_timer_disable_dyn_tick(void)
-{
-        omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
-        return 0;
-}
-
-static struct dyn_tick_timer omap_dyn_tick_timer = {
-        .enable         = omap_32k_timer_enable_dyn_tick,
-        .disable        = omap_32k_timer_disable_dyn_tick,
-        .reprogram      = omap_32k_timer_reprogram,
-        .handler        = omap_32k_timer_handler,
-};
-#endif  /* CONFIG_NO_IDLE_HZ */
-
 static struct irqaction omap_32k_timer_irq = {
         .name           = "32KHz timer",
         .flags          = IRQF_DISABLED | IRQF_TIMER,
@@ -285,13 +221,8 @@ static struct irqaction omap_32k_timer_irq = {
 
 static __init void omap_init_32k_timer(void)
 {
-#ifdef CONFIG_NO_IDLE_HZ
-        omap_timer.dyn_tick = &omap_dyn_tick_timer;
-#endif
-
         if (cpu_class_is_omap1())
                 setup_irq(INT_OS_TIMER, &omap_32k_timer_irq);
-        omap_timer.offset  = omap_32k_timer_gettimeoffset;
         omap_32k_last_tick = omap_32k_sync_timer_read();
 
 #ifdef CONFIG_ARCH_OMAP2
@@ -308,7 +239,16 @@ static __init void omap_init_32k_timer(void)
         }
 #endif
 
-        omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
+        clockevent_32k_timer.mult = div_sc(OMAP_32K_TICKS_PER_SEC,
+                                           NSEC_PER_SEC,
+                                           clockevent_32k_timer.shift);
+        clockevent_32k_timer.max_delta_ns =
+                clockevent_delta2ns(0xfffffffe, &clockevent_32k_timer);
+        clockevent_32k_timer.min_delta_ns =
+                clockevent_delta2ns(1, &clockevent_32k_timer);
+
+        clockevent_32k_timer.cpumask = cpumask_of_cpu(0);
+        clockevents_register_device(&clockevent_32k_timer);
 }
 
 /*
@@ -326,5 +266,4 @@ static void __init omap_timer_init(void)
 
 struct sys_timer omap_timer = {
         .init           = omap_timer_init,
-        .offset         = NULL,         /* Initialized later */
 };