drivers/media/pci/cx25821/cx25821-i2c.c - kernel/lockdown - Git at Google

 /*
  *  Driver for the Conexant CX25821 PCIe bridge
  *
  *  Copyright (C) 2009 Conexant Systems Inc.
  *  Authors  <shu.lin@conexant.com>, <hiep.huynh@conexant.com>
  *	Based on Steven Toth <stoth@linuxtv.org> cx23885 driver
  *
  *  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.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/module.h>
 #include <linux/i2c.h>
 #include "cx25821.h"

 static unsigned int i2c_debug;
 module_param(i2c_debug, int, 0644);
 MODULE_PARM_DESC(i2c_debug, "enable debug messages [i2c]");

 static unsigned int i2c_scan;
 module_param(i2c_scan, int, 0444);
 MODULE_PARM_DESC(i2c_scan, "scan i2c bus at insmod time");

 #define dprintk(level, fmt, arg...)					\
 do {									\
 	if (i2c_debug >= level)						\
 		printk(KERN_DEBUG "%s/0: " fmt, dev->name, ##arg);	\
 } while (0)

 #define I2C_WAIT_DELAY 32
 #define I2C_WAIT_RETRY 64

 #define I2C_EXTEND  (1 << 3)
 #define I2C_NOSTOP  (1 << 4)

 static inline int i2c_slave_did_ack(struct i2c_adapter *i2c_adap)
 {
 	struct cx25821_i2c *bus = i2c_adap->algo_data;
 	struct cx25821_dev *dev = bus->dev;
 	return cx_read(bus->reg_stat) & 0x01;
 }

 static inline int i2c_is_busy(struct i2c_adapter *i2c_adap)
 {
 	struct cx25821_i2c *bus = i2c_adap->algo_data;
 	struct cx25821_dev *dev = bus->dev;
 	return cx_read(bus->reg_stat) & 0x02 ? 1 : 0;
 }

 static int i2c_wait_done(struct i2c_adapter *i2c_adap)
 {
 	int count;

 	for (count = 0; count < I2C_WAIT_RETRY; count++) {
 		if (!i2c_is_busy(i2c_adap))
 			break;
 		udelay(I2C_WAIT_DELAY);
 	}

 	if (I2C_WAIT_RETRY == count)
 		return 0;

 	return 1;
 }

 static int i2c_sendbytes(struct i2c_adapter *i2c_adap,
 			 const struct i2c_msg *msg, int joined_rlen)
 {
 	struct cx25821_i2c *bus = i2c_adap->algo_data;
 	struct cx25821_dev *dev = bus->dev;
 	u32 wdata, addr, ctrl;
 	int retval, cnt;

 	if (joined_rlen)
 		dprintk(1, "%s(msg->wlen=%d, nextmsg->rlen=%d)\n", __func__,
 			msg->len, joined_rlen);
 	else
 		dprintk(1, "%s(msg->len=%d)\n", __func__, msg->len);

 	/* Deal with i2c probe functions with zero payload */
 	if (msg->len == 0) {
 		cx_write(bus->reg_addr, msg->addr << 25);
 		cx_write(bus->reg_ctrl, bus->i2c_period | (1 << 2));

 		if (!i2c_wait_done(i2c_adap))
 			return -EIO;

 		if (!i2c_slave_did_ack(i2c_adap))
 			return -EIO;

 		dprintk(1, "%s(): returns 0\n", __func__);
 		return 0;
 	}

 	/* dev, reg + first byte */
 	addr = (msg->addr << 25) | msg->buf[0];
 	wdata = msg->buf[0];

 	ctrl = bus->i2c_period | (1 << 12) | (1 << 2);

 	if (msg->len > 1)
 		ctrl |= I2C_NOSTOP | I2C_EXTEND;
 	else if (joined_rlen)
 		ctrl |= I2C_NOSTOP;

 	cx_write(bus->reg_addr, addr);
 	cx_write(bus->reg_wdata, wdata);
 	cx_write(bus->reg_ctrl, ctrl);

 	retval = i2c_wait_done(i2c_adap);
 	if (retval < 0)
 		goto err;

 	if (retval == 0)
 		goto eio;

 	if (i2c_debug) {
 		if (!(ctrl & I2C_NOSTOP))
 			printk(" >\n");
 	}

 	for (cnt = 1; cnt < msg->len; cnt++) {
 		/* following bytes */
 		wdata = msg->buf[cnt];
 		ctrl = bus->i2c_period | (1 << 12) | (1 << 2);

