1/*
2 * drivers/i2c/busses/i2c-ixp4xx.c
3 *
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.
9 *
10 * Author: Deepak Saxena <dsaxena@plexity.net>
11 *
12 * Copyright (c) 2003-2004 MontaVista Software Inc.
13 *
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.
17 *
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.
23 *
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.
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
36#include <asm/hardware.h>	/* Pick up IXP4xx-specific bits */
37
38static inline int ixp4xx_scl_pin(void *data)
39{
40	return ((struct ixp4xx_i2c_pins*)data)->scl_pin;
41}
42
43static inline int ixp4xx_sda_pin(void *data)
44{
45	return ((struct ixp4xx_i2c_pins*)data)->sda_pin;
46}
47
48static void ixp4xx_bit_setscl(void *data, int val)
49{
50	gpio_line_set(ixp4xx_scl_pin(data), 0);
51	gpio_line_config(ixp4xx_scl_pin(data),
52		val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT );
53}
54
55static void ixp4xx_bit_setsda(void *data, int val)
56{
57	gpio_line_set(ixp4xx_sda_pin(data), 0);
58	gpio_line_config(ixp4xx_sda_pin(data),
59		val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT );
60}
61
62static int ixp4xx_bit_getscl(void *data)
63{
64	int scl;
65
66	gpio_line_config(ixp4xx_scl_pin(data), IXP4XX_GPIO_IN );
67	gpio_line_get(ixp4xx_scl_pin(data), &scl);
68
69	return scl;
70}
71
72static int ixp4xx_bit_getsda(void *data)
73{
74	int sda;
75
76	gpio_line_config(ixp4xx_sda_pin(data), IXP4XX_GPIO_IN );
77	gpio_line_get(ixp4xx_sda_pin(data), &sda);
78
79	return sda;
80}
81
82struct ixp4xx_i2c_data {
83	struct ixp4xx_i2c_pins *gpio_pins;
84	struct i2c_adapter adapter;
85	struct i2c_algo_bit_data algo_data;
86};
87
88static int ixp4xx_i2c_remove(struct platform_device *plat_dev)
89{
90	struct ixp4xx_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 ixp4xx_i2c_probe(struct platform_device *plat_dev)
102{
103	int err;
104	struct ixp4xx_i2c_pins *gpio = plat_dev->dev.platform_data;
105	struct ixp4xx_i2c_data *drv_data =
106		kzalloc(sizeof(struct ixp4xx_i2c_data), GFP_KERNEL);
107
108	if(!drv_data)
109		return -ENOMEM;
110
111	drv_data->gpio_pins = gpio;
112
113	/*
114	 * We could make a lot of these structures static, but
115	 * certain platforms may have multiple GPIO-based I2C
116	 * buses for various device domains, so we need per-device
117	 * algo_data->data.
118	 */
119	drv_data->algo_data.data = gpio;
120	drv_data->algo_data.setsda = ixp4xx_bit_setsda;
121	drv_data->algo_data.setscl = ixp4xx_bit_setscl;
122	drv_data->algo_data.getsda = ixp4xx_bit_getsda;
123	drv_data->algo_data.getscl = ixp4xx_bit_getscl;
124	drv_data->algo_data.udelay = 10;
125	drv_data->algo_data.timeout = 100;
126
127	drv_data->adapter.id = I2C_HW_B_IXP4XX;
128	drv_data->adapter.class = I2C_CLASS_HWMON;
129	strlcpy(drv_data->adapter.name, plat_dev->dev.driver->name,
130		sizeof(drv_data->adapter.name));
131	drv_data->adapter.algo_data = &drv_data->algo_data;
132
133	drv_data->adapter.dev.parent = &plat_dev->dev;
134
135	gpio_line_config(gpio->scl_pin, IXP4XX_GPIO_IN);
136	gpio_line_config(gpio->sda_pin, IXP4XX_GPIO_IN);
137	gpio_line_set(gpio->scl_pin, 0);
138	gpio_line_set(gpio->sda_pin, 0);
139
140	err = i2c_bit_add_bus(&drv_data->adapter);
141	if (err) {
142		printk(KERN_ERR "ERROR: Could not install %s\n", plat_dev->dev.bus_id);
143
144		kfree(drv_data);
145		return err;
146	}
147
148	platform_set_drvdata(plat_dev, drv_data);
149
150	return 0;
151}
152
153static struct platform_driver ixp4xx_i2c_driver = {
154	.probe		= ixp4xx_i2c_probe,
155	.remove		= ixp4xx_i2c_remove,
156	.driver		= {
157		.name	= "IXP4XX-I2C",
158		.owner	= THIS_MODULE,
159	},
160};
161
162static int __init ixp4xx_i2c_init(void)
163{
164	return platform_driver_register(&ixp4xx_i2c_driver);
165}
166
167static void __exit ixp4xx_i2c_exit(void)
168{
169	platform_driver_unregister(&ixp4xx_i2c_driver);
170}
171
172module_init(ixp4xx_i2c_init);
173module_exit(ixp4xx_i2c_exit);
174
175MODULE_DESCRIPTION("GPIO-based I2C adapter for IXP4xx systems");
176MODULE_LICENSE("GPL");
177MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
178