Logo Search packages:      
Sourcecode: linux version File versions  Download package

i2c-algo-pca.c

/*
 *  i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters                
 *    Copyright (C) 2004 Arcom Control Systems
 *
 *  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.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.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-pca.h>
#include "i2c-algo-pca.h"

#define DRIVER "i2c-algo-pca"

#define DEB1(fmt, args...) do { if (i2c_debug>=1) printk(fmt, ## args); } while(0)
#define DEB2(fmt, args...) do { if (i2c_debug>=2) printk(fmt, ## args); } while(0)
#define DEB3(fmt, args...) do { if (i2c_debug>=3) printk(fmt, ## args); } while(0)

static int i2c_debug;

#define pca_outw(adap, reg, val) adap->write_byte(adap, reg, val)
#define pca_inw(adap, reg) adap->read_byte(adap, reg)

#define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
#define pca_clock(adap) adap->get_clock(adap)
#define pca_own(adap) adap->get_own(adap)
#define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
#define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
#define pca_wait(adap) adap->wait_for_interrupt(adap)

/*
 * Generate a start condition on the i2c bus.
 *
 * returns after the start condition has occurred
 */
static void pca_start(struct i2c_algo_pca_data *adap)
{
      int sta = pca_get_con(adap);
      DEB2("=== START\n");
      sta |= I2C_PCA_CON_STA;
      sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
      pca_set_con(adap, sta);
      pca_wait(adap);
}

/*
 * Generate a repeated start condition on the i2c bus
 *
 * return after the repeated start condition has occurred
 */
static void pca_repeated_start(struct i2c_algo_pca_data *adap)
{
      int sta = pca_get_con(adap);
      DEB2("=== REPEATED START\n");
      sta |= I2C_PCA_CON_STA;
      sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
      pca_set_con(adap, sta);
      pca_wait(adap);
}

/*
 * Generate a stop condition on the i2c bus
 *
 * returns after the stop condition has been generated
 *
 * STOPs do not generate an interrupt or set the SI flag, since the
 * part returns the idle state (0xf8). Hence we don't need to
 * pca_wait here.
 */
static void pca_stop(struct i2c_algo_pca_data *adap)
{
      int sta = pca_get_con(adap);
      DEB2("=== STOP\n");
      sta |= I2C_PCA_CON_STO;
      sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
      pca_set_con(adap, sta);
}

/*
 * Send the slave address and R/W bit
 *
 * returns after the address has been sent
 */
static void pca_address(struct i2c_algo_pca_data *adap, 
                  struct i2c_msg *msg)
{
      int sta = pca_get_con(adap);
      int addr;

      addr = ( (0x7f & msg->addr) << 1 );
      if (msg->flags & I2C_M_RD )
            addr |= 1;
      DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n", 
           msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
      
      pca_outw(adap, I2C_PCA_DAT, addr);

      sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
      pca_set_con(adap, sta);

      pca_wait(adap);
}

/*
 * Transmit a byte.
 *
 * Returns after the byte has been transmitted
 */
static void pca_tx_byte(struct i2c_algo_pca_data *adap, 
                  __u8 b)
{
      int sta = pca_get_con(adap);
      DEB2("=== WRITE %#04x\n", b);
      pca_outw(adap, I2C_PCA_DAT, b);

      sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
      pca_set_con(adap, sta);

      pca_wait(adap);
}

/*
 * Receive a byte
 *
 * returns immediately.
 */
static void pca_rx_byte(struct i2c_algo_pca_data *adap, 
                  __u8 *b, int ack)
{
      *b = pca_inw(adap, I2C_PCA_DAT);
      DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
}

/* 
 * Setup ACK or NACK for next received byte and wait for it to arrive.
 *
 * Returns after next byte has arrived.
 */
static void pca_rx_ack(struct i2c_algo_pca_data *adap, 
                   int ack)
{
      int sta = pca_get_con(adap);

      sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);

      if ( ack )
            sta |= I2C_PCA_CON_AA;

      pca_set_con(adap, sta);
      pca_wait(adap);
}

/* 
 * Reset the i2c bus / SIO 
 */
static void pca_reset(struct i2c_algo_pca_data *adap)
{
      /* apparently only an external reset will do it. not a lot can be done */
      printk(KERN_ERR DRIVER ": Haven't figured out how to do a reset yet\n");
}

static int pca_xfer(struct i2c_adapter *i2c_adap,
                    struct i2c_msg *msgs,
                    int num)
{
        struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
        struct i2c_msg *msg = NULL;
        int curmsg;
      int numbytes = 0;
      int state;
      int ret;
      int timeout = 100;

      while ((state = pca_status(adap)) != 0xf8 && timeout--) {
            msleep(10);
      }
      if (state != 0xf8) {
            dev_dbg(&i2c_adap->dev, "bus is not idle. status is %#04x\n", state);
            return -EIO;
      }

