1 files changed, 107 insertions, 0 deletions

diff --git a/arch/arm/kernel/time.c b/arch/arm/kernel/time.c
index c232f24f4a60..1b7fcd50c3e2 100644
--- a/arch/arm/kernel/time.c
+++ b/arch/arm/kernel/time.c
@@ -381,6 +381,99 @@ 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;
+}
+
+/*
+ * Reprogram the system timer for at least the calculated time interval.
+ * This function should be called from the idle thread with IRQs disabled,
+ * immediately before sleeping.
+ */
+void timer_dyn_reprogram(void)
+{
+        struct dyn_tick_timer *dyn_tick = system_timer->dyn_tick;
+
+        write_seqlock(&xtime_lock);
+        if (dyn_tick->state & DYN_TICK_ENABLED)
+                dyn_tick->reprogram(next_timer_interrupt() - jiffies);
+        write_sequnlock(&xtime_lock);
+}
+
+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 +481,20 @@ 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;
 }