Commit | Line | Data |
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1c23af90 HS |
1 | /* |
2 | * Bitbanging I2C bus driver using the GPIO API | |
3 | * | |
4 | * Copyright (C) 2007 Atmel Corporation | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | */ | |
10 | #include <linux/i2c.h> | |
11 | #include <linux/i2c-algo-bit.h> | |
12 | #include <linux/i2c-gpio.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/module.h> | |
5a0e3ad6 | 15 | #include <linux/slab.h> |
1c23af90 HS |
16 | #include <linux/platform_device.h> |
17 | ||
18 | #include <asm/gpio.h> | |
19 | ||
20 | /* Toggle SDA by changing the direction of the pin */ | |
21 | static void i2c_gpio_setsda_dir(void *data, int state) | |
22 | { | |
23 | struct i2c_gpio_platform_data *pdata = data; | |
24 | ||
25 | if (state) | |
26 | gpio_direction_input(pdata->sda_pin); | |
27 | else | |
28 | gpio_direction_output(pdata->sda_pin, 0); | |
29 | } | |
30 | ||
31 | /* | |
32 | * Toggle SDA by changing the output value of the pin. This is only | |
33 | * valid for pins configured as open drain (i.e. setting the value | |
34 | * high effectively turns off the output driver.) | |
35 | */ | |
36 | static void i2c_gpio_setsda_val(void *data, int state) | |
37 | { | |
38 | struct i2c_gpio_platform_data *pdata = data; | |
39 | ||
40 | gpio_set_value(pdata->sda_pin, state); | |
41 | } | |
42 | ||
43 | /* Toggle SCL by changing the direction of the pin. */ | |
44 | static void i2c_gpio_setscl_dir(void *data, int state) | |
45 | { | |
46 | struct i2c_gpio_platform_data *pdata = data; | |
47 | ||
48 | if (state) | |
49 | gpio_direction_input(pdata->scl_pin); | |
50 | else | |
51 | gpio_direction_output(pdata->scl_pin, 0); | |
52 | } | |
53 | ||
54 | /* | |
55 | * Toggle SCL by changing the output value of the pin. This is used | |
56 | * for pins that are configured as open drain and for output-only | |
57 | * pins. The latter case will break the i2c protocol, but it will | |
58 | * often work in practice. | |
59 | */ | |
60 | static void i2c_gpio_setscl_val(void *data, int state) | |
61 | { | |
62 | struct i2c_gpio_platform_data *pdata = data; | |
63 | ||
64 | gpio_set_value(pdata->scl_pin, state); | |
65 | } | |
66 | ||
4d6ceed4 | 67 | static int i2c_gpio_getsda(void *data) |
1c23af90 HS |
68 | { |
69 | struct i2c_gpio_platform_data *pdata = data; | |
70 | ||
71 | return gpio_get_value(pdata->sda_pin); | |
72 | } | |
73 | ||
4d6ceed4 | 74 | static int i2c_gpio_getscl(void *data) |
1c23af90 HS |
75 | { |
76 | struct i2c_gpio_platform_data *pdata = data; | |
77 | ||
78 | return gpio_get_value(pdata->scl_pin); | |
79 | } | |
80 | ||
1efe7c55 | 81 | static int __devinit i2c_gpio_probe(struct platform_device *pdev) |
1c23af90 HS |
82 | { |
83 | struct i2c_gpio_platform_data *pdata; | |
84 | struct i2c_algo_bit_data *bit_data; | |
85 | struct i2c_adapter *adap; | |
86 | int ret; | |
87 | ||
88 | pdata = pdev->dev.platform_data; | |
89 | if (!pdata) | |
90 | return -ENXIO; | |
91 | ||
92 | ret = -ENOMEM; | |
93 | adap = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL); | |
94 | if (!adap) | |
95 | goto err_alloc_adap; | |
96 | bit_data = kzalloc(sizeof(struct i2c_algo_bit_data), GFP_KERNEL); | |
97 | if (!bit_data) | |
98 | goto err_alloc_bit_data; | |
99 | ||
100 | ret = gpio_request(pdata->sda_pin, "sda"); | |
101 | if (ret) | |
102 | goto err_request_sda; | |
103 | ret = gpio_request(pdata->scl_pin, "scl"); | |
104 | if (ret) | |
105 | goto err_request_scl; | |
106 | ||
107 | if (pdata->sda_is_open_drain) { | |
108 | gpio_direction_output(pdata->sda_pin, 1); | |
109 | bit_data->setsda = i2c_gpio_setsda_val; | |
110 | } else { | |
111 | gpio_direction_input(pdata->sda_pin); | |
112 | bit_data->setsda = i2c_gpio_setsda_dir; | |
113 | } | |