 		if (cnt < msg->len - 1)
 			ctrl |= I2C_NOSTOP | I2C_EXTEND;
 		else if (joined_rlen)
 			ctrl |= I2C_NOSTOP;

 		cx_write(bus->reg_addr, addr);
 		cx_write(bus->reg_wdata, wdata);
 		cx_write(bus->reg_ctrl, ctrl);

 		retval = i2c_wait_done(i2c_adap);
 		if (retval < 0)
 			goto err;

 		if (retval == 0)
 			goto eio;

 		if (i2c_debug) {
 			dprintk(1, " %02x", msg->buf[cnt]);
 			if (!(ctrl & I2C_NOSTOP))
 				dprintk(1, " >\n");
 		}
 	}

 	return msg->len;

 eio:
 	retval = -EIO;
 err:
 	if (i2c_debug)
 		pr_err(" ERR: %d\n", retval);
 	return retval;
 }

 static int i2c_readbytes(struct i2c_adapter *i2c_adap,
 			 const struct i2c_msg *msg, int joined)
 {
 	struct cx25821_i2c *bus = i2c_adap->algo_data;
 	struct cx25821_dev *dev = bus->dev;
 	u32 ctrl, cnt;
 	int retval;

 	if (i2c_debug && !joined)
 		dprintk(1, "6-%s(msg->len=%d)\n", __func__, msg->len);

 	/* Deal with i2c probe functions with zero payload */
 	if (msg->len == 0) {
 		cx_write(bus->reg_addr, msg->addr << 25);
 		cx_write(bus->reg_ctrl, bus->i2c_period | (1 << 2) | 1);
 		if (!i2c_wait_done(i2c_adap))
 			return -EIO;
 		if (!i2c_slave_did_ack(i2c_adap))
 			return -EIO;

 		dprintk(1, "%s(): returns 0\n", __func__);
 		return 0;
 	}

 	if (i2c_debug) {
 		if (joined)
 			dprintk(1, " R");
 		else
 			dprintk(1, " <R %02x", (msg->addr << 1) + 1);
 	}

 	for (cnt = 0; cnt < msg->len; cnt++) {

 		ctrl = bus->i2c_period | (1 << 12) | (1 << 2) | 1;

 		if (cnt < msg->len - 1)
 			ctrl |= I2C_NOSTOP | I2C_EXTEND;

 		cx_write(bus->reg_addr, msg->addr << 25);
 		cx_write(bus->reg_ctrl, ctrl);

 		retval = i2c_wait_done(i2c_adap);
 		if (retval < 0)
 			goto err;
 		if (retval == 0)
 			goto eio;
 		msg->buf[cnt] = cx_read(bus->reg_rdata) & 0xff;

 		if (i2c_debug) {
 			dprintk(1, " %02x", msg->buf[cnt]);
 			if (!(ctrl & I2C_NOSTOP))
 				dprintk(1, " >\n");
 		}
 	}

 	return msg->len;
 eio:
 	retval = -EIO;
 err:
 	if (i2c_debug)
 		pr_err(" ERR: %d\n", retval);
 	return retval;
 }

 static int i2c_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num)
 {
 	struct cx25821_i2c *bus = i2c_adap->algo_data;
 	struct cx25821_dev *dev = bus->dev;
 	int i, retval = 0;

 	dprintk(1, "%s(num = %d)\n", __func__, num);

 	for (i = 0; i < num; i++) {
 		dprintk(1, "%s(num = %d) addr = 0x%02x  len = 0x%x\n",
 			__func__, num, msgs[i].addr, msgs[i].len);

 		if (msgs[i].flags & I2C_M_RD) {
 			/* read */
 			retval = i2c_readbytes(i2c_adap, &msgs[i], 0);
 		} else if (i + 1 < num && (msgs[i + 1].flags & I2C_M_RD) &&
 			   msgs[i].addr == msgs[i + 1].addr) {
 			/* write then read from same address */
 			retval = i2c_sendbytes(i2c_adap, &msgs[i],
 					msgs[i + 1].len);

 			if (retval < 0)
 				goto err;
 			i++;
 			retval = i2c_readbytes(i2c_adap, &msgs[i], 1);
 		} else {
 			/* write */
 			retval = i2c_sendbytes(i2c_adap, &msgs[i], 0);
 		}

 		if (retval < 0)
 			goto err;
 	}
 	return num;

