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/module.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#include <asm/proc-fns.h>
  23
  24static atomic_t master = ATOMIC_INIT(0);
  25static DEFINE_SPINLOCK(master_lock);
  26
  27static inline int ux500_enter_idle(struct cpuidle_device *dev,
  28                                   struct cpuidle_driver *drv, int index)
  29{
  30        int this_cpu = smp_processor_id();
  31        bool recouple = false;
  32
  33        if (atomic_inc_return(&master) == num_online_cpus()) {
  34
  35                /* With this lock, we prevent the other cpu to exit and enter
  36                 * this function again and become the master */
  37                if (!spin_trylock(&master_lock))
  38                        goto wfi;
  39
  40                /* decouple the gic from the A9 cores */
  41                if (prcmu_gic_decouple()) {
  42                        spin_unlock(&master_lock);
  43                        goto out;
  44                }
  45
  46                /* If an error occur, we will have to recouple the gic
  47                 * manually */
  48                recouple = true;
  49
  50                /* At this state, as the gic is decoupled, if the other
  51                 * cpu is in WFI, we have the guarantee it won't be wake
  52                 * up, so we can safely go to retention */
  53                if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
  54                        goto out;
  55
  56                /* The prcmu will be in charge of watching the interrupts
  57                 * and wake up the cpus */
  58                if (prcmu_copy_gic_settings())
  59                        goto out;
  60
  61                /* Check in the meantime an interrupt did
  62                 * not occur on the gic ... */
  63                if (prcmu_gic_pending_irq())
  64                        goto out;
  65
  66                /* ... and the prcmu */
  67                if (prcmu_pending_irq())
  68                        goto out;
  69
  70                /* Go to the retention state, the prcmu will wait for the
  71                 * cpu to go WFI and this is what happens after exiting this
  72                 * 'master' critical section */
  73                if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
  74                        goto out;
  75
  76                /* When we switch to retention, the prcmu is in charge
  77                 * of recoupling the gic automatically */
  78                recouple = false;
  79
  80                spin_unlock(&master_lock);
  81        }
  82wfi:
  83        cpu_do_idle();
  84out:
  85        atomic_dec(&master);
  86
  87        if (recouple) {
  88                prcmu_gic_recouple();
  89                spin_unlock(&master_lock);
  90        }
  91
  92        return index;
  93}
  94
  95static struct cpuidle_driver ux500_idle_driver = {
  96        .name = "ux500_idle",
  97        .owner = THIS_MODULE,
  98        .states = {
  99                ARM_CPUIDLE_WFI_STATE,
 100                {
 101                        .enter            = ux500_enter_idle,
 102                        .exit_latency     = 70,
 103                        .target_residency = 260,
 104                        .flags            = CPUIDLE_FLAG_TIME_VALID |
 105                                            CPUIDLE_FLAG_TIMER_STOP,
 106                        .name             = "ApIdle",
 107                        .desc             = "ARM Retention",
 108                },
 109        },
 110        .safe_state_index = 0,
 111        .state_count = 2,
 112};
 113
 114static int dbx500_cpuidle_probe(struct platform_device *pdev)
 115{
 116        /* Configure wake up reasons */
 117        prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
 118                             PRCMU_WAKEUP(ABB));
 119
 120        return cpuidle_register(&ux500_idle_driver, NULL);
 121}
 122
 123static struct platform_driver dbx500_cpuidle_plat_driver = {
 124        .driver = {
 125                .name = "cpuidle-dbx500",
 126                .owner = THIS_MODULE,
 127        },
 128        .probe = dbx500_cpuidle_probe,
 129};
 130
 131module_platform_driver(dbx500_cpuidle_plat_driver);
 132
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