i2c-simtec.c

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/*
 * Copyright (C) 2005 Simtec Electronics
 *  Ben Dooks <[email protected]>
 *
 * Simtec Generic I2C Controller
 *
 * 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
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/io.h>

#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>

struct simtec_i2c_data {
    struct resource     *ioarea;
    void __iomem        *reg;
    struct i2c_adapter   adap;
    struct i2c_algo_bit_data bit;
};

#define CMD_SET_SDA (1<<2)
#define CMD_SET_SCL (1<<3)

#define STATE_SDA   (1<<0)
#define STATE_SCL   (1<<1)

/* i2c bit-bus functions */

static void simtec_i2c_setsda(void *pw, int state)
{
    struct simtec_i2c_data *pd = pw;
    writeb(CMD_SET_SDA | (state ? STATE_SDA : 0), pd->reg);
}

static void simtec_i2c_setscl(void *pw, int state)
{
    struct simtec_i2c_data *pd = pw;
    writeb(CMD_SET_SCL | (state ? STATE_SCL : 0), pd->reg);
}

static int simtec_i2c_getsda(void *pw)
{
    struct simtec_i2c_data *pd = pw;
    return readb(pd->reg) & STATE_SDA ? 1 : 0;
}

static int simtec_i2c_getscl(void *pw)
{
    struct simtec_i2c_data *pd = pw;
    return readb(pd->reg) & STATE_SCL ? 1 : 0;
}

/* device registration */

static int simtec_i2c_probe(struct platform_device *dev)
{
    struct simtec_i2c_data *pd;
    struct resource *res;
    int size;
    int ret;

    pd = kzalloc(sizeof(struct simtec_i2c_data), GFP_KERNEL);
    if (pd == NULL) {
        dev_err(&dev->dev, "cannot allocate private data\n");
        return -ENOMEM;
    }

    platform_set_drvdata(dev, pd);

    res = platform_get_resource(dev, IORESOURCE_MEM, 0);
    if (res == NULL) {
        dev_err(&dev->dev, "cannot find IO resource\n");
        ret = -ENOENT;
        goto err;
    }

    size = resource_size(res);

    pd->ioarea = request_mem_region(res->start, size, dev->name);
    if (pd->ioarea == NULL) {
        dev_err(&dev->dev, "cannot request IO\n");
        ret = -ENXIO;
        goto err;
    }

    pd->reg = ioremap(res->start, size);
    if (pd->reg == NULL) {
        dev_err(&dev->dev, "cannot map IO\n");
        ret = -ENXIO;
        goto err_res;
    }

    /* setup the private data */

    pd->adap.owner = THIS_MODULE;
    pd->adap.algo_data = &pd->bit;
    pd->adap.dev.parent = &dev->dev;

    strlcpy(pd->adap.name, "Simtec I2C", sizeof(pd->adap.name));

    pd->bit.data = pd;
    pd->bit.setsda = simtec_i2c_setsda;
    pd->bit.setscl = simtec_i2c_setscl;
    pd->bit.getsda = simtec_i2c_getsda;
    pd->bit.getscl = simtec_i2c_getscl;
    pd->bit.timeout = HZ;
    pd->bit.udelay = 20;

    ret = i2c_bit_add_bus(&pd->adap);
    if (ret)
        goto err_all;

    return 0;

 err_all:
    iounmap(pd->reg);

 err_res:
    release_resource(pd->ioarea);
    kfree(pd->ioarea);

 err:
    kfree(pd);
    return ret;
}

static int simtec_i2c_remove(struct platform_device *dev)
{
    struct simtec_i2c_data *pd = platform_get_drvdata(dev);

    i2c_del_adapter(&pd->adap);

    iounmap(pd->reg);
    release_resource(pd->ioarea);
    kfree(pd->ioarea);
    kfree(pd);

    return 0;
}

/* device driver */

static struct platform_driver simtec_i2c_driver = {
    .driver     = {
        .name       = "simtec-i2c",
        .owner      = THIS_MODULE,
    },
    .probe      = simtec_i2c_probe,
    .remove     = simtec_i2c_remove,
};

module_platform_driver(simtec_i2c_driver);

MODULE_DESCRIPTION("Simtec Generic I2C Bus driver");
MODULE_AUTHOR("Ben Dooks <[email protected]>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:simtec-i2c");