1 /*
2 * I2C multiplexer using GPIO API
3 *
4 * Peter Korsgaard <peter.korsgaard@barco.com>
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
11 #include <linux/i2c.h>
12 #include <linux/i2c-mux.h>
13 #include <linux/platform_data/i2c-mux-gpio.h>
14 #include <linux/platform_device.h>
15 #include <linux/module.h>
16 #include <linux/slab.h>
17 #include <linux/gpio.h>
18 #include "../../gpio/gpiolib.h"
19 #include <linux/of_gpio.h>
20
21 struct gpiomux {
22 struct i2c_mux_gpio_platform_data data;
23 unsigned gpio_base;
24 struct gpio_desc **gpios;
25 int *values;
26 };
27
i2c_mux_gpio_set(const struct gpiomux * mux,unsigned val)28 static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
29 {
30 int i;
31
32 for (i = 0; i < mux->data.n_gpios; i++)
33 mux->values[i] = (val >> i) & 1;
34
35 gpiod_set_array_value_cansleep(mux->data.n_gpios,
36 mux->gpios, mux->values);
37 }
38
i2c_mux_gpio_select(struct i2c_mux_core * muxc,u32 chan)39 static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
40 {
41 struct gpiomux *mux = i2c_mux_priv(muxc);
42
43 i2c_mux_gpio_set(mux, chan);
44
45 return 0;
46 }
47
i2c_mux_gpio_deselect(struct i2c_mux_core * muxc,u32 chan)48 static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
49 {
50 struct gpiomux *mux = i2c_mux_priv(muxc);
51
52 i2c_mux_gpio_set(mux, mux->data.idle);
53
54 return 0;
55 }
56
match_gpio_chip_by_label(struct gpio_chip * chip,void * data)57 static int match_gpio_chip_by_label(struct gpio_chip *chip,
58 void *data)
59 {
60 return !strcmp(chip->label, data);
61 }
62
63 #ifdef CONFIG_OF
i2c_mux_gpio_probe_dt(struct gpiomux * mux,struct platform_device * pdev)64 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
65 struct platform_device *pdev)
66 {
67 struct device_node *np = pdev->dev.of_node;
68 struct device_node *adapter_np, *child;
69 struct i2c_adapter *adapter;
70 unsigned *values, *gpios;
71 int i = 0, ret;
72
73 if (!np)
74 return -ENODEV;
75
76 adapter_np = of_parse_phandle(np, "i2c-parent", 0);
77 if (!adapter_np) {
78 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
79 return -ENODEV;
80 }
81 adapter = of_find_i2c_adapter_by_node(adapter_np);
82 of_node_put(adapter_np);
83 if (!adapter)
84 return -EPROBE_DEFER;
85
86 mux->data.parent = i2c_adapter_id(adapter);
87 put_device(&adapter->dev);
88
89 mux->data.n_values = of_get_child_count(np);
90
91 values = devm_kcalloc(&pdev->dev,
92 mux->data.n_values, sizeof(*mux->data.values),
93 GFP_KERNEL);
94 if (!values) {
95 dev_err(&pdev->dev, "Cannot allocate values array");
96 return -ENOMEM;
97 }
98
99 for_each_child_of_node(np, child) {
100 of_property_read_u32(child, "reg", values + i);
101 i++;
102 }
103 mux->data.values = values;
104
105 if (of_property_read_u32(np, "idle-state", &mux->data.idle))
106 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
107
108 mux->data.n_gpios = of_gpio_named_count(np, "mux-gpios");
109 if (mux->data.n_gpios < 0) {
110 dev_err(&pdev->dev, "Missing mux-gpios property in the DT.\n");
111 return -EINVAL;
112 }
113
114 gpios = devm_kcalloc(&pdev->dev,
115 mux->data.n_gpios, sizeof(*mux->data.gpios),
116 GFP_KERNEL);
117 if (!gpios) {
118 dev_err(&pdev->dev, "Cannot allocate gpios array");
119 return -ENOMEM;
120 }
121
122 for (i = 0; i < mux->data.n_gpios; i++) {
123 ret = of_get_named_gpio(np, "mux-gpios", i);
124 if (ret < 0)
125 return ret;
126 gpios[i] = ret;
127 }
128
129 mux->data.gpios = gpios;
130
131 return 0;
132 }
133 #else
i2c_mux_gpio_probe_dt(struct gpiomux * mux,struct platform_device * pdev)134 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
135 struct platform_device *pdev)
136 {
137 return 0;
138 }
139 #endif
140
i2c_mux_gpio_probe(struct platform_device * pdev)141 static int i2c_mux_gpio_probe(struct platform_device *pdev)
142 {
143 struct i2c_mux_core *muxc;
144 struct gpiomux *mux;
145 struct i2c_adapter *parent;
146 struct i2c_adapter *root;
147 unsigned initial_state, gpio_base;
148 int i, ret;
149
150 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
151 if (!mux)
152 return -ENOMEM;
153
154 if (!dev_get_platdata(&pdev->dev)) {
155 ret = i2c_mux_gpio_probe_dt(mux, pdev);
156 if (ret < 0)
157 return ret;
158 } else {
159 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
160 sizeof(mux->data));
161 }
162
163 /*
164 * If a GPIO chip name is provided, the GPIO pin numbers provided are
165 * relative to its base GPIO number. Otherwise they are absolute.
