linux/drivers/cpuidle/cpuidle-ux500.c
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   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 = "cpuidle-dbx500",
 121        },
 122        .probe = dbx500_cpuidle_probe,
 123};
 124builtin_platform_driver(dbx500_cpuidle_plat_driver);
 125