drivers/i2c/algos/i2c-algo-pcf.c - kernel/quantenna - Git at Google

 /*
  * i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters
  *
  *   Copyright (C) 1995-1997 Simon G. Vogl
  *		   1998-2000 Hans Berglund
  *
  *  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.
  *
  * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
  * Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey
  * <mbailey@littlefeet-inc.com>
  *
  * Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
  * messages, proper stop/repstart signaling during receive, added detect code
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/i2c.h>
 #include <linux/i2c-algo-pcf.h>
 #include "i2c-algo-pcf.h"


 #define DEB2(x) if (i2c_debug >= 2) x
 #define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */
 #define DEBPROTO(x) if (i2c_debug >= 9) x;
 	/* debug the protocol by showing transferred bits */
 #define DEF_TIMEOUT 16

 /*
  * module parameters:
  */
 static int i2c_debug;

 /* setting states on the bus with the right timing: */

 #define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
 #define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
 #define get_own(adap) adap->getown(adap->data)
 #define get_clock(adap) adap->getclock(adap->data)
 #define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
 #define i2c_inb(adap) adap->getpcf(adap->data, 0)

 /* other auxiliary functions */

 static void i2c_start(struct i2c_algo_pcf_data *adap)
 {
 	DEBPROTO(printk(KERN_DEBUG "S "));
 	set_pcf(adap, 1, I2C_PCF_START);
 }

 static void i2c_repstart(struct i2c_algo_pcf_data *adap)
 {
 	DEBPROTO(printk(" Sr "));
 	set_pcf(adap, 1, I2C_PCF_REPSTART);
 }

 static void i2c_stop(struct i2c_algo_pcf_data *adap)
 {
 	DEBPROTO(printk("P\n"));
 	set_pcf(adap, 1, I2C_PCF_STOP);
 }

 static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
 {
 	DEB2(printk(KERN_INFO
 		"i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
 		*status));
 	/*
 	 * Cleanup from LAB -- reset and enable ESO.
 	 * This resets the PCF8584; since we've lost the bus, no
 	 * further attempts should be made by callers to clean up
 	 * (no i2c_stop() etc.)
 	 */
 	set_pcf(adap, 1, I2C_PCF_PIN);
 	set_pcf(adap, 1, I2C_PCF_ESO);
 	/*
 	 * We pause for a time period sufficient for any running
 	 * I2C transaction to complete -- the arbitration logic won't
 	 * work properly until the next START is seen.
 	 * It is assumed the bus driver or client has set a proper value.
 	 *
 	 * REVISIT: should probably use msleep instead of mdelay if we
 	 * know we can sleep.
 	 */
 	if (adap->lab_mdelay)
 		mdelay(adap->lab_mdelay);

 	DEB2(printk(KERN_INFO
 		"i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
 		get_pcf(adap, 1)));
 }

 static int wait_for_bb(struct i2c_algo_pcf_data *adap)
 {

 	int timeout = DEF_TIMEOUT;
 	int status;

 	status = get_pcf(adap, 1);

 	while (!(status & I2C_PCF_BB) && --timeout) {
 		udelay(100); /* wait for 100 us */
 		status = get_pcf(adap, 1);
 	}

 	if (timeout == 0) {
 		printk(KERN_ERR "Timeout waiting for Bus Busy\n");
 		return -ETIMEDOUT;
 	}

 	return 0;
 }

 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
 {

 	int timeout = DEF_TIMEOUT;

 	*status = get_pcf(adap, 1);

 	while ((*status & I2C_PCF_PIN) && --timeout) {
 		adap->waitforpin(adap->data);
 		*status = get_pcf(adap, 1);
 	}
 	if (*status & I2C_PCF_LAB) {
 		handle_lab(adap, status);
 		return -EINTR;
 	}

 	if (timeout == 0)
 		return -ETIMEDOUT;

 	return 0;
 }

 /*
  * This should perform the 'PCF8584 initialization sequence' as described
  * in the Philips IC12 data book (1995, Aug 29).
  * There should be a 30 clock cycle wait after reset, I assume this
  * has been fulfilled.
  * There should be a delay at the end equal to the longest I2C message
  * to synchronize the BB-bit (in multimaster systems). How long is
  * this? I assume 1 second is always long enough.
  *
  * vdovikin: added detect code for PCF8584
  */
 static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)
 {
 	unsigned char temp;

 	DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n",
 				get_pcf(adap, 1)));

