[PATCH 096/112] cpuidle: Add a poll_idle method

Len Brown
2008-02-07T09:36:54Z

From: venkatesh.pallipadi@intel.com <venkatesh.pallipadi@intel.com>

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>
---
arch/x86/Kconfig | 3 +++
drivers/acpi/processor_idle.c | 4 +++-
drivers/cpuidle/cpuidle.c | 41 +++++++++++++++++++++++++++++++++++++++++
include/linux/cpuidle.h | 13 ++++++++++---
4 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e6728bd..fd42650 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -105,6 +105,9 @@ config GENERIC_TIME_VSYSCALL
bool
default X86_64

+config ARCH_HAS_CPU_RELAX
+ def_bool y
+
config HAVE_SETUP_PER_CPU_AREA
def_bool X86_64

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index fea7159..32488e6 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -1628,7 +1628,7 @@ struct cpuidle_driver acpi_idle_driver = {
*/
static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
{
- int i, count = 0;
+ int i, count = CPUIDLE_DRIVER_STATE_START;
struct acpi_processor_cx *cx;
struct cpuidle_state *state;
struct cpuidle_device *dev = &pr->power.dev;
@@ -1687,6 +1687,8 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
}

count++;
+ if (count == CPUIDLE_STATE_MAX)
+ break;
}

dev->state_count = count;
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 2a98d99..2c4b2d4 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))) {
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index b0fd85a..385d45b 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -46,9 +46,10 @@ struct cpuidle_state {
/* Idle State Flags */
#define CPUIDLE_FLAG_TIME_VALID (0x01) /* is residency time measurable? */
#define CPUIDLE_FLAG_CHECK_BM (0x02) /* BM activity will exit state */
-#define CPUIDLE_FLAG_SHALLOW (0x10) /* low latency, minimal savings */
-#define CPUIDLE_FLAG_BALANCED (0x20) /* medium latency, moderate savings */
-#define CPUIDLE_FLAG_DEEP (0x40) /* high latency, large savings */
+#define CPUIDLE_FLAG_POLL (0x10) /* no latency, no savings */
+#define CPUIDLE_FLAG_SHALLOW (0x20) /* low latency, minimal savings */
+#define CPUIDLE_FLAG_BALANCED (0x40) /* medium latency, moderate savings */
+#define CPUIDLE_FLAG_DEEP (0x80) /* high latency, large savings */

#define CPUIDLE_DRIVER_FLAGS_MASK (0xFFFF0000)

@@ -178,4 +179,10 @@ static inline void cpuidle_unregister_governor(struct cpuidle_governor *gov) { }

#endif

+#ifdef CONFIG_ARCH_HAS_CPU_RELAX
+#define CPUIDLE_DRIVER_STATE_START 1
+#else
+#define CPUIDLE_DRIVER_STATE_START 0
+#endif
+
#endif /* _LINUX_CPUIDLE_H */
--
1.5.4.23.gef5b9