diff options
| -rw-r--r-- | arch/sh/Kconfig | 18 | ||||
| -rw-r--r-- | arch/sh/kernel/time.c | 124 | ||||
| -rw-r--r-- | include/asm-sh/timer.h | 21 |
3 files changed, 162 insertions, 1 deletions
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig index 48308dc86e3..aa1ebc561b8 100644 --- a/arch/sh/Kconfig +++ b/arch/sh/Kconfig @@ -423,6 +423,24 @@ config SH_TIMER_IRQ default "140" if CPU_SUBTYPE_SH7206 default "16" +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. + + Please note that dynamic tick may affect the accuracy of + timekeeping on some platforms depending on the implementation. + config SH_PCLK_FREQ int "Peripheral clock frequency (in Hz)" default "27000000" if CPU_SUBTYPE_SH73180 || CPU_SUBTYPE_SH7343 diff --git a/arch/sh/kernel/time.c b/arch/sh/kernel/time.c index c55d6f217a4..1b91c721497 100644 --- a/arch/sh/kernel/time.c +++ b/arch/sh/kernel/time.c @@ -174,6 +174,108 @@ 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 = sys_timer->dyn_tick; + unsigned long flags; + int ret = -ENODEV; + + if (dyn_tick) { + spin_lock_irqsave(&dyn_tick->lock, flags); + ret = 0; + if (!(dyn_tick->state & DYN_TICK_ENABLED)) { + ret = dyn_tick->enable(); + + if (ret == 0) + dyn_tick->state |= DYN_TICK_ENABLED; + } + spin_unlock_irqrestore(&dyn_tick->lock, flags); + } + + return ret; +} + +static int timer_dyn_tick_disable(void) +{ + struct dyn_tick_timer *dyn_tick = sys_timer->dyn_tick; + unsigned long flags; + int ret = -ENODEV; + + if (dyn_tick) { + spin_lock_irqsave(&dyn_tick->lock, flags); + ret = 0; + if (dyn_tick->state & DYN_TICK_ENABLED) { + ret = dyn_tick->disable(); + + if (ret == 0) + dyn_tick->state &= ~DYN_TICK_ENABLED; + } + spin_unlock_irqrestore(&dyn_tick->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 = sys_timer->dyn_tick; + unsigned long next, seq, flags; + + if (!dyn_tick) + return; + + spin_lock_irqsave(&dyn_tick->lock, flags); + if (dyn_tick->state & DYN_TICK_ENABLED) { + next = next_timer_interrupt(); + do { + seq = read_seqbegin(&xtime_lock); + dyn_tick->reprogram(next - jiffies); + } while (read_seqretry(&xtime_lock, seq)); + } + spin_unlock_irqrestore(&dyn_tick->lock, flags); +} + +static ssize_t timer_show_dyn_tick(struct sys_device *dev, char *buf) +{ + return sprintf(buf, "%i\n", + (sys_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); @@ -181,7 +283,22 @@ static int __init timer_init_sysfs(void) return ret; sys_timer->dev.cls = &timer_sysclass; - return sysdev_register(&sys_timer->dev); + ret = sysdev_register(&sys_timer->dev); + +#ifdef CONFIG_NO_IDLE_HZ + if (ret == 0 && sys_timer->dyn_tick) { + ret = sysdev_create_file(&sys_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; } device_initcall(timer_init_sysfs); @@ -205,6 +322,11 @@ void __init time_init(void) sys_timer = get_sys_timer(); printk(KERN_INFO "Using %s for system timer\n", sys_timer->name); +#ifdef CONFIG_NO_IDLE_HZ + if (sys_timer->dyn_tick) + spin_lock_init(&sys_timer->dyn_tick->lock); +#endif + #if defined(CONFIG_SH_KGDB) /* * Set up kgdb as requested. We do it here because the serial diff --git a/include/asm-sh/timer.h b/include/asm-sh/timer.h index 5a014bca9d5..17b5e76a4c3 100644 --- a/include/asm-sh/timer.h +++ b/include/asm-sh/timer.h @@ -18,8 +18,29 @@ struct sys_timer { struct sys_device dev; struct sys_timer_ops *ops; + +#ifdef CONFIG_NO_IDLE_HZ + struct dyn_tick_timer *dyn_tick; +#endif }; +#ifdef CONFIG_NO_IDLE_HZ +#define DYN_TICK_ENABLED (1 << 1) + +struct dyn_tick_timer { + spinlock_t lock; + 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 *); +}; + +void timer_dyn_reprogram(void); +#else +#define timer_dyn_reprogram() do { } while (0) +#endif + #define TICK_SIZE (tick_nsec / 1000) extern struct sys_timer tmu_timer, cmt_timer, mtu2_timer; |