linux/drivers/cpuidle/cpuidle-ux500.c
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   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);
 128
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