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
20 struct gpiomux {
21 struct i2c_mux_gpio_platform_data data;
22 int ngpios;
23 struct gpio_desc **gpios;
24 };
25
i2c_mux_gpio_set(const struct gpiomux * mux,unsigned int val)26 static 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
i2c_mux_gpio_select(struct i2c_mux_core * muxc,u32 chan)35 static 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
i2c_mux_gpio_deselect(struct i2c_mux_core * muxc,u32 chan)47 static 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
i2c_mux_gpio_probe_fw(struct gpiomux * mux,struct platform_device * pdev)56 static 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
i2c_mux_gpio_probe(struct platform_device * pdev)128 static 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
226 add_adapter_failed:
227 i2c_mux_del_adapters(muxc);
228 alloc_failed:
229 i2c_put_adapter(parent);
230
231 return ret;
232 }
233
i2c_mux_gpio_remove(struct platform_device * pdev)234 static 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
242 static const struct of_device_id i2c_mux_gpio_of_match[] = {
243 { .compatible = "i2c-mux-gpio", },
244 {},
245 };
246 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
247
248 static struct platform_driver i2c_mux_gpio_driver = {
249 .probe = i2c_mux_gpio_probe,
250 .remove_new = i2c_mux_gpio_remove,
251 .driver = {
252 .name = "i2c-mux-gpio",
253 .of_match_table = i2c_mux_gpio_of_match,
254 },
255 };
256
257 module_platform_driver(i2c_mux_gpio_driver);
258
259 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
260 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
261 MODULE_LICENSE("GPL");
262 MODULE_ALIAS("platform:i2c-mux-gpio");
263