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authorvenkatesh.pallipadi@intel.com <venkatesh.pallipadi@intel.com>2008-01-31 17:35:06 -0800
committerLen Brown <len.brown@intel.com>2008-02-07 02:20:15 -0500
commit9a0b841586c3c6c846effdbe75885c2ebc0031b0 (patch)
treed9522222094b6357c7933489b98c7249326e1cf8 /drivers/cpuidle
parent9b12e18cdc1553de62d931e73443c806347cd974 (diff)
downloadlinux-9a0b841586c3c6c846effdbe75885c2ebc0031b0.tar.bz2
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.c41
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))) {