/*
    tda9840 - i2c-driver for the tda9840 by SGS Thomson

    Copyright (C) 1998-2003 Michael Hunold <michael@mihu.de>
    Copyright (C) 2008 Hans Verkuil <hverkuil@xs4all.nl>

    The tda9840 is a stereo/dual sound processor with digital
    identification. It can be found at address 0x84 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 <media/v4l2-chip-ident.h>

MODULE_AUTHOR("Michael Hunold <michael@mihu.de>");
MODULE_DESCRIPTION("tda9840 driver");
MODULE_LICENSE("GPL");

static int debug;
module_param(debug, int, 0644);

MODULE_PARM_DESC(debug, "Debug level (0-1)");

#define SWITCH          0x00
#define LEVEL_ADJUST    0x02
#define STEREO_ADJUST   0x03
#define TEST            0x04

#define TDA9840_SET_MUTE                0x00
#define TDA9840_SET_MONO                0x10
#define TDA9840_SET_STEREO              0x2a
#define TDA9840_SET_LANG1               0x12
#define TDA9840_SET_LANG2               0x1e
#define TDA9840_SET_BOTH                0x1a
#define TDA9840_SET_BOTH_R              0x16
#define TDA9840_SET_EXTERNAL            0x7a


static void tda9840_write(struct v4l2_subdev *sd, u8 reg, u8 val)
{
        struct i2c_client *client = v4l2_get_subdevdata(sd);

        if (i2c_smbus_write_byte_data(client, reg, val))
                v4l2_dbg(1, debug, sd, "error writing %02x to %02x\n",
                                val, reg);
}

static int tda9840_status(struct v4l2_subdev *sd)
{
        struct i2c_client *client = v4l2_get_subdevdata(sd);
        u8 byte;

        if (1 != i2c_master_recv(client, &byte, 1)) {
                v4l2_dbg(1, debug, sd,
                        "i2c_master_recv() failed\n");
                return -EIO;
        }

        if (byte & 0x80) {
                v4l2_dbg(1, debug, sd,
                        "TDA9840_DETECT: register contents invalid\n");
                return -EINVAL;
        }

        v4l2_dbg(1, debug, sd, "TDA9840_DETECT: byte: 0x%02x\n", byte);
        return byte & 0x60;
}

static int tda9840_s_tuner(struct v4l2_subdev *sd, const struct v4l2_tuner *t)
{
        int stat = tda9840_status(sd);
        int byte;

        if (t->index)
                return -EINVAL;

        stat = stat < 0 ? 0 : stat;
        if (stat == 0 || stat == 0x60) /* mono input */
                byte = TDA9840_SET_MONO;
        else if (stat == 0x40) /* stereo input */
                byte = (t->audmode == V4L2_TUNER_MODE_MONO) ?
                        TDA9840_SET_MONO : TDA9840_SET_STEREO;
        else { /* bilingual */
                switch (t->audmode) {
                case V4L2_TUNER_MODE_LANG1_LANG2:
                        byte = TDA9840_SET_BOTH;
                        break;
                case V4L2_TUNER_MODE_LANG2:
                        byte = TDA9840_SET_LANG2;
                        break;
                default:
                        byte = TDA9840_SET_LANG1;
                        break;
                }
        }
        v4l2_dbg(1, debug, sd, "TDA9840_SWITCH: 0x%02x\n", byte);
        tda9840_write(sd, SWITCH, byte);
        return 0;
}

static int tda9840_g_tuner(struct v4l2_subdev *sd, struct v4l2_tuner *t)
{
        int stat = tda9840_status(sd);

        if (stat < 0)
                return stat;

        t->rxsubchans = V4L2_TUNER_SUB_MONO;

        switch (stat & 0x60) {
        case 0x00:
                t->rxsubchans = V4L2_TUNER_SUB_MONO;
                break;
        case 0x20:
                t->rxsubchans = V4L2_TUNER_SUB_LANG1 | V4L2_TUNER_SUB_LANG2;
                break;
        case 0x40:
                t->rxsubchans = V4L2_TUNER_SUB_STEREO | V4L2_TUNER_SUB_MONO;
                break;
        default: /* Incorrect detect */
                t->rxsubchans = V4L2_TUNER_MODE_MONO;
                break;
        }
        return 0;
}

static int tda9840_g_chip_ident(struct v4l2_subdev *sd, struct v4l2_dbg_chip_ident *chip)
{
        struct i2c_client *client = v4l2_get_subdevdata(sd);

        return v4l2_chip_ident_i2c_client(client, chip, V4L2_IDENT_TDA9840, 0);
}

/* ----------------------------------------------------------------------- */

static const struct v4l2_subdev_core_ops tda9840_core_ops = {
        .g_chip_ident = tda9840_g_chip_ident,
};

static const struct v4l2_subdev_tuner_ops tda9840_tuner_ops = {
        .s_tuner = tda9840_s_tuner,
        .g_tuner = tda9840_g_tuner,
};

static const struct v4l2_subdev_ops tda9840_ops = {
        .core = &tda9840_core_ops,
        .tuner = &tda9840_tuner_ops,
};

/* ----------------------------------------------------------------------- */

static int tda9840_probe(struct i2c_client *client,
                          const struct i2c_device_id *id)
{
        struct v4l2_subdev *sd;

        /* let's see whether this adapter can support what we need */
        if (!i2c_check_functionality(client->adapter,
                        I2C_FUNC_SMBUS_READ_BYTE_DATA |
                        I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
                return -EIO;

        v4l_info(client, "chip found @ 0x%x (%s)\n",
                        client->addr << 1, client->adapter->name);

        sd = kzalloc(sizeof(struct v4l2_subdev), GFP_KERNEL);
        if (sd == NULL)
                return -ENOMEM;
        v4l2_i2c_subdev_init(sd, client, &tda9840_ops);

        /* set initial values for level & stereo - adjustment, mode */
        tda9840_write(sd, LEVEL_ADJUST, 0);
        tda9840_write(sd, STEREO_ADJUST, 0);
        tda9840_write(sd, SWITCH, TDA9840_SET_STEREO);
        return 0;
}

static int tda9840_remove(struct i2c_client *client)
{
        struct v4l2_subdev *sd = i2c_get_clientdata(client);

        v4l2_device_unregister_subdev(sd);
        kfree(sd);
        return 0;
}

static const struct i2c_device_id tda9840_id[] = {
        { "tda9840", 0 },
        { }
};
MODULE_DEVICE_TABLE(i2c, tda9840_id);

static struct i2c_driver tda9840_driver = {
        .driver = {
                .owner  = THIS_MODULE,
                .name   = "tda9840",
        },
        .probe          = tda9840_probe,
        .remove         = tda9840_remove,
        .id_table       = tda9840_id,
};

module_i2c_driver(tda9840_driver);