      DEB1("{{{ XFER %d messages\n", num);

      if (i2c_debug>=2) {
            for (curmsg = 0; curmsg < num; curmsg++) {
                  int addr, i;
                  msg = &msgs[curmsg];
                  
                  addr = (0x7f & msg->addr) ;
            
                  if (msg->flags & I2C_M_RD )
                        printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n", 
                               curmsg, msg->len, addr, (addr<<1) | 1);
                  else {
                        printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s", 
                               curmsg, msg->len, addr, addr<<1,
                               msg->len == 0 ? "" : ", ");
                        for(i=0; i < msg->len; i++)
                              printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
                        printk("]\n");
                  }
            }
      }

      curmsg = 0;
      ret = -EREMOTEIO;
      while (curmsg < num) {
            state = pca_status(adap);

            DEB3("STATE is 0x%02x\n", state);
            msg = &msgs[curmsg];

            switch (state) {
            case 0xf8: /* On reset or stop the bus is idle */
                  pca_start(adap);
                  break;

            case 0x08: /* A START condition has been transmitted */
            case 0x10: /* A repeated start condition has been transmitted */
                  pca_address(adap, msg);
                  break;
                  
            case 0x18: /* SLA+W has been transmitted; ACK has been received */
            case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
                  if (numbytes < msg->len) {
                        pca_tx_byte(adap, msg->buf[numbytes]);
                        numbytes++;
                        break;
                  }
                  curmsg++; numbytes = 0;
                  if (curmsg == num)
                        pca_stop(adap);
                  else
                        pca_repeated_start(adap);
                  break;

            case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
                  DEB2("NOT ACK received after SLA+W\n");
                  pca_stop(adap);
                  goto out;

            case 0x40: /* SLA+R has been transmitted; ACK has been received */
                  pca_rx_ack(adap, msg->len > 1);
                  break;

            case 0x50: /* Data bytes has been received; ACK has been returned */
                  if (numbytes < msg->len) {
                        pca_rx_byte(adap, &msg->buf[numbytes], 1);
                        numbytes++;
                        pca_rx_ack(adap, numbytes < msg->len - 1);
                        break;
                  }
                  curmsg++; numbytes = 0;
                  if (curmsg == num)
                        pca_stop(adap);
                  else
                        pca_repeated_start(adap);
                  break;

            case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
                  DEB2("NOT ACK received after SLA+R\n");
                  pca_stop(adap);
                  goto out;

            case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
                  DEB2("NOT ACK received after data byte\n");
                  goto out;

            case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
                  DEB2("Arbitration lost\n");
                  goto out;
                  
            case 0x58: /* Data byte has been received; NOT ACK has been returned */
                  if ( numbytes == msg->len - 1 ) {
                        pca_rx_byte(adap, &msg->buf[numbytes], 0);
                        curmsg++; numbytes = 0;
                        if (curmsg == num)
                              pca_stop(adap);
                        else
                              pca_repeated_start(adap);
                  } else {
                        DEB2("NOT ACK sent after data byte received. "
                             "Not final byte. numbytes %d. len %d\n",
                             numbytes, msg->len);
                        pca_stop(adap);
                        goto out;
                  }
                  break;
            case 0x70: /* Bus error - SDA stuck low */
                  DEB2("BUS ERROR - SDA Stuck low\n");
                  pca_reset(adap);
                  goto out;
            case 0x90: /* Bus error - SCL stuck low */
                  DEB2("BUS ERROR - SCL Stuck low\n");
                  pca_reset(adap);
                  goto out;
            case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
                  DEB2("BUS ERROR - Illegal START or STOP\n");
                  pca_reset(adap);
                  goto out;
            default:
                  printk(KERN_ERR DRIVER ": unhandled SIO state 0x%02x\n", state);
                  break;
            }
            
      }

      ret = curmsg;
 out:
      DEB1(KERN_CRIT "}}} transfered %d/%d messages. "
           "status is %#04x. control is %#04x\n", 
           curmsg, num, pca_status(adap),
           pca_get_con(adap));
      return ret;
}

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

static int pca_init(struct i2c_algo_pca_data *adap)
{
      static int freqs[] = {330,288,217,146,88,59,44,36};
      int own, clock;

      own = pca_own(adap);
      clock = pca_clock(adap);
      DEB1(KERN_INFO DRIVER ": own address is %#04x\n", own);
      DEB1(KERN_INFO DRIVER ": clock freqeuncy is %dkHz\n", freqs[clock]);

      pca_outw(adap, I2C_PCA_ADR, own << 1);

      pca_set_con(adap, I2C_PCA_CON_ENSIO | clock);
      udelay(500); /* 500 ┬Ás for oscilator to stabilise */

      return 0;
}

static const struct i2c_algorithm pca_algo = {
      .master_xfer      = pca_xfer,
      .functionality    = pca_func,
};

/* 
 * registering functions to load algorithms at runtime 
 */
int i2c_pca_add_bus(struct i2c_adapter *adap)
{
      struct i2c_algo_pca_data *pca_adap = adap->algo_data;
      int rval;

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

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

      if ((rval = pca_init(pca_adap)))
            return rval;

      rval = i2c_add_adapter(adap);

      return rval;
}
EXPORT_SYMBOL(i2c_pca_add_bus);

MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>");
MODULE_DESCRIPTION("I2C-Bus PCA9564 algorithm");
MODULE_LICENSE("GPL");

module_param(i2c_debug, int, 0);

Generated by  Doxygen 1.6.0   Back to index