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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * I2C multiplexer using GPIO API
4 *
5 * Peter Korsgaard <peter.korsgaard@barco.com>
6 */
7
8#include <linux/i2c.h>
9#include <linux/i2c-mux.h>
10#include <linux/platform_data/i2c-mux-gpio.h>
11#include <linux/platform_device.h>
12#include <linux/module.h>
13#include <linux/slab.h>
14#include <linux/bits.h>
15#include <linux/gpio/consumer.h>
16/* FIXME: stop poking around inside gpiolib */
17#include "../../gpio/gpiolib.h"
18
19struct gpiomux {
20 struct i2c_mux_gpio_platform_data data;
21 int ngpios;
22 struct gpio_desc **gpios;
23};
24
25static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
26{
27 DECLARE_BITMAP(values, BITS_PER_TYPE(val));
28
29 values[0] = val;
30
31 gpiod_set_array_value_cansleep(mux->ngpios, mux->gpios, NULL, values);
32}
33
34static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
35{
36 struct gpiomux *mux = i2c_mux_priv(muxc);
37
38 i2c_mux_gpio_set(mux, chan);
39
40 return 0;
41}
42
43static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
44{
45 struct gpiomux *mux = i2c_mux_priv(muxc);
46
47 i2c_mux_gpio_set(mux, mux->data.idle);
48
49 return 0;
50}
51
52#ifdef CONFIG_OF
53static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
54 struct platform_device *pdev)
55{
56 struct device_node *np = pdev->dev.of_node;
57 struct device_node *adapter_np, *child;
58 struct i2c_adapter *adapter;
59 unsigned *values;
60 int i = 0;
61
62 if (!np)
63 return -ENODEV;
64
65 adapter_np = of_parse_phandle(np, "i2c-parent", 0);
66 if (!adapter_np) {
67 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
68 return -ENODEV;
69 }
70 adapter = of_find_i2c_adapter_by_node(adapter_np);
71 of_node_put(adapter_np);
72 if (!adapter)
73 return -EPROBE_DEFER;
74
75 mux->data.parent = i2c_adapter_id(adapter);
76 put_device(&adapter->dev);
77
78 mux->data.n_values = of_get_child_count(np);
79
80 values = devm_kcalloc(&pdev->dev,
81 mux->data.n_values, sizeof(*mux->data.values),
82 GFP_KERNEL);
83 if (!values) {
84 dev_err(&pdev->dev, "Cannot allocate values array");
85 return -ENOMEM;
86 }
87
88 for_each_child_of_node(np, child) {
89 of_property_read_u32(child, "reg", values + i);
90 i++;
91 }
92 mux->data.values = values;
93
94 if (of_property_read_u32(np, "idle-state", &mux->data.idle))
95 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
96
97 return 0;
98}
99#else
100static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
101 struct platform_device *pdev)
102{
103 return 0;
104}
105#endif
106
107static int i2c_mux_gpio_probe(struct platform_device *pdev)
108{
109 struct i2c_mux_core *muxc;
110 struct gpiomux *mux;
111 struct i2c_adapter *parent;
112 struct i2c_adapter *root;
113 unsigned initial_state;
114 int i, ngpios, ret;
115
116 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
117 if (!mux)
118 return -ENOMEM;
119
120 if (!dev_get_platdata(&pdev->dev)) {
121 ret = i2c_mux_gpio_probe_dt(mux, pdev);
122 if (ret < 0)
123 return ret;
124 } else {
125 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
126 sizeof(mux->data));
127 }
128
129 ngpios = gpiod_count(&pdev->dev, "mux");
130 if (ngpios <= 0) {
131 dev_err(&pdev->dev, "no valid gpios provided\n");
132 return ngpios ?: -EINVAL;
133 }
134 mux->ngpios = ngpios;
135
136 parent = i2c_get_adapter(mux->data.parent);
137 if (!parent)
138 return -EPROBE_DEFER;
139
140 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
141 ngpios * sizeof(*mux->gpios), 0,
142 i2c_mux_gpio_select, NULL);
143 if (!muxc) {
144 ret = -ENOMEM;
145 goto alloc_failed;
146 }
147 mux->gpios = muxc->priv;
148 muxc->priv = mux;
149
150 platform_set_drvdata(pdev, muxc);
151
152 root = i2c_root_adapter(&parent->dev);
153
154 muxc->mux_locked = true;
155
156 if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
157 initial_state = mux->data.idle;
158 muxc->deselect = i2c_mux_gpio_deselect;
159 } else {
160 initial_state = mux->data.values[0];
161 }
162
