text:  /*
      tea6420 - i2c-driver for the tea6420 by SGS Thomson
  
      Copyright (C) 1998-2003 Michael Hunold <michael@mihu.de>
      Copyright (C) 2008 Hans Verkuil <hverkuil@xs4all.nl>
  
      The tea6420 is a bus controlled audio-matrix with 5 stereo inputs,
      4 stereo outputs and gain control for each output.
      It is cascadable, i.e. it can be found at the addresses 0x98
      and 0x9a on the i2c-bus.
  
      For detailed informations download the specifications directly
      from SGS Thomson at http://www.st.com
  
      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.
  
      This program is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      GNU General Public License for more details.
  
      You should have received a copy of the GNU General Public License
      along with this program; if not, write to the Free Software
      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
    */
  
  
  #include <linux/module.h>
  #include <linux/ioctl.h>
  #include <linux/slab.h>
  #include <linux/i2c.h>
  #include <media/v4l2-device.h>
  #include "tea6420.h"
  
  MODULE_AUTHOR("Michael Hunold <michael@mihu.de>");
  MODULE_DESCRIPTION("tea6420 driver");
  MODULE_LICENSE("GPL");
  
  static int debug;
  module_param(debug, int, 0644);
  
  MODULE_PARM_DESC(debug, "Debug level (0-1)");
  
  
  /* make a connection between the input 'i' and the output 'o'
     with gain 'g' (note: i = 6 means 'mute') */
  static int tea6420_s_routing(struct v4l2_subdev *sd,
  			     u32 i, u32 o, u32 config)
  {
  	struct i2c_client *client = v4l2_get_subdevdata(sd);
  	int g = (o >> 4) & 0xf;
  	u8 byte;
  	int ret;
  
  	o &= 0xf;
  	v4l2_dbg(1, debug, sd, "i=%d, o=%d, g=%d\n", i, o, g);
  
  	/* check if the parameters are valid */
  	if (i < 1 || i > 6 || o < 1 || o > 4 || g < 0 || g > 6 || g % 2 != 0)
  		return -EINVAL;
  
  	byte = ((o - 1) << 5);
  	byte |= (i - 1);
  
  	/* to understand this, have a look at the tea6420-specs (p.5) */
  	switch (g) {
  	case 0:
  		byte |= (3 << 3);
  		break;
  	case 2:
  		byte |= (2 << 3);
  		break;
  	case 4:
  		byte |= (1 << 3);
  		break;
  	case 6:
  		break;
  	}
  
  	ret = i2c_smbus_write_byte(client, byte);
  	if (ret) {
  		v4l2_dbg(1, debug, sd,
  			"i2c_smbus_write_byte() failed, ret:%d\n", ret);
  		return -EIO;
  	}
  	return 0;
  }
  
  /* ----------------------------------------------------------------------- */
  
  static const struct v4l2_subdev_audio_ops tea6420_audio_ops = {
  	.s_routing = tea6420_s_routing,
  };
  
  static const struct v4l2_subdev_ops tea6420_ops = {
  	.audio = &tea6420_audio_ops,
  };
  
  static int tea6420_probe(struct i2c_client *client,
  			  const struct i2c_device_id *id)
  {
  	struct v4l2_subdev *sd;
  	int err, i;
  
  	/* let's see whether this adapter can support what we need */
  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WRITE_BYTE))
  		return -EIO;
  
  	v4l_info(client, "chip found @ 0x%x (%s)\n",
  			client->addr << 1, client->adapter->name);
  
  	sd = devm_kzalloc(&client->dev, sizeof(*sd), GFP_KERNEL);
  	if (sd == NULL)
  		return -ENOMEM;
  	v4l2_i2c_subdev_init(sd, client, &tea6420_ops);
  
  	/* set initial values: set "mute"-input to all outputs at gain 0 */
  	err = 0;
  	for (i = 1; i < 5; i++)
  		err += tea6420_s_routing(sd, 6, i, 0);
  	if (err) {
  		v4l_dbg(1, debug, client, "could not initialize tea6420\n");
  		return -ENODEV;
  	}
  	return 0;
  }
  
  static int tea6420_remove(struct i2c_client *client)
  {
  	struct v4l2_subdev *sd = i2c_get_clientdata(client);
  
  	v4l2_device_unregister_subdev(sd);
  	return 0;
  }
  
  static const struct i2c_device_id tea6420_id[] = {
  	{ "tea6420", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, tea6420_id);
  
  static struct i2c_driver tea6420_driver = {
  	.driver = {
  		.name	= "tea6420",
  	},
  	.probe		= tea6420_probe,
  	.remove		= tea6420_remove,
  	.id_table	= tea6420_id,
  };
  
  module_i2c_driver(tea6420_driver);
  