/*
   * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
   *
   * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
   * and Jonas Aaberg <jonas.aberg@stericsson.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.
   */
  
  #include <linux/module.h>
  #include <linux/cpuidle.h>
  #include <linux/spinlock.h>
  #include <linux/atomic.h>
  #include <linux/smp.h>
  #include <linux/mfd/dbx500-prcmu.h>
  #include <linux/platform_data/arm-ux500-pm.h>
  #include <linux/platform_device.h>
  
  #include <asm/cpuidle.h>
  #include <asm/proc-fns.h>
  
  static atomic_t master = ATOMIC_INIT(0);
  static DEFINE_SPINLOCK(master_lock);
  
  static inline int ux500_enter_idle(struct cpuidle_device *dev,
  				   struct cpuidle_driver *drv, int index)
  {
  	int this_cpu = smp_processor_id();
  	bool recouple = false;
  
  	if (atomic_inc_return(&master) == num_online_cpus()) {
  
  		/* With this lock, we prevent the other cpu to exit and enter
  		 * this function again and become the master */
  		if (!spin_trylock(&master_lock))
  			goto wfi;
  
  		/* decouple the gic from the A9 cores */
  		if (prcmu_gic_decouple()) {
  			spin_unlock(&master_lock);
  			goto out;
  		}
  
  		/* If an error occur, we will have to recouple the gic
  		 * manually */
  		recouple = true;
  
  		/* At this state, as the gic is decoupled, if the other
  		 * cpu is in WFI, we have the guarantee it won't be wake
  		 * up, so we can safely go to retention */
  		if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
  			goto out;
  
  		/* The prcmu will be in charge of watching the interrupts
  		 * and wake up the cpus */
  		if (prcmu_copy_gic_settings())
  			goto out;
  
  		/* Check in the meantime an interrupt did
  		 * not occur on the gic ... */
  		if (prcmu_gic_pending_irq())
  			goto out;
  
  		/* ... and the prcmu */
  		if (prcmu_pending_irq())
  			goto out;
  
  		/* Go to the retention state, the prcmu will wait for the
  		 * cpu to go WFI and this is what happens after exiting this
  		 * 'master' critical section */
  		if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
  			goto out;
  
  		/* When we switch to retention, the prcmu is in charge
  		 * of recoupling the gic automatically */
  		recouple = false;
  
  		spin_unlock(&master_lock);
  	}
  wfi:
  	cpu_do_idle();
  out:
  	atomic_dec(&master);
  
  	if (recouple) {
  		prcmu_gic_recouple();
  		spin_unlock(&master_lock);
  	}
  
  	return index;
  }
  
  static struct cpuidle_driver ux500_idle_driver = {
  	.name = "ux500_idle",
  	.owner = THIS_MODULE,
  	.states = {
  		ARM_CPUIDLE_WFI_STATE,
  		{
  			.enter		  = ux500_enter_idle,
  			.exit_latency	  = 70,
  			.target_residency = 260,
  			.flags		  = CPUIDLE_FLAG_TIME_VALID |
  			                    CPUIDLE_FLAG_TIMER_STOP,
  			.name		  = "ApIdle",
  			.desc		  = "ARM Retention",
  		},
  	},
  	.safe_state_index = 0,
  	.state_count = 2,
  };
  
  static int dbx500_cpuidle_probe(struct platform_device *pdev)
  {
  	/* Configure wake up reasons */
  	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
  			     PRCMU_WAKEUP(ABB));
  
  	return cpuidle_register(&ux500_idle_driver, NULL);
  }
  
  static struct platform_driver dbx500_cpuidle_plat_driver = {
  	.driver = {
  		.name = "cpuidle-dbx500",
  		.owner = THIS_MODULE,
  	},
  	.probe = dbx500_cpuidle_probe,
  };
  
  module_platform_driver(dbx500_cpuidle_plat_driver);