/*
   * 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., 51 Franklin Street, Fifth Floor, Boston,
   *  MA 02110-1301 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/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
  "));
  	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)
  ",
  		*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)
  ",
  		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
  ");
  		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
  ",
  				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).
  ", 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).
  ", 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).
  ", 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).
  ", 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).
  ", temp));
  		return -ENXIO;
  	}
  
  	printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.
  ");
  
  	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
  ",
  				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.
  ");
  			return -EREMOTEIO; /* got a better one ?? */
  		}
  		if (status & I2C_PCF_LRB) {
  			i2c_stop(adap);
  			dev_err(&i2c_adap->dev, "i2c_write: error - no ack.
  ");
  			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.
  ");
  			return -1;
  		}
  
  		if ((status & I2C_PCF_LRB) && (i != count)) {
  			i2c_stop(adap);
  			dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.
  ");
  			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
  ");)
  		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
  ",
  		     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
  ");)
  			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
  ");)
  			i = -EREMOTEIO;
  			goto out;
  		}
  
  		DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d
  ",
  			    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.
  ",ret));
  			} else {
  				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.
  ",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.
  ",ret));
  			} else {
  				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.
  ",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.
  "));
  
  	/* 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");