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i2c-simtec.c

/*
 * Copyright (C) 2005 Simtec Electronics
 *    Ben Dooks <ben@simtec.co.uk>
 *
 * 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/i2c.h>
#include <linux/i2c-algo-bit.h>

#include <asm/io.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 = (res->end-res->start)+1;

      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,
};

static int __init i2c_adap_simtec_init(void)
{
      return platform_driver_register(&simtec_i2c_driver);
}

static void __exit i2c_adap_simtec_exit(void)
{
      platform_driver_unregister(&simtec_i2c_driver);
}

module_init(i2c_adap_simtec_init);
module_exit(i2c_adap_simtec_exit);

MODULE_DESCRIPTION("Simtec Generic I2C Bus driver");
MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
MODULE_LICENSE("GPL");

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