Commit 238c5a50 authored by Deepak Saxena's avatar Deepak Saxena

[PATCH] I2C: Support for IXP42x GPIO-based I2C

Following is an updated patch to add support for using the GPIO lines
on an Intel IXP42x SOC for I2C.  Changes since last patch include:

- Cleanups as per Jean Delvare's comments

- Rename functions as 42x instead of 425

- Change the comments at the top of the file to better reflect the
  purpose of this driver.

This code has been tested with the eeprom client driver and worked
w/o any problems.
parent 1b1bbe1d
......@@ -144,6 +144,17 @@ config I2C_ITE
This support is also available as a module. If so, the module
will be called i2c-ite.
config I2C_IXP42X
tristate "IXP42x GPIO-Based I2C Interface"
depends on I2C && ARCH_IXP425
select I2C_ALGOBIT
help
Say Y here if you have an Intel IXP42x(420,421,422,425) based
system and are using GPIO lines for an I2C bus.
This support is also available as a module. If so, the module
will be called i2c-ixp42x.
config I2C_KEYWEST
tristate "Powermac Keywest I2C interface"
depends on I2C && PPC_PMAC
......
......@@ -15,6 +15,7 @@ obj-$(CONFIG_I2C_IBM_IIC) += i2c-ibm_iic.o
obj-$(CONFIG_I2C_IOP3XX) += i2c-iop3xx.o
obj-$(CONFIG_I2C_ISA) += i2c-isa.o
obj-$(CONFIG_I2C_ITE) += i2c-ite.o
obj-$(CONFIG_I2C_IXP42X) += i2c-ixp42x.o
obj-$(CONFIG_I2C_KEYWEST) += i2c-keywest.o
obj-$(CONFIG_I2C_NFORCE2) += i2c-nforce2.o
obj-$(CONFIG_I2C_PHILIPSPAR) += i2c-philips-par.o
......
/*
* drivers/i2c/i2c-adap-ixp42x.c
*
* Intel's IXP42x 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 IXP42x-specific platform_data
* pointer to pass the GPIO numbers to the driver. This
* allows us to support all the different IXP42x platforms
* w/o having to put #ifdefs in this driver.
*
* See arch/arm/mach-ixp42x/ixdp425.c for an example of building a
* device list and filling in the ixp42x_i2c_pins data structure
* that is passed as the platform_data to this driver.
*/
#include <linux/config.h>
#ifdef CONFIG_I2C_DEBUG_BUS
#define DEBUG 1
#endif
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <asm/hardware.h> /* Pick up IXP42x-specific bits */
static inline int ixp42x_scl_pin(void *data)
{
return ((struct ixp42x_i2c_pins*)data)->scl_pin;
}
static inline int ixp42x_sda_pin(void *data)
{
return ((struct ixp42x_i2c_pins*)data)->sda_pin;
}
static void ixp42x_bit_setscl(void *data, int val)
{
gpio_line_set(ixp42x_scl_pin(data), 0);
gpio_line_config(ixp42x_scl_pin(data),
val ? IXP425_GPIO_IN : IXP425_GPIO_OUT );
}
static void ixp42x_bit_setsda(void *data, int val)
{
gpio_line_set(ixp42x_sda_pin(data), 0);
gpio_line_config(ixp42x_sda_pin(data),
val ? IXP425_GPIO_IN : IXP425_GPIO_OUT );
}
static int ixp42x_bit_getscl(void *data)
{
int scl;
gpio_line_config(ixp42x_scl_pin(data), IXP425_GPIO_IN );
gpio_line_get(ixp42x_scl_pin(data), &scl);
return scl;
}
static int ixp42x_bit_getsda(void *data)
{
int sda;
gpio_line_config(ixp42x_sda_pin(data), IXP425_GPIO_IN );
gpio_line_get(ixp42x_sda_pin(data), &sda);
return sda;
}
struct ixp42x_i2c_data {
struct ixp42x_i2c_pins *gpio_pins;
struct i2c_adapter adapter;
struct i2c_algo_bit_data algo_data;
};
static int ixp42x_i2c_remove(struct device *dev)
{
struct platform_device *plat_dev = to_platform_device(dev);
struct ixp42x_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 ixp42x_i2c_probe(struct device *dev)
{
int err;
struct platform_device *plat_dev = to_platform_device(dev);
struct ixp42x_i2c_pins *gpio = plat_dev->dev.platform_data;
struct ixp42x_i2c_data *drv_data =
kmalloc(sizeof(struct ixp42x_i2c_data), GFP_KERNEL);
if(!drv_data)
return -ENOMEM;
memzero(drv_data, sizeof(struct ixp42x_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 = ixp42x_bit_setsda;
drv_data->algo_data.setscl = ixp42x_bit_setscl;
drv_data->algo_data.getsda = ixp42x_bit_getsda;
drv_data->algo_data.getscl = ixp42x_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_IXP425,
drv_data->adapter.algo_data = &drv_data->algo_data,
drv_data->adapter.dev.parent = &plat_dev->dev;
gpio_line_config(gpio->scl_pin, IXP425_GPIO_IN);
gpio_line_config(gpio->sda_pin, IXP425_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 ixp42x_i2c_driver = {
.name = "IXP42X-I2C",
.bus = &platform_bus_type,
.probe = ixp42x_i2c_probe,
.remove = ixp42x_i2c_remove,
};
static int __init ixp42x_i2c_init(void)
{
return driver_register(&ixp42x_i2c_driver);
}
static void __exit ixp42x_i2c_exit(void)
{
driver_unregister(&ixp42x_i2c_driver);
}
module_init(ixp42x_i2c_init);
module_exit(ixp42x_i2c_exit);
MODULE_DESCRIPTION("GPIO-based I2C driver for IXP42x systems");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
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