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/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/bits.h>
15 #include <linux/gpio/consumer.h>
16 /* FIXME: stop poking around inside gpiolib */
17 #include "../../gpio/gpiolib.h"
18
19 struct gpiomux {
20 struct i2c_mux_gpio_platform_data data;
21 int ngpios;
22 struct gpio_desc **gpios;
23 };
24
i2c_mux_gpio_set(const struct gpiomux * mux,unsigned val)25 static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
26 {
27 DECLARE_BITMAP(values, BITS_PER_TYPE(val));
28
29 values[0] = val;
30
31 gpiod_set_array_value_cansleep(mux->ngpios, mux->gpios, NULL, values);
32 }
33
i2c_mux_gpio_select(struct i2c_mux_core * muxc,u32 chan)34 static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
35 {
36 struct gpiomux *mux = i2c_mux_priv(muxc);
37
38 i2c_mux_gpio_set(mux, chan);
39
40 return 0;
41 }
42
i2c_mux_gpio_deselect(struct i2c_mux_core * muxc,u32 chan)43 static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
44 {
45 struct gpiomux *mux = i2c_mux_priv(muxc);
46
47 i2c_mux_gpio_set(mux, mux->data.idle);
48
49 return 0;
50 }
51
52 #ifdef CONFIG_OF
i2c_mux_gpio_probe_dt(struct gpiomux * mux,struct platform_device * pdev)53 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
54 struct platform_device *pdev)
55 {
56 struct device_node *np = pdev->dev.of_node;
57 struct device_node *adapter_np, *child;
58 struct i2c_adapter *adapter;
59 unsigned *values;
60 int i = 0;
61
62 if (!np)
63 return -ENODEV;
64
65 adapter_np = of_parse_phandle(np, "i2c-parent", 0);
66 if (!adapter_np) {
67 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
68 return -ENODEV;
69 }
70 adapter = of_find_i2c_adapter_by_node(adapter_np);
71 of_node_put(adapter_np);
72 if (!adapter)
73 return -EPROBE_DEFER;
74
75 mux->data.parent = i2c_adapter_id(adapter);
76 put_device(&adapter->dev);
77
78 mux->data.n_values = of_get_child_count(np);
79
80 values = devm_kcalloc(&pdev->dev,
81 mux->data.n_values, sizeof(*mux->data.values),
82 GFP_KERNEL);
83 if (!values) {
84 dev_err(&pdev->dev, "Cannot allocate values array");
85 return -ENOMEM;
86 }
87
88 for_each_child_of_node(np, child) {
89 of_property_read_u32(child, "reg", values + i);
90 i++;
91 }
92 mux->data.values = values;
93
94 if (of_property_read_u32(np, "idle-state", &mux->data.idle))
95 mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
96
97 return 0;
98 }
99 #else
i2c_mux_gpio_probe_dt(struct gpiomux * mux,struct platform_device * pdev)100 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
101 struct platform_device *pdev)
102 {
103 return 0;
104 }
105 #endif
106
i2c_mux_gpio_probