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 | 16 | #include <linux/platform_device.h> |
8ffaa0f4 JCPV |
17 | #include <linux/gpio.h> |
18 | #include <linux/of_gpio.h> | |
19 | #include <linux/of_i2c.h> | |
20 | ||
21 | struct i2c_gpio_private_data { | |
22 | struct i2c_adapter adap; | |
23 | struct i2c_algo_bit_data bit_data; | |
24 | struct i2c_gpio_platform_data pdata; | |
25 | }; | |
1c23af90 HS |
26 | |
27 | /* Toggle SDA by changing the direction of the pin */ | |
28 | static void i2c_gpio_setsda_dir(void *data, int state) | |
29 | { | |
30 | struct i2c_gpio_platform_data *pdata = data; | |
31 | ||
32 | if (state) | |
33 | gpio_direction_input(pdata->sda_pin); | |
34 | else | |
35 | gpio_direction_output(pdata->sda_pin, 0); | |
36 | } | |
37 | ||
38 | /* | |
39 | * Toggle SDA by changing the output value of the pin. This is only | |
40 | * valid for pins configured as open drain (i.e. setting the value | |
41 | * high effectively turns off the output driver.) | |
42 | */ | |
43 | static void i2c_gpio_setsda_val(void *data, int state) | |
44 | { | |
45 | struct i2c_gpio_platform_data *pdata = data; | |
46 | ||
47 | gpio_set_value(pdata->sda_pin, state); | |
48 | } | |
49 | ||
50 | /* Toggle SCL by changing the direction of the pin. */ | |
51 | static void i2c_gpio_setscl_dir(void *data, int state) | |
52 | { | |
53 | struct i2c_gpio_platform_data *pdata = data; | |
54 | ||
55 | if (state) | |
56 | gpio_direction_input(pdata->scl_pin); | |
57 | else | |
58 | gpio_direction_output(pdata->scl_pin, 0); | |
59 | } | |
60 | ||
61 | /* | |
62 | * Toggle SCL by changing the output value of the pin. This is used | |
63 | * for pins that are configured as open drain and for output-only | |
64 | * pins. The latter case will break the i2c protocol, but it will | |
65 | * often work in practice. | |
66 | */ | |
67 | static void i2c_gpio_setscl_val(void *data, int state) | |
68 | { | |
69 | struct i2c_gpio_platform_data *pdata = data; | |
70 | ||
71 | gpio_set_value(pdata->scl_pin, state); | |
72 | } | |
73 | ||
4d6ceed4 | 74 | static int i2c_gpio_getsda(void *data) |
1c23af90 HS |
75 | { |
76 | struct i2c_gpio_platform_data *pdata = data; | |
77 | ||
78 | return gpio_get_value(pdata->sda_pin); | |
79 | } | |
80 | ||
4d6ceed4 | 81 | static int i2c_gpio_getscl(void *data) |
1c23af90 HS |
82 | { |
83 | struct i2c_gpio_platform_data *pdata = data; | |
84 | ||
85 | return gpio_get_value(pdata->scl_pin); | |
86 | } | |
87 | ||
1b295c83 JD |
88 | static int of_i2c_gpio_get_pins(struct device_node *np, |
89 | unsigned int *sda_pin, unsigned int *scl_pin) | |
8ffaa0f4 | 90 | { |
8ffaa0f4 JCPV |
91 | if (of_gpio_count(np) < 2) |
92 | return -ENODEV; | |
93 | ||
1b295c83 JD |
94 | *sda_pin = of_get_gpio(np, 0); |
95 | *scl_pin = of_get_gpio(np, 1); | |
8ffaa0f4 | 96 | |
1b295c83 | 97 | if (!gpio_is_valid(*sda_pin) || !gpio_is_valid(*scl_pin)) { |
8ffaa0f4 | 98 | pr_err("%s: invalid GPIO pins, sda=%d/scl=%d\n", |
1b295c83 | 99 | np->full_name, *sda_pin, *scl_pin); |
8ffaa0f4 JCPV |
100 | return -ENODEV; |
101 | } | |
102 | ||
1b295c83 JD |
103 | return 0; |
104 | } | |
105 | ||
106 | static void of_i2c_gpio_get_props(struct device_node *np, | |
107 | struct i2c_gpio_platform_data *pdata) | |
108 | { | |
109 | u32 reg; | |
110 | ||
8ffaa0f4 JCPV |
111 | of_property_read_u32(np, "i2c-gpio,delay-us", &pdata->udelay); |
112 | ||