163 for (i = 0; i < ngpios; i++) {
164 struct device *gpio_dev;
165 struct gpio_desc *gpiod;
166 enum gpiod_flags flag;
167
168 if (initial_state & BIT(i))
169 flag = GPIOD_OUT_HIGH;
170 else
171 flag = GPIOD_OUT_LOW;
172 gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
173 if (IS_ERR(gpiod)) {
174 ret = PTR_ERR(gpiod);
175 goto alloc_failed;
176 }
177
178 mux->gpios[i] = gpiod;
179
180 if (!muxc->mux_locked)
181 continue;
182
183 /* FIXME: find a proper way to access the GPIO device */
184 gpio_dev = &gpiod->gdev->dev;
185 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
186 }
187
188 if (muxc->mux_locked)
189 dev_info(&pdev->dev, "mux-locked i2c mux\n");
190
191 for (i = 0; i < mux->data.n_values; i++) {
192 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
193 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
194
195 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
196 if (ret)
197 goto add_adapter_failed;
198 }
199
200 dev_info(&pdev->dev, "%d port mux on %s adapter\n",
201 mux->data.n_values, parent->name);
202
203 return 0;
204
205add_adapter_failed:
206 i2c_mux_del_adapters(muxc);
207alloc_failed:
208 i2c_put_adapter(parent);
209
210 return ret;
211}
212
213static int i2c_mux_gpio_remove(struct platform_device *pdev)
214{
215 struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
216
217 i2c_mux_del_adapters(muxc);
218 i2c_put_adapter(muxc->parent);
219
220 return 0;
221}
222
223static const struct of_device_id i2c_mux_gpio_of_match[] = {
224 { .compatible = "i2c-mux-gpio", },
225 {},
226};
227MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
228
229static struct platform_driver i2c_mux_gpio_driver = {
230 .probe = i2c_mux_gpio_probe,
231 .remove = i2c_mux_gpio_remove,
232 .driver = {
233 .name = "i2c-mux-gpio",
234 .of_match_table = i2c_mux_gpio_of_match,
235 },
236};
237
238module_platform_driver(i2c_mux_gpio_driver);
239
240MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
241MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
242MODULE_LICENSE("GPL");
243MODULE_ALIAS("platform:i2c-mux-gpio");
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/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
21struct gpiomux {
22 struct i2c_mux_gpio_platform_data data;
23 unsigned gpio_base;
24 struct gpio_desc **gpios;
25 int *values;
26};
27
28static 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
39static 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
48static 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
57static 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
64static 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_kzalloc(&pdev->dev,
92 sizeof(*mux->data.values) * mux->data.n_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_kzalloc(&pdev->dev,
115 sizeof(*mux->data.gpios) * mux->data.n_gpios, GFP_KERNEL);
116 if (!gpios) {
117 dev_err(&pdev->dev, "Cannot allocate gpios array");
118 return -ENOMEM;
119 }
120
121 for (i = 0; i < mux->data.n_gpios; i++) {
122 ret = of_get_named_gpio(np, "mux-gpios", i);
123 if (ret < 0)
124 return ret;
125 gpios[i] = ret;
126 }
127
128 mux->data.gpios = gpios;
129
130 return 0;
131}
132#else
133static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
134 struct platform_device *pdev)
135{
136 return 0;
137}
138#endif
139
140static int i2c_mux_gpio_probe(struct platform_device *pdev)
141{
142 struct i2c_mux_core *muxc;
143 struct gpiomux *mux;
144 struct i2c_adapter *parent;
145 struct i2c_adapter *root;
146 unsigned initial_state, gpio_base;
147 int i, ret;
148
149 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
150 if (!mux)
151 return -ENOMEM;
152
153 if (!dev_get_platdata(&pdev->dev)) {
154 ret = i2c_mux_gpio_probe_dt(mux, pdev);
155 if (ret < 0)
156 return ret;
157 } else {
158 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
159 sizeof(mux->data));
160 }
161
162 /*
163 * If a GPIO chip name is provided, the GPIO pin numbers provided are
164 * relative to its base GPIO number. Otherwise they are absolute.