 	/* S1=0x80: S0 selected, serial interface off */
 	set_pcf(adap, 1, I2C_PCF_PIN);
 	/*
 	 * check to see S1 now used as R/W ctrl -
 	 * PCF8584 does that when ESO is zero
 	 */
 	if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
 		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
 		return -ENXIO; /* definitely not PCF8584 */
 	}

 	/* load own address in S0, effective address is (own << 1) */
 	i2c_outb(adap, get_own(adap));
 	/* check it's really written */
 	if ((temp = i2c_inb(adap)) != get_own(adap)) {
 		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
 		return -ENXIO;
 	}

 	/* S1=0xA0, next byte in S2 */
 	set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
 	/* check to see S2 now selected */
 	if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
 		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
 		return -ENXIO;
 	}

 	/* load clock register S2 */
 	i2c_outb(adap, get_clock(adap));
 	/* check it's really written, the only 5 lowest bits does matter */
 	if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
 		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
 		return -ENXIO;
 	}

 	/* Enable serial interface, idle, S0 selected */
 	set_pcf(adap, 1, I2C_PCF_IDLE);

 	/* check to see PCF is really idled and we can access status register */
 	if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
 		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
 		return -ENXIO;
 	}

 	printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");

 	return 0;
 }

 static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
 			 int count, int last)
 {
 	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 	int wrcount, status, timeout;

 	for (wrcount=0; wrcount<count; ++wrcount) {
 		DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
 				buf[wrcount] & 0xff));
 		i2c_outb(adap, buf[wrcount]);
 		timeout = wait_for_pin(adap, &status);
 		if (timeout) {
 			if (timeout == -EINTR)
 				return -EINTR; /* arbitration lost */

 			i2c_stop(adap);
 			dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
 			return -EREMOTEIO; /* got a better one ?? */
 		}
 		if (status & I2C_PCF_LRB) {
 			i2c_stop(adap);
 			dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
 			return -EREMOTEIO; /* got a better one ?? */
 		}
 	}
 	if (last)
 		i2c_stop(adap);
 	else
 		i2c_repstart(adap);

 	return wrcount;
 }

 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
 			 int count, int last)
 {
 	int i, status;
 	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 	int wfp;

 	/* increment number of bytes to read by one -- read dummy byte */
 	for (i = 0; i <= count; i++) {

 		if ((wfp = wait_for_pin(adap, &status))) {
 			if (wfp == -EINTR)
 				return -EINTR; /* arbitration lost */

 			i2c_stop(adap);
 			dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
 			return -1;
 		}

 		if ((status & I2C_PCF_LRB) && (i != count)) {
 			i2c_stop(adap);
 			dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
 			return -1;
 		}

 		if (i == count - 1) {
 			set_pcf(adap, 1, I2C_PCF_ESO);
 		} else if (i == count) {
 			if (last)
 				i2c_stop(adap);
 			else
 				i2c_repstart(adap);
 		}

 		if (i)
 			buf[i - 1] = i2c_inb(adap);
 		else
 			i2c_inb(adap); /* dummy read */
 	}

 	return i - 1;
 }


 static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
 			 struct i2c_msg *msg)
 {
 	unsigned short flags = msg->flags;
 	unsigned char addr;

 	addr = msg->addr << 1;
 	if (flags & I2C_M_RD)
 		addr |= 1;
 	if (flags & I2C_M_REV_DIR_ADDR)
 		addr ^= 1;
 	i2c_outb(adap, addr);

 	return 0;
 }

 static int pcf_xfer(struct i2c_adapter *i2c_adap,
 		    struct i2c_msg *msgs,
 		    int num)
 {
 	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
 	struct i2c_msg *pmsg;
 	int i;
 	int ret=0, timeout, status;

 	if (adap->xfer_begin)
 		adap->xfer_begin(adap->data);

 	/* Check for bus busy */
 	timeout = wait_for_bb(adap);
 	if (timeout) {
 		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
 			    "Timeout waiting for BB in pcf_xfer\n");)
 		i = -EIO;
 		goto out;
 	}

 	for (i = 0;ret >= 0 && i < num; i++) {
 		pmsg = &msgs[i];

 		DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
 		     pmsg->flags & I2C_M_RD ? "read" : "write",
 		     pmsg->len, pmsg->addr, i + 1, num);)

 		ret = pcf_doAddress(adap, pmsg);