 err:
 	return retval;
 }


 static u32 cx25821_functionality(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_SMBUS_EMUL | I2C_FUNC_I2C | I2C_FUNC_SMBUS_WORD_DATA |
 		I2C_FUNC_SMBUS_READ_WORD_DATA | I2C_FUNC_SMBUS_WRITE_WORD_DATA;
 }

 static struct i2c_algorithm cx25821_i2c_algo_template = {
 	.master_xfer = i2c_xfer,
 	.functionality = cx25821_functionality,
 #ifdef NEED_ALGO_CONTROL
 	.algo_control = dummy_algo_control,
 #endif
 };

 static struct i2c_adapter cx25821_i2c_adap_template = {
 	.name = "cx25821",
 	.owner = THIS_MODULE,
 	.algo = &cx25821_i2c_algo_template,
 };

 static struct i2c_client cx25821_i2c_client_template = {
 	.name = "cx25821 internal",
 };

 /* init + register i2c adapter */
 int cx25821_i2c_register(struct cx25821_i2c *bus)
 {
 	struct cx25821_dev *dev = bus->dev;

 	dprintk(1, "%s(bus = %d)\n", __func__, bus->nr);

 	bus->i2c_adap = cx25821_i2c_adap_template;
 	bus->i2c_client = cx25821_i2c_client_template;
 	bus->i2c_adap.dev.parent = &dev->pci->dev;

 	strlcpy(bus->i2c_adap.name, bus->dev->name, sizeof(bus->i2c_adap.name));

 	bus->i2c_adap.algo_data = bus;
 	i2c_set_adapdata(&bus->i2c_adap, &dev->v4l2_dev);
 	i2c_add_adapter(&bus->i2c_adap);

 	bus->i2c_client.adapter = &bus->i2c_adap;

 	/* set up the I2c */
 	bus->i2c_client.addr = (0x88 >> 1);

 	return bus->i2c_rc;
 }

 int cx25821_i2c_unregister(struct cx25821_i2c *bus)
 {
 	i2c_del_adapter(&bus->i2c_adap);
 	return 0;
 }

 #if 0 /* Currently unused */
 static void cx25821_av_clk(struct cx25821_dev *dev, int enable)
 {
 	/* write 0 to bus 2 addr 0x144 via i2x_xfer() */
 	char buffer[3];
 	struct i2c_msg msg;
 	dprintk(1, "%s(enabled = %d)\n", __func__, enable);

 	/* Register 0x144 */
 	buffer[0] = 0x01;
 	buffer[1] = 0x44;
 	if (enable == 1)
 		buffer[2] = 0x05;
 	else
 		buffer[2] = 0x00;

 	msg.addr = 0x44;
 	msg.flags = I2C_M_TEN;
 	msg.len = 3;
 	msg.buf = buffer;

 	i2c_xfer(&dev->i2c_bus[0].i2c_adap, &msg, 1);
 }
 #endif

 int cx25821_i2c_read(struct cx25821_i2c *bus, u16 reg_addr, int *value)
 {
 	struct i2c_client *client = &bus->i2c_client;
 	int v = 0;
 	u8 addr[2] = { 0, 0 };
 	u8 buf[4] = { 0, 0, 0, 0 };

 	struct i2c_msg msgs[2] = {
 		{
 			.addr = client->addr,
 			.flags = 0,
 			.len = 2,
 			.buf = addr,
 		}, {
 			.addr = client->addr,
 			.flags = I2C_M_RD,
 			.len = 4,
 			.buf = buf,
 		}
 	};

 	addr[0] = (reg_addr >> 8);
 	addr[1] = (reg_addr & 0xff);
 	msgs[0].addr = 0x44;
 	msgs[1].addr = 0x44;

 	i2c_xfer(client->adapter, msgs, 2);

 	v = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
 	*value = v;

 	return v;
 }

 int cx25821_i2c_write(struct cx25821_i2c *bus, u16 reg_addr, int value)
 {
 	struct i2c_client *client = &bus->i2c_client;
 	int retval = 0;
 	u8 buf[6] = { 0, 0, 0, 0, 0, 0 };

 	struct i2c_msg msgs[1] = {
 		{
 			.addr = client->addr,
 			.flags = 0,
 			.len = 6,
 			.buf = buf,
 		}
 	};

 	buf[0] = reg_addr >> 8;
 	buf[1] = reg_addr & 0xff;
 	buf[5] = (value >> 24) & 0xff;
 	buf[4] = (value >> 16) & 0xff;
 	buf[3] = (value >> 8) & 0xff;
 	buf[2] = value & 0xff;
 	client->flags = 0;
 	msgs[0].addr = 0x44;

