1 // SPDX-License-Identifier: GPL-2.0-only
3 * I2C multiplexer using GPIO API
5 * Peter Korsgaard <peter.korsgaard@barco.com>
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/gpio.h>
15 #include "../../gpio/gpiolib.h"
16 #include <linux/of_gpio.h>
19 struct i2c_mux_gpio_platform_data data;
21 struct gpio_desc **gpios;
24 static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
26 DECLARE_BITMAP(values, BITS_PER_TYPE(val));
30 gpiod_set_array_value_cansleep(mux->data.n_gpios, mux->gpios, NULL,
34 static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
36 struct gpiomux *mux = i2c_mux_priv(muxc);
38 i2c_mux_gpio_set(mux, chan);
43 static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
45 struct gpiomux *mux = i2c_mux_priv(muxc);
47 i2c_mux_gpio_set(mux, mux->data.idle);
52 static int match_gpio_chip_by_label(struct gpio_chip *chip,
55 return !strcmp(chip->label, data);
59 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
60 struct platform_device *pdev)
62 struct device_node *np = pdev->dev.of_node;
63 struct device_node *adapter_np, *child;
64 struct i2c_adapter *adapter;
65 unsigned *values, *gpios;
71 adapter_np = of_parse_phandle(np, "i2c-parent", 0);
73 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
76 adapter = of_find_i2c_adapter_by_node(adapter_np);
77 of_node_put(adapter_np);
81 mux->data.parent = i2c_adapter_id(adapter);
82 put_device(&adapter->dev);
84 mux->data.n_values = of_get_child_count(np);
86 values = devm_kcalloc(&pdev->dev,
87 mux->data.n_values, sizeof(*mux->data.values),
90 dev_err(&pdev->dev, "Cannot allocate values array");
94 for_each_child_of_node(np, child) {
95 of_property_read_u32(child, "reg", values + i);
98 mux->data.values = values;
100 if (of_property_read_u32(np, "idle-state", &mux->data.idle))
101 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
103 mux->data.n_gpios = of_gpio_named_count(np, "mux-gpios");
104 if (mux->data.n_gpios < 0) {
105 dev_err(&pdev->dev, "Missing mux-gpios property in the DT.\n");
109 gpios = devm_kcalloc(&pdev->dev,
110 mux->data.n_gpios, sizeof(*mux->data.gpios),
113 dev_err(&pdev->dev, "Cannot allocate gpios array");
117 for (i = 0; i < mux->data.n_gpios; i++) {
118 ret = of_get_named_gpio(np, "mux-gpios", i);
124 mux->data.gpios = gpios;
129 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
130 struct platform_device *pdev)
136 static int i2c_mux_gpio_probe(struct platform_device *pdev)
138 struct i2c_mux_core *muxc;
140 struct i2c_adapter *parent;
141 struct i2c_adapter *root;
142 unsigned initial_state, gpio_base;
145 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
149 if (!dev_get_platdata(&pdev->dev)) {
150 ret = i2c_mux_gpio_probe_dt(mux, pdev);
154 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
159 * If a GPIO chip name is provided, the GPIO pin numbers provided are
160 * relative to its base GPIO number. Otherwise they are absolute.
162 if (mux->data.gpio_chip) {
163 struct gpio_chip *gpio;
165 gpio = gpiochip_find(mux->data.gpio_chip,
166 match_gpio_chip_by_label);
168 return -EPROBE_DEFER;
170 gpio_base = gpio->base;
175 parent = i2c_get_adapter(mux->data.parent);
177 return -EPROBE_DEFER;
179 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
180 mux->data.n_gpios * sizeof(*mux->gpios), 0,
181 i2c_mux_gpio_select, NULL);
186 mux->gpios = muxc->priv;
189 platform_set_drvdata(pdev, muxc);
191 root = i2c_root_adapter(&parent->dev);
193 muxc->mux_locked = true;
194 mux->gpio_base = gpio_base;
196 if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
197 initial_state = mux->data.idle;
198 muxc->deselect = i2c_mux_gpio_deselect;
200 initial_state = mux->data.values[0];
203 for (i = 0; i < mux->data.n_gpios; i++) {
204 struct device *gpio_dev;
205 struct gpio_desc *gpio_desc;
207 ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
209 dev_err(&pdev->dev, "Failed to request GPIO %d\n",
211 goto err_request_gpio;
214 ret = gpio_direction_output(gpio_base + mux->data.gpios[i],
215 initial_state & (1 << i));
218 "Failed to set direction of GPIO %d to output\n",
220 i++; /* gpio_request above succeeded, so must free */
221 goto err_request_gpio;
224 gpio_desc = gpio_to_desc(gpio_base + mux->data.gpios[i]);
225 mux->gpios[i] = gpio_desc;
227 if (!muxc->mux_locked)
230 gpio_dev = &gpio_desc->gdev->dev;
231 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
234 if (muxc->mux_locked)
235 dev_info(&pdev->dev, "mux-locked i2c mux\n");
237 for (i = 0; i < mux->data.n_values; i++) {
238 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
239 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
241 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
243 goto add_adapter_failed;
246 dev_info(&pdev->dev, "%d port mux on %s adapter\n",
247 mux->data.n_values, parent->name);
252 i2c_mux_del_adapters(muxc);
253 i = mux->data.n_gpios;
256 gpio_free(gpio_base + mux->data.gpios[i - 1]);
258 i2c_put_adapter(parent);
263 static int i2c_mux_gpio_remove(struct platform_device *pdev)
265 struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
266 struct gpiomux *mux = i2c_mux_priv(muxc);
269 i2c_mux_del_adapters(muxc);
271 for (i = 0; i < mux->data.n_gpios; i++)
272 gpio_free(mux->gpio_base + mux->data.gpios[i]);
274 i2c_put_adapter(muxc->parent);
279 static const struct of_device_id i2c_mux_gpio_of_match[] = {
280 { .compatible = "i2c-mux-gpio", },
283 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
285 static struct platform_driver i2c_mux_gpio_driver = {
286 .probe = i2c_mux_gpio_probe,
287 .remove = i2c_mux_gpio_remove,
289 .name = "i2c-mux-gpio",
290 .of_match_table = i2c_mux_gpio_of_match,
294 module_platform_driver(i2c_mux_gpio_driver);
296 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
297 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
298 MODULE_LICENSE("GPL");
299 MODULE_ALIAS("platform:i2c-mux-gpio");