 		/* Send START */
 		if (i == 0)
 			i2c_start(adap);

 		/* Wait for PIN (pending interrupt NOT) */
 		timeout = wait_for_pin(adap, &status);
 		if (timeout) {
 			if (timeout == -EINTR) {
 				/* arbitration lost */
 				i = -EINTR;
 				goto out;
 			}
 			i2c_stop(adap);
 			DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
 				    "for PIN(1) in pcf_xfer\n");)
 			i = -EREMOTEIO;
 			goto out;
 		}

 		/* Check LRB (last rcvd bit - slave ack) */
 		if (status & I2C_PCF_LRB) {
 			i2c_stop(adap);
 			DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
 			i = -EREMOTEIO;
 			goto out;
 		}

 		DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
 			    i, msgs[i].addr, msgs[i].flags, msgs[i].len);)

 		if (pmsg->flags & I2C_M_RD) {
 			ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
 					    (i + 1 == num));

 			if (ret != pmsg->len) {
 				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 					    "only read %d bytes.\n",ret));
 			} else {
 				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
 			}
 		} else {
 			ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
 					    (i + 1 == num));

 			if (ret != pmsg->len) {
 				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
 					    "only wrote %d bytes.\n",ret));
 			} else {
 				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
 			}
 		}
 	}

 out:
 	if (adap->xfer_end)
 		adap->xfer_end(adap->data);
 	return i;
 }

 static u32 pcf_func(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 	       I2C_FUNC_PROTOCOL_MANGLING;
 }

 /* exported algorithm data: */
 static const struct i2c_algorithm pcf_algo = {
 	.master_xfer	= pcf_xfer,
 	.functionality	= pcf_func,
 };

 /*
  * registering functions to load algorithms at runtime
  */
 int i2c_pcf_add_bus(struct i2c_adapter *adap)
 {
 	struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
 	int rval;

 	DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));

 	/* register new adapter to i2c module... */
 	adap->algo = &pcf_algo;

 	if ((rval = pcf_init_8584(pcf_adap)))
 		return rval;

 	rval = i2c_add_adapter(adap);

 	return rval;
 }
 EXPORT_SYMBOL(i2c_pcf_add_bus);

 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
 MODULE_LICENSE("GPL");

 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(i2c_debug,
 	"debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");
	/*
	* i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters
	*
	* Copyright (C) 1995-1997 Simon G. Vogl
	* 1998-2000 Hans Berglund
	*
	* 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.
	*
	* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
	* Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey
	* <mbailey@littlefeet-inc.com>
	*
	* Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
	* messages, proper stop/repstart signaling during receive, added detect code
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/delay.h>
	#include <linux/errno.h>
	#include <linux/i2c.h>
	#include <linux/i2c-algo-pcf.h>
	#include "i2c-algo-pcf.h"


	#define DEB2(x) if (i2c_debug >= 2) x
	#define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */
	#define DEBPROTO(x) if (i2c_debug >= 9) x;
	/* debug the protocol by showing transferred bits */
	#define DEF_TIMEOUT 16

	/*
	* module parameters:
	*/
	static int i2c_debug;

	/* setting states on the bus with the right timing: */

	#define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
	#define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
	#define get_own(adap) adap->getown(adap->data)
	#define get_clock(adap) adap->getclock(adap->data)
	#define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
	#define i2c_inb(adap) adap->getpcf(adap->data, 0)

	/* other auxiliary functions */

	static void i2c_start(struct i2c_algo_pcf_data *adap)
	{
	DEBPROTO(printk(KERN_DEBUG "S "));
	set_pcf(adap, 1, I2C_PCF_START);
	}

	static void i2c_repstart(struct i2c_algo_pcf_data *adap)
	{
	DEBPROTO(printk(" Sr "));
	set_pcf(adap, 1, I2C_PCF_REPSTART);
	}

	static void i2c_stop(struct i2c_algo_pcf_data *adap)
	{
	DEBPROTO(printk("P\n"));
	set_pcf(adap, 1, I2C_PCF_STOP);
	}

	static void handle_lab(struct i2c_algo_pcf_data adap, const int status)
	{
	DEB2(printk(KERN_INFO
	"i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
	*status));
	/*
	* Cleanup from LAB -- reset and enable ESO.
	* This resets the PCF8584; since we've lost the bus, no
	* further attempts should be made by callers to clean up
	* (no i2c_stop() etc.)
	*/
	set_pcf(adap, 1, I2C_PCF_PIN);
	set_pcf(adap, 1, I2C_PCF_ESO);
	/*
	* We pause for a time period sufficient for any running
	* I2C transaction to complete -- the arbitration logic won't
	* work properly until the next START is seen.
	* It is assumed the bus driver or client has set a proper value.
	*
	* REVISIT: should probably use msleep instead of mdelay if we
	* know we can sleep.
	*/
	if (adap->lab_mdelay)
	mdelay(adap->lab_mdelay);

