1 /*
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
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 <mach/hardware.h> /* Pick up IXP2000-specific bits */
37 #include <mach/gpio.h>
38
39 static inline int ixp2000_scl_pin(void *data)
40 {
41 return ((struct ixp2000_i2c_pins*)data)->scl_pin;
42 }
43
44 static inline int ixp2000_sda_pin(void *data)
45 {
46 return ((struct ixp2000_i2c_pins*)data)->sda_pin;
47 }
48
49
50 static void ixp2000_bit_setscl(void *data, int val)
51 {
52 int i = 5000;
53
54 if (val) {
55 gpio_line_config(ixp2000_scl_pin(data), GPIO_IN);
56 while(!gpio_line_get(ixp2000_scl_pin(data)) && i--);
57 } else {
58 gpio_line_config(ixp2000_scl_pin(data), GPIO_OUT);
59 }
60 }
61
62 static void ixp2000_bit_setsda(void *data, int val)
63 {
64 if (val) {
65 gpio_line_config(ixp2000_sda_pin(data), GPIO_IN);
66 } else {
67 gpio_line_config(ixp2000_sda_pin(data), GPIO_OUT);
68 }
69 }
70
71 static int ixp2000_bit_getscl(void *data)
72 {
73 return gpio_line_get(ixp2000_scl_pin(data));
74 }
75
76 static int ixp2000_bit_getsda(void *data)
77 {
78 return gpio_line_get(ixp2000_sda_pin(data));
79 }
80
81 struct ixp2000_i2c_data {
82 struct ixp2000_i2c_pins *gpio_pins;
83 struct i2c_adapter adapter;
84 struct i2c_algo_bit_data algo_data;
85 };
86
87 static int ixp2000_i2c_remove(struct platform_device *plat_dev)
88 {
89 struct ixp2000_i2c_data *drv_data = platform_get_drvdata(plat_dev);
90
91 platform_set_drvdata(plat_dev, NULL);
92
93 i2c_del_adapter(&drv_data->adapter);
94
95 kfree(drv_data);
96
97 return 0;
98 }
99
100 static int ixp2000_i2c_probe(struct platform_device *plat_dev)
101 {
102 int err;
103 struct ixp2000_i2c_pins *gpio = plat_dev->dev.platform_data;
104 struct ixp2000_i2c_data *drv_data =
105 kzalloc(sizeof(struct ixp2000_i2c_data), GFP_KERNEL);
106
107 if (!drv_data)
108 return -ENOMEM;
109 drv_data->gpio_pins = gpio;
110
111 drv_data->algo_data.data = gpio;
112 drv_data->algo_data.setsda = ixp2000_bit_setsda;
113 drv_data->algo_data.setscl = ixp2000_bit_setscl;
114 drv_data->algo_data.getsda = ixp2000_bit_getsda;
115 drv_data->algo_data.getscl = ixp2000_bit_getscl;
116 drv_data->algo_data.udelay = 6;
117 drv_data->algo_data.timeout = HZ;
118
119 strlcpy(drv_data->adapter.name, plat_dev->dev.driver->name,
120 sizeof(drv_data->adapter.name));
121 drv_data->adapter.algo_data = &drv_data->algo_data,
122
123 drv_data->adapter.dev.parent = &plat_dev->dev;
124
125 gpio_line_config(gpio->sda_pin, GPIO_IN);
126 gpio_line_config(gpio->scl_pin, GPIO_IN);
127 gpio_line_set(gpio->scl_pin, 0);
128 gpio_line_set(gpio->sda_pin, 0);
129
130 if ((err = i2c_bit_add_bus(&drv_data->adapter)) != 0) {
131 dev_err(&plat_dev->dev, "Could not install, error %d\n", err);
132 kfree(drv_data);
133 return err;
134 }
135
136 platform_set_drvdata(plat_dev, drv_data);
137
138 return 0;
139 }
140
141 static struct platform_driver ixp2000_i2c_driver = {
142 .probe = ixp2000_i2c_probe,
143 .remove = ixp2000_i2c_remove,
144 .driver = {
145 .name = "IXP2000-I2C",
146 .owner = THIS_MODULE,
147 },
148 };
149
150 static int __init ixp2000_i2c_init(void)
151 {
152 return platform_driver_register(&ixp2000_i2c_driver);
153 }
154
155 static void __exit ixp2000_i2c_exit(void)
156 {
157 platform_driver_unregister(&ixp2000_i2c_driver);
158 }
159
160 module_init(ixp2000_i2c_init);
161 module_exit(ixp2000_i2c_exit);
162
163 MODULE_AUTHOR ("Deepak Saxena <dsaxena@plexity.net>");
164 MODULE_DESCRIPTION("IXP2000 GPIO-based I2C bus driver");
165 MODULE_LICENSE("GPL");
166 MODULE_ALIAS("platform:IXP2000-I2C");
167
168
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