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 /*

    tea6415c - i2c-driver for the tea6415c by SGS Thomson

    Copyright (C) 1998-2003 Michael Hunold <michael@mihu.de>

    The tea6415c is a bus controlled video-matrix-switch

    with 8 inputs and 6 outputs.

    It is cascadable, i.e. it can be found at the addresses

    0x86 and 0x06 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 vs 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 Mvss Ave, Cambridge, MA 02139, USA.

  */

#include <linux/module.h>

#include <linux/ioctl.h>

#include <linux/i2c.h>

#include "tea6415c.h"

static int debug = 0;            /* insmod parameter */

module_param(debug, int, 0644);

MODULE_PARM_DESC(debug, "Turn on/off device debugging (default:off).");

#define dprintk(args...) \

            do { if (debug) { printk("%s: %s()[%d]: ", KBUILD_MODNAME, __FUNCTION__, __LINE__); printk(args); } } while (0)

#define TEA6415C_NUM_INPUTS     8

#define TEA6415C_NUM_OUTPUTS    6

/* addresses to scan, found only at 0x03 and/or 0x43 (7-bit) */

static unsigned short normal_i2c[] = { I2C_TEA6415C_1, I2C_TEA6415C_2, I2C_CLIENT_END };

/* magic definition of all other variables and things */

I2C_CLIENT_INSMOD;

static struct i2c_driver driver;

static struct i2c_client client_template;

/* this function is called by i2c_probe */

static int detect(struct i2c_adapter *adapter, int address, int kind)

{

        struct i2c_client *client = NULL;

        int err = 0;

        /* let's see whether this adapter can support what we need */

        if (0 == i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE)) {

                return 0;

        }

        /* allocate memory for client structure */

        client = kmalloc(sizeof(struct i2c_client), GFP_KERNEL);

        if (0 == client) {

                return -ENOMEM;

        }

        /* fill client structure */

        memcpy(client, &client_template, sizeof(struct i2c_client));

        client->addr = address;

        client->adapter = adapter;

        /* tell the i2c layer a new client has arrived */

        if (0 != (err = i2c_attach_client(client))) {

                kfree(client);

                return err;

        }

        printk("tea6415c: detected @ 0x%02x on adapter %s\n", address, &client->adapter->name[0]);

        return 0;

}

static int attach(struct i2c_adapter *adapter)

{

        /* let's see whether this is a know adapter we can attach to */

        if (adapter->id != I2C_HW_SAA7146) {

                dprintk("refusing to probe on unknown adapter [name='%s',id=0x%x]\n", adapter->name, adapter->id);

                return -ENODEV;

        }

        return i2c_probe(adapter, &addr_data, &detect);

}

static int detach(struct i2c_client *client)

{

        int ret = i2c_detach_client(client);

        kfree(client);

        return ret;

}

/* makes a connection between the input-pin 'i' and the output-pin 'o'

   for the tea6415c-client 'client' */

static int switch_matrix(struct i2c_client *client, int i, int o)

{

        u8 byte = 0;

        int ret;

        dprintk("adr:0x%02x, i:%d, o:%d\n", client->addr, i, o);

        /* check if the pins are valid */

        if (0 == ((1 == i ||  3 == i ||  5 == i ||  6 == i ||  8 == i || 10 == i || 20 == i || 11 == i)

              && (18 == o || 17 == o || 16 == o || 15 == o || 14 == o || 13 == o)))

                return -1;

        /* to understand this, have a look at the tea6415c-specs (p.5) */

        switch (o) {

        case 18:

                byte = 0x00;

                break;

        case 14:

                byte = 0x20;

                break;

        case 16:

                byte = 0x10;

                break;

        case 17:

                byte = 0x08;

                break;

        case 15:

                byte = 0x18;

                break;

        case 13:

                byte = 0x28;

                break;

        };

        switch (i) {

        case 5:

                byte |= 0x00;

                break;

        case 8:

                byte |= 0x04;

                break;

        case 3:

                byte |= 0x02;

                break;

        case 20:

                byte |= 0x06;

                break;

        case 6:

                byte |= 0x01;

                break;

        case 10:

                byte |= 0x05;

                break;

        case 1:

                byte |= 0x03;

                break;

        case 11:

                byte |= 0x07;

                break;

        };

        ret = i2c_smbus_write_byte(client, byte);

        if (ret) {

                dprintk("i2c_smbus_write_byte() failed, ret:%d\n", ret);

                return -EIO;

        }

        return ret;

}

static int command(struct i2c_client *client, unsigned int cmd, void *arg)

{

        struct tea6415c_multiplex *v = (struct tea6415c_multiplex *)arg;

        int result = 0;

        switch (cmd) {

        case TEA6415C_SWITCH:

                result = switch_matrix(client, v->in, v->out);

                break;

        default:

                return -ENOIOCTLCMD;

        }

        return result;

}

static struct i2c_driver driver = {

        .driver = {

                .name = "tea6415c",

        },

        .id     = I2C_DRIVERID_TEA6415C,

        .attach_adapter = attach,

        .detach_client  = detach,

        .command        = command,

};

static struct i2c_client client_template = {

        .name = "tea6415c",

        .driver = &driver,

};

static int __init this_module_init(void)

{

        return i2c_add_driver(&driver);

}

static void __exit this_module_exit(void)

{

        i2c_del_driver(&driver);

}

module_init(this_module_init);

module_exit(this_module_exit);

MODULE_AUTHOR("Michael Hunold <michael@mihu.de>");

MODULE_DESCRIPTION("tea6415c driver");

MODULE_LICENSE("GPL");