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
  23 static atomic_t master = ATOMIC_INIT(0);
  24 static DEFINE_SPINLOCK(master_lock);
  25
  26 static 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         }
  81 wfi:
  82         cpu_do_idle();
  83 out:
  84         atomic_dec(&master);
  85
  86         if (recouple) {
  87                 prcmu_gic_recouple();
  88                 spin_unlock(&master_lock);
  89         }
  90
  91         return index;
  92 }
  93
  94 static 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
 112 static 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
 121 static struct platform_driver dbx500_cpuidle_plat_driver = {
 122         .driver = {
 123                 .name = "cpuidle-dbx500",
 124         },
 125         .probe = dbx500_cpuidle_probe,
 126 };
 127
 128 module_platform_driver(dbx500_cpuidle_plat_driver);