 	retval = i2c_xfer(client->adapter, msgs, 1);

 	return retval;
 }
	/*
	* Driver for the Conexant CX25821 PCIe bridge
	*
	* Copyright (C) 2009 Conexant Systems Inc.
	* Authors <shu.lin@conexant.com>, <hiep.huynh@conexant.com>
	* Based on Steven Toth <stoth@linuxtv.org> cx23885 driver
	*
	* 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.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/module.h>
	#include <linux/i2c.h>
	#include "cx25821.h"

	static unsigned int i2c_debug;
	module_param(i2c_debug, int, 0644);
	MODULE_PARM_DESC(i2c_debug, "enable debug messages [i2c]");

	static unsigned int i2c_scan;
	module_param(i2c_scan, int, 0444);
	MODULE_PARM_DESC(i2c_scan, "scan i2c bus at insmod time");

	#define dprintk(level, fmt, arg...) \
	do { \
	if (i2c_debug >= level) \
	printk(KERN_DEBUG "%s/0: " fmt, dev->name, ##arg); \
	} while (0)

	#define I2C_WAIT_DELAY 32
	#define I2C_WAIT_RETRY 64

	#define I2C_EXTEND (1 << 3)
	#define I2C_NOSTOP (1 << 4)

	static inline int i2c_slave_did_ack(struct i2c_adapter *i2c_adap)
	{
	struct cx25821_i2c *bus = i2c_adap->algo_data;
	struct cx25821_dev *dev = bus->dev;
	return cx_read(bus->reg_stat) & 0x01;
	}

	static inline int i2c_is_busy(struct i2c_adapter *i2c_adap)
	{
	struct cx25821_i2c *bus = i2c_adap->algo_data;
	struct cx25821_dev *dev = bus->dev;
	return cx_read(bus->reg_stat) & 0x02 ? 1 : 0;
	}

	static int i2c_wait_done(struct i2c_adapter *i2c_adap)
	{
	int count;

	for (count = 0; count < I2C_WAIT_RETRY; count++) {
	if (!i2c_is_busy(i2c_adap))
	break;
	udelay(I2C_WAIT_DELAY);
	}

	if (I2C_WAIT_RETRY == count)
	return 0;

	return 1;
	}

	static int i2c_sendbytes(struct i2c_adapter *i2c_adap,
	const struct i2c_msg *msg, int joined_rlen)
	{
	struct cx25821_i2c *bus = i2c_adap->algo_data;
	struct cx25821_dev *dev = bus->dev;
	u32 wdata, addr, ctrl;
	int retval, cnt;

	if (joined_rlen)
	dprintk(1, "%s(msg->wlen=%d, nextmsg->rlen=%d)\n", __func__,
	msg->len, joined_rlen);
	else
	dprintk(1, "%s(msg->len=%d)\n", __func__, msg->len);

	/* Deal with i2c probe functions with zero payload */
	if (msg->len == 0) {
	cx_write(bus->reg_addr, msg->addr << 25);
	cx_write(bus->reg_ctrl, bus->i2c_period \| (1 << 2));

	if (!i2c_wait_done(i2c_adap))
	return -EIO;

	if (!i2c_slave_did_ack(i2c_adap))
	return -EIO;

	dprintk(1, "%s(): returns 0\n", __func__);
	return 0;
	}

	/* dev, reg + first byte */
	addr = (msg->addr << 25) \| msg->buf[0];
	wdata = msg->buf[0];

	ctrl = bus->i2c_period \| (1 << 12) \| (1 << 2);

	if (msg->len > 1)
	ctrl \|= I2C_NOSTOP \| I2C_EXTEND;
	else if (joined_rlen)
	ctrl \|= I2C_NOSTOP;

	cx_write(bus->reg_addr, addr);
	cx_write(bus->reg_wdata, wdata);
	cx_write(bus->reg_ctrl, ctrl);

	retval = i2c_wait_done(i2c_adap);
	if (retval < 0)
	goto err;

	if (retval == 0)
	goto eio;

	if (i2c_debug) {
	if (!(ctrl & I2C_NOSTOP))
	printk(" >\n");
	}

	for (cnt = 1; cnt < msg->len; cnt++) {
	/* following bytes */
	wdata = msg->buf[cnt];
	ctrl = bus->i2c_period \| (1 << 12) \| (1 << 2);

