[deliverable/linux.git] / arch / sh / kernel / idle.c

/*
 * The idle loop for all SuperH platforms.
 *
 *  Copyright (C) 2002 - 2009  Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/pm.h>
#include <linux/tick.h>
#include <linux/preempt.h>
#include <linux/thread_info.h>
#include <linux/irqflags.h>
#include <linux/smp.h>
#include <asm/pgalloc.h>
#include <asm/system.h>
#include <asm/atomic.h>

void (*pm_idle)(void) = NULL;

static int hlt_counter;

static int __init nohlt_setup(char *__unused)
{
	hlt_counter = 1;
	return 1;
}
__setup("nohlt", nohlt_setup);

static int __init hlt_setup(char *__unused)
{
	hlt_counter = 0;
	return 1;
}
__setup("hlt", hlt_setup);

static inline int hlt_works(void)
{
	return !hlt_counter;
}

/*
 * On SMP it's slightly faster (but much more power-consuming!)
 * to poll the ->work.need_resched flag instead of waiting for the
 * cross-CPU IPI to arrive. Use this option with caution.
 */
static void poll_idle(void)
{
	local_irq_enable();
	while (!need_resched())
		cpu_relax();
}

void default_idle(void)
{
	if (hlt_works()) {
		clear_thread_flag(TIF_POLLING_NRFLAG);
		smp_mb__after_clear_bit();

		set_bl_bit();
		if (!need_resched()) {
			local_irq_enable();
			cpu_sleep();
		} else
			local_irq_enable();

		set_thread_flag(TIF_POLLING_NRFLAG);
		clear_bl_bit();
	} else
		poll_idle();
}

/*
 * The idle thread. There's no useful work to be done, so just try to conserve
 * power and have a low exit latency (ie sit in a loop waiting for somebody to
 * say that they'd like to reschedule)
 */
void cpu_idle(void)
{
	unsigned int cpu = smp_processor_id();

	set_thread_flag(TIF_POLLING_NRFLAG);

	/* endless idle loop with no priority at all */
	while (1) {
		tick_nohz_stop_sched_tick(1);

		while (!need_resched() && cpu_online(cpu)) {
			check_pgt_cache();
			rmb();

			local_irq_disable();
			/* Don't trace irqs off for idle */
			stop_critical_timings();
			pm_idle();
			/*
			 * Sanity check to ensure that pm_idle() returns
			 * with IRQs enabled
			 */
			WARN_ON(irqs_disabled());
			start_critical_timings();
		}

		tick_nohz_restart_sched_tick();
		preempt_enable_no_resched();
		schedule();
		preempt_disable();
	}
}

void __init select_idle_routine(void)
{
	/*
	 * If a platform has set its own idle routine, leave it alone.
	 */
	if (pm_idle)
		return;

	if (hlt_works())
		pm_idle = default_idle;
	else
		pm_idle = poll_idle;
}

static void do_nothing(void *unused)
{
}

void stop_this_cpu(void *unused)
{
	local_irq_disable();
	cpu_clear(smp_processor_id(), cpu_online_map);

