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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/bits.h>
9#include <linux/delay.h>
10#include <linux/gpio/consumer.h>
11#include <linux/gpio/driver.h>
12#include <linux/i2c.h>
13#include <linux/i2c-mux.h>
14#include <linux/module.h>
15#include <linux/overflow.h>
16#include <linux/platform_data/i2c-mux-gpio.h>
17#include <linux/platform_device.h>
18#include <linux/slab.h>
19
20struct gpiomux {
21 struct i2c_mux_gpio_platform_data data;
22 int ngpios;
23 struct gpio_desc **gpios;
24};
25
26static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned int val)
27{
28 DECLARE_BITMAP(values, BITS_PER_TYPE(val));
29
30 values[0] = val;
31
32 gpiod_set_array_value_cansleep(mux->ngpios, mux->gpios, NULL, values);
33}
34
35static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
36{
37 struct gpiomux *mux = i2c_mux_priv(muxc);
38
39 i2c_mux_gpio_set(mux, chan);
40
41 if (mux->data.settle_time)
42 fsleep(mux->data.settle_time);
43
44 return 0;
45}
46
47static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
48{
49 struct gpiomux *mux = i2c_mux_priv(muxc);
50
51 i2c_mux_gpio_set(mux, mux->data.idle);
52
53 return 0;
54}
55
56static int i2c_mux_gpio_probe_fw(struct gpiomux *mux,
57 struct platform_device *pdev)
58{
59 struct device *dev = &pdev->dev;
60 struct fwnode_handle *fwnode = dev_fwnode(dev);
61 struct device_node *np = dev->of_node;
62 struct device_node *adapter_np;
63 struct i2c_adapter *adapter = NULL;
64 struct fwnode_handle *child;
65 unsigned int *values;
66 int rc, i = 0;
67
68 if (is_of_node(fwnode)) {
69 if (!np)
70 return -ENODEV;
71
72 adapter_np = of_parse_phandle(np, "i2c-parent", 0);
73 if (!adapter_np) {
74 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
75 return -ENODEV;
76 }
77 adapter = of_find_i2c_adapter_by_node(adapter_np);
78 of_node_put(adapter_np);
79
80 } else if (is_acpi_node(fwnode)) {
81 /*
82 * In ACPI land the mux should be a direct child of the i2c
83 * bus it muxes.
84 */
85 acpi_handle dev_handle = ACPI_HANDLE(dev->parent);
86
87 adapter = i2c_acpi_find_adapter_by_handle(dev_handle);
88 }
89
90 if (!adapter)
91 return -EPROBE_DEFER;
92
93 mux->data.parent = i2c_adapter_id(adapter);
94 put_device(&adapter->dev);
95
96 mux->data.n_values = device_get_child_node_count(dev);
97 values = devm_kcalloc(dev,
98 mux->data.n_values, sizeof(*mux->data.values),
99 GFP_KERNEL);
100 if (!values) {
101 dev_err(dev, "Cannot allocate values array");
102 return -ENOMEM;
103 }
104
105 device_for_each_child_node(dev, child) {
106 if (is_of_node(child)) {
107 fwnode_property_read_u32(child, "reg", values + i);
108 } else if (is_acpi_node(child)) {
109 rc = acpi_get_local_address(ACPI_HANDLE_FWNODE(child), values + i);
110 if (rc) {
111 fwnode_handle_put(child);
112 return dev_err_probe(dev, rc, "Cannot get address\n");
113 }
114 }
115
116 i++;
117 }
118 mux->data.values = values;
119
120 if (device_property_read_u32(dev, "idle-state", &mux->data.idle))
121 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
122
123 device_property_read_u32(dev, "settle-time-us", &mux->data.settle_time);
124
125 return 0;
126}
127
128static int i2c_mux_gpio_probe(struct platform_device *pdev)
129{
130 struct i2c_mux_core *muxc;
131 struct gpiomux *mux;
132 struct i2c_adapter *parent;
