2 * drivers/i2c/i2c-adap-ixp4xx.c
4 * Intel's IXP4xx XScale NPU chipsets (IXP420, 421, 422, 425) do not have
5 * an on board I2C controller but provide 16 GPIO pins that are often
6 * used to create an I2C bus. This driver provides an i2c_adapter
7 * interface that plugs in under algo_bit and drives the GPIO pins
8 * as instructed by the alogorithm driver.
10 * Author: Deepak Saxena <dsaxena@plexity.net>
12 * Copyright (c) 2003-2004 MontaVista Software Inc.
14 * This file is licensed under the terms of the GNU General Public
15 * License version 2. This program is licensed "as is" without any
16 * warranty of any kind, whether express or implied.
18 * NOTE: Since different platforms will use different GPIO pins for
19 * I2C, this driver uses an IXP4xx-specific platform_data
20 * pointer to pass the GPIO numbers to the driver. This
21 * allows us to support all the different IXP4xx platforms
22 * w/o having to put #ifdefs in this driver.
24 * See arch/arm/mach-ixp4xx/ixdp425.c for an example of building a
25 * device list and filling in the ixp4xx_i2c_pins data structure
26 * that is passed as the platform_data to this driver.
29 #include <linux/kernel.h>
30 #include <linux/init.h>
31 #include <linux/device.h>
32 #include <linux/module.h>
33 #include <linux/i2c.h>
34 #include <linux/i2c-algo-bit.h>
36 #include <asm/hardware.h> /* Pick up IXP4xx-specific bits */
38 static struct device_driver ixp4xx_i2c_driver;
40 static inline int ixp4xx_scl_pin(void *data)
42 return ((struct ixp4xx_i2c_pins*)data)->scl_pin;
45 static inline int ixp4xx_sda_pin(void *data)
47 return ((struct ixp4xx_i2c_pins*)data)->sda_pin;
50 static void ixp4xx_bit_setscl(void *data, int val)
52 gpio_line_set(ixp4xx_scl_pin(data), 0);
53 gpio_line_config(ixp4xx_scl_pin(data),
54 val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT );
57 static void ixp4xx_bit_setsda(void *data, int val)
59 gpio_line_set(ixp4xx_sda_pin(data), 0);
60 gpio_line_config(ixp4xx_sda_pin(data),
61 val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT );
64 static int ixp4xx_bit_getscl(void *data)
68 gpio_line_config(ixp4xx_scl_pin(data), IXP4XX_GPIO_IN );
69 gpio_line_get(ixp4xx_scl_pin(data), &scl);
74 static int ixp4xx_bit_getsda(void *data)
78 gpio_line_config(ixp4xx_sda_pin(data), IXP4XX_GPIO_IN );
79 gpio_line_get(ixp4xx_sda_pin(data), &sda);
84 struct ixp4xx_i2c_data {
85 struct ixp4xx_i2c_pins *gpio_pins;
86 struct i2c_adapter adapter;
87 struct i2c_algo_bit_data algo_data;
90 static int ixp4xx_i2c_remove(struct device *dev)
92 struct platform_device *plat_dev = to_platform_device(dev);
93 struct ixp4xx_i2c_data *drv_data = dev_get_drvdata(&plat_dev->dev);
95 dev_set_drvdata(&plat_dev->dev, NULL);
97 i2c_bit_del_bus(&drv_data->adapter);
104 static int ixp4xx_i2c_probe(struct device *dev)
107 struct platform_device *plat_dev = to_platform_device(dev);
108 struct ixp4xx_i2c_pins *gpio = plat_dev->dev.platform_data;
109 struct ixp4xx_i2c_data *drv_data =
110 kmalloc(sizeof(struct ixp4xx_i2c_data), GFP_KERNEL);
115 memzero(drv_data, sizeof(struct ixp4xx_i2c_data));
116 drv_data->gpio_pins = gpio;
119 * We could make a lot of these structures static, but
120 * certain platforms may have multiple GPIO-based I2C
121 * buses for various device domains, so we need per-device
124 drv_data->algo_data.data = gpio;
125 drv_data->algo_data.setsda = ixp4xx_bit_setsda;
126 drv_data->algo_data.setscl = ixp4xx_bit_setscl;
127 drv_data->algo_data.getsda = ixp4xx_bit_getsda;
128 drv_data->algo_data.getscl = ixp4xx_bit_getscl;
129 drv_data->algo_data.udelay = 10;
130 drv_data->algo_data.mdelay = 10;
131 drv_data->algo_data.timeout = 100;
133 drv_data->adapter.id = I2C_HW_B_IXP4XX;
134 strlcpy(drv_data->adapter.name, ixp4xx_i2c_driver.name,
136 drv_data->adapter.algo_data = &drv_data->algo_data;
138 drv_data->adapter.dev.parent = &plat_dev->dev;
140 gpio_line_config(gpio->scl_pin, IXP4XX_GPIO_IN);
141 gpio_line_config(gpio->sda_pin, IXP4XX_GPIO_IN);
142 gpio_line_set(gpio->scl_pin, 0);
143 gpio_line_set(gpio->sda_pin, 0);
145 if ((err = i2c_bit_add_bus(&drv_data->adapter) != 0)) {
146 printk(KERN_ERR "ERROR: Could not install %s\n", dev->bus_id);
152 dev_set_drvdata(&plat_dev->dev, drv_data);
157 static struct device_driver ixp4xx_i2c_driver = {
158 .owner = THIS_MODULE,
159 .name = "IXP4XX-I2C",
160 .bus = &platform_bus_type,
161 .probe = ixp4xx_i2c_probe,
162 .remove = ixp4xx_i2c_remove,
165 static int __init ixp4xx_i2c_init(void)
167 return driver_register(&ixp4xx_i2c_driver);
170 static void __exit ixp4xx_i2c_exit(void)
172 driver_unregister(&ixp4xx_i2c_driver);
175 module_init(ixp4xx_i2c_init);
176 module_exit(ixp4xx_i2c_exit);
178 MODULE_DESCRIPTION("GPIO-based I2C adapter for IXP4xx systems");
179 MODULE_LICENSE("GPL");
180 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");