Commit 9a0b8415 authored by venkatesh.pallipadi@intel.com's avatar venkatesh.pallipadi@intel.com Committed by Len Brown
Browse files

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: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 9b12e18c

arch/x86/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -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

drivers/acpi/processor_idle.c

+3 −1
Original line number Diff line number Diff line
@@ -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;

drivers/cpuidle/cpuidle.c

+41 −0
Original line number Diff line number Diff line
@@ -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))) {

include/linux/cpuidle.h

+10 −3
Original line number Diff line number Diff line
@@ -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 */