diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index bfcf4228036892a4aaab3ab31db6a7c8bb8b7e73..c8d94dcd8ef7daed544f14d5ac2db98c0236c952 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -346,6 +346,21 @@ config PREEMPT
Say Y here if you are building a kernel for a desktop, embedded
or real-time system. Say N if you are unsure.
+config NO_IDLE_HZ
+ bool "Dynamic tick timer"
+ help
+ Select this option if you want to disable continuous timer ticks
+ and have them programmed to occur as required. This option saves
+ power as the system can remain in idle state for longer.
+
+ By default dynamic tick is disabled during the boot, and can be
+ manually enabled with:
+
+ echo 1 > /sys/devices/system/timer/timer0/dyn_tick
+
+ Alternatively, if you want dynamic tick automatically enabled
+ during boot, pass "dyntick=enable" via the kernel command string.
+
config ARCH_DISCONTIGMEM_ENABLE
bool
default (ARCH_LH7A40X && !LH7A40X_CONTIGMEM)
diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
index ff187f4308f01ec786056f07b82299d8adf90cb2..395137a8fad276ce20cb250d58920f7c12fac501 100644
--- a/arch/arm/kernel/irq.c
+++ b/arch/arm/kernel/irq.c
@@ -4,6 +4,10 @@
* Copyright (C) 1992 Linus Torvalds
* Modifications for ARM processor Copyright (C) 1995-2000 Russell King.
*
+ * Support for Dynamic Tick Timer Copyright (C) 2004-2005 Nokia Corporation.
+ * Dynamic Tick Timer written by Tony Lindgren <tony@atomide.com> and
+ * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>.
+ *
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
@@ -37,6 +41,7 @@
#include <asm/irq.h>
#include <asm/system.h>
#include <asm/mach/irq.h>
+#include <asm/mach/time.h>
/*
* Maximum IRQ count. Currently, this is arbitary. However, it should
@@ -329,6 +334,15 @@ __do_irq(unsigned int irq, struct irqaction *action, struct pt_regs *regs)
spin_unlock(&irq_controller_lock);
+#ifdef CONFIG_NO_IDLE_HZ
+ if (!(action->flags & SA_TIMER) && system_timer->dyn_tick != NULL) {
+ write_seqlock(&xtime_lock);
+ if (system_timer->dyn_tick->state & DYN_TICK_ENABLED)
+ system_timer->dyn_tick->handler(irq, 0, regs);
+ write_sequnlock(&xtime_lock);
+ }
+#endif
+
if (!(action->flags & SA_INTERRUPT))
local_irq_enable();
diff --git a/arch/arm/kernel/time.c b/arch/arm/kernel/time.c
index c232f24f4a60042806958f8e74e685af473e3196..06054c9ba07435ac33b4962caa0c8fd5378269b3 100644
--- a/arch/arm/kernel/time.c
+++ b/arch/arm/kernel/time.c
@@ -381,6 +381,95 @@ static struct sysdev_class timer_sysclass = {
.resume = timer_resume,
};
+#ifdef CONFIG_NO_IDLE_HZ
+static int timer_dyn_tick_enable(void)
+{
+ struct dyn_tick_timer *dyn_tick = system_timer->dyn_tick;
+ unsigned long flags;
+ int ret = -ENODEV;
+
+ if (dyn_tick) {
+ write_seqlock_irqsave(&xtime_lock, flags);
+ ret = 0;
+ if (!(dyn_tick->state & DYN_TICK_ENABLED)) {
+ ret = dyn_tick->enable();
+
+ if (ret == 0)
+ dyn_tick->state |= DYN_TICK_ENABLED;
+ }
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+ }
+
+ return ret;
+}
+
+static int timer_dyn_tick_disable(void)
+{
+ struct dyn_tick_timer *dyn_tick = system_timer->dyn_tick;
+ unsigned long flags;
+ int ret = -ENODEV;
+
+ if (dyn_tick) {
+ write_seqlock_irqsave(&xtime_lock, flags);
+ ret = 0;