	for (;;)
		cpu_sleep();
}

/*
 * cpu_idle_wait - Used to ensure that all the CPUs discard old value of
 * pm_idle and update to new pm_idle value. Required while changing pm_idle
 * handler on SMP systems.
 *
 * Caller must have changed pm_idle to the new value before the call. Old
 * pm_idle value will not be used by any CPU after the return of this function.
 */
void cpu_idle_wait(void)
{
	smp_mb();
	/* kick all the CPUs so that they exit out of pm_idle */
	smp_call_function(do_nothing, NULL, 1);
}
EXPORT_SYMBOL_GPL(cpu_idle_wait);
Commit	Line	Data
	1	/*
	2	* The idle loop for all SuperH platforms.
	3	*
	4	* Copyright (C) 2002 - 2009 Paul Mundt
	5	*
	6	* This file is subject to the terms and conditions of the GNU General Public
	7	* License. See the file "COPYING" in the main directory of this archive
	8	* for more details.
	9	*/
	10	#include <linux/module.h>
	11	#include <linux/init.h>
	12	#include <linux/mm.h>
	13	#include <linux/pm.h>
	14	#include <linux/tick.h>
	15	#include <linux/preempt.h>
	16	#include <linux/thread_info.h>
	17	#include <linux/irqflags.h>
	18	#include <linux/smp.h>
	19	#include <asm/pgalloc.h>
	20	#include <asm/system.h>
	21	#include <asm/atomic.h>
	22
	23	void (*pm_idle)(void) = NULL;
	24
	25	static int hlt_counter;
	26
	27	static int __init nohlt_setup(char *__unused)
	28	{
	29	hlt_counter = 1;
	30	return 1;
	31	}
	32	__setup("nohlt", nohlt_setup);
	33
	34	static int __init hlt_setup(char *__unused)
	35	{
	36	hlt_counter = 0;
	37	return 1;
	38	}
	39	__setup("hlt", hlt_setup);
	40
	41	static inline int hlt_works(void)
	42	{
	43	return !hlt_counter;
	44	}
	45
	46	/*
	47	* On SMP it's slightly faster (but much more power-consuming!)
	48	* to poll the ->work.need_resched flag instead of waiting for the
	49	* cross-CPU IPI to arrive. Use this option with caution.
	50	*/
	51	static void poll_idle(void)
	52	{
	53	local_irq_enable();
	54	while (!need_resched())
	55	cpu_relax();
	56	}
	57
	58	void default_idle(void)
	59	{
	60	if (hlt_works()) {
	61	clear_thread_flag(TIF_POLLING_NRFLAG);
	62	smp_mb__after_clear_bit();
	63
	64	set_bl_bit();
	65	if (!need_resched()) {
	66	local_irq_enable();
	67	cpu_sleep();
	68	} else
	69	local_irq_enable();
	70
	71	set_thread_flag(TIF_POLLING_NRFLAG);
	72	clear_bl_bit();
	73	} else
	74	poll_idle();
	75	}
	76
	77	/*
	78	* The idle thread. There's no useful work to be done, so just try to conserve
	79	* power and have a low exit latency (ie sit in a loop waiting for somebody to
	80	* say that they'd like to reschedule)
	81	*/
	82	void cpu_idle(void)
	83	{
	84	unsigned int cpu = smp_processor_id();
	85
	86	set_thread_flag(TIF_POLLING_NRFLAG);
	87
	88	/* endless idle loop with no priority at all */
	89	while (1) {
	90	tick_nohz_stop_sched_tick(1);
	91
	92	while (!need_resched() && cpu_online(cpu)) {
	93	check_pgt_cache();
	94	rmb();
	95
	96	local_irq_disable();
	97	/* Don't trace irqs off for idle */
	98	stop_critical_timings();
	99	pm_idle();
	100	/*
	101	* Sanity check to ensure that pm_idle() returns
	102	* with IRQs enabled
	103	*/
	104	WARN_ON(irqs_disabled());
	105	start_critical_timings();
	106	}
	107
	108	tick_nohz_restart_sched_tick();
	109	preempt_enable_no_resched();
	110	schedule();
	111	preempt_disable();
	112	}
	113	}
	114
	115	void __init select_idle_routine(void)
	116	{
	117	/*
	118	* If a platform has set its own idle routine, leave it alone.
	119	*/
	120	if (pm_idle)
	121	return;
	122
	123	if (hlt_works())
	124	pm_idle = default_idle;
	125	else
	126	pm_idle = poll_idle;
	127	}
	128
	129	static void do_nothing(void *unused)
	130	{
	131	}
	132
	133	void stop_this_cpu(void *unused)
	134	{
	135	local_irq_disable();
	136	cpu_clear(smp_processor_id(), cpu_online_map);
	137
	138	for (;;)
	139	cpu_sleep();
	140	}
	141
	142	/*
	143	* cpu_idle_wait - Used to ensure that all the CPUs discard old value of
	144	* pm_idle and update to new pm_idle value. Required while changing pm_idle
	145	* handler on SMP systems.
	146	*
	147	* Caller must have changed pm_idle to the new value before the call. Old
	148	* pm_idle value will not be used by any CPU after the return of this function.
	149	*/
	150	void cpu_idle_wait(void)
	151	{
	152	smp_mb();
	153	/* kick all the CPUs so that they exit out of pm_idle */
	154	smp_call_function(do_nothing, NULL, 1);
	155	}
	156	EXPORT_SYMBOL_GPL(cpu_idle_wait);