[ARM] 2864/1: VST aka CONFIG_NO_IDLE_HZ support for SA11x0
Patch from Nicolas Pitre
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index dc0fafc..68dfdba 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -365,8 +365,8 @@
Please note that dynamic tick may affect the accuracy of
timekeeping on some platforms depending on the implementation.
- Currently at least OMAP and PXA2xx platforms are known to have
- accurate timekeeping with dynamic tick.
+ Currently at least OMAP, PXA2xx and SA11x0 platforms are known
+ to have accurate timekeeping with dynamic tick.
config ARCH_DISCONTIGMEM_ENABLE
bool
diff --git a/arch/arm/mach-sa1100/time.c b/arch/arm/mach-sa1100/time.c
index a084b38..47e0420 100644
--- a/arch/arm/mach-sa1100/time.c
+++ b/arch/arm/mach-sa1100/time.c
@@ -70,6 +70,11 @@
return usec;
}
+#ifdef CONFIG_NO_IDLE_HZ
+static unsigned long initial_match;
+static int match_posponed;
+#endif
+
static irqreturn_t
sa1100_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
@@ -77,6 +82,13 @@
write_seqlock(&xtime_lock);
+#ifdef CONFIG_NO_IDLE_HZ
+ if (match_posponed) {
+ match_posponed = 0;
+ OSMR0 = initial_match;
+ }
+#endif
+
/*
* Loop until we get ahead of the free running timer.
* This ensures an exact clock tick count and time accuracy.
@@ -119,6 +131,42 @@
OSCR = 0; /* initialize free-running timer, force first match */
}
+#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;
+ }
+}
+
+static irqreturn_t
+sa1100_dyn_tick_handler(int irq, void *dev_id, struct pt_regs *regs)
+{
+ if (match_posponed) {
+ match_posponed = 0;
+ OSMR0 = initial_match;
+ if ((signed long)(initial_match - OSCR) <= 0)
+ return sa1100_timer_interrupt(irq, dev_id, regs);
+ }
+ return IRQ_NONE;
+}
+
+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;
@@ -155,4 +203,7 @@
.suspend = sa1100_timer_suspend,
.resume = sa1100_timer_resume,
.offset = sa1100_gettimeoffset,
+#ifdef CONFIG_NO_IDLE_HZ
+ .dyn_tick = &sa1100_dyn_tick,
+#endif
};