linux-imx

/*

 * 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.

 *

 * 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\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.

     *