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