1/*
  2 * drivers/i2c/busses/i2c-ixp2000.c
  3 *
  4 * I2C adapter for IXP2000 systems using GPIOs for I2C bus
  5 *
  6 * Author: Deepak Saxena <dsaxena@plexity.net>
  7 * Based on IXDP2400 code by: Naeem M. Afzal <naeem.m.afzal@intel.com>
  8 * Made generic by: Jeff Daly <jeffrey.daly@intel.com>
  9 *
 10 * Copyright (c) 2003-2004 MontaVista Software Inc.
 11 *
 12 * This file is licensed under  the terms of the GNU General Public 
 13 * License version 2. This program is licensed "as is" without any 
 14 * warranty of any kind, whether express or implied.
 15 *
 16 * From Jeff Daly:
 17 *
 18 * I2C adapter driver for Intel IXDP2xxx platforms. This should work for any
 19 * IXP2000 platform if it uses the HW GPIO in the same manner.  Basically, 
 20 * SDA and SCL GPIOs have external pullups.  Setting the respective GPIO to 
 21 * an input will make the signal a '1' via the pullup.  Setting them to 
 22 * outputs will pull them down. 
 23 *
 24 * The GPIOs are open drain signals and are used as configuration strap inputs
 25 * during power-up so there's generally a buffer on the board that needs to be 
 26 * 'enabled' to drive the GPIOs.
 27 */
 28
 29#include <linux/kernel.h>
 30#include <linux/init.h>
 31#include <linux/platform_device.h>
 32#include <linux/module.h>
 33#include <linux/i2c.h>
 34#include <linux/i2c-algo-bit.h>
 35#include <linux/slab.h>
 36
 37#include <mach/hardware.h>	/* Pick up IXP2000-specific bits */
 38#include <mach/gpio.h>
 39
 40static inline int ixp2000_scl_pin(void *data)
 41{
 42	return ((struct ixp2000_i2c_pins*)data)->scl_pin;
 43}
 44
 45static inline int ixp2000_sda_pin(void *data)
 46{
 47	return ((struct ixp2000_i2c_pins*)data)->sda_pin;
 48}
 49
 50
 51static void ixp2000_bit_setscl(void *data, int val)
 52{
 53	int i = 5000;
 54
 55	if (val) {
 56		gpio_line_config(ixp2000_scl_pin(data), GPIO_IN);
 57		while(!gpio_line_get(ixp2000_scl_pin(data)) && i--);
 58	} else {
 59		gpio_line_config(ixp2000_scl_pin(data), GPIO_OUT);
 60	}
 61}
 62
 63static void ixp2000_bit_setsda(void *data, int val)
 64{
 65	if (val) {
 66		gpio_line_config(ixp2000_sda_pin(data), GPIO_IN);
 67	} else {
 68		gpio_line_config(ixp2000_sda_pin(data), GPIO_OUT);
 69	}
 70}
 71
 72static int ixp2000_bit_getscl(void *data)
 73{
 74	return gpio_line_get(ixp2000_scl_pin(data));
 75}
 76
 77static int ixp2000_bit_getsda(void *data)
 78{
 79	return gpio_line_get(ixp2000_sda_pin(data));
 80}
 81
 82struct ixp2000_i2c_data {
 83	struct ixp2000_i2c_pins *gpio_pins;
 84	struct i2c_adapter adapter;
 85	struct i2c_algo_bit_data algo_data;
 86};
 87
 88static int ixp2000_i2c_remove(struct platform_device *plat_dev)
 89{
 90	struct ixp2000_i2c_data *drv_data = platform_get_drvdata(plat_dev);
 91
 92	platform_set_drvdata(plat_dev, NULL);
 93
 94	i2c_del_adapter(&drv_data->adapter);
 95
 96	kfree(drv_data);
 97
 98	return 0;
 99}
100
101static int ixp2000_i2c_probe(struct platform_device *plat_dev)
102{
103	int err;
104	struct ixp2000_i2c_pins *gpio = plat_dev->dev.platform_data;
105	struct ixp2000_i2c_data *drv_data = 
106		kzalloc(sizeof(struct ixp2000_i2c_data), GFP_KERNEL);
107
108	if (!drv_data)
109		return -ENOMEM;
110	drv_data->gpio_pins = gpio;
111
112	drv_data->algo_data.data = gpio;
113	drv_data->algo_data.setsda = ixp2000_bit_setsda;
114	drv_data->algo_data.setscl = ixp2000_bit_setscl;
115	drv_data->algo_data.getsda = ixp2000_bit_getsda;
116	drv_data->algo_data.getscl = ixp2000_bit_getscl;
117	drv_data->algo_data.udelay = 6;
118	drv_data->algo_data.timeout = HZ;
119
120	strlcpy(drv_data->adapter.name, plat_dev->dev.driver->name,
121		sizeof(drv_data->adapter.name));
122	drv_data->adapter.algo_data = &drv_data->algo_data,
123
124	drv_data->adapter.dev.parent = &plat_dev->dev;
125
126	gpio_line_config(gpio->sda_pin, GPIO_IN);
127	gpio_line_config(gpio->scl_pin, GPIO_IN);
128	gpio_line_set(gpio->scl_pin, 0);
129	gpio_line_set(gpio->sda_pin, 0);
130
131	if ((err = i2c_bit_add_bus(&drv_data->adapter)) != 0) {
132		dev_err(&plat_dev->dev, "Could not install, error %d\n", err);
133		kfree(drv_data);
134		return err;
135	} 
136
137	platform_set_drvdata(plat_dev, drv_data);
138
139	return 0;
140}
141
142static struct platform_driver ixp2000_i2c_driver = {
143	.probe		= ixp2000_i2c_probe,
144	.remove		= ixp2000_i2c_remove,
145	.driver		= {
146		.name	= "IXP2000-I2C",
147		.owner	= THIS_MODULE,
148	},
149};
150
151static int __init ixp2000_i2c_init(void)
152{
153	return platform_driver_register(&ixp2000_i2c_driver);
154}
155
156static void __exit ixp2000_i2c_exit(void)
157{
158	platform_driver_unregister(&ixp2000_i2c_driver);
159}
160
161module_init(ixp2000_i2c_init);
162module_exit(ixp2000_i2c_exit);
163
164MODULE_AUTHOR ("Deepak Saxena <dsaxena@plexity.net>");
165MODULE_DESCRIPTION("IXP2000 GPIO-based I2C bus driver");
166MODULE_LICENSE("GPL");
167MODULE_ALIAS("platform:IXP2000-I2C");
168