[linux.git] / arch / arm / mach-ux500 / cpuidle.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 <asm/cpuidle.h>
#include <asm/proc-fns.h>

#include "db8500-regs.h"
#include "id.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)
{
	if (!(cpu_is_u8500_family() || cpu_is_ux540_family()))
		return -ENODEV;

	/* 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 <[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>
3ebabaa5 DL	19
	20	#include <asm/cpuidle.h>
	21	#include <asm/proc-fns.h>
	22
174e7796	23	#include "db8500-regs.h"
2c06897e	24	#include "id.h"
174e7796	25
3ebabaa5 DL	26	static atomic_t master = ATOMIC_INIT(0);
3ebabaa5 DL	27	static DEFINE_SPINLOCK(master_lock);
3ebabaa5 DL	28
	29	static inline int ux500_enter_idle(struct cpuidle_device *dev,
	30	struct cpuidle_driver *drv, int index)
	31	{
	32	int this_cpu = smp_processor_id();
	33	bool recouple = false;
	34
3ebabaa5 DL	35	if (atomic_inc_return(&master) == num_online_cpus()) {
	36
	37	/* With this lock, we prevent the other cpu to exit and enter
	38	* this function again and become the master */
	39	if (!spin_trylock(&master_lock))
	40	goto wfi;
	41
	42	/* decouple the gic from the A9 cores */
5cc23666 SZ	43	if (prcmu_gic_decouple()) {
5cc23666 SZ	44	spin_unlock(&master_lock);
3ebabaa5	45	goto out;
5cc23666	46	}
3ebabaa5 DL	47
	48	/* If an error occur, we will have to recouple the gic
	49	* manually */
	50	recouple = true;
	51
	52	/* At this state, as the gic is decoupled, if the other
	53	* cpu is in WFI, we have the guarantee it won't be wake
	54	* up, so we can safely go to retention */
	55	if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
	56	goto out;
	57
	58	/* The prcmu will be in charge of watching the interrupts
	59	* and wake up the cpus */
	60	if (prcmu_copy_gic_settings())
	61	goto out;
	62
	63	/* Check in the meantime an interrupt did
	64	* not occur on the gic ... */
	65	if (prcmu_gic_pending_irq())
	66	goto out;
	67
	68	/* ... and the prcmu */
	69	if (prcmu_pending_irq())
	70	goto out;
	71
	72	/* Go to the retention state, the prcmu will wait for the
	73	* cpu to go WFI and this is what happens after exiting this
	74	* 'master' critical section */
	75	if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
	76	goto out;
	77
	78	/* When we switch to retention, the prcmu is in charge
	79	* of recoupling the gic automatically */
	80	recouple = false;
	81
	82	spin_unlock(&master_lock);
	83	}
	84	wfi:
	85	cpu_do_idle();
	86	out:
	87	atomic_dec(&master);
	88
	89	if (recouple) {
	90	prcmu_gic_recouple();
	91	spin_unlock(&master_lock);
	92	}
	93
3ebabaa5 DL	94	return index;
	95	}
	96
	97	static struct cpuidle_driver ux500_idle_driver = {
	98	.name = "ux500_idle",
	99	.owner = THIS_MODULE,
3ebabaa5 DL	100	.states = {
	101	ARM_CPUIDLE_WFI_STATE,
	102	{
	103	.enter = ux500_enter_idle,
	104	.exit_latency = 70,
	105	.target_residency = 260,
d2b578e5 DL	106	.flags = CPUIDLE_FLAG_TIME_VALID \|
d2b578e5 DL	107	CPUIDLE_FLAG_TIMER_STOP,
3ebabaa5 DL	108	.name = "ApIdle",
	109	.desc = "ARM Retention",
	110	},
	111	},
	112	.safe_state_index = 0,
	113	.state_count = 2,
	114	};
	115
3ebabaa5 DL	116	int __init ux500_idle_init(void)
3ebabaa5 DL	117	{
2c06897e LJ	118	if (!(cpu_is_u8500_family() \|\| cpu_is_ux540_family()))
	119	return -ENODEV;
	120
1e22a8c6	121	/* Configure wake up reasons */
3ebabaa5 DL	122	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) \| PRCMU_WAKEUP(RTC) \|
	123	PRCMU_WAKEUP(ABB));
	124
e8928e2e	125	return cpuidle_register(&ux500_idle_driver, NULL);
3ebabaa5 DL	126	}
	127
	128	device_initcall(ux500_idle_init);