/*

   * ARM/ARM64 generic CPU idle driver.

   *
   * Copyright (C) 2014 ARM Ltd.
   * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
   *
   * 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.
   */

  #define pr_fmt(fmt) "CPUidle arm: " fmt

  
  #include <linux/cpuidle.h>
  #include <linux/cpumask.h>
  #include <linux/cpu_pm.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/of.h>

  #include <linux/slab.h>

  
  #include <asm/cpuidle.h>

  
  #include "dt_idle_states.h"
  
  /*

   * arm_enter_idle_state - Programs CPU to enter the specified state

   *
   * dev: cpuidle device
   * drv: cpuidle driver
   * idx: state index
   *
   * Called from the CPUidle framework to program the device to the
   * specified target state selected by the governor.
   */

  static int arm_enter_idle_state(struct cpuidle_device *dev,
  				struct cpuidle_driver *drv, int idx)

  {

  	/*
  	 * Pass idle state index to arm_cpuidle_suspend which in turn
  	 * will call the CPU ops suspend protocol with idle index as a
  	 * parameter.
  	 */
  	return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, idx);

  }

  static struct cpuidle_driver arm_idle_driver = {
  	.name = "arm_idle",

  	.owner = THIS_MODULE,
  	/*
  	 * State at index 0 is standby wfi and considered standard
  	 * on all ARM platforms. If in some platforms simple wfi
  	 * can't be used as "state 0", DT bindings must be implemented
  	 * to work around this issue and allow installing a special
  	 * handler for idle state index 0.
  	 */
  	.states[0] = {

  		.enter                  = arm_enter_idle_state,

  		.exit_latency           = 1,
  		.target_residency       = 1,
  		.power_usage		= UINT_MAX,

  		.name                   = "WFI",

  		.desc                   = "ARM WFI",

  	}
  };

  static const struct of_device_id arm_idle_state_match[] __initconst = {

  	{ .compatible = "arm,idle-state",

  	  .data = arm_enter_idle_state },

  	{ },
  };
  
  /*

   * arm_idle_init

   *

   * Registers the arm specific cpuidle driver with the cpuidle

   * framework. It relies on core code to parse the idle states
   * and initialize them using driver data structures accordingly.
   */

  static int __init arm_idle_init(void)

  {
  	int cpu, ret;

  	struct cpuidle_driver *drv = &arm_idle_driver;

  	struct cpuidle_device *dev;

  
  	/*
  	 * Initialize idle states data, starting at index 1.
  	 * This driver is DT only, if no DT idle states are detected (ret == 0)
  	 * let the driver initialization fail accordingly since there is no
  	 * reason to initialize the idle driver if only wfi is supported.
  	 */

  	ret = dt_init_idle_driver(drv, arm_idle_state_match, 1);

  	if (ret <= 0)

  		return ret ? : -ENODEV;

  	ret = cpuidle_register_driver(drv);
  	if (ret) {
  		pr_err("Failed to register cpuidle driver
  ");
  		return ret;
  	}

  	/*
  	 * Call arch CPU operations in order to initialize
  	 * idle states suspend back-end specific data
  	 */
  	for_each_possible_cpu(cpu) {

  		ret = arm_cpuidle_init(cpu);

  
  		/*
  		 * Skip the cpuidle device initialization if the reported
  		 * failure is a HW misconfiguration/breakage (-ENXIO).
  		 */
  		if (ret == -ENXIO)
  			continue;

  		if (ret) {
  			pr_err("CPU %d failed to init idle CPU ops
  ", cpu);

  			goto out_fail;
  		}
  
  		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
  		if (!dev) {
  			pr_err("Failed to allocate cpuidle device
  ");

  			ret = -ENOMEM;

  			goto out_fail;
  		}
  		dev->cpu = cpu;
  
  		ret = cpuidle_register_device(dev);
  		if (ret) {
  			pr_err("Failed to register cpuidle device for CPU %d
  ",
  			       cpu);
  			kfree(dev);
  			goto out_fail;

  		}
  	}

  	return 0;
  out_fail:
  	while (--cpu >= 0) {
  		dev = per_cpu(cpuidle_devices, cpu);
  		cpuidle_unregister_device(dev);
  		kfree(dev);
  	}
  
  	cpuidle_unregister_driver(drv);
  
  	return ret;

  }

  device_initcall(arm_idle_init);