	if (cnt < msg->len - 1)
	ctrl \|= I2C_NOSTOP \| I2C_EXTEND;
	else if (joined_rlen)
	ctrl \|= I2C_NOSTOP;

	cx_write(bus->reg_addr, addr);
	cx_write(bus->reg_wdata, wdata);
	cx_write(bus->reg_ctrl, ctrl);

	retval = i2c_wait_done(i2c_adap);
	if (retval < 0)
	goto err;

	if (retval == 0)
	goto eio;

	if (i2c_debug) {
	dprintk(1, " %02x", msg->buf[cnt]);
	if (!(ctrl & I2C_NOSTOP))
	dprintk(1, " >\n");
	}
	}

	return msg->len;

	eio:
	retval = -EIO;
	err:
	if (i2c_debug)
	pr_err(" ERR: %d\n", retval);
	return retval;
	}

	static int i2c_readbytes(struct i2c_adapter *i2c_adap,
	const struct i2c_msg *msg, int joined)
	{
	struct cx25821_i2c *bus = i2c_adap->algo_data;
	struct cx25821_dev *dev = bus->dev;
	u32 ctrl, cnt;
	int retval;

	if (i2c_debug && !joined)
	dprintk(1, "6-%s(msg->len=%d)\n", __func__, msg->len);

	/* Deal with i2c probe functions with zero payload */
	if (msg->len == 0) {
	cx_write(bus->reg_addr, msg->addr << 25);
	cx_write(bus->reg_ctrl, bus->i2c_period \| (1 << 2) \| 1);
	if (!i2c_wait_done(i2c_adap))
	return -EIO;
	if (!i2c_slave_did_ack(i2c_adap))
	return -EIO;

	dprintk(1, "%s(): returns 0\n", __func__);
	return 0;
	}

	if (i2c_debug) {
	if (joined)
	dprintk(1, " R");
	else
	dprintk(1, " <R %02x", (msg->addr << 1) + 1);
	}

	for (cnt = 0; cnt < msg->len; cnt++) {

	ctrl = bus->i2c_period \| (1 << 12) \| (1 << 2) \| 1;

	if (cnt < msg->len - 1)
	ctrl \|= I2C_NOSTOP \| I2C_EXTEND;

	cx_write(bus->reg_addr, msg->addr << 25);
	cx_write(bus->reg_ctrl, ctrl);

	retval = i2c_wait_done(i2c_adap);
	if (retval < 0)
	goto err;
	if (retval == 0)
	goto eio;
	msg->buf[cnt] = cx_read(bus->reg_rdata) & 0xff;

	if (i2c_debug) {
	dprintk(1, " %02x", msg->buf[cnt]);
	if (!(ctrl & I2C_NOSTOP))
	dprintk(1, " >\n");
	}
	}

	return msg->len;
	eio:
	retval = -EIO;
	err:
	if (i2c_debug)
	pr_err(" ERR: %d\n", retval);
	return retval;
	}

	static int i2c_xfer(struct i2c_adapter i2c_adap, struct i2c_msg msgs, int num)
	{
	struct cx25821_i2c *bus = i2c_adap->algo_data;
	struct cx25821_dev *dev = bus->dev;
	int i, retval = 0;

	dprintk(1, "%s(num = %d)\n", __func__, num);

	for (i = 0; i < num; i++) {
	dprintk(1, "%s(num = %d) addr = 0x%02x len = 0x%x\n",
	__func__, num, msgs[i].addr, msgs[i].len);

	if (msgs[i].flags & I2C_M_RD) {
	/* read */
	retval = i2c_readbytes(i2c_adap, &msgs[i], 0);
	} else if (i + 1 < num && (msgs[i + 1].flags & I2C_M_RD) &&
	msgs[i].addr == msgs[i + 1].addr) {
	/* write then read from same address */
	retval = i2c_sendbytes(i2c_adap, &msgs[i],
	msgs[i + 1].len);

	if (retval < 0)
	goto err;
	i++;
	retval = i2c_readbytes(i2c_adap, &msgs[i], 1);
	} else {
	/* write */
	retval = i2c_sendbytes(i2c_adap, &msgs[i], 0);
	}

	if (retval < 0)
	goto err;
	}
	return num;

	err:
	return retval;
	}


	static u32 cx25821_functionality(struct i2c_adapter *adap)
	{
	return I2C_FUNC_SMBUS_EMUL \| I2C_FUNC_I2C \| I2C_FUNC_SMBUS_WORD_DATA \|
	I2C_FUNC_SMBUS_READ_WORD_DATA \| I2C_FUNC_SMBUS_WRITE_WORD_DATA;
	}

