cpuidle-ux500.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
  4 *
  5 * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
  6 * and Jonas Aaberg <jonas.aberg@stericsson.com>.
  7 */
  8
  9#include <linux/init.h>
 10#include <linux/cpuidle.h>
 11#include <linux/spinlock.h>
 12#include <linux/atomic.h>
 13#include <linux/smp.h>
 14#include <linux/mfd/dbx500-prcmu.h>
 15#include <linux/platform_data/arm-ux500-pm.h>
 16#include <linux/platform_device.h>
 17
 18#include <asm/cpuidle.h>
 19
 20static atomic_t master = ATOMIC_INIT(0);
 21static DEFINE_SPINLOCK(master_lock);
 22
 23static inline int ux500_enter_idle(struct cpuidle_device *dev,
 24				   struct cpuidle_driver *drv, int index)
 25{
 26	int this_cpu = smp_processor_id();
 27	bool recouple = false;
 28
 29	if (atomic_inc_return(&master) == num_online_cpus()) {
 30
 31		/* With this lock, we prevent the other cpu to exit and enter
 32		 * this function again and become the master */
 33		if (!spin_trylock(&master_lock))
 34			goto wfi;
 35
 36		/* decouple the gic from the A9 cores */
 37		if (prcmu_gic_decouple()) {
 38			spin_unlock(&master_lock);
 39			goto out;
 40		}
 41
 42		/* If an error occur, we will have to recouple the gic
 43		 * manually */
 44		recouple = true;
 45
 46		/* At this state, as the gic is decoupled, if the other
 47		 * cpu is in WFI, we have the guarantee it won't be wake
 48		 * up, so we can safely go to retention */
 49		if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
 50			goto out;
 51
 52		/* The prcmu will be in charge of watching the interrupts
 53		 * and wake up the cpus */
 54		if (prcmu_copy_gic_settings())
 55			goto out;
 56
 57		/* Check in the meantime an interrupt did
 58		 * not occur on the gic ... */
 59		if (prcmu_gic_pending_irq())
 60			goto out;
 61
 62		/* ... and the prcmu */
 63		if (prcmu_pending_irq())
 64			goto out;
 65
 66		/* Go to the retention state, the prcmu will wait for the
 67		 * cpu to go WFI and this is what happens after exiting this
 68		 * 'master' critical section */
 69		if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
 70			goto out;
 71
 72		/* When we switch to retention, the prcmu is in charge
 73		 * of recoupling the gic automatically */
 74		recouple = false;
 75
 76		spin_unlock(&master_lock);
 77	}
 78wfi:
 79	cpu_do_idle();
 80out:
 81	atomic_dec(&master);
 82
 83	if (recouple) {
 84		prcmu_gic_recouple();
 85		spin_unlock(&master_lock);
 86	}
 87
 88	return index;
 89}
 90
 91static struct cpuidle_driver ux500_idle_driver = {
 92	.name = "ux500_idle",
 93	.owner = THIS_MODULE,
 94	.states = {
 95		ARM_CPUIDLE_WFI_STATE,
 96		{
 97			.enter		  = ux500_enter_idle,
 98			.exit_latency	  = 70,
 99			.target_residency = 260,
100			.flags		  = CPUIDLE_FLAG_TIMER_STOP,
101			.name		  = "ApIdle",
102			.desc		  = "ARM Retention",
103		},
104	},
105	.safe_state_index = 0,
106	.state_count = 2,
107};
108
109static int dbx500_cpuidle_probe(struct platform_device *pdev)
110{
111	/* Configure wake up reasons */
112	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
113			     PRCMU_WAKEUP(ABB));
114
115	return cpuidle_register(&ux500_idle_driver, NULL);
116}
117
118static struct platform_driver dbx500_cpuidle_plat_driver = {
119	.driver = {
120		.name = "db8500-cpuidle",
121	},
122	.probe = dbx500_cpuidle_probe,
123};
124builtin_platform_driver(dbx500_cpuidle_plat_driver);