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/init.h>
 13#include <linux/cpuidle.h>
 14#include <linux/spinlock.h>
 15#include <linux/atomic.h>
 16#include <linux/smp.h>
 17#include <linux/mfd/dbx500-prcmu.h>
 18#include <linux/platform_data/arm-ux500-pm.h>
 19#include <linux/platform_device.h>
 20
 21#include <asm/cpuidle.h>
 22
 23static atomic_t master = ATOMIC_INIT(0);
 24static DEFINE_SPINLOCK(master_lock);
 25
 26static 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
 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 */
 40		if (prcmu_gic_decouple()) {
 41			spin_unlock(&master_lock);
 42			goto out;
 43		}
 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	}
 81wfi:
 82	cpu_do_idle();
 83out:
 84	atomic_dec(&master);
 85
 86	if (recouple) {
 87		prcmu_gic_recouple();
 88		spin_unlock(&master_lock);
 89	}
 90
 91	return index;
 92}
 93
 94static struct cpuidle_driver ux500_idle_driver = {
 95	.name = "ux500_idle",
 96	.owner = THIS_MODULE,
 97	.states = {
 98		ARM_CPUIDLE_WFI_STATE,
 99		{
100			.enter		  = ux500_enter_idle,
101			.exit_latency	  = 70,
102			.target_residency = 260,
103			.flags		  = CPUIDLE_FLAG_TIMER_STOP,
104			.name		  = "ApIdle",
105			.desc		  = "ARM Retention",
106		},
107	},
108	.safe_state_index = 0,
109	.state_count = 2,
110};
111
112static int dbx500_cpuidle_probe(struct platform_device *pdev)
113{
114	/* Configure wake up reasons */
115	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
116			     PRCMU_WAKEUP(ABB));
117
118	return cpuidle_register(&ux500_idle_driver, NULL);
119}
120
121static struct platform_driver dbx500_cpuidle_plat_driver = {
122	.driver = {
123		.name = "cpuidle-dbx500",
124	},
125	.probe = dbx500_cpuidle_probe,
126};
127builtin_platform_driver(dbx500_cpuidle_plat_driver);