[PATCH] ARM: 2771/1: Dynamic Tick support for OMAP, take 4

Patch from Tony Lindgren

This patch adds support for Dynamic Tick Timer for OMAP.
This patch is an updated version of ARM patch 2642/1 to
make it work with the already integrated generic ARM
dyntick support.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-omap/pm.c

@@ -41,7 +41,9 @@
 #include <linux/pm.h>
 
 #include <asm/io.h>
+#include <asm/mach/time.h>
 #include <asm/mach-types.h>
+
 #include <asm/arch/omap16xx.h>
 #include <asm/arch/pm.h>
 #include <asm/arch/mux.h>
@@ -80,13 +82,13 @@ void omap_pm_idle(void)
 		return;
 	}
 	mask32 = omap_readl(ARM_SYSST);
-	local_fiq_enable();
-	local_irq_enable();
 
-#if defined(CONFIG_OMAP_32K_TIMER) && defined(CONFIG_NO_IDLE_HZ)
-	/* Override timer to use VST for the next cycle */
-	omap_32k_timer_next_vst_interrupt();
-#endif
+	/*
+	 * Since an interrupt may set up a timer, we don't want to
+	 * reprogram the hardware timer with interrupts enabled.
+	 * Re-enable interrupts only after returning from idle.
+	 */
+	timer_dyn_reprogram();
 
 	if ((mask32 & DSP_IDLE) == 0) {
 		__asm__ volatile ("mcr	p15, 0, r0, c7, c0, 4");
@@ -102,6 +104,8 @@ void omap_pm_idle(void)
 
 		func_ptr();
 	}
+	local_fiq_enable();
+	local_irq_enable();
 }
 
 /*

arch/arm/mach-omap/time.c

@@ -4,7 +4,7 @@
  * OMAP Timers
  *
  * Copyright (C) 2004 Nokia Corporation
- * Partial timer rewrite and additional VST timer support by
+ * Partial timer rewrite and additional dynamic tick timer support by
  * Tony Lindgen <tony@atomide.com> and
  * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
  *
@@ -261,7 +261,6 @@ unsigned long long sched_clock(void)
  * so with HZ = 100, TVR = 327.68.
  */
 #define OMAP_32K_TIMER_TICK_PERIOD	((32768 / HZ) - 1)
-#define MAX_SKIP_JIFFIES		25
 #define TIMER_32K_SYNCHRONIZED		0xfffbc410
 
 #define JIFFIES_TO_HW_TICKS(nr_jiffies, clock_rate)			\
@@ -347,6 +346,42 @@ static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id,
 	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)
+{
+	omap_32k_timer_start(JIFFIES_TO_HW_TICKS(next_tick, 32768) + 1);
+}
+
+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_interrupt,
+};
+#endif	/* CONFIG_NO_IDLE_HZ */
+
 static struct irqaction omap_32k_timer_irq = {
 	.name		= "32KHz timer",
 	.flags		= SA_INTERRUPT | SA_TIMER,
@@ -355,6 +390,11 @@ 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
+
 	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();