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
  20 #include <asm/cpuidle.h>
  21 #include <asm/proc-fns.h>
  22
  23 static atomic_t master = ATOMIC_INIT(0);
  24 static DEFINE_SPINLOCK(master_lock);
  25 static DEFINE_PER_CPU(struct cpuidle_device, ux500_cpuidle_device);
  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         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &this_cpu);
  34
  35         if (atomic_inc_return(&master) == num_online_cpus()) {
  36
  37                 /* With this lock, we prevent the other cpu to exit and enter
  38                  * this function again and become the master */
  39                 if (!spin_trylock(&master_lock))
  40                         goto wfi;
  41
  42                 /* decouple the gic from the A9 cores */
  43                 if (prcmu_gic_decouple())
  44                         goto out;
  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         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &this_cpu);
  93
  94         return index;
  95 }
  96
  97 static struct cpuidle_driver ux500_idle_driver = {
  98         .name = "ux500_idle",
  99         .owner = THIS_MODULE,
 100         .en_core_tk_irqen = 1,
 101         .states = {
 102                 ARM_CPUIDLE_WFI_STATE,
 103                 {
 104                         .enter            = ux500_enter_idle,
 105                         .exit_latency     = 70,
 106                         .target_residency = 260,
 107                         .flags            = CPUIDLE_FLAG_TIME_VALID,
 108                         .name             = "ApIdle",
 109                         .desc             = "ARM Retention",
 110                 },
 111         },
 112         .safe_state_index = 0,
 113         .state_count = 2,
 114 };
 115
 116 /*
 117  * For each cpu, setup the broadcast timer because we will
 118  * need to migrate the timers for the states >= ApIdle.
 119  */
 120 static void ux500_setup_broadcast_timer(void *arg)
 121 {
 122         int cpu = smp_processor_id();
 123         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON, &cpu);
 124 }
 125
 126 int __init ux500_idle_init(void)
 127 {
 128         int ret, cpu;
 129         struct cpuidle_device *device;
 130
 131         /* Configure wake up reasons */
 132         prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
 133                              PRCMU_WAKEUP(ABB));
 134
 135         /*
 136          * Configure the timer broadcast for each cpu, that must
 137          * be done from the cpu context, so we use a smp cross
 138          * call with 'on_each_cpu'.
 139          */
 140         on_each_cpu(ux500_setup_broadcast_timer, NULL, 1);
 141
 142         ret = cpuidle_register_driver(&ux500_idle_driver);
 143         if (ret) {
 144                 printk(KERN_ERR "failed to register ux500 idle driver\n");
 145                 return ret;
 146         }
 147
 148         for_each_online_cpu(cpu) {
 149                 device = &per_cpu(ux500_cpuidle_device, cpu);
 150                 device->cpu = cpu;
 151                 ret = cpuidle_register_device(device);
 152                 if (ret) {
 153                         printk(KERN_ERR "Failed to register cpuidle "
 154                                "device for cpu%d\n", cpu);
 155                         goto out_unregister;
 156                 }
 157         }
 158 out:
 159         return ret;
 160
 161 out_unregister:
 162         for_each_online_cpu(cpu) {
 163                 device = &per_cpu(ux500_cpuidle_device, cpu);
 164                 cpuidle_unregister_device(device);
 165         }
 166
 167         cpuidle_unregister_driver(&ux500_idle_driver);
 168         goto out;
 169 }
 170
 171 device_initcall(ux500_idle_init);