arch/arm/mach-ux500/cpuidle.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/clockchips.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/atomic.h>
  17 #include <linux/smp.h>
  18 #include <linux/mfd/dbx500-prcmu.h>
  19 #include <linux/platform_data/arm-ux500-pm.h>
  20
  21 #include <asm/cpuidle.h>
  22 #include <asm/proc-fns.h>
  23
  24 #include "db8500-regs.h"
  25
  26 static atomic_t master = ATOMIC_INIT(0);
  27 static DEFINE_SPINLOCK(master_lock);
  28 static DEFINE_PER_CPU(struct cpuidle_device, ux500_cpuidle_device);
  29
  30 static inline int ux500_enter_idle(struct cpuidle_device *dev,
  31                                    struct cpuidle_driver *drv, int index)
  32 {
  33         int this_cpu = smp_processor_id();
  34         bool recouple = false;
  35
  36         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &this_cpu);
  37
  38         if (atomic_inc_return(&master) == num_online_cpus()) {
  39
  40                 /* With this lock, we prevent the other cpu to exit and enter
  41                  * this function again and become the master */
  42                 if (!spin_trylock(&master_lock))
  43                         goto wfi;
  44
  45                 /* decouple the gic from the A9 cores */
  46                 if (prcmu_gic_decouple()) {
  47                         spin_unlock(&master_lock);
  48                         goto out;
  49                 }
  50
  51                 /* If an error occur, we will have to recouple the gic
  52                  * manually */
  53                 recouple = true;
  54
  55                 /* At this state, as the gic is decoupled, if the other
  56                  * cpu is in WFI, we have the guarantee it won't be wake
  57                  * up, so we can safely go to retention */
  58                 if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
  59                         goto out;
  60
  61                 /* The prcmu will be in charge of watching the interrupts
  62                  * and wake up the cpus */
  63                 if (prcmu_copy_gic_settings())
  64                         goto out;
  65
  66                 /* Check in the meantime an interrupt did
  67                  * not occur on the gic ... */
  68                 if (prcmu_gic_pending_irq())
  69                         goto out;
  70
  71                 /* ... and the prcmu */
  72                 if (prcmu_pending_irq())
  73                         goto out;
  74
  75                 /* Go to the retention state, the prcmu will wait for the
  76                  * cpu to go WFI and this is what happens after exiting this
  77                  * 'master' critical section */
  78                 if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
  79                         goto out;
  80
  81                 /* When we switch to retention, the prcmu is in charge
  82                  * of recoupling the gic automatically */
  83                 recouple = false;
  84
  85                 spin_unlock(&master_lock);
  86         }
  87 wfi:
  88         cpu_do_idle();
  89 out:
  90         atomic_dec(&master);
  91
  92         if (recouple) {
  93                 prcmu_gic_recouple();
  94                 spin_unlock(&master_lock);
  95         }
  96
  97         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &this_cpu);
  98
  99         return index;
 100 }
 101
 102 static struct cpuidle_driver ux500_idle_driver = {
 103         .name = "ux500_idle",
 104         .owner = THIS_MODULE,
 105         .en_core_tk_irqen = 1,
 106         .states = {
 107                 ARM_CPUIDLE_WFI_STATE,
 108                 {
 109                         .enter            = ux500_enter_idle,
 110                         .exit_latency     = 70,
 111                         .target_residency = 260,
 112                         .flags            = CPUIDLE_FLAG_TIME_VALID,
 113                         .name             = "ApIdle",
 114                         .desc             = "ARM Retention",
 115                 },
 116         },
 117         .safe_state_index = 0,
 118         .state_count = 2,
 119 };
 120
 121 /*
 122  * For each cpu, setup the broadcast timer because we will
 123  * need to migrate the timers for the states >= ApIdle.
 124  */
 125 static void ux500_setup_broadcast_timer(void *arg)
 126 {
 127         int cpu = smp_processor_id();
 128         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON, &cpu);
 129 }
 130
 131 int __init ux500_idle_init(void)
 132 {
 133         int ret, cpu;
 134         struct cpuidle_device *device;
 135
 136         /* Configure wake up reasons */
 137         prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
 138                              PRCMU_WAKEUP(ABB));
 139
 140         /*
 141          * Configure the timer broadcast for each cpu, that must
 142          * be done from the cpu context, so we use a smp cross
 143          * call with 'on_each_cpu'.
 144          */
 145         on_each_cpu(ux500_setup_broadcast_timer, NULL, 1);
 146
 147         ret = cpuidle_register_driver(&ux500_idle_driver);
 148         if (ret) {
 149                 printk(KERN_ERR "failed to register ux500 idle driver\n");
 150                 return ret;
 151         }
 152
 153         for_each_online_cpu(cpu) {
 154                 device = &per_cpu(ux500_cpuidle_device, cpu);
 155                 device->cpu = cpu;
 156                 ret = cpuidle_register_device(device);
 157                 if (ret) {
 158                         printk(KERN_ERR "Failed to register cpuidle "
 159                                "device for cpu%d\n", cpu);
 160                         goto out_unregister;
 161                 }
 162         }
 163 out:
 164         return ret;
 165
 166 out_unregister:
 167         for_each_online_cpu(cpu) {
 168                 device = &per_cpu(ux500_cpuidle_device, cpu);
 169                 cpuidle_unregister_device(device);
 170         }
 171
 172         cpuidle_unregister_driver(&ux500_idle_driver);
 173         goto out;
 174 }
 175
 176 device_initcall(ux500_idle_init);