drivers/cpuidle/cpuidle-ux500.c

   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
  24 static atomic_t master = ATOMIC_INIT(0);
  25 static DEFINE_SPINLOCK(master_lock);
  26
  27 static 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         }
  82 wfi:
  83         cpu_do_idle();
  84 out:
  85         atomic_dec(&master);
  86
  87         if (recouple) {
  88                 prcmu_gic_recouple();
  89                 spin_unlock(&master_lock);
  90         }
  91
  92         return index;
  93 }
  94
  95 static 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
 114 static int __init 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
 123 static 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
 131 module_platform_driver(dbx500_cpuidle_plat_driver);