/*
   * Linux driver model AC97 bus interface
   *
   * Author:	Nicolas Pitre
   * Created:	Jan 14, 2005
   * Copyright:	(C) MontaVista Software Inc.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   */

  #include <linux/module.h>

  #include <linux/init.h>
  #include <linux/device.h>
  #include <linux/string.h>

  #include <sound/ac97_codec.h>

  
  /*

   * snd_ac97_check_id() - Reads and checks the vendor ID of the device
   * @ac97: The AC97 device to check
   * @id: The ID to compare to
   * @id_mask: Mask that is applied to the device ID before comparing to @id
   *
   * If @id is 0 this function returns true if the read device vendor ID is
   * a valid ID. If @id is non 0 this functions returns true if @id
   * matches the read vendor ID. Otherwise the function returns false.
   */
  static bool snd_ac97_check_id(struct snd_ac97 *ac97, unsigned int id,
  	unsigned int id_mask)
  {
  	ac97->id = ac97->bus->ops->read(ac97, AC97_VENDOR_ID1) << 16;
  	ac97->id |= ac97->bus->ops->read(ac97, AC97_VENDOR_ID2);
  
  	if (ac97->id == 0x0 || ac97->id == 0xffffffff)
  		return false;
  
  	if (id != 0 && id != (ac97->id & id_mask))
  		return false;
  
  	return true;
  }
  
  /**
   * snd_ac97_reset() - Reset AC'97 device
   * @ac97: The AC'97 device to reset
   * @try_warm: Try a warm reset first
   * @id: Expected device vendor ID
   * @id_mask: Mask that is applied to the device ID before comparing to @id
   *
   * This function resets the AC'97 device. If @try_warm is true the function
   * first performs a warm reset. If the warm reset is successful the function
   * returns 1. Otherwise or if @try_warm is false the function issues cold reset
   * followed by a warm reset. If this is successful the function returns 0,
   * otherwise a negative error code. If @id is 0 any valid device ID will be
   * accepted, otherwise only the ID that matches @id and @id_mask is accepted.
   */
  int snd_ac97_reset(struct snd_ac97 *ac97, bool try_warm, unsigned int id,
  	unsigned int id_mask)
  {
  	struct snd_ac97_bus_ops *ops = ac97->bus->ops;
  
  	if (try_warm && ops->warm_reset) {
  		ops->warm_reset(ac97);
  		if (snd_ac97_check_id(ac97, id, id_mask))
  			return 1;
  	}
  
  	if (ops->reset)
  		ops->reset(ac97);
  	if (ops->warm_reset)
  		ops->warm_reset(ac97);
  
  	if (snd_ac97_check_id(ac97, id, id_mask))
  		return 0;
  
  	return -ENODEV;
  }
  EXPORT_SYMBOL_GPL(snd_ac97_reset);
  
  /*

   * Let drivers decide whether they want to support given codec from their

   * probe method. Drivers have direct access to the struct snd_ac97
   * structure and may  decide based on the id field amongst other things.

   */
  static int ac97_bus_match(struct device *dev, struct device_driver *drv)
  {

  	return 1;

  }

  struct bus_type ac97_bus_type = {
  	.name		= "ac97",
  	.match		= ac97_bus_match,

  };
  
  static int __init ac97_bus_init(void)
  {
  	return bus_register(&ac97_bus_type);
  }
  
  subsys_initcall(ac97_bus_init);
  
  static void __exit ac97_bus_exit(void)
  {
  	bus_unregister(&ac97_bus_type);
  }
  
  module_exit(ac97_bus_exit);
  
  EXPORT_SYMBOL(ac97_bus_type);
  
  MODULE_LICENSE("GPL");