drivers/i2c/algos/i2c-algo-pcf.c - kernel/msm - Gitiles

 /* ------------------------------------------------------------------------- */
 /* 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.

     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.		     */
 /* ------------------------------------------------------------------------- */

 /* 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/slab.h>
 #include <linux/init.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("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 int wait_for_bb(struct i2c_algo_pcf_data *adap) {

 	int timeout = DEF_TIMEOUT;
 	int status;

 	status = get_pcf(adap, 1);
 #ifndef STUB_I2C
 	while (timeout-- && !(status & I2C_PCF_BB)) {
 		udelay(100); /* wait for 100 us */
 		status = get_pcf(adap, 1);
 	}
 #endif
 	if (timeout <= 0) {
 		printk(KERN_ERR "Timeout waiting for Bus Busy\n");
 	}

 	return (timeout<=0);
 }


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

 	int timeout = DEF_TIMEOUT;

 	*status = get_pcf(adap, 1);
 #ifndef STUB_I2C
 	while (timeout-- && (*status & I2C_PCF_PIN)) {
 		adap->waitforpin();
 		*status = get_pcf(adap, 1);
 	}
 	if (*status & I2C_PCF_LAB) {
 		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);
 		/* TODO: we should 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.
 		 */
 		DEB2(printk(KERN_INFO
 			"i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
 			get_pcf(adap,1)));
 		return(-EINTR);
 	}
 #endif
 	if (timeout <= 0)
 		return(-1);
 	else
 		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; /* definetly 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: deteted and initialized PCF8584.\n");

 	return 0;
 }


 /* ----- Utility functions
  */

 static inline int try_address(struct i2c_algo_pcf_data *adap,
 		       unsigned char addr, int retries)
 {
 	int i, status, ret = -1;
 	int wfp;
 	for (i=0;i<retries;i++) {
 		i2c_outb(adap, addr);
 		i2c_start(adap);
 		status = get_pcf(adap, 1);
 		if ((wfp = wait_for_pin(adap, &status)) >= 0) {
 			if ((status & I2C_PCF_LRB) == 0) {
 				i2c_stop(adap);
 				break;	/* success! */
 			}
 		}
 		if (wfp == -EINTR) {
 			/* arbitration lost */
 			udelay(adap->udelay);
 			return -EINTR;
 		}
 		i2c_stop(adap);
 		udelay(adap->udelay);
 	}
 	DEB2(if (i) printk(KERN_DEBUG "i2c-algo-pcf.o: needed %d retries for %d\n",i,
 	                   addr));
 	return ret;
 }


 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) {
 				/* arbitration lost */
 				return -EINTR;
 			}
 			i2c_stop(adap);
 			dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
 			return -EREMOTEIO; /* got a better one ?? */
 		}
 #ifndef STUB_I2C
 		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 ?? */
 		}
 #endif
 	}
 	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) {
 				/* arbitration lost */
 				return -EINTR;
 			}
 			i2c_stop(adap);
 			dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
 			return (-1);
 		}

 #ifndef STUB_I2C
 		if ((status & I2C_PCF_LRB) && (i != count)) {
 			i2c_stop(adap);
 			dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
 			return (-1);
 		}
 #endif

 		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 inline int pcf_doAddress(struct i2c_algo_pcf_data *adap,
                                 struct i2c_msg *msg, int retries)
 {
 	unsigned short flags = msg->flags;
 	unsigned char addr;
 	int ret;
 	if ( (flags & I2C_M_TEN)  ) {
 		/* a ten bit address */
 		addr = 0xf0 | (( msg->addr >> 7) & 0x03);
 		DEB2(printk(KERN_DEBUG "addr0: %d\n",addr));
 		/* try extended address code...*/
 		ret = try_address(adap, addr, retries);
 		if (ret!=1) {
 			printk(KERN_ERR "died at extended address code.\n");
 			return -EREMOTEIO;
 		}
 		/* the remaining 8 bit address */
 		i2c_outb(adap,msg->addr & 0x7f);
 /* Status check comes here */
 		if (ret != 1) {
 			printk(KERN_ERR "died at 2nd address code.\n");
 			return -EREMOTEIO;
 		}
 		if ( flags & I2C_M_RD ) {
 			i2c_repstart(adap);
 			/* okay, now switch into reading mode */
 			addr |= 0x01;
 			ret = try_address(adap, addr, retries);
 			if (ret!=1) {
 				printk(KERN_ERR "died at extended address code.\n");
 				return -EREMOTEIO;
 			}
 		}
 	} else {		/* normal 7bit address	*/
 		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;


 	/* 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");)
 		return -EIO;
 	}

 	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, i2c_adap->retries);

 		/* 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 */
 				return (-EINTR);
 			}
 			i2c_stop(adap);
 			DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
 				    "for PIN(1) in pcf_xfer\n");)
 			return (-EREMOTEIO);
 		}

 #ifndef STUB_I2C
 		/* 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");)
 			return (-EREMOTEIO);
 		}
 #endif

 		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);)

 		/* Read */
 		if (pmsg->flags & I2C_M_RD) {
 			/* read bytes into buffer*/
 			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 { /* Write */
 			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));
 			}
 		}
 	}

 	return (i);
 }

 static u32 pcf_func(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 	       I2C_FUNC_10BIT_ADDR | 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;

 	adap->timeout = 100;		/* default values, should	*/
 	adap->retries = 3;		/* be replaced by defines	*/

 	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.

