/* ------------------------------------------------------------------------ *
 * i2c-parport-light.c I2C bus over parallel port                           *
 * ------------------------------------------------------------------------ *
   Copyright (C) 2003-2007 Jean Delvare <khali@linux-fr.org>
   
   Based on older i2c-velleman.c driver
   Copyright (C) 1995-2000 Simon G. Vogl
   With some changes from:
   Frodo Looijaard <frodol@dds.nl>
   Kyösti Mälkki <kmalkki@cc.hut.fi>
   
   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/init.h>
#include <linux/platform_device.h>
#include <linux/ioport.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <asm/io.h>
#include "i2c-parport.h"

#define DEFAULT_BASE 0x378
#define DRVNAME "i2c-parport-light"

static struct platform_device *pdev;

static u16 base;
module_param(base, ushort, 0);
MODULE_PARM_DESC(base, "Base I/O address");

/* ----- Low-level parallel port access ----------------------------------- */

static inline void port_write(unsigned char p, unsigned char d)
{
        outb(d, base+p);
}

static inline unsigned char port_read(unsigned char p)
{
        return inb(base+p);
}

/* ----- Unified line operation functions --------------------------------- */

static inline void line_set(int state, const struct lineop *op)
{
        u8 oldval = port_read(op->port);

        /* Touch only the bit(s) needed */
        if ((op->inverted && !state) || (!op->inverted && state))
                port_write(op->port, oldval | op->val);
        else
                port_write(op->port, oldval & ~op->val);
}

static inline int line_get(const struct lineop *op)
{
        u8 oldval = port_read(op->port);

        return ((op->inverted && (oldval & op->val) != op->val)
            || (!op->inverted && (oldval & op->val) == op->val));
}

/* ----- I2C algorithm call-back functions and structures ----------------- */

static void parport_setscl(void *data, int state)
{
        line_set(state, &adapter_parm[type].setscl);
}

static void parport_setsda(void *data, int state)
{
        line_set(state, &adapter_parm[type].setsda);
}

static int parport_getscl(void *data)
{
        return line_get(&adapter_parm[type].getscl);
}

static int parport_getsda(void *data)
{
        return line_get(&adapter_parm[type].getsda);
}

/* Encapsulate the functions above in the correct structure
   Note that getscl will be set to NULL by the attaching code for adapters
   that cannot read SCL back */
static struct i2c_algo_bit_data parport_algo_data = {
        .setsda         = parport_setsda,
        .setscl         = parport_setscl,
        .getsda         = parport_getsda,
        .getscl         = parport_getscl,
        .udelay         = 50,
        .timeout        = HZ,
}; 

/* ----- Driver registration ---------------------------------------------- */

static struct i2c_adapter parport_adapter = {
        .owner          = THIS_MODULE,
        .class          = I2C_CLASS_HWMON,
        .algo_data      = &parport_algo_data,
        .name           = "Parallel port adapter (light)",
};

static int __devinit i2c_parport_probe(struct platform_device *pdev)
{
        int err;

        /* Reset hardware to a sane state (SCL and SDA high) */
        parport_setsda(NULL, 1);
        parport_setscl(NULL, 1);
        /* Other init if needed (power on...) */
        if (adapter_parm[type].init.val)
                line_set(1, &adapter_parm[type].init);

        parport_adapter.dev.parent = &pdev->dev;
        err = i2c_bit_add_bus(&parport_adapter);
        if (err)
                dev_err(&pdev->dev, "Unable to register with I2C\n");
        return err;
}

static int __devexit i2c_parport_remove(struct platform_device *pdev)
{
        i2c_del_adapter(&parport_adapter);

        /* Un-init if needed (power off...) */
        if (adapter_parm[type].init.val)
                line_set(0, &adapter_parm[type].init);

        return 0;
}

static struct platform_driver i2c_parport_driver = {
        .driver = {
                .owner  = THIS_MODULE,
                .name   = DRVNAME,
        },
        .probe          = i2c_parport_probe,
        .remove         = __devexit_p(i2c_parport_remove),
};

static int __init i2c_parport_device_add(u16 address)
{
        int err;

        pdev = platform_device_alloc(DRVNAME, -1);
        if (!pdev) {
                err = -ENOMEM;
                printk(KERN_ERR DRVNAME ": Device allocation failed\n");
                goto exit;
        }

        err = platform_device_add(pdev);
        if (err) {
                printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
                       err);
                goto exit_device_put;
        }

        return 0;

exit_device_put:
        platform_device_put(pdev);
exit:
        return err;
}

static int __init i2c_parport_init(void)
{
        int err;

        if (type < 0) {
                printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
                return -ENODEV;
        }

        if (type >= ARRAY_SIZE(adapter_parm)) {
                printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
                return -ENODEV;
        }

        if (base == 0) {
                pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
                base = DEFAULT_BASE;
        }

        if (!request_region(base, 3, DRVNAME))
                return -EBUSY;

        if (!adapter_parm[type].getscl.val)
                parport_algo_data.getscl = NULL;

        /* Sets global pdev as a side effect */
        err = i2c_parport_device_add(base);
        if (err)
                goto exit_release;

        err = platform_driver_register(&i2c_parport_driver);
        if (err)
                goto exit_device;

        return 0;

exit_device:
        platform_device_unregister(pdev);
exit_release:
        release_region(base, 3);
        return err;
}

static void __exit i2c_parport_exit(void)
{
        platform_driver_unregister(&i2c_parport_driver);
        platform_device_unregister(pdev);
        release_region(base, 3);
}

MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
MODULE_DESCRIPTION("I2C bus over parallel port (light)");
MODULE_LICENSE("GPL");

module_init(i2c_parport_init);
module_exit(i2c_parport_exit);