arch/arm/mach-imx/cpuidle-imx6q.c

   1 /*
   2  * Copyright (C) 2012 Freescale Semiconductor, Inc.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/clockchips.h>
  10 #include <linux/cpuidle.h>
  11 #include <linux/module.h>
  12 #include <asm/cpuidle.h>
  13 #include <asm/proc-fns.h>
  14
  15 #include "common.h"
  16 #include "cpuidle.h"
  17
  18 static atomic_t master = ATOMIC_INIT(0);
  19 static DEFINE_SPINLOCK(master_lock);
  20
  21 static int imx6q_enter_wait(struct cpuidle_device *dev,
  22                             struct cpuidle_driver *drv, int index)
  23 {
  24         int cpu = dev->cpu;
  25
  26         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
  27
  28         if (atomic_inc_return(&master) == num_online_cpus()) {
  29                 /*
  30                  * With this lock, we prevent other cpu to exit and enter
  31                  * this function again and become the master.
  32                  */
  33                 if (!spin_trylock(&master_lock))
  34                         goto idle;
  35                 imx6q_set_lpm(WAIT_UNCLOCKED);
  36                 cpu_do_idle();
  37                 imx6q_set_lpm(WAIT_CLOCKED);
  38                 spin_unlock(&master_lock);
  39                 goto done;
  40         }
  41
  42 idle:
  43         cpu_do_idle();
  44 done:
  45         atomic_dec(&master);
  46         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
  47
  48         return index;
  49 }
  50
  51 /*
  52  * For each cpu, setup the broadcast timer because local timer
  53  * stops for the states other than WFI.
  54  */
  55 static void imx6q_setup_broadcast_timer(void *arg)
  56 {
  57         int cpu = smp_processor_id();
  58
  59         clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON, &cpu);
  60 }
  61
  62 static struct cpuidle_driver imx6q_cpuidle_driver = {
  63         .name = "imx6q_cpuidle",
  64         .owner = THIS_MODULE,
  65         .en_core_tk_irqen = 1,
  66         .states = {
  67                 /* WFI */
  68                 ARM_CPUIDLE_WFI_STATE,
  69                 /* WAIT */
  70                 {
  71                         .exit_latency = 50,
  72                         .target_residency = 75,
  73                         .flags = CPUIDLE_FLAG_TIME_VALID,
  74                         .enter = imx6q_enter_wait,
  75                         .name = "WAIT",
  76                         .desc = "Clock off",
  77                 },
  78         },
  79         .state_count = 2,
  80         .safe_state_index = 0,
  81 };
  82
  83 int __init imx6q_cpuidle_init(void)
  84 {
  85         /* Need to enable SCU standby for entering WAIT modes */
  86         imx_scu_standby_enable();
  87
  88         /* Set chicken bit to get a reliable WAIT mode support */
  89         imx6q_set_chicken_bit();
  90
  91         /* Configure the broadcast timer on each cpu */
  92         on_each_cpu(imx6q_setup_broadcast_timer, NULL, 1);
  93
  94         return imx_cpuidle_init(&imx6q_cpuidle_driver);
  95 }