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/cpuidle.h>
  10 #include <linux/module.h>
  11 #include <asm/cpuidle.h>
  12
  13 #include <soc/imx/cpuidle.h>
  14
  15 #include "common.h"
  16 #include "cpuidle.h"
  17 #include "hardware.h"
  18
  19 static atomic_t master = ATOMIC_INIT(0);
  20 static DEFINE_SPINLOCK(master_lock);
  21
  22 static int imx6q_enter_wait(struct cpuidle_device *dev,
  23                             struct cpuidle_driver *drv, int index)
  24 {
  25         if (atomic_inc_return(&master) == num_online_cpus()) {
  26                 /*
  27                  * With this lock, we prevent other cpu to exit and enter
  28                  * this function again and become the master.
  29                  */
  30                 if (!spin_trylock(&master_lock))
  31                         goto idle;
  32                 imx6_set_lpm(WAIT_UNCLOCKED);
  33                 cpu_do_idle();
  34                 imx6_set_lpm(WAIT_CLOCKED);
  35                 spin_unlock(&master_lock);
  36                 goto done;
  37         }
  38
  39 idle:
  40         cpu_do_idle();
  41 done:
  42         atomic_dec(&master);
  43
  44         return index;
  45 }
  46
  47 static struct cpuidle_driver imx6q_cpuidle_driver = {
  48         .name = "imx6q_cpuidle",
  49         .owner = THIS_MODULE,
  50         .states = {
  51                 /* WFI */
  52                 ARM_CPUIDLE_WFI_STATE,
  53                 /* WAIT */
  54                 {
  55                         .exit_latency = 50,
  56                         .target_residency = 75,
  57                         .flags = CPUIDLE_FLAG_TIMER_STOP,
  58                         .enter = imx6q_enter_wait,
  59                         .name = "WAIT",
  60                         .desc = "Clock off",
  61                 },
  62         },
  63         .state_count = 2,
  64         .safe_state_index = 0,
  65 };
  66
  67 /*
  68  * i.MX6 Q/DL has an erratum (ERR006687) that prevents the FEC from waking the
  69  * CPUs when they are in wait(unclocked) state. As the hardware workaround isn't
  70  * applicable to all boards, disable the deeper idle state when the workaround
  71  * isn't present and the FEC is in use.
  72  */
  73 void imx6q_cpuidle_fec_irqs_used(void)
  74 {
  75         imx6q_cpuidle_driver.states[1].disabled = true;
  76 }
  77 EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_used);
  78
  79 void imx6q_cpuidle_fec_irqs_unused(void)
  80 {
  81         imx6q_cpuidle_driver.states[1].disabled = false;
  82 }
  83 EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_unused);
  84
  85 int __init imx6q_cpuidle_init(void)
  86 {
  87         /* Set INT_MEM_CLK_LPM bit to get a reliable WAIT mode support */
  88         imx6_set_int_mem_clk_lpm(true);
  89
  90         return cpuidle_register(&imx6q_cpuidle_driver, NULL);
  91 }