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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 <linux/of_gpio.h>
19
20struct gpiomux {
21 struct i2c_adapter *parent;
22 struct i2c_adapter **adap; /* child busses */
23 struct i2c_mux_gpio_platform_data data;
24 unsigned gpio_base;
25};
26
27static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
28{
29 int i;
30
31 for (i = 0; i < mux->data.n_gpios; i++)
32 gpio_set_value_cansleep(mux->gpio_base + mux->data.gpios[i],
33 val & (1 << i));
34}
35
36static int i2c_mux_gpio_select(struct i2c_adapter *adap, void *data, u32 chan)
37{
38 struct gpiomux *mux = data;
39
40 i2c_mux_gpio_set(mux, chan);
41
42 return 0;
43}
44
45static int i2c_mux_gpio_deselect(struct i2c_adapter *adap, void *data, u32 chan)
46{
47 struct gpiomux *mux = data;
48
49 i2c_mux_gpio_set(mux, mux->data.idle);
50
51 return 0;
52}
53
54static int match_gpio_chip_by_label(struct gpio_chip *chip,
55 void *data)
56{
57 return !strcmp(chip->label, data);
58}
59
60#ifdef CONFIG_OF
61static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
62 struct platform_device *pdev)
63{
64 struct device_node *np = pdev->dev.of_node;
65 struct device_node *adapter_np, *child;
66 struct i2c_adapter *adapter;
67 unsigned *values, *gpios;
68 int i = 0, ret;
69
70 if (!np)
71 return -ENODEV;
72
73 adapter_np = of_parse_phandle(np, "i2c-parent", 0);
74 if (!adapter_np) {
75 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
76 return -ENODEV;
77 }
78 adapter = of_find_i2c_adapter_by_node(adapter_np);
79 of_node_put(adapter_np);
80 if (!adapter)
81 return -EPROBE_DEFER;
82
83 mux->data.parent = i2c_adapter_id(adapter);
84 put_device(&adapter->dev);
85
86 mux->data.n_values = of_get_child_count(np);
87
88 values = devm_kzalloc(&pdev->dev,
89 sizeof(*mux->data.values) * mux->data.n_values,
90 GFP_KERNEL);
91 if (!values) {
92 dev_err(&pdev->dev, "Cannot allocate values array");
93 return -ENOMEM;
94 }
95
96 for_each_child_of_node(np, child) {
97 of_property_read_u32(child, "reg", values + i);
98 i++;
99 }
100 mux->data.values = values;
101
102 if (of_property_read_u32(np, "idle-state", &mux->data.idle))
103 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
104
105 mux->data.n_gpios = of_gpio_named_count(np, "mux-gpios");
106 if (mux->data.n_gpios < 0) {
107 dev_err(&pdev->dev, "Missing mux-gpios property in the DT.\n");
108 return -EINVAL;
109 }
110
111 gpios = devm_kzalloc(&pdev->dev,
112 sizeof(*mux->data.gpios) * mux->data.n_gpios, GFP_KERNEL);
113 if (!gpios) {
114 dev_err(&pdev->dev, "Cannot allocate gpios array");
115 return -ENOMEM;
116 }
117
118 for (i = 0; i < mux->data.n_gpios; i++) {
119 ret = of_get_named_gpio(np, "mux-gpios", i);
120 if (ret < 0)
121 return ret;
122 gpios[i] = ret;
123 }
124
125 mux->data.gpios = gpios;
126
127 return 0;
128}
129#else
130static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
131 struct platform_device *pdev)
132{
133 return 0;
134}
135#endif
136
137static int i2c_mux_gpio_probe(struct platform_device *pdev)
138{
139 struct gpiomux *mux;
140 struct i2c_adapter *parent;
141 int (*deselect) (struct i2c_adapter *, void *, u32);
142 unsigned initial_state, gpio_base;
143 int i, ret;
144
145 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
146 if (!mux) {
147 dev_err(&pdev->dev, "Cannot allocate gpiomux structure");
148 return -ENOMEM;
149 }
150
151 platform_set_drvdata(pdev, mux);
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 mux->parent = parent;
184 mux->gpio_base = gpio_base;
185
186 mux->adap = devm_kzalloc(&pdev->dev,
187 sizeof(*mux->adap) * mux->data.n_values,
188 GFP_KERNEL);
189 if (!mux->adap) {
190 dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
191 ret = -ENOMEM;
192 goto alloc_failed;
193 }
194
195 if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
196 initial_state = mux->data.idle;
197 deselect = i2c_mux_gpio_deselect;
198 } else {
199 initial_state = mux->data.values[0];
200 deselect = NULL;
201 }
202
203 for (i = 0; i < mux->data.n_gpios; i++) {
204 ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
205 if (ret) {
206 dev_err(&pdev->dev, "Failed to request GPIO %d\n",
207 mux->data.gpios[i]);
208 goto err_request_gpio;
209 }
210
211 ret = gpio_direction_output(gpio_base + mux->data.gpios[i],
212 initial_state & (1 << i));
213 if (ret) {
214 dev_err(&pdev->dev,
215 "Failed to set direction of GPIO %d to output\n",
216 mux->data.gpios[i]);
217 i++; /* gpio_request above succeeded, so must free */
218 goto err_request_gpio;
219 }
220 }
221
222 for (i = 0; i < mux->data.n_values; i++) {
223 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
224 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
225
226 mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr,
227 mux->data.values[i], class,
228 i2c_mux_gpio_select, deselect);
229 if (!mux->adap[i]) {
230 ret = -ENODEV;
231 dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
232 goto add_adapter_failed;
233 }
234 }
235
236 dev_info(&pdev->dev, "%d port mux on %s adapter\n",
237 mux->data.n_values, parent->name);
238
239 return 0;
240
241add_adapter_failed:
242 for (; i > 0; i--)
243 i2c_del_mux_adapter(mux->adap[i - 1]);
244 i = mux->data.n_gpios;
245err_request_gpio:
246 for (; i > 0; i--)
247 gpio_free(gpio_base + mux->data.gpios[i - 1]);
248alloc_failed:
249 i2c_put_adapter(parent);
250
251 return ret;
252}
253
254static int i2c_mux_gpio_remove(struct platform_device *pdev)
255{
256 struct gpiomux *mux = platform_get_drvdata(pdev);
257 int i;
258
259 for (i = 0; i < mux->data.n_values; i++)
260 i2c_del_mux_adapter(mux->adap[i]);
261
262 for (i = 0; i < mux->data.n_gpios; i++)
263 gpio_free(mux->gpio_base + mux->data.gpios[i]);
264
265 i2c_put_adapter(mux->parent);
266
267 return 0;
268}
269
270static const struct of_device_id i2c_mux_gpio_of_match[] = {
271 { .compatible = "i2c-mux-gpio", },
272 {},
273};
274MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
275
276static struct platform_driver i2c_mux_gpio_driver = {
277 .probe = i2c_mux_gpio_probe,
278 .remove = i2c_mux_gpio_remove,
279 .driver = {
280 .name = "i2c-mux-gpio",
281 .of_match_table = i2c_mux_gpio_of_match,
282 },
283};
284
285module_platform_driver(i2c_mux_gpio_driver);
286
287MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
288MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
289MODULE_LICENSE("GPL");
290MODULE_ALIAS("platform:i2c-mux-gpio");
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");