166 */
167 if (mux->data.gpio_chip) {
168 struct gpio_chip *gpio;
169
170 gpio = gpiochip_find(mux->data.gpio_chip,
171 match_gpio_chip_by_label);
172 if (!gpio)
173 return -EPROBE_DEFER;
174
175 gpio_base = gpio->base;
176 } else {
177 gpio_base = 0;
178 }
179
180 parent = i2c_get_adapter(mux->data.parent);
181 if (!parent)
182 return -EPROBE_DEFER;
183
184 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
185 mux->data.n_gpios * sizeof(*mux->gpios) +
186 mux->data.n_gpios * sizeof(*mux->values), 0,
187 i2c_mux_gpio_select, NULL);
188 if (!muxc) {
189 ret = -ENOMEM;
190 goto alloc_failed;
191 }
192 mux->gpios = muxc->priv;
193 mux->values = (int *)(mux->gpios + mux->data.n_gpios);
194 muxc->priv = mux;
195
196 platform_set_drvdata(pdev, muxc);
197
198 root = i2c_root_adapter(&parent->dev);
199
200 muxc->mux_locked = true;
201 mux->gpio_base = gpio_base;
202
203 if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
204 initial_state = mux->data.idle;
205 muxc->deselect = i2c_mux_gpio_deselect;
206 } else {
207 initial_state = mux->data.values[0];
208 }
209
210 for (i = 0; i < mux->data.n_gpios; i++) {
211 struct device *gpio_dev;
212 struct gpio_desc *gpio_desc;
213
214 ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
215 if (ret) {
216 dev_err(&pdev->dev, "Failed to request GPIO %d\n",
217 mux->data.gpios[i]);
218 goto err_request_gpio;
219 }
220
221 ret = gpio_direction_output(gpio_base + mux->data.gpios[i],
222 initial_state & (1 << i));
223 if (ret) {
224 dev_err(&pdev->dev,
225 "Failed to set direction of GPIO %d to output\n",
226 mux->data.gpios[i]);
227 i++; /* gpio_request above succeeded, so must free */
228 goto err_request_gpio;
229 }
230
231 gpio_desc = gpio_to_desc(gpio_base + mux->data.gpios[i]);
232 mux->gpios[i] = gpio_desc;
233
234 if (!muxc->mux_locked)
235 continue;
236
237 gpio_dev = &gpio_desc->gdev->dev;
238 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
239 }
240
241 if (muxc->mux_locked)
242 dev_info(&pdev->dev, "mux-locked i2c mux\n");
243
244 for (i = 0; i < mux->data.n_values; i++) {
245 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
246 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
247
248 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
249 if (ret)
250 goto add_adapter_failed;
251 }
252
253 dev_info(&pdev->dev, "%d port mux on %s adapter\n",
254 mux->data.n_values, parent->name);
255
256 return 0;
257
258 add_adapter_failed:
259 i2c_mux_del_adapters(muxc);
260 i = mux->data.n_gpios;
261 err_request_gpio:
262 for (; i > 0; i--)
263 gpio_free(gpio_base + mux->data.gpios[i - 1]);
264 alloc_failed:
265 i2c_put_adapter(parent);
266
267 return ret;
268 }
269
i2c_mux_gpio_remove(struct platform_device * pdev)270 static int i2c_mux_gpio_remove(struct platform_device *pdev)
271 {
272 struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
273 struct gpiomux *mux = i2c_mux_priv(muxc);
274 int i;
275
276 i2c_mux_del_adapters(muxc);
277
278 for (i = 0; i < mux->data.n_gpios; i++)
279 gpio_free(mux->gpio_base + mux->data.gpios[i]);
280
281 i2c_put_adapter(muxc->parent);
282
283 return 0;
284 }
285
286 static const struct of_device_id i2c_mux_gpio_of_match[] = {
287 { .compatible = "i2c-mux-gpio", },
288 {},
289 };
290 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
291
292 static struct platform_driver i2c_mux_gpio_driver = {
293 .probe = i2c_mux_gpio_probe,
294 .remove = i2c_mux_gpio_remove,
295 .driver = {
296 .name = "i2c-mux-gpio",
297 .of_match_table = i2c_mux_gpio_of_match,
298 },
299 };
300
301 module_platform_driver(i2c_mux_gpio_driver);
302
303 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
304 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
305 MODULE_LICENSE("GPL");
306 MODULE_ALIAS("platform:i2c-mux-gpio");
307