	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. */
	/* ------------------------------------------------------------------------- */

	/* 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/slab.h>
	#include <linux/init.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("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 int wait_for_bb(struct i2c_algo_pcf_data *adap) {

	int timeout = DEF_TIMEOUT;
	int status;

	status = get_pcf(adap, 1);
	#ifndef STUB_I2C
	while (timeout-- && !(status & I2C_PCF_BB)) {
	udelay(100); /* wait for 100 us */
	status = get_pcf(adap, 1);
	}
	#endif
	if (timeout <= 0) {
	printk(KERN_ERR "Timeout waiting for Bus Busy\n");
	}

	return (timeout<=0);
	}


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

	int timeout = DEF_TIMEOUT;

	*status = get_pcf(adap, 1);
	#ifndef STUB_I2C
	while (timeout-- && (*status & I2C_PCF_PIN)) {
	adap->waitforpin();
	*status = get_pcf(adap, 1);
	}
	if (*status & I2C_PCF_LAB) {
	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);
	/* TODO: we should 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.
	*/
	DEB2(printk(KERN_INFO
	"i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
	get_pcf(adap,1)));
	return(-EINTR);
	}
	#endif
	if (timeout <= 0)
	return(-1);
	else
	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; /* definetly 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: deteted and initialized PCF8584.\n");

	return 0;
	}


	/* ----- Utility functions
	*/

	static inline int try_address(struct i2c_algo_pcf_data *adap,
	unsigned char addr, int retries)
	{
	int i, status, ret = -1;
	int wfp;
	for (i=0;i<retries;i++) {
	i2c_outb(adap, addr);
	i2c_start(adap);
	status = get_pcf(adap, 1);
	if ((wfp = wait_for_pin(adap, &status)) >= 0) {
	if ((status & I2C_PCF_LRB) == 0) {
	i2c_stop(adap);
	break; /* success! */
	}
	}
	if (wfp == -EINTR) {
	/* arbitration lost */
	udelay(adap->udelay);
	return -EINTR;
	}
	i2c_stop(adap);
	udelay(adap->udelay);
	}
	DEB2(if (i) printk(KERN_DEBUG "i2c-algo-pcf.o: needed %d retries for %d\n",i,
	addr));
	return ret;
	}


	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) {
	/* arbitration lost */
	return -EINTR;
	}
	i2c_stop(adap);
	dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
	return -EREMOTEIO; /* got a better one ?? */
	}
	#ifndef STUB_I2C
	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 ?? */
	}
	#endif
	}
	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) {
	/* arbitration lost */
	return -EINTR;
	}
	i2c_stop(adap);
	dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
	return (-1);
	}

	#ifndef STUB_I2C
	if ((status & I2C_PCF_LRB) && (i != count)) {
	i2c_stop(adap);
	dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
	return (-1);
	}
	#endif

	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 inline int pcf_doAddress(struct i2c_algo_pcf_data *adap,
	struct i2c_msg *msg, int retries)
	{
	unsigned short flags = msg->flags;
	unsigned char addr;
	int ret;
	if ( (flags & I2C_M_TEN) ) {
	/* a ten bit address */
	addr = 0xf0 \| (( msg->addr >> 7) & 0x03);
	DEB2(printk(KERN_DEBUG "addr0: %d\n",addr));
	/* try extended address code...*/
	ret = try_address(adap, addr, retries);
	if (ret!=1) {
	printk(KERN_ERR "died at extended address code.\n");
	return -EREMOTEIO;
	}
	/* the remaining 8 bit address */
	i2c_outb(adap,msg->addr & 0x7f);
	/* Status check comes here */
	if (ret != 1) {
	printk(KERN_ERR "died at 2nd address code.\n");
	return -EREMOTEIO;
	}
	if ( flags & I2C_M_RD ) {
	i2c_repstart(adap);
	/* okay, now switch into reading mode */
	addr \|= 0x01;
	ret = try_address(adap, addr, retries);
	if (ret!=1) {
	printk(KERN_ERR "died at extended address code.\n");
	return -EREMOTEIO;
	}
	}
	} else { /* normal 7bit address */
	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;


	/* 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");)
	return -EIO;
	}

	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, i2c_adap->retries);

	/* 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 */
	return (-EINTR);
	}
	i2c_stop(adap);
	DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
	"for PIN(1) in pcf_xfer\n");)
	return (-EREMOTEIO);
	}

	#ifndef STUB_I2C
	/* 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");)
	return (-EREMOTEIO);
	}
	#endif

	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);)

	/* Read */
	if (pmsg->flags & I2C_M_RD) {
	/* read bytes into buffer*/
	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 { /* Write */
	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));
	}
	}
	}

	return (i);
	}

	static u32 pcf_func(struct i2c_adapter *adap)
	{
	return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL \|
	I2C_FUNC_10BIT_ADDR \| 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;

	adap->timeout = 100; /* default values, should */
	adap->retries = 3; /* be replaced by defines */

	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");