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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#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>
35
36#include <asm/hardware.h> /* Pick up IXP42000-specific bits */
37
38static inline int ixp2000_scl_pin(void *data)
39{
40 return ((struct ixp2000_i2c_pins*)data)->scl_pin;
41}
42
43static inline int ixp2000_sda_pin(void *data)
44{
45 return ((struct ixp2000_i2c_pins*)data)->sda_pin;
46}
47
48
49static void ixp2000_bit_setscl(void *data, int val)
50{
51 int i = 5000;
52
53 if (val) {
54 gpio_line_config(ixp2000_scl_pin(data), GPIO_IN);
55 while(!gpio_line_get(ixp2000_scl_pin(data)) && i--);
56 } else {
57 gpio_line_config(ixp2000_scl_pin(data), GPIO_OUT);
58 }
59}
60
61static void ixp2000_bit_setsda(void *data, int val)
62{
63 if (val) {
64 gpio_line_config(ixp2000_sda_pin(data), GPIO_IN);
65 } else {
66 gpio_line_config(ixp2000_sda_pin(data), GPIO_OUT);
67 }
68}
69
70static int ixp2000_bit_getscl(void *data)
71{
72 return gpio_line_get(ixp2000_scl_pin(data));
73}
74
75static int ixp2000_bit_getsda(void *data)
76{
77 return gpio_line_get(ixp2000_sda_pin(data));
78}
79
80struct ixp2000_i2c_data {
81 struct ixp2000_i2c_pins *gpio_pins;
82 struct i2c_adapter adapter;
83 struct i2c_algo_bit_data algo_data;
84};
85
86static int ixp2000_i2c_remove(struct device *dev)
87{
88 struct platform_device *plat_dev = to_platform_device(dev);
89 struct ixp2000_i2c_data *drv_data = dev_get_drvdata(&plat_dev->dev);
90
91 dev_set_drvdata(&plat_dev->dev, NULL);
92
93 i2c_bit_del_bus(&drv_data->adapter);
94
95 kfree(drv_data);
96
97 return 0;
98}
99
100static int ixp2000_i2c_probe(struct device *dev)
101{
102 int err;
103 struct platform_device *plat_dev = to_platform_device(dev);
104 struct ixp2000_i2c_pins *gpio = plat_dev->dev.platform_data;
105 struct ixp2000_i2c_data *drv_data =
106 kmalloc(sizeof(struct ixp2000_i2c_data), GFP_KERNEL);
107
108 if (!drv_data)
109 return -ENOMEM;
110 memzero(drv_data, sizeof(*drv_data));
111 drv_data->gpio_pins = gpio;
112
113 drv_data->algo_data.data = gpio;
114 drv_data->algo_data.setsda = ixp2000_bit_setsda;
115 drv_data->algo_data.setscl = ixp2000_bit_setscl;
116 drv_data->algo_data.getsda = ixp2000_bit_getsda;
117 drv_data->algo_data.getscl = ixp2000_bit_getscl;
118 drv_data->algo_data.udelay = 6;
119 drv_data->algo_data.mdelay = 6;
120 drv_data->algo_data.timeout = 100;
121
122 drv_data->adapter.id = I2C_HW_B_IXP2000,
123 drv_data->adapter.algo_data = &drv_data->algo_data,
124
125 drv_data->adapter.dev.parent = &plat_dev->dev;
126
127 gpio_line_config(gpio->sda_pin, GPIO_IN);
128 gpio_line_config(gpio->scl_pin, GPIO_IN);
129 gpio_line_set(gpio->scl_pin, 0);
130 gpio_line_set(gpio->sda_pin, 0);
131
132 if ((err = i2c_bit_add_bus(&drv_data->adapter)) != 0) {
133 dev_err(dev, "Could not install, error %d\n", err);
134 kfree(drv_data);
135 return err;
136 }
137
138 dev_set_drvdata(&plat_dev->dev, drv_data);
139
140 return 0;
141}
142
143static struct device_driver ixp2000_i2c_driver = {
144 .name = "IXP2000-I2C",
145 .bus = &platform_bus_type,
146 .probe = ixp2000_i2c_probe,
147 .remove = ixp2000_i2c_remove,
148};
149
150static int __init ixp2000_i2c_init(void)
151{
152 return driver_register(&ixp2000_i2c_driver);
153}
154
155static void __exit ixp2000_i2c_exit(void)
156{
157 driver_unregister(&ixp2000_i2c_driver);
158}
159
160module_init(ixp2000_i2c_init);
161module_exit(ixp2000_i2c_exit);
162
163MODULE_AUTHOR ("Deepak Saxena <dsaxena@plexity.net>");
164MODULE_DESCRIPTION("IXP2000 GPIO-based I2C bus driver");
165MODULE_LICENSE("GPL");
166