text: /*
   * Copyright (C) 2012 Freescale Semiconductor, Inc.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #include <linux/cpuidle.h>
  #include <linux/module.h>
  #include <asm/cpuidle.h>
  
  #include "common.h"
  #include "cpuidle.h"
  #include "hardware.h"
  
  static atomic_t master = ATOMIC_INIT(0);
  static DEFINE_SPINLOCK(master_lock);
  
  static int imx6q_enter_wait(struct cpuidle_device *dev,
  			    struct cpuidle_driver *drv, int index)
  {
  	if (atomic_inc_return(&master) == num_online_cpus()) {
  		/*
  		 * With this lock, we prevent other cpu to exit and enter
  		 * this function again and become the master.
  		 */
  		if (!spin_trylock(&master_lock))
  			goto idle;
  		imx6_set_lpm(WAIT_UNCLOCKED);
  		cpu_do_idle();
  		imx6_set_lpm(WAIT_CLOCKED);
  		spin_unlock(&master_lock);
  		goto done;
  	}
  
  idle:
  	cpu_do_idle();
  done:
  	atomic_dec(&master);
  
  	return index;
  }
  
  static struct cpuidle_driver imx6q_cpuidle_driver = {
  	.name = "imx6q_cpuidle",
  	.owner = THIS_MODULE,
  	.states = {
  		/* WFI */
  		ARM_CPUIDLE_WFI_STATE,
  		/* WAIT */
  		{
  			.exit_latency = 50,
  			.target_residency = 75,
  			.flags = CPUIDLE_FLAG_TIMER_STOP,
  			.enter = imx6q_enter_wait,
  			.name = "WAIT",
  			.desc = "Clock off",
  		},
  	},
  	.state_count = 2,
  	.safe_state_index = 0,
  };
  
  int __init imx6q_cpuidle_init(void)
  {
  	/* Set INT_MEM_CLK_LPM bit to get a reliable WAIT mode support */
  	imx6q_set_int_mem_clk_lpm(true);
  
  	return cpuidle_register(&imx6q_cpuidle_driver, NULL);
  }
  