	DEB2(printk(KERN_INFO
	"i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
	get_pcf(adap, 1)));
	}

	static int wait_for_bb(struct i2c_algo_pcf_data *adap)
	{

	int timeout = DEF_TIMEOUT;
	int status;

	status = get_pcf(adap, 1);

	while (!(status & I2C_PCF_BB) && --timeout) {
	udelay(100); /* wait for 100 us */
	status = get_pcf(adap, 1);
	}

	if (timeout == 0) {
	printk(KERN_ERR "Timeout waiting for Bus Busy\n");
	return -ETIMEDOUT;
	}

	return 0;
	}

	static int wait_for_pin(struct i2c_algo_pcf_data adap, int status)
	{

	int timeout = DEF_TIMEOUT;

	*status = get_pcf(adap, 1);

	while ((*status & I2C_PCF_PIN) && --timeout) {
	adap->waitforpin(adap->data);
	*status = get_pcf(adap, 1);
	}
	if (*status & I2C_PCF_LAB) {
	handle_lab(adap, status);
	return -EINTR;
	}

	if (timeout == 0)
	return -ETIMEDOUT;

	return 0;
	}

	/*
	* This should perform the 'PCF8584 initialization sequence' as described
	* in the Philips IC12 data book (1995, Aug 29).
	* There should be a 30 clock cycle wait after reset, I assume this
	* has been fulfilled.
	* There should be a delay at the end equal to the longest I2C message
	* to synchronize the BB-bit (in multimaster systems). How long is
	* this? I assume 1 second is always long enough.
	*
	* vdovikin: added detect code for PCF8584
	*/
	static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)
	{
	unsigned char temp;

	DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n",
	get_pcf(adap, 1)));

	/* S1=0x80: S0 selected, serial interface off */
	set_pcf(adap, 1, I2C_PCF_PIN);
	/*
	* check to see S1 now used as R/W ctrl -
	* PCF8584 does that when ESO is zero
	*/
	if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
	DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
	return -ENXIO; /* definitely not PCF8584 */
	}

	/* load own address in S0, effective address is (own << 1) */
	i2c_outb(adap, get_own(adap));
	/* check it's really written */
	if ((temp = i2c_inb(adap)) != get_own(adap)) {
	DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
	return -ENXIO;
	}

	/* S1=0xA0, next byte in S2 */
	set_pcf(adap, 1, I2C_PCF_PIN \| I2C_PCF_ES1);
	/* check to see S2 now selected */
	if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
	DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
	return -ENXIO;
	}

	/* load clock register S2 */
	i2c_outb(adap, get_clock(adap));
	/* check it's really written, the only 5 lowest bits does matter */
	if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
	DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
	return -ENXIO;
	}

	/* Enable serial interface, idle, S0 selected */
	set_pcf(adap, 1, I2C_PCF_IDLE);

	/* check to see PCF is really idled and we can access status register */
	if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN \| I2C_PCF_BB)) {
	DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
	return -ENXIO;
	}

	printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");

	return 0;
	}

	static int pcf_sendbytes(struct i2c_adapter i2c_adap, const char buf,
	int count, int last)
	{
	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
	int wrcount, status, timeout;

	for (wrcount=0; wrcount<count; ++wrcount) {
	DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
	buf[wrcount] & 0xff));
	i2c_outb(adap, buf[wrcount]);
	timeout = wait_for_pin(adap, &status);
	if (timeout) {
	if (timeout == -EINTR)
	return -EINTR; /* arbitration lost */

	i2c_stop(adap);
	dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
	return -EREMOTEIO; /* got a better one ?? */
	}
	if (status & I2C_PCF_LRB) {
	i2c_stop(adap);
	dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
	return -EREMOTEIO; /* got a better one ?? */
	}
	}
	if (last)
	i2c_stop(adap);
	else
	i2c_repstart(adap);

	return wrcount;
	}

	static int pcf_readbytes(struct i2c_adapter i2c_adap, char buf,
	int count, int last)
	{
	int i, status;
	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
	int wfp;

