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
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 val)26 static 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
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 return 0;
42 }
43
i2c_mux_gpio_deselect(struct i2c_mux_core * muxc,u32 chan)44 static 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
i2c_mux_gpio_probe_fw(struct gpiomux * mux,struct platform_device * pdev)53 static 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
i2c_mux_gpio_probe(struct platform_device * pdev)122 static 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
220 add_adapter_failed:
221 i2c_mux_del_adapters(muxc);
222 alloc_failed:
223 i2c_put_adapter(parent);
224
225 return ret;
226 }
227
i2c_mux_gpio_remove(struct platform_device * pdev)228 static 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
238 static const struct of_device_id i2c_mux_gpio_of_match[] = {
239 { .compatible = "i2c-mux-gpio", },
240 {},
241 };
242 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
243
244 static 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
253 module_platform_driver(i2c_mux_gpio_driver);
254
255 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
256 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
257 MODULE_LICENSE("GPL");
258 MODULE_ALIAS("platform:i2c-mux-gpio");
259
