/*
   * drivers/base/power/common.c - Common device power management code.
   *
   * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
   *
   * This file is released under the GPLv2.
   */
  
  #include <linux/kernel.h>
  #include <linux/device.h>
  #include <linux/export.h>
  #include <linux/slab.h>
  #include <linux/pm_clock.h>
  #include <linux/acpi.h>
  #include <linux/pm_domain.h>
  
  /**
   * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device.
   * @dev: Device to handle.
   *
   * If power.subsys_data is NULL, point it to a new object, otherwise increment
   * its reference counter.  Return 1 if a new object has been created, otherwise
   * return 0 or error code.
   */
  int dev_pm_get_subsys_data(struct device *dev)
  {
  	struct pm_subsys_data *psd;
  
  	psd = kzalloc(sizeof(*psd), GFP_KERNEL);
  	if (!psd)
  		return -ENOMEM;
  
  	spin_lock_irq(&dev->power.lock);
  
  	if (dev->power.subsys_data) {
  		dev->power.subsys_data->refcount++;
  	} else {
  		spin_lock_init(&psd->lock);
  		psd->refcount = 1;
  		dev->power.subsys_data = psd;
  		pm_clk_init(dev);
  		psd = NULL;
  	}
  
  	spin_unlock_irq(&dev->power.lock);
  
  	/* kfree() verifies that its argument is nonzero. */
  	kfree(psd);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data);
  
  /**
   * dev_pm_put_subsys_data - Drop reference to power.subsys_data.
   * @dev: Device to handle.
   *
   * If the reference counter of power.subsys_data is zero after dropping the
   * reference, power.subsys_data is removed.  Return 1 if that happens or 0
   * otherwise.
   */
  int dev_pm_put_subsys_data(struct device *dev)
  {
  	struct pm_subsys_data *psd;
  	int ret = 1;
  
  	spin_lock_irq(&dev->power.lock);
  
  	psd = dev_to_psd(dev);
  	if (!psd)
  		goto out;
  
  	if (--psd->refcount == 0) {
  		dev->power.subsys_data = NULL;
  	} else {
  		psd = NULL;
  		ret = 0;
  	}
  
   out:
  	spin_unlock_irq(&dev->power.lock);
  	kfree(psd);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);
  
  /**
   * dev_pm_domain_attach - Attach a device to its PM domain.
   * @dev: Device to attach.
   * @power_on: Used to indicate whether we should power on the device.
   *
   * The @dev may only be attached to a single PM domain. By iterating through
   * the available alternatives we try to find a valid PM domain for the device.
   * As attachment succeeds, the ->detach() callback in the struct dev_pm_domain
   * should be assigned by the corresponding attach function.
   *
   * This function should typically be invoked from subsystem level code during
   * the probe phase. Especially for those that holds devices which requires
   * power management through PM domains.
   *
   * Callers must ensure proper synchronization of this function with power
   * management callbacks.
   *
   * Returns 0 on successfully attached PM domain or negative error code.
   */
  int dev_pm_domain_attach(struct device *dev, bool power_on)
  {
  	int ret;
  
  	ret = acpi_dev_pm_attach(dev, power_on);
  	if (ret)
  		ret = genpd_dev_pm_attach(dev);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(dev_pm_domain_attach);
  
  /**
   * dev_pm_domain_detach - Detach a device from its PM domain.
   * @dev: Device to attach.
   * @power_off: Used to indicate whether we should power off the device.
   *
   * This functions will reverse the actions from dev_pm_domain_attach() and thus
   * try to detach the @dev from its PM domain. Typically it should be invoked
   * from subsystem level code during the remove phase.
   *
   * Callers must ensure proper synchronization of this function with power
   * management callbacks.
   */
  void dev_pm_domain_detach(struct device *dev, bool power_off)
  {
  	if (dev->pm_domain && dev->pm_domain->detach)
  		dev->pm_domain->detach(dev, power_off);
  }
  EXPORT_SYMBOL_GPL(dev_pm_domain_detach);