Free Electrons

Embedded Linux Experts

/* linux/drivers/i2c/busses/scx200_i2c.c

   Copyright (c) 2001,2002 Christer Weinigel <>

   National Semiconductor SCx200 I2C bus on GPIO pins

   Based on i2c-velleman.c Copyright (C) 1995-96, 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
   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/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <asm/io.h>

#include <linux/scx200_gpio.h>

#define NAME "scx200_i2c"

MODULE_AUTHOR("Christer Weinigel <>");
MODULE_DESCRIPTION("NatSemi SCx200 I2C Driver");

static int scl = CONFIG_SCx200_I2C_SCL;
static int sda = CONFIG_SCx200_I2C_SDA;

module_param(scl, int, 0);
MODULE_PARM_DESC(scl, "GPIO line for SCL");
module_param(sda, int, 0);
MODULE_PARM_DESC(sda, "GPIO line for SDA");

static void scx200_i2c_setscl(void *data, int state)
	scx200_gpio_set(scl, state);

static void scx200_i2c_setsda(void *data, int state)
	scx200_gpio_set(sda, state);

static int scx200_i2c_getscl(void *data)
	return scx200_gpio_get(scl);

static int scx200_i2c_getsda(void *data)
	return scx200_gpio_get(sda);

/* ------------------------------------------------------------------------
 * 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 scx200_i2c_data = {
	.setsda		= scx200_i2c_setsda,
	.setscl		= scx200_i2c_setscl,
	.getsda		= scx200_i2c_getsda,
	.getscl		= scx200_i2c_getscl,
	.udelay		= 10,
	.timeout	= HZ,

static struct i2c_adapter scx200_i2c_ops = {
	.owner		   = THIS_MODULE,
	.class             = I2C_CLASS_HWMON | I2C_CLASS_SPD,
	.algo_data	   = &scx200_i2c_data,
	.name	= "NatSemi SCx200 I2C",

static int scx200_i2c_init(void)
	pr_debug(NAME ": NatSemi SCx200 I2C Driver\n");

	if (!scx200_gpio_present()) {
		printk(KERN_ERR NAME ": no SCx200 gpio pins available\n");
		return -ENODEV;

	pr_debug(NAME ": SCL=GPIO%02u, SDA=GPIO%02u\n", scl, sda);

	if (scl == -1 || sda == -1 || scl == sda) {
		printk(KERN_ERR NAME ": scl and sda must be specified\n");
		return -EINVAL;

	/* Configure GPIOs as open collector outputs */
	scx200_gpio_configure(scl, ~2, 5);
	scx200_gpio_configure(sda, ~2, 5);

	if (i2c_bit_add_bus(&scx200_i2c_ops) < 0) {
		printk(KERN_ERR NAME ": adapter %s registration failed\n", ;
		return -ENODEV;
	return 0;

static void scx200_i2c_cleanup(void)


    Local variables:
        compile-command: "make -k -C ../.. SUBDIRS=drivers/i2c modules"
        c-basic-offset: 8