[deliverable/linux.git] / arch / arm / mach-ux500 / cpuidle.c

/*
 * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
 *
 * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
 * and Jonas Aaberg <jonas.aberg@stericsson.com>.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/cpuidle.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>
#include <linux/smp.h>
#include <linux/mfd/dbx500-prcmu.h>
#include <linux/platform_data/arm-ux500-pm.h>

#include <asm/cpuidle.h>
#include <asm/proc-fns.h>

#include "db8500-regs.h"

static atomic_t master = ATOMIC_INIT(0);
static DEFINE_SPINLOCK(master_lock);

static inline int ux500_enter_idle(struct cpuidle_device *dev,
				   struct cpuidle_driver *drv, int index)
{
	int this_cpu = smp_processor_id();
	bool recouple = false;

	if (atomic_inc_return(&master) == num_online_cpus()) {

		/* With this lock, we prevent the other cpu to exit and enter
		 * this function again and become the master */
		if (!spin_trylock(&master_lock))
			goto wfi;

		/* decouple the gic from the A9 cores */
		if (prcmu_gic_decouple()) {
			spin_unlock(&master_lock);
			goto out;
		}

		/* If an error occur, we will have to recouple the gic
		 * manually */
		recouple = true;

		/* At this state, as the gic is decoupled, if the other
		 * cpu is in WFI, we have the guarantee it won't be wake
		 * up, so we can safely go to retention */
		if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
			goto out;

		/* The prcmu will be in charge of watching the interrupts
		 * and wake up the cpus */
		if (prcmu_copy_gic_settings())
			goto out;

		/* Check in the meantime an interrupt did
		 * not occur on the gic ... */
		if (prcmu_gic_pending_irq())
			goto out;

		/* ... and the prcmu */
		if (prcmu_pending_irq())
			goto out;

		/* Go to the retention state, the prcmu will wait for the
		 * cpu to go WFI and this is what happens after exiting this
		 * 'master' critical section */
		if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
			goto out;

		/* When we switch to retention, the prcmu is in charge
		 * of recoupling the gic automatically */
		recouple = false;

		spin_unlock(&master_lock);
	}
wfi:
	cpu_do_idle();
out:
	atomic_dec(&master);

	if (recouple) {
		prcmu_gic_recouple();
		spin_unlock(&master_lock);
	}

	return index;
}

static struct cpuidle_driver ux500_idle_driver = {
	.name = "ux500_idle",
	.owner = THIS_MODULE,
	.states = {
		ARM_CPUIDLE_WFI_STATE,
		{
			.enter		  = ux500_enter_idle,
			.exit_latency	  = 70,
			.target_residency = 260,
			.flags		  = CPUIDLE_FLAG_TIME_VALID |
			                    CPUIDLE_FLAG_TIMER_STOP,
			.name		  = "ApIdle",
			.desc		  = "ARM Retention",
		},
	},
	.safe_state_index = 0,
	.state_count = 2,
};

int __init ux500_idle_init(void)
{
	/* Configure wake up reasons */
	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
			     PRCMU_WAKEUP(ABB));

	return cpuidle_register(&ux500_idle_driver, NULL);
}

device_initcall(ux500_idle_init);
Commit	Line	Data
3ebabaa5 DL	1	/*
	2	* Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
	3	*
	4	* Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
	5	* and Jonas Aaberg <jonas.aberg@stericsson.com>.
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*/
	11
	12	#include <linux/module.h>
	13	#include <linux/cpuidle.h>
3ebabaa5 DL	14	#include <linux/spinlock.h>
	15	#include <linux/atomic.h>
	16	#include <linux/smp.h>
	17	#include <linux/mfd/dbx500-prcmu.h>
1e22a8c6	18	#include <linux/platform_data/arm-ux500-pm.h>
3ebabaa5 DL	19
	20	#include <asm/cpuidle.h>
	21	#include <asm/proc-fns.h>
	22
174e7796 LW	23	#include "db8500-regs.h"
174e7796 LW	24
3ebabaa5 DL	25	static atomic_t master = ATOMIC_INIT(0);
3ebabaa5 DL	26	static DEFINE_SPINLOCK(master_lock);
3ebabaa5 DL	27
	28	static inline int ux500_enter_idle(struct cpuidle_device *dev,
	29	struct cpuidle_driver *drv, int index)
	30	{
	31	int this_cpu = smp_processor_id();
	32	bool recouple = false;
	33
3ebabaa5 DL	34	if (atomic_inc_return(&master) == num_online_cpus()) {
	35
	36	/* With this lock, we prevent the other cpu to exit and enter
	37	* this function again and become the master */
	38	if (!spin_trylock(&master_lock))
	39	goto wfi;
	40
	41	/* decouple the gic from the A9 cores */
5cc23666 SZ	42	if (prcmu_gic_decouple()) {
5cc23666 SZ	43	spin_unlock(&master_lock);
3ebabaa5	44	goto out;
5cc23666	45	}
3ebabaa5 DL	46
	47	/* If an error occur, we will have to recouple the gic
	48	* manually */
	49	recouple = true;
	50
	51	/* At this state, as the gic is decoupled, if the other
	52	* cpu is in WFI, we have the guarantee it won't be wake
	53	* up, so we can safely go to retention */
	54	if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
	55	goto out;
	56
	57	/* The prcmu will be in charge of watching the interrupts
	58	* and wake up the cpus */
	59	if (prcmu_copy_gic_settings())
	60	goto out;
	61
	62	/* Check in the meantime an interrupt did
	63	* not occur on the gic ... */
	64	if (prcmu_gic_pending_irq())
	65	goto out;
	66
	67	/* ... and the prcmu */
	68	if (prcmu_pending_irq())
	69	goto out;
	70
	71	/* Go to the retention state, the prcmu will wait for the
	72	* cpu to go WFI and this is what happens after exiting this
	73	* 'master' critical section */
	74	if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
	75	goto out;
	76
	77	/* When we switch to retention, the prcmu is in charge
	78	* of recoupling the gic automatically */
	79	recouple = false;
	80
	81	spin_unlock(&master_lock);
	82	}
	83	wfi:
	84	cpu_do_idle();
	85	out:
	86	atomic_dec(&master);
	87
	88	if (recouple) {
	89	prcmu_gic_recouple();
	90	spin_unlock(&master_lock);
	91	}
	92
3ebabaa5 DL	93	return index;
	94	}
	95
	96	static struct cpuidle_driver ux500_idle_driver = {
	97	.name = "ux500_idle",
	98	.owner = THIS_MODULE,
3ebabaa5 DL	99	.states = {
	100	ARM_CPUIDLE_WFI_STATE,
	101	{
	102	.enter = ux500_enter_idle,
	103	.exit_latency = 70,
	104	.target_residency = 260,
d2b578e5 DL	105	.flags = CPUIDLE_FLAG_TIME_VALID \|
d2b578e5 DL	106	CPUIDLE_FLAG_TIMER_STOP,
3ebabaa5 DL	107	.name = "ApIdle",
	108	.desc = "ARM Retention",
	109	},
	110	},
	111	.safe_state_index = 0,
	112	.state_count = 2,
	113	};
	114
3ebabaa5 DL	115	int __init ux500_idle_init(void)
3ebabaa5 DL	116	{
1e22a8c6	117	/* Configure wake up reasons */
3ebabaa5 DL	118	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) \| PRCMU_WAKEUP(RTC) \|
	119	PRCMU_WAKEUP(ABB));
	120
e8928e2e	121	return cpuidle_register(&ux500_idle_driver, NULL);
3ebabaa5 DL	122	}
	123
	124	device_initcall(ux500_idle_init);