/*
* drivers/i2c/i2c-adap-ixp4xx.c
*
* Intel's IXP4xx XScale NPU chipsets (IXP420, 421, 422, 425) do not have
* an on board I2C controller but provide 16 GPIO pins that are often
* used to create an I2C bus. This driver provides an i2c_adapter
* interface that plugs in under algo_bit and drives the GPIO pins
* as instructed by the alogorithm driver.
*
* Author: Deepak Saxena <dsaxena@plexity.net>
*
* Copyright (c) 2003-2004 MontaVista Software Inc.
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*
* NOTE: Since different platforms will use different GPIO pins for
* I2C, this driver uses an IXP4xx-specific platform_data
* pointer to pass the GPIO numbers to the driver. This
* allows us to support all the different IXP4xx platforms
* w/o having to put #ifdefs in this driver.
*
* See arch/arm/mach-ixp4xx/ixdp425.c for an example of building a
* device list and filling in the ixp4xx_i2c_pins data structure
* that is passed as the platform_data to this driver.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <asm/hardware.h> /* Pick up IXP4xx-specific bits */
static inline int ixp4xx_scl_pin(void *data)
{
return ((struct ixp4xx_i2c_pins*)data)->scl_pin;
}
static inline int ixp4xx_sda_pin(void *data)
{
return ((struct ixp4xx_i2c_pins*)data)->sda_pin;
}
static void ixp4xx_bit_setscl(void *data, int val)
{
gpio_line_set(ixp4xx_scl_pin(data), 0);
gpio_line_config(ixp4xx_scl_pin(data),
val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT );
}
static void ixp4xx_bit_setsda(void *data, int val)
{
gpio_line_set(ixp4xx_sda_pin(data), 0);
gpio_line_config(ixp4xx_sda_pin(data),
val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT );
}
static int ixp4xx_bit_getscl(void *data)
{
int scl;
gpio_line_config(ixp4xx_scl_pin(data), IXP4XX_GPIO_IN );
gpio_line_get(ixp4xx_scl_pin(data), &scl);
return scl;
}
static int ixp4xx_bit_getsda(void *data)
{
int sda;
gpio_line_config(ixp4xx_sda_pin(data), IXP4XX_GPIO_IN );
gpio_line_get(ixp4xx_sda_pin(data), &sda);
return sda;
}
struct ixp4xx_i2c_data {
struct ixp4xx_i2c_pins *gpio_pins;
struct i2c_adapter adapter;
struct i2c_algo_bit_data algo_data;
};
static int ixp4xx_i2c_remove(struct device *dev)
{
struct platform_device *plat_dev = to_platform_device(dev);
struct ixp4xx_i2c_data *drv_data = dev_get_drvdata(&plat_dev->dev);
dev_set_drvdata(&plat_dev->dev, NULL);
i2c_bit_del_bus(&drv_data->adapter);
kfree(drv_data);
return 0;
}
static int ixp4xx_i2c_probe(struct device *dev)
{
int err;
struct platform_device *plat_dev = to_platform_device(dev);
struct ixp4xx_i2c_pins *gpio = plat_dev->dev.platform_data;
struct ixp4xx_i2c_data *drv_data =
kmalloc(sizeof(struct ixp4xx_i2c_data), GFP_KERNEL);
if(!drv_data)
return -ENOMEM;
memzero(drv_data, sizeof(struct ixp4xx_i2c_data));
drv_data->gpio_pins = gpio;
/*
* We could make a lot of these structures static, but
* certain platforms may have multiple GPIO-based I2C
* buses for various device domains, so we need per-device
* algo_data->data.
*/
drv_data->algo_data.data = gpio;
drv_data->algo_data.setsda = ixp4xx_bit_setsda;
drv_data->algo_data.setscl = ixp4xx_bit_setscl;
drv_data->algo_data.getsda = ixp4xx_bit_getsda;
drv_data->algo_data.getscl = ixp4xx_bit_getscl;
drv_data->algo_data.udelay = 10;
drv_data->algo_data.mdelay = 10;
drv_data->algo_data.timeout = 100;
drv_data->adapter.id = I2C_HW_B_IXP4XX;
drv_data->adapter.algo_data = &drv_data->algo_data;
drv_data->adapter.dev.parent = &plat_dev->dev;
gpio_line_config(gpio->scl_pin, IXP4XX_GPIO_IN);
gpio_line_config(gpio->sda_pin, IXP4XX_GPIO_IN);
gpio_line_set(gpio->scl_pin, 0);
gpio_line_set(gpio->sda_pin, 0);
if ((err = i2c_bit_add_bus(&drv_data->adapter) != 0)) {
printk(KERN_ERR "ERROR: Could not install %s\n", dev->bus_id);
kfree(drv_data);
return err;
}
dev_set_drvdata(&plat_dev->dev, drv_data);
return 0;
}
static struct device_driver ixp4xx_i2c_driver = {
.name = "IXP4XX-I2C",
.bus = &platform_bus_type,
.probe = ixp4xx_i2c_probe,
.remove = ixp4xx_i2c_remove,
};
static int __init ixp4xx_i2c_init(void)
{
return driver_register(&ixp4xx_i2c_driver);
}
static void __exit ixp4xx_i2c_exit(void)
{
driver_unregister(&ixp4xx_i2c_driver);
}
module_init(ixp4xx_i2c_init);
module_exit(ixp4xx_i2c_exit);
MODULE_DESCRIPTION("GPIO-based I2C adapter for IXP4xx systems");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