	static struct i2c_algorithm cx25821_i2c_algo_template = {
	.master_xfer = i2c_xfer,
	.functionality = cx25821_functionality,
	#ifdef NEED_ALGO_CONTROL
	.algo_control = dummy_algo_control,
	#endif
	};

	static struct i2c_adapter cx25821_i2c_adap_template = {
	.name = "cx25821",
	.owner = THIS_MODULE,
	.algo = &cx25821_i2c_algo_template,
	};

	static struct i2c_client cx25821_i2c_client_template = {
	.name = "cx25821 internal",
	};

	/* init + register i2c adapter */
	int cx25821_i2c_register(struct cx25821_i2c *bus)
	{
	struct cx25821_dev *dev = bus->dev;

	dprintk(1, "%s(bus = %d)\n", __func__, bus->nr);

	bus->i2c_adap = cx25821_i2c_adap_template;
	bus->i2c_client = cx25821_i2c_client_template;
	bus->i2c_adap.dev.parent = &dev->pci->dev;

	strlcpy(bus->i2c_adap.name, bus->dev->name, sizeof(bus->i2c_adap.name));

	bus->i2c_adap.algo_data = bus;
	i2c_set_adapdata(&bus->i2c_adap, &dev->v4l2_dev);
	i2c_add_adapter(&bus->i2c_adap);

	bus->i2c_client.adapter = &bus->i2c_adap;

	/* set up the I2c */
	bus->i2c_client.addr = (0x88 >> 1);

	return bus->i2c_rc;
	}

	int cx25821_i2c_unregister(struct cx25821_i2c *bus)
	{
	i2c_del_adapter(&bus->i2c_adap);
	return 0;
	}

	#if 0 /* Currently unused */
	static void cx25821_av_clk(struct cx25821_dev *dev, int enable)
	{
	/* write 0 to bus 2 addr 0x144 via i2x_xfer() */
	char buffer[3];
	struct i2c_msg msg;
	dprintk(1, "%s(enabled = %d)\n", __func__, enable);

	/* Register 0x144 */
	buffer[0] = 0x01;
	buffer[1] = 0x44;
	if (enable == 1)
	buffer[2] = 0x05;
	else
	buffer[2] = 0x00;

	msg.addr = 0x44;
	msg.flags = I2C_M_TEN;
	msg.len = 3;
	msg.buf = buffer;

	i2c_xfer(&dev->i2c_bus[0].i2c_adap, &msg, 1);
	}
	#endif

	int cx25821_i2c_read(struct cx25821_i2c bus, u16 reg_addr, int value)
	{
	struct i2c_client *client = &bus->i2c_client;
	int v = 0;
	u8 addr[2] = { 0, 0 };
	u8 buf[4] = { 0, 0, 0, 0 };

	struct i2c_msg msgs[2] = {
	{
	.addr = client->addr,
	.flags = 0,
	.len = 2,
	.buf = addr,
	}, {
	.addr = client->addr,
	.flags = I2C_M_RD,
	.len = 4,
	.buf = buf,
	}
	};

	addr[0] = (reg_addr >> 8);
	addr[1] = (reg_addr & 0xff);
	msgs[0].addr = 0x44;
	msgs[1].addr = 0x44;

	i2c_xfer(client->adapter, msgs, 2);

	v = (buf[3] << 24) \| (buf[2] << 16) \| (buf[1] << 8) \| buf[0];
	*value = v;

	return v;
	}

	int cx25821_i2c_write(struct cx25821_i2c *bus, u16 reg_addr, int value)
	{
	struct i2c_client *client = &bus->i2c_client;
	int retval = 0;
	u8 buf[6] = { 0, 0, 0, 0, 0, 0 };

	struct i2c_msg msgs[1] = {
	{
	.addr = client->addr,
	.flags = 0,
	.len = 6,
	.buf = buf,
	}
	};

	buf[0] = reg_addr >> 8;
	buf[1] = reg_addr & 0xff;
	buf[5] = (value >> 24) & 0xff;
	buf[4] = (value >> 16) & 0xff;
	buf[3] = (value >> 8) & 0xff;
	buf[2] = value & 0xff;
	client->flags = 0;
	msgs[0].addr = 0x44;

	retval = i2c_xfer(client->adapter, msgs, 1);

	return retval;
	}