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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/overflow.h>
11#include <linux/platform_data/i2c-mux-gpio.h>
12#include <linux/platform_device.h>
13#include <linux/module.h>
14#include <linux/slab.h>
15#include <linux/bits.h>
16#include <linux/gpio/consumer.h>
17/* FIXME: stop poking around inside gpiolib */
18#include "../../gpio/gpiolib.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 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 return 0;
42}
43
44static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
45{
46 struct gpiomux *mux = i2c_mux_priv(muxc);
47
48 i2c_mux_gpio_set(mux, mux->data.idle);
49
50 return 0;
51}
52
53static int i2c_mux_gpio_probe_fw(struct gpiomux *mux,
54 struct platform_device *pdev)
55{
56 struct device *dev = &pdev->dev;
57 struct fwnode_handle *fwnode = dev_fwnode(dev);
58 struct device_node *np = dev->of_node;
59 struct device_node *adapter_np;
60 struct i2c_adapter *adapter = NULL;
61 struct fwnode_handle *child;
62 unsigned *values;
63 int rc, i = 0;
64
65 if (is_of_node(fwnode)) {
66 if (!np)
67 return -ENODEV;
68
69 adapter_np = of_parse_phandle(np, "i2c-parent", 0);
70 if (!adapter_np) {
71 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
72 return -ENODEV;
73 }
74 adapter = of_find_i2c_adapter_by_node(adapter_np);
75 of_node_put(adapter_np);
76
77 } else if (is_acpi_node(fwnode)) {
78 /*
79 * In ACPI land the mux should be a direct child of the i2c
80 * bus it muxes.
81 */
82 acpi_handle dev_handle = ACPI_HANDLE(dev->parent);
83
84 adapter = i2c_acpi_find_adapter_by_handle(dev_handle);
85 }
86
87 if (!adapter)
88 return -EPROBE_DEFER;
89
90 mux->data.parent = i2c_adapter_id(adapter);
91 put_device(&adapter->dev);
92
93 mux->data.n_values = device_get_child_node_count(dev);
94 values = devm_kcalloc(dev,
95 mux->data.n_values, sizeof(*mux->data.values),
96 GFP_KERNEL);
97 if (!values) {
98 dev_err(dev, "Cannot allocate values array");
99 return -ENOMEM;
100 }
101
102 device_for_each_child_node(dev, child) {
103 if (is_of_node(child)) {
104 fwnode_property_read_u32(child, "reg", values + i);
105
106 } else if (is_acpi_node(child)) {
107 rc = acpi_get_local_address(ACPI_HANDLE_FWNODE(child), values + i);
108 if (rc)
109 return dev_err_probe(dev, rc, "Cannot get address\n");
110 }
111
112 i++;
113 }
114 mux->data.values = values;
115
116 if (device_property_read_u32(dev, "idle-state", &mux->data.idle))
117 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
118
119 return 0;
120}
121
122static int i2c_mux_gpio_probe(struct platform_device *pdev)
123{
124 struct i2c_mux_core *muxc;
125 struct gpiomux *mux;
126 struct i2c_adapter *parent;
127 struct i2c_adapter *root;
128 unsigned initial_state;
129 int i, ngpios, ret;
130
131 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
132 if (!mux)
133 return -ENOMEM;
134
135 if (!dev_get_platdata(&pdev->dev)) {
136 ret = i2c_mux_gpio_probe_fw(mux, pdev);
137 if (ret < 0)
138 return ret;
139 } else {
140 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
141 sizeof(mux->data));
142 }
143
144 ngpios = gpiod_count(&pdev->dev, "mux");
145 if (ngpios <= 0) {
146 dev_err(&pdev->dev, "no valid gpios provided\n");
147 return ngpios ?: -EINVAL;
148 }
149 mux->ngpios = ngpios;
150
151 parent = i2c_get_adapter(mux->data.parent);
152 if (!parent)
153 return -EPROBE_DEFER;
154
155 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
156 array_size(ngpios, sizeof(*mux->gpios)), 0,
157 i2c_mux_gpio_select, NULL);
158 if (!muxc) {
159 ret = -ENOMEM;
160 goto alloc_failed;
161 }
162 mux->gpios = muxc->priv;
163 muxc->priv = mux;
164
165 platform_set_drvdata(pdev, muxc);
166
167 root = i2c_root_adapter(&parent->dev);
168
169 muxc->mux_locked = true;
170
171 if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
172 initial_state = mux->data.idle;
173 muxc->deselect = i2c_mux_gpio_deselect;
174 } else {
175 initial_state = mux->data.values[0];
176 }
177
178 for (i = 0; i < ngpios; i++) {
179 struct device *gpio_dev;
180 struct gpio_desc *gpiod;
181 enum gpiod_flags flag;
182
183 if (initial_state & BIT(i))
184 flag = GPIOD_OUT_HIGH;
185 else
186 flag = GPIOD_OUT_LOW;
187 gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
188 if (IS_ERR(gpiod)) {
189 ret = PTR_ERR(gpiod);
190 goto alloc_failed;
191 }
192
193 mux->gpios[i] = gpiod;
194
195 if (!muxc->mux_locked)
196 continue;
197
198 /* FIXME: find a proper way to access the GPIO device */
199 gpio_dev = &gpiod->gdev->dev;
200 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
201 }
202
203 if (muxc->mux_locked)
204 dev_info(&pdev->dev, "mux-locked i2c mux\n");
205