165 */
166 if (mux->data.gpio_chip) {
167 struct gpio_chip *gpio;
168
169 gpio = gpiochip_find(mux->data.gpio_chip,
170 match_gpio_chip_by_label);
171 if (!gpio)
172 return -EPROBE_DEFER;
173
174 gpio_base = gpio->base;
175 } else {
176 gpio_base = 0;
177 }
178
179 parent = i2c_get_adapter(mux->data.parent);
180 if (!parent)
181 return -EPROBE_DEFER;
182
183 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
184 mux->data.n_gpios * sizeof(*mux->gpios) +
185 mux->data.n_gpios * sizeof(*mux->values), 0,
186 i2c_mux_gpio_select, NULL);
187 if (!muxc) {
188 ret = -ENOMEM;
189 goto alloc_failed;
190 }
191 mux->gpios = muxc->priv;
192 mux->values = (int *)(mux->gpios + mux->data.n_gpios);
193 muxc->priv = mux;
194
195 platform_set_drvdata(pdev, muxc);
196
197 root = i2c_root_adapter(&parent->dev);
198
199 muxc->mux_locked = true;
200 mux->gpio_base = gpio_base;
201
202 if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
203 initial_state = mux->data.idle;
204 muxc->deselect = i2c_mux_gpio_deselect;
205 } else {
206 initial_state = mux->data.values[0];
207 }
208
209 for (i = 0; i < mux->data.n_gpios; i++) {
210 struct device *gpio_dev;
211 struct gpio_desc *gpio_desc;
212
213 ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
214 if (ret) {
215 dev_err(&pdev->dev, "Failed to request GPIO %d\n",
216 mux->data.gpios[i]);
217 goto err_request_gpio;
218 }
219
220 ret = gpio_direction_output(gpio_base + mux->data.gpios[i],
221 initial_state & (1 << i));
222 if (ret) {
223 dev_err(&pdev->dev,
224 "Failed to set direction of GPIO %d to output\n",
225 mux->data.gpios[i]);
226 i++; /* gpio_request above succeeded, so must free */
227 goto err_request_gpio;
228 }
229
230 gpio_desc = gpio_to_desc(gpio_base + mux->data.gpios[i]);
231 mux->gpios[i] = gpio_desc;
232
233 if (!muxc->mux_locked)
234 continue;
235
236 gpio_dev = &gpio_desc->gdev->dev;
237 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
238 }
239
240 if (muxc->mux_locked)
241 dev_info(&pdev->dev, "mux-locked i2c mux\n");
242
243 for (i = 0; i < mux->data.n_values; i++) {
244 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
245 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
246
247 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
248 if (ret)
249 goto add_adapter_failed;
250 }
251
252 dev_info(&pdev->dev, "%d port mux on %s adapter\n",
253 mux->data.n_values, parent->name);
254
255 return 0;
256
257add_adapter_failed:
258 i2c_mux_del_adapters(muxc);
259 i = mux->data.n_gpios;
260err_request_gpio:
261 for (; i > 0; i--)
262 gpio_free(gpio_base + mux->data.gpios[i - 1]);
263alloc_failed:
264 i2c_put_adapter(parent);
265
266 return ret;
267}
268
269static int i2c_mux_gpio_remove(struct platform_device *pdev)
270{
271 struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
272 struct gpiomux *mux = i2c_mux_priv(muxc);
273 int i;
274
275 i2c_mux_del_adapters(muxc);
276
277 for (i = 0; i < mux->data.n_gpios; i++)
278 gpio_free(mux->gpio_base + mux->data.gpios[i]);
279
280 i2c_put_adapter(muxc->parent);
281
282 return 0;
283}
284
285static const struct of_device_id i2c_mux_gpio_of_match[] = {
286 { .compatible = "i2c-mux-gpio", },
287 {},
288};
289MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
290
291static struct platform_driver i2c_mux_gpio_driver = {
292 .probe = i2c_mux_gpio_probe,
293 .remove = i2c_mux_gpio_remove,
294 .driver = {
295 .name = "i2c-mux-gpio",
296 .of_match_table = i2c_mux_gpio_of_match,
297 },
298};
299
300module_platform_driver(i2c_mux_gpio_driver);
301
302MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
303MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
304MODULE_LICENSE("GPL");
305MODULE_ALIAS("platform:i2c-mux-gpio");