133 struct i2c_adapter *root;
134 unsigned int initial_state;
135 int i, ngpios, ret;
136
137 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
138 if (!mux)
139 return -ENOMEM;
140
141 if (!dev_get_platdata(&pdev->dev)) {
142 ret = i2c_mux_gpio_probe_fw(mux, pdev);
143 if (ret < 0)
144 return ret;
145 } else {
146 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
147 sizeof(mux->data));
148 }
149
150 ngpios = gpiod_count(&pdev->dev, "mux");
151 if (ngpios <= 0) {
152 dev_err(&pdev->dev, "no valid gpios provided\n");
153 return ngpios ?: -EINVAL;
154 }
155 mux->ngpios = ngpios;
156
157 parent = i2c_get_adapter(mux->data.parent);
158 if (!parent)
159 return -EPROBE_DEFER;
160
161 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
162 array_size(ngpios, sizeof(*mux->gpios)), 0,
163 i2c_mux_gpio_select, NULL);
164 if (!muxc) {
165 ret = -ENOMEM;
166 goto alloc_failed;
167 }
168 mux->gpios = muxc->priv;
169 muxc->priv = mux;
170
171 platform_set_drvdata(pdev, muxc);
172
173 root = i2c_root_adapter(&parent->dev);
174
175 muxc->mux_locked = true;
176
177 if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
178 initial_state = mux->data.idle;
179 muxc->deselect = i2c_mux_gpio_deselect;
180 } else {
181 initial_state = mux->data.values[0];
182 }
183
184 for (i = 0; i < ngpios; i++) {
185 struct gpio_device *gdev;
186 struct device *dev;
187 struct gpio_desc *gpiod;
188 enum gpiod_flags flag;
189
190 if (initial_state & BIT(i))
191 flag = GPIOD_OUT_HIGH;
192 else
193 flag = GPIOD_OUT_LOW;
194 gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
195 if (IS_ERR(gpiod)) {
196 ret = PTR_ERR(gpiod);
197 goto alloc_failed;
198 }
199
200 mux->gpios[i] = gpiod;
201
202 if (!muxc->mux_locked)
203 continue;
204
205 gdev = gpiod_to_gpio_device(gpiod);
206 dev = gpio_device_to_device(gdev);
207 muxc->mux_locked = i2c_root_adapter(dev) == root;
208 }
209
210 if (muxc->mux_locked)
211 dev_info(&pdev->dev, "mux-locked i2c mux\n");
212
213 for (i = 0; i < mux->data.n_values; i++) {
214 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
215
216 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i]);
217 if (ret)
218 goto add_adapter_failed;
219 }
220
221 dev_info(&pdev->dev, "%d port mux on %s adapter\n",
222 mux->data.n_values, parent->name);
223
224 return 0;
225
226add_adapter_failed:
227 i2c_mux_del_adapters(muxc);
228alloc_failed:
229 i2c_put_adapter(parent);
230
231 return ret;
232}
233
234static void i2c_mux_gpio_remove(struct platform_device *pdev)
235{
236 struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
237
238 i2c_mux_del_adapters(muxc);
239 i2c_put_adapter(muxc->parent);
240}
241
242static const struct of_device_id i2c_mux_gpio_of_match[] = {
243 { .compatible = "i2c-mux-gpio", },
244 {},
245};
246MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
247
248static struct platform_driver i2c_mux_gpio_driver = {
249 .probe = i2c_mux_gpio_probe,
250 .remove = i2c_mux_gpio_remove,
251 .driver = {
252 .name = "i2c-mux-gpio",
253 .of_match_table = i2c_mux_gpio_of_match,
254 },
255};
256
257module_platform_driver(i2c_mux_gpio_driver);
258
259MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
260MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
261MODULE_LICENSE("GPL");
262MODULE_ALIAS("platform:i2c-mux-gpio");