206 for (i = 0; i < mux->data.n_values; i++) {
207 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
208 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
209
210 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
211 if (ret)
212 goto add_adapter_failed;
213 }
214
215 dev_info(&pdev->dev, "%d port mux on %s adapter\n",
216 mux->data.n_values, parent->name);
217
218 return 0;
219
220add_adapter_failed:
221 i2c_mux_del_adapters(muxc);
222alloc_failed:
223 i2c_put_adapter(parent);
224
225 return ret;
226}
227
228static int i2c_mux_gpio_remove(struct platform_device *pdev)
229{
230 struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
231
232 i2c_mux_del_adapters(muxc);
233 i2c_put_adapter(muxc->parent);
234
235 return 0;
236}
237
238static const struct of_device_id i2c_mux_gpio_of_match[] = {
239 { .compatible = "i2c-mux-gpio", },
240 {},
241};
242MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
243
244static struct platform_driver i2c_mux_gpio_driver = {
245 .probe = i2c_mux_gpio_probe,
246 .remove = i2c_mux_gpio_remove,
247 .driver = {
248 .name = "i2c-mux-gpio",
249 .of_match_table = i2c_mux_gpio_of_match,
250 },
251};
252
253module_platform_driver(i2c_mux_gpio_driver);
254
255MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
256MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
257MODULE_LICENSE("GPL");
258MODULE_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 <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 if (!adapter) {
80 dev_err(&pdev->dev, "Cannot find parent bus\n");
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 dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
182 mux->data.parent);
183 return -EPROBE_DEFER;
184 }
185
186 mux->parent = parent;
187 mux->gpio_base = gpio_base;
188
189 mux->adap = devm_kzalloc(&pdev->dev,
190 sizeof(*mux->adap) * mux->data.n_values,
191 GFP_KERNEL);
192 if (!mux->adap) {
193 dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
194 ret = -ENOMEM;
195 goto alloc_failed;
196 }
197
198 if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
199 initial_state = mux->data.idle;
200 deselect = i2c_mux_gpio_deselect;
201 } else {
202 initial_state = mux->data.values[0];
203 deselect = NULL;
204 }
205
206 for (i = 0; i < mux->data.n_gpios; i++) {
207 ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
208 if (ret) {
209 dev_err(&pdev->dev, "Failed to request GPIO %d\n",
210 mux->data.gpios[i]);
211 goto err_request_gpio;
212 }
213
214 ret = gpio_direction_output(gpio_base + mux->data.gpios[i],
215 initial_state & (1 << i));
216 if (ret) {
217 dev_err(&pdev->dev,
218 "Failed to set direction of GPIO %d to output\n",
219 mux->data.gpios[i]);
220 i++; /* gpio_request above succeeded, so must free */
221 goto err_request_gpio;
222 }
223 }
224
225 for (i = 0; i < mux->data.n_values; i++) {
226 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
227 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
228
229 mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr,
230 mux->data.values[i], class,
231 i2c_mux_gpio_select, deselect);
232 if (!mux->adap[i]) {
233 ret = -ENODEV;
234 dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
235 goto add_adapter_failed;
236 }
237 }
238
239 dev_info(&pdev->dev, "%d port mux on %s adapter\n",
240 mux->data.n_values, parent->name);
241
242 return 0;
243
244add_adapter_failed:
245 for (; i > 0; i--)
246 i2c_del_mux_adapter(mux->adap[i - 1]);
247 i = mux->data.n_gpios;
248err_request_gpio:
249 for (; i > 0; i--)
250 gpio_free(gpio_base + mux->data.gpios[i - 1]);
251alloc_failed:
252 i2c_put_adapter(parent);
253
254 return ret;
255}
256
257static int i2c_mux_gpio_remove(struct platform_device *pdev)
258{
259 struct gpiomux *mux = platform_get_drvdata(pdev);
260 int i;
261
262 for (i = 0; i < mux->data.n_values; i++)
263 i2c_del_mux_adapter(mux->adap[i]);
264
265 for (i = 0; i < mux->data.n_gpios; i++)
266 gpio_free(mux->gpio_base + mux->data.gpios[i]);
267
268 i2c_put_adapter(mux->parent);
269
270 return 0;
271}
272
273static const struct of_device_id i2c_mux_gpio_of_match[] = {
274 { .compatible = "i2c-mux-gpio", },
275 {},
276};
277MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
278
279static struct platform_driver i2c_mux_gpio_driver = {
280 .probe = i2c_mux_gpio_probe,
281 .remove = i2c_mux_gpio_remove,
282 .driver = {
283 .owner = THIS_MODULE,
284 .name = "i2c-mux-gpio",
285 .of_match_table = i2c_mux_gpio_of_match,
286 },
287};
288
289module_platform_driver(i2c_mux_gpio_driver);
290
291MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
292MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
293MODULE_LICENSE("GPL");
294MODULE_ALIAS("platform:i2c-mux-gpio");