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/* ------------------------------------------------------------------------- */
/* i2c-elv.c i2c-hw access for philips style parallel port adapters          */
/* ------------------------------------------------------------------------- */
/*   Copyright (C) 1995-2000 Simon G. Vogl

    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 even
   Frodo Looijaard <frodol@dds.nl> */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <asm/io.h>

#define DEFAULT_BASE 0x378
static int base=0;
static unsigned char port_data = 0;

/* ----- global defines ----------------------------------------------- */
#define DEB(x)          /* should be reasonable open, close &c.         */
#define DEB2(x)         /* low level debugging - very slow              */
#define DEBE(x) x       /* error messages                               */
#define DEBINIT(x) x    /* detection status messages                    */

/* --- Convenience defines for the parallel port:                       */
#define BASE    (unsigned int)(data)
#define DATA    BASE                    /* Centronics data port         */
#define STAT    (BASE+1)                /* Centronics status port       */
#define CTRL    (BASE+2)                /* Centronics control port      */


/* ----- local functions ---------------------------------------------- */


static void bit_elv_setscl(void *data, int state)
{
        if (state) {
                port_data &= 0xfe;
        } else {
                port_data |=1;
        }
        outb(port_data, DATA);
}

static void bit_elv_setsda(void *data, int state)
{
        if (state) {
                port_data &=0xfd;
        } else {
                port_data |=2;
        }
        outb(port_data, DATA);
}

static int bit_elv_getscl(void *data)
{
        return ( 0 == ( (inb_p(STAT)) & 0x08 ) );
}

static int bit_elv_getsda(void *data)
{
        return ( 0 == ( (inb_p(STAT)) & 0x40 ) );
}

static int bit_elv_init(void)
{
        if (!request_region(base, (base == 0x3bc) ? 3 : 8,
                                "i2c (ELV adapter)"))
                return -ENODEV;

        if (inb(base+1) & 0x80) {       /* BUSY should be high  */
                DEBINIT(printk(KERN_DEBUG "i2c-elv.o: Busy was low.\n"));
                goto fail;
        }

        outb(0x0c,base+2);      /* SLCT auf low         */
        udelay(400);
        if (!(inb(base+1) && 0x10)) {
                outb(0x04,base+2);
                DEBINIT(printk(KERN_DEBUG "i2c-elv.o: Select was high.\n"));
                goto fail;
        }

        port_data = 0;
        bit_elv_setsda((void*)base,1);
        bit_elv_setscl((void*)base,1);
        return 0;

fail:
        release_region(base , (base == 0x3bc) ? 3 : 8);
        return -ENODEV;
}

/* ------------------------------------------------------------------------
 * Encapsulate the above functions in the correct operations structure.
 * This is only done when more than one hardware adapter is supported.
 */
static struct i2c_algo_bit_data bit_elv_data = {
        .setsda         = bit_elv_setsda,
        .setscl         = bit_elv_setscl,
        .getsda         = bit_elv_getsda,
        .getscl         = bit_elv_getscl,
        .udelay         = 80,
        .mdelay         = 80,
        .timeout        = HZ
};

static struct i2c_adapter bit_elv_ops = {
        .owner          = THIS_MODULE,
        .algo_data      = &bit_elv_data,
        .name           = "ELV Parallel port adaptor",
};

static int __init i2c_bitelv_init(void)
{
        printk(KERN_INFO "i2c ELV parallel port adapter driver\n");
        if (base==0) {
                /* probe some values */
                base=DEFAULT_BASE;
                bit_elv_data.data=(void*)DEFAULT_BASE;
                if (bit_elv_init()==0) {
                        if(i2c_bit_add_bus(&bit_elv_ops) < 0)
                                return -ENODEV;
                } else {
                        return -ENODEV;
                }
        } else {
                i2c_set_adapdata(&bit_elv_ops, (void *)base);
                if (bit_elv_init()==0) {
                        if(i2c_bit_add_bus(&bit_elv_ops) < 0)
                                return -ENODEV;
                } else {
                        return -ENODEV;
                }
        }
        printk(KERN_DEBUG "i2c-elv.o: found device at %#x.\n",base);
        return 0;
}

static void __exit i2c_bitelv_exit(void)
{
        i2c_bit_del_bus(&bit_elv_ops);
        release_region(base , (base == 0x3bc) ? 3 : 8);
}

MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
MODULE_DESCRIPTION("I2C-Bus adapter routines for ELV parallel port adapter");
MODULE_LICENSE("GPL");

MODULE_PARM(base, "i");

module_init(i2c_bitelv_init);
module_exit(i2c_bitelv_exit);