	/* increment number of bytes to read by one -- read dummy byte */
	for (i = 0; i <= count; i++) {

	if ((wfp = wait_for_pin(adap, &status))) {
	if (wfp == -EINTR)
	return -EINTR; /* arbitration lost */

	i2c_stop(adap);
	dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
	return -1;
	}

	if ((status & I2C_PCF_LRB) && (i != count)) {
	i2c_stop(adap);
	dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
	return -1;
	}

	if (i == count - 1) {
	set_pcf(adap, 1, I2C_PCF_ESO);
	} else if (i == count) {
	if (last)
	i2c_stop(adap);
	else
	i2c_repstart(adap);
	}

	if (i)
	buf[i - 1] = i2c_inb(adap);
	else
	i2c_inb(adap); /* dummy read */
	}

	return i - 1;
	}


	static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
	struct i2c_msg *msg)
	{
	unsigned short flags = msg->flags;
	unsigned char addr;

	addr = msg->addr << 1;
	if (flags & I2C_M_RD)
	addr \|= 1;
	if (flags & I2C_M_REV_DIR_ADDR)
	addr ^= 1;
	i2c_outb(adap, addr);

	return 0;
	}

	static int pcf_xfer(struct i2c_adapter *i2c_adap,
	struct i2c_msg *msgs,
	int num)
	{
	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
	struct i2c_msg *pmsg;
	int i;
	int ret=0, timeout, status;

	if (adap->xfer_begin)
	adap->xfer_begin(adap->data);

	/* Check for bus busy */
	timeout = wait_for_bb(adap);
	if (timeout) {
	DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
	"Timeout waiting for BB in pcf_xfer\n");)
	i = -EIO;
	goto out;
	}

	for (i = 0;ret >= 0 && i < num; i++) {
	pmsg = &msgs[i];

	DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
	pmsg->flags & I2C_M_RD ? "read" : "write",
	pmsg->len, pmsg->addr, i + 1, num);)

	ret = pcf_doAddress(adap, pmsg);

	/* Send START */
	if (i == 0)
	i2c_start(adap);

	/* Wait for PIN (pending interrupt NOT) */
	timeout = wait_for_pin(adap, &status);
	if (timeout) {
	if (timeout == -EINTR) {
	/* arbitration lost */
	i = -EINTR;
	goto out;
	}
	i2c_stop(adap);
	DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
	"for PIN(1) in pcf_xfer\n");)
	i = -EREMOTEIO;
	goto out;
	}

	/* Check LRB (last rcvd bit - slave ack) */
	if (status & I2C_PCF_LRB) {
	i2c_stop(adap);
	DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
	i = -EREMOTEIO;
	goto out;
	}

	DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
	i, msgs[i].addr, msgs[i].flags, msgs[i].len);)

	if (pmsg->flags & I2C_M_RD) {
	ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
	(i + 1 == num));

	if (ret != pmsg->len) {
	DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
	"only read %d bytes.\n",ret));
	} else {
	DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
	}
	} else {
	ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
	(i + 1 == num));

	if (ret != pmsg->len) {
	DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
	"only wrote %d bytes.\n",ret));
	} else {
	DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
	}
	}
	}

	out:
	if (adap->xfer_end)
	adap->xfer_end(adap->data);
	return i;
	}

	static u32 pcf_func(struct i2c_adapter *adap)
	{
	return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL \|
	I2C_FUNC_PROTOCOL_MANGLING;
	}

	/* exported algorithm data: */
	static const struct i2c_algorithm pcf_algo = {
	.master_xfer = pcf_xfer,
	.functionality = pcf_func,
	};

	/*
	* registering functions to load algorithms at runtime
	*/
	int i2c_pcf_add_bus(struct i2c_adapter *adap)
	{
	struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
	int rval;

	DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));

	/* register new adapter to i2c module... */
	adap->algo = &pcf_algo;

	if ((rval = pcf_init_8584(pcf_adap)))
	return rval;

	rval = i2c_add_adapter(adap);

	return rval;
	}
	EXPORT_SYMBOL(i2c_pcf_add_bus);

	MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
	MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
	MODULE_LICENSE("GPL");

	module_param(i2c_debug, int, S_IRUGO \| S_IWUSR);
	MODULE_PARM_DESC(i2c_debug,
	"debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");