+ if (dyn_tick->state & DYN_TICK_ENABLED) {
+ ret = dyn_tick->disable();
+
+ if (ret == 0)
+ dyn_tick->state &= ~DYN_TICK_ENABLED;
+ }
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+ }
+
+ return ret;
+}
+
+void timer_dyn_reprogram(void)
+{
+ struct dyn_tick_timer *dyn_tick = system_timer->dyn_tick;
+ unsigned long flags;
+
+ write_seqlock_irqsave(&xtime_lock, flags);
+ if (dyn_tick->state & DYN_TICK_ENABLED)
+ dyn_tick->reprogram(next_timer_interrupt() - jiffies);
+ write_sequnlock_irqrestore(&xtime_lock, flags);
+}
+
+static ssize_t timer_show_dyn_tick(struct sys_device *dev, char *buf)
+{
+ return sprintf(buf, "%i\n",
+ (system_timer->dyn_tick->state & DYN_TICK_ENABLED) >> 1);
+}
+
+static ssize_t timer_set_dyn_tick(struct sys_device *dev, const char *buf,
+ size_t count)
+{
+ unsigned int enable = simple_strtoul(buf, NULL, 2);
+
+ if (enable)
+ timer_dyn_tick_enable();
+ else
+ timer_dyn_tick_disable();
+
+ return count;
+}
+static SYSDEV_ATTR(dyn_tick, 0644, timer_show_dyn_tick, timer_set_dyn_tick);
+
+/*
+ * dyntick=enable|disable
+ */
+static char dyntick_str[4] __initdata = "";
+
+static int __init dyntick_setup(char *str)
+{
+ if (str)
+ strlcpy(dyntick_str, str, sizeof(dyntick_str));
+ return 1;
+}
+
+__setup("dyntick=", dyntick_setup);
+#endif
+
static int __init timer_init_sysfs(void)
{
int ret = sysdev_class_register(&timer_sysclass);
@@ -388,6 +477,20 @@ static int __init timer_init_sysfs(void)
system_timer->dev.cls = &timer_sysclass;
ret = sysdev_register(&system_timer->dev);
}
+
+#ifdef CONFIG_NO_IDLE_HZ
+ if (ret == 0 && system_timer->dyn_tick) {
+ ret = sysdev_create_file(&system_timer->dev, &attr_dyn_tick);
+
+ /*
+ * Turn on dynamic tick after calibrate delay
+ * for correct bogomips
+ */
+ if (ret == 0 && dyntick_str[0] == 'e')
+ ret = timer_dyn_tick_enable();
+ }
+#endif
+
return ret;
}
diff --git a/include/asm-arm/mach/time.h b/include/asm-arm/mach/time.h
index 5cf4fd659fd54d4b64e2c4dbd9faa1690da22f72..047980ad18d119aeb2e6136bba3221294fb75883 100644
--- a/include/asm-arm/mach/time.h
+++ b/include/asm-arm/mach/time.h
@@ -39,8 +39,29 @@ struct sys_timer {
void (*suspend)(void);
void (*resume)(void);
unsigned long (*offset)(void);
+
+#ifdef CONFIG_NO_IDLE_HZ
+ struct dyn_tick_timer *dyn_tick;
+#endif
+};
+
+#ifdef CONFIG_NO_IDLE_HZ
+
+#define DYN_TICK_SKIPPING (1 << 2)
+#define DYN_TICK_ENABLED (1 << 1)
+#define DYN_TICK_SUITABLE (1 << 0)
+
+struct dyn_tick_timer {
+ unsigned int state; /* Current state */
+ int (*enable)(void); /* Enables dynamic tick */
+ int (*disable)(void); /* Disables dynamic tick */
+ void (*reprogram)(unsigned long); /* Reprograms the timer */
+ int (*handler)(int, void *, struct pt_regs *);
};
+void timer_dyn_reprogram(void);
+#endif
+
extern struct sys_timer *system_timer;
extern void timer_tick(struct pt_regs *);
diff --git a/include/asm-arm/signal.h b/include/asm-arm/signal.h
index 46e69ae395af53a9d2c7db10be7479ec12836678..760f6e65af05583c2faea5b1997989d8435c5c3b 100644
--- a/include/asm-arm/signal.h
+++ b/include/asm-arm/signal.h
@@ -114,6 +114,7 @@ typedef unsigned long sigset_t;
#define SIGSTKSZ 8192
#ifdef __KERNEL__
+#define SA_TIMER 0x40000000
#define SA_IRQNOMASK 0x08000000
#endif