114 | ||
115 | if (pdata->scl_is_open_drain || pdata->scl_is_output_only) { | |
116 | gpio_direction_output(pdata->scl_pin, 1); | |
117 | bit_data->setscl = i2c_gpio_setscl_val; | |
118 | } else { | |
119 | gpio_direction_input(pdata->scl_pin); | |
120 | bit_data->setscl = i2c_gpio_setscl_dir; | |
121 | } | |
122 | ||
123 | if (!pdata->scl_is_output_only) | |
124 | bit_data->getscl = i2c_gpio_getscl; | |
125 | bit_data->getsda = i2c_gpio_getsda; | |
126 | ||
127 | if (pdata->udelay) | |
128 | bit_data->udelay = pdata->udelay; | |
129 | else if (pdata->scl_is_output_only) | |
130 | bit_data->udelay = 50; /* 10 kHz */ | |
131 | else | |
132 | bit_data->udelay = 5; /* 100 kHz */ | |
133 | ||
134 | if (pdata->timeout) | |
135 | bit_data->timeout = pdata->timeout; | |
136 | else | |
137 | bit_data->timeout = HZ / 10; /* 100 ms */ | |
138 | ||
139 | bit_data->data = pdata; | |
140 | ||
141 | adap->owner = THIS_MODULE; | |
142 | snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id); | |
143 | adap->algo_data = bit_data; | |
3401b2ff | 144 | adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD; |
1c23af90 HS |
145 | adap->dev.parent = &pdev->dev; |
146 | ||
7e69c3ac AN |
147 | /* |
148 | * If "dev->id" is negative we consider it as zero. | |
149 | * The reason to do so is to avoid sysfs names that only make | |
150 | * sense when there are multiple adapters. | |
151 | */ | |
9a3180e7 | 152 | adap->nr = (pdev->id != -1) ? pdev->id : 0; |
7e69c3ac | 153 | ret = i2c_bit_add_numbered_bus(adap); |
1c23af90 HS |
154 | if (ret) |
155 | goto err_add_bus; | |
156 | ||
157 | platform_set_drvdata(pdev, adap); | |
158 | ||
159 | dev_info(&pdev->dev, "using pins %u (SDA) and %u (SCL%s)\n", | |
160 | pdata->sda_pin, pdata->scl_pin, | |
161 | pdata->scl_is_output_only | |
162 | ? ", no clock stretching" : ""); | |
163 | ||
164 | return 0; | |
165 | ||
166 | err_add_bus: | |
167 | gpio_free(pdata->scl_pin); | |
168 | err_request_scl: | |
169 | gpio_free(pdata->sda_pin); | |
170 | err_request_sda: | |
171 | kfree(bit_data); | |
172 | err_alloc_bit_data: | |
173 | kfree(adap); | |
174 | err_alloc_adap: | |
175 | return ret; | |
176 | } | |
177 | ||
1efe7c55 | 178 | static int __devexit i2c_gpio_remove(struct platform_device *pdev) |
1c23af90 HS |
179 | { |
180 | struct i2c_gpio_platform_data *pdata; | |
181 | struct i2c_adapter *adap; | |
182 | ||
183 | adap = platform_get_drvdata(pdev); | |
184 | pdata = pdev->dev.platform_data; | |
185 | ||
186 | i2c_del_adapter(adap); | |
187 | gpio_free(pdata->scl_pin); | |
188 | gpio_free(pdata->sda_pin); | |
189 | kfree(adap->algo_data); | |
190 | kfree(adap); | |
191 | ||
192 | return 0; | |
193 | } | |
194 | ||
195 | static struct platform_driver i2c_gpio_driver = { | |
196 | .driver = { | |
197 | .name = "i2c-gpio", | |
198 | .owner = THIS_MODULE, | |
199 | }, | |
1efe7c55 BD |
200 | .probe = i2c_gpio_probe, |
201 | .remove = __devexit_p(i2c_gpio_remove), | |
1c23af90 HS |
202 | }; |
203 | ||
204 | static int __init i2c_gpio_init(void) | |
205 | { | |
206 | int ret; | |
207 | ||
1efe7c55 | 208 | ret = platform_driver_register(&i2c_gpio_driver); |
1c23af90 HS |
209 | if (ret) |
210 | printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret); | |
211 | ||
212 | return ret; | |
213 | } | |
b8680784 | 214 | subsys_initcall(i2c_gpio_init); |
1c23af90 HS |
215 | |
216 | static void __exit i2c_gpio_exit(void) | |
217 | { | |
218 | platform_driver_unregister(&i2c_gpio_driver); | |
219 | } | |
220 | module_exit(i2c_gpio_exit); | |
221 | ||
222 | MODULE_AUTHOR("Haavard Skinnemoen <hskinnemoen@atmel.com>"); | |
223 | MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver"); | |
224 | MODULE_LICENSE("GPL"); | |
add8eda7 | 225 | MODULE_ALIAS("platform:i2c-gpio"); |