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i2c-algo-pcf.c

/* ------------------------------------------------------------------------- */
/* 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");

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