i2c-algo-pcf.c

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/*
 * 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 <[email protected]> and
 * Frodo Looijaard <[email protected]>, and also from Martin Bailey
 * <[email protected]>
 *
 * Partially rewriten by Oleg I. Vdovikin <[email protected]> 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/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(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 <[email protected]>");
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");