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| author | venkatesh.pallipadi@intel.com <venkatesh.pallipadi@intel.com> | 2008-01-31 17:35:06 -0800 |
|---|---|---|
| committer | Len Brown <len.brown@intel.com> | 2008-02-07 02:20:15 -0500 |
| commit | 9a0b841586c3c6c846effdbe75885c2ebc0031b0 (patch) | |
| tree | d9522222094b6357c7933489b98c7249326e1cf8 /drivers/cpuidle | |
| parent | 9b12e18cdc1553de62d931e73443c806347cd974 (diff) | |
| download | lwn-9a0b841586c3c6c846effdbe75885c2ebc0031b0.tar.gz lwn-9a0b841586c3c6c846effdbe75885c2ebc0031b0.zip | |
cpuidle: Add a poll_idle method
Add a default poll idle state with 0 latency. Provides an option to users
to use poll_idle by using 0 as the latency requirement.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers/cpuidle')
| -rw-r--r-- | drivers/cpuidle/cpuidle.c | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 2a98d99cbd46..2c4b2d47973e 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -15,6 +15,7 @@ #include <linux/pm_qos_params.h> #include <linux/cpu.h> #include <linux/cpuidle.h> +#include <linux/ktime.h> #include "cpuidle.h" @@ -180,6 +181,44 @@ void cpuidle_disable_device(struct cpuidle_device *dev) EXPORT_SYMBOL_GPL(cpuidle_disable_device); +#ifdef CONFIG_ARCH_HAS_CPU_RELAX +static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st) +{ + ktime_t t1, t2; + s64 diff; + int ret; + + t1 = ktime_get(); + local_irq_enable(); + while (!need_resched()) + cpu_relax(); + + t2 = ktime_get(); + diff = ktime_to_us(ktime_sub(t2, t1)); + if (diff > INT_MAX) + diff = INT_MAX; + + ret = (int) diff; + return ret; +} + +static void poll_idle_init(struct cpuidle_device *dev) +{ + struct cpuidle_state *state = &dev->states[0]; + + cpuidle_set_statedata(state, NULL); + + snprintf(state->name, CPUIDLE_NAME_LEN, "C0 (poll idle)"); + state->exit_latency = 0; + state->target_residency = 0; + state->power_usage = -1; + state->flags = CPUIDLE_FLAG_POLL | CPUIDLE_FLAG_TIME_VALID; + state->enter = poll_idle; +} +#else +static void poll_idle_init(struct cpuidle_device *dev) {} +#endif /* CONFIG_ARCH_HAS_CPU_RELAX */ + /** * cpuidle_register_device - registers a CPU's idle PM feature * @dev: the cpu @@ -198,6 +237,8 @@ int cpuidle_register_device(struct cpuidle_device *dev) mutex_lock(&cpuidle_lock); + poll_idle_init(dev); + per_cpu(cpuidle_devices, dev->cpu) = dev; list_add(&dev->device_list, &cpuidle_detected_devices); if ((ret = cpuidle_add_sysfs(sys_dev))) { |