113 | if (!of_property_read_u32(np, "i2c-gpio,timeout-ms", ®)) | |
114 | pdata->timeout = msecs_to_jiffies(reg); | |
115 | ||
116 | pdata->sda_is_open_drain = | |
117 | of_property_read_bool(np, "i2c-gpio,sda-open-drain"); | |
118 | pdata->scl_is_open_drain = | |
119 | of_property_read_bool(np, "i2c-gpio,scl-open-drain"); | |
120 | pdata->scl_is_output_only = | |
121 | of_property_read_bool(np, "i2c-gpio,scl-output-only"); | |
8ffaa0f4 JCPV |
122 | } |
123 | ||
0b255e92 | 124 | static int i2c_gpio_probe(struct platform_device *pdev) |
1c23af90 | 125 | { |
8ffaa0f4 | 126 | struct i2c_gpio_private_data *priv; |
1c23af90 HS |
127 | struct i2c_gpio_platform_data *pdata; |
128 | struct i2c_algo_bit_data *bit_data; | |
129 | struct i2c_adapter *adap; | |
1b295c83 | 130 | unsigned int sda_pin, scl_pin; |
1c23af90 HS |
131 | int ret; |
132 | ||
1b295c83 | 133 | /* First get the GPIO pins; if it fails, we'll defer the probe. */ |
8ffaa0f4 | 134 | if (pdev->dev.of_node) { |
1b295c83 JD |
135 | ret = of_i2c_gpio_get_pins(pdev->dev.of_node, |
136 | &sda_pin, &scl_pin); | |
8ffaa0f4 JCPV |
137 | if (ret) |
138 | return ret; | |
139 | } else { | |
140 | if (!pdev->dev.platform_data) | |
141 | return -ENXIO; | |
1b295c83 JD |
142 | pdata = pdev->dev.platform_data; |
143 | sda_pin = pdata->sda_pin; | |
144 | scl_pin = pdata->scl_pin; | |
8ffaa0f4 | 145 | } |
1c23af90 | 146 | |
1b295c83 JD |
147 | ret = gpio_request(sda_pin, "sda"); |
148 | if (ret) { | |
149 | if (ret == -EINVAL) | |
150 | ret = -EPROBE_DEFER; /* Try again later */ | |
1c23af90 | 151 | goto err_request_sda; |
1b295c83 JD |
152 | } |
153 | ret = gpio_request(scl_pin, "scl"); | |
154 | if (ret) { | |
155 | if (ret == -EINVAL) | |
156 | ret = -EPROBE_DEFER; /* Try again later */ | |
1c23af90 | 157 | goto err_request_scl; |
1b295c83 JD |
158 | } |
159 | ||
160 | priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); | |
161 | if (!priv) { | |
162 | ret = -ENOMEM; | |
163 | goto err_add_bus; | |
164 | } | |
165 | adap = &priv->adap; | |
166 | bit_data = &priv->bit_data; | |
167 | pdata = &priv->pdata; | |
168 | ||
169 | if (pdev->dev.of_node) { | |
170 | pdata->sda_pin = sda_pin; | |
171 | pdata->scl_pin = scl_pin; | |
172 | of_i2c_gpio_get_props(pdev->dev.of_node, pdata); | |
173 | } else { | |
174 | memcpy(pdata, pdev->dev.platform_data, sizeof(*pdata)); | |
175 | } | |
1c23af90 HS |
176 | |
177 | if (pdata->sda_is_open_drain) { | |
178 | gpio_direction_output(pdata->sda_pin, 1); | |
179 | bit_data->setsda = i2c_gpio_setsda_val; | |
180 | } else { | |
181 | gpio_direction_input(pdata->sda_pin); | |
182 | bit_data->setsda = i2c_gpio_setsda_dir; | |
183 | } | |
184 | ||
185 | if (pdata->scl_is_open_drain || pdata->scl_is_output_only) { | |
186 | gpio_direction_output(pdata->scl_pin, 1); | |
187 | bit_data->setscl = i2c_gpio_setscl_val; | |
188 | } else { | |
189 | gpio_direction_input(pdata->scl_pin); | |
190 | bit_data->setscl = i2c_gpio_setscl_dir; | |
191 | } | |
192 | ||
193 | if (!pdata->scl_is_output_only) | |
194 | bit_data->getscl = i2c_gpio_getscl; | |
195 | bit_data->getsda = i2c_gpio_getsda; | |
196 | ||
197 | if (pdata->udelay) | |
198 | bit_data->udelay = pdata->udelay; | |
199 | else if (pdata->scl_is_output_only) | |
200 | bit_data->udelay = 50; /* 10 kHz */ | |
201 | else | |
202 | bit_data->udelay = 5; /* 100 kHz */ | |
203 | ||
204 | if (pdata->timeout) | |
205 | bit_data->timeout = pdata->timeout; | |
206 | else | |
207 | bit_data->timeout = HZ / 10; /* 100 ms */ | |
208 | ||
209 | bit_data->data = pdata; | |
210 | ||
211 | adap->owner = THIS_MODULE; | |
58a7371a BS |
212 | if (pdev->dev.of_node) |
213 | strlcpy(adap->name, dev_name(&pdev->dev), sizeof(adap->name)); | |
214 | else | |
215 | snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id); | |
216 | ||
1c23af90 | 217 | adap->algo_data = bit_data; |
3401b2ff | 218 | adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD; |
1c23af90 | 219 | adap->dev.parent = &pdev->dev; |
8ffaa0f4 | 220 | adap->dev.of_node = pdev->dev.of_node; |
1c23af90 | 221 | |
44454baa | 222 | adap->nr = pdev->id; |
7e69c3ac | 223 | ret = i2c_bit_add_numbered_bus(adap); |
1c23af90 HS |
224 | if (ret) |
225 | goto err_add_bus; | |
226 | ||
8ffaa0f4 JCPV |
227 | of_i2c_register_devices(adap); |
228 | ||
229 | platform_set_drvdata(pdev, priv); | |
1c23af90 HS |
230 | |
231 | dev_info(&pdev->dev, "using pins %u (SDA) and %u (SCL%s)\n", | |
232 | pdata->sda_pin, pdata->scl_pin, | |
233 | pdata->scl_is_output_only | |
234 | ? ", no clock stretching" : ""); | |
235 | ||
236 | return 0; | |
237 | ||
238 | err_add_bus: | |
1b295c83 | 239 | gpio_free(scl_pin); |
1c23af90 | 240 | err_request_scl: |
1b295c83 | 241 | gpio_free(sda_pin); |
1c23af90 | 242 | err_request_sda: |
1c23af90 HS |
243 | return ret; |
244 | } | |
245 | ||
0b255e92 | 246 | static int i2c_gpio_remove(struct platform_device *pdev) |
1c23af90 | 247 | { |
8ffaa0f4 | 248 | struct i2c_gpio_private_data *priv; |
1c23af90 HS |
249 | struct i2c_gpio_platform_data *pdata; |
250 | struct i2c_adapter *adap; | |
251 | ||
8ffaa0f4 JCPV |
252 | priv = platform_get_drvdata(pdev); |
253 | adap = &priv->adap; | |
254 | pdata = &priv->pdata; | |
1c23af90 HS |
255 | |
256 | i2c_del_adapter(adap); | |
257 | gpio_free(pdata->scl_pin); | |
258 | gpio_free(pdata->sda_pin); | |
1c23af90 HS |
259 | |
260 | return 0; | |
261 | } | |
262 | ||
8ffaa0f4 JCPV |
263 | #if defined(CONFIG_OF) |
264 | static const struct of_device_id i2c_gpio_dt_ids[] = { | |
265 | { .compatible = "i2c-gpio", }, | |
266 | { /* sentinel */ } | |
267 | }; | |
268 | ||
269 | MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids); | |
270 | #endif | |
271 | ||
1c23af90 HS |
272 | static struct platform_driver i2c_gpio_driver = { |
273 | .driver = { | |
274 | .name = "i2c-gpio", | |
275 | .owner = THIS_MODULE, | |
8ffaa0f4 | 276 | .of_match_table = of_match_ptr(i2c_gpio_dt_ids), |
1c23af90 | 277 | }, |
1efe7c55 | 278 | .probe = i2c_gpio_probe, |
0b255e92 | 279 | .remove = i2c_gpio_remove, |
1c23af90 HS |
280 | }; |
281 | ||
282 | static int __init i2c_gpio_init(void) | |
283 | { | |
284 | int ret; | |
285 | ||
1efe7c55 | 286 | ret = platform_driver_register(&i2c_gpio_driver); |
1c23af90 HS |
287 | if (ret) |
288 | printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret); | |
289 | ||
290 | return ret; | |
291 | } | |
b8680784 | 292 | subsys_initcall(i2c_gpio_init); |
1c23af90 HS |
293 | |
294 | static void __exit i2c_gpio_exit(void) | |
295 | { | |
296 | platform_driver_unregister(&i2c_gpio_driver); | |
297 | } | |
298 | module_exit(i2c_gpio_exit); | |
299 | ||
e05503ef | 300 | MODULE_AUTHOR("Haavard Skinnemoen (Atmel)"); |
1c23af90 HS |
301 | MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver"); |
302 | MODULE_LICENSE("GPL"); | |
add8eda7 | 303 | MODULE_ALIAS("platform:i2c-gpio"); |