[linux.git] / drivers / cpuidle / cpuidle-ux500.c

/*
 * Copyright (c) 2012 Linaro : Daniel Lezcano <[email protected]> (IBM)
 *
 * Based on the work of Rickard Andersson <[email protected]>
 * and Jonas Aaberg <[email protected]>.
 *
 * 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 <linux/platform_device.h>

#include <asm/cpuidle.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_TIMER_STOP,
			.name		  = "ApIdle",
			.desc		  = "ARM Retention",
		},
	},
	.safe_state_index = 0,
	.state_count = 2,
};

static int dbx500_cpuidle_probe(struct platform_device *pdev)
{
	/* Configure wake up reasons */
	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
			     PRCMU_WAKEUP(ABB));

	return cpuidle_register(&ux500_idle_driver, NULL);
}

static struct platform_driver dbx500_cpuidle_plat_driver = {
	.driver = {
		.name = "cpuidle-dbx500",
	},
	.probe = dbx500_cpuidle_probe,
};

module_platform_driver(dbx500_cpuidle_plat_driver);
Commit	Line	Data
3ebabaa5 DL	1	/*
	2	* Copyright (c) 2012 Linaro : Daniel Lezcano <[email protected]> (IBM)
	3	*
	4	* Based on the work of Rickard Andersson <[email protected]>
	5	* and Jonas Aaberg <[email protected]>.
	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>
8025395f	19	#include <linux/platform_device.h>
3ebabaa5 DL	20
3ebabaa5 DL	21	#include <asm/cpuidle.h>
3ebabaa5 DL	22
	23	static atomic_t master = ATOMIC_INIT(0);
	24	static DEFINE_SPINLOCK(master_lock);
3ebabaa5 DL	25
	26	static inline int ux500_enter_idle(struct cpuidle_device *dev,
	27	struct cpuidle_driver *drv, int index)
	28	{
	29	int this_cpu = smp_processor_id();
	30	bool recouple = false;
	31
3ebabaa5 DL	32	if (atomic_inc_return(&master) == num_online_cpus()) {
	33
	34	/* With this lock, we prevent the other cpu to exit and enter
	35	* this function again and become the master */
	36	if (!spin_trylock(&master_lock))
	37	goto wfi;
	38
	39	/* decouple the gic from the A9 cores */
5cc23666 SZ	40	if (prcmu_gic_decouple()) {
5cc23666 SZ	41	spin_unlock(&master_lock);
3ebabaa5	42	goto out;
5cc23666	43	}
3ebabaa5 DL	44
	45	/* If an error occur, we will have to recouple the gic
	46	* manually */
	47	recouple = true;
	48
	49	/* At this state, as the gic is decoupled, if the other
	50	* cpu is in WFI, we have the guarantee it won't be wake
	51	* up, so we can safely go to retention */
	52	if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
	53	goto out;
	54
	55	/* The prcmu will be in charge of watching the interrupts
	56	* and wake up the cpus */
	57	if (prcmu_copy_gic_settings())
	58	goto out;
	59
	60	/* Check in the meantime an interrupt did
	61	* not occur on the gic ... */
	62	if (prcmu_gic_pending_irq())
	63	goto out;
	64
	65	/* ... and the prcmu */
	66	if (prcmu_pending_irq())
	67	goto out;
	68
	69	/* Go to the retention state, the prcmu will wait for the
	70	* cpu to go WFI and this is what happens after exiting this
	71	* 'master' critical section */
	72	if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
	73	goto out;
	74
	75	/* When we switch to retention, the prcmu is in charge
	76	* of recoupling the gic automatically */
	77	recouple = false;
	78
	79	spin_unlock(&master_lock);
	80	}
	81	wfi:
	82	cpu_do_idle();
	83	out:
	84	atomic_dec(&master);
	85
	86	if (recouple) {
	87	prcmu_gic_recouple();
	88	spin_unlock(&master_lock);
	89	}
	90
3ebabaa5 DL	91	return index;
	92	}
	93
	94	static struct cpuidle_driver ux500_idle_driver = {
	95	.name = "ux500_idle",
	96	.owner = THIS_MODULE,
3ebabaa5 DL	97	.states = {
	98	ARM_CPUIDLE_WFI_STATE,
	99	{
	100	.enter = ux500_enter_idle,
	101	.exit_latency = 70,
	102	.target_residency = 260,
b82b6cca	103	.flags = CPUIDLE_FLAG_TIMER_STOP,
3ebabaa5 DL	104	.name = "ApIdle",
	105	.desc = "ARM Retention",
	106	},
	107	},
	108	.safe_state_index = 0,
	109	.state_count = 2,
	110	};
	111
2c2b24d9	112	static int dbx500_cpuidle_probe(struct platform_device *pdev)
3ebabaa5	113	{
1e22a8c6	114	/* Configure wake up reasons */
3ebabaa5 DL	115	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) \| PRCMU_WAKEUP(RTC) \|
	116	PRCMU_WAKEUP(ABB));
	117
e8928e2e	118	return cpuidle_register(&ux500_idle_driver, NULL);
3ebabaa5 DL	119	}
3ebabaa5 DL	120
8025395f LW	121	static struct platform_driver dbx500_cpuidle_plat_driver = {
	122	.driver = {
	123	.name = "cpuidle-dbx500",
8025395f LW	124	},
	125	.probe = dbx500_cpuidle_probe,
	126	};
	127
	128	module_platform_driver(dbx500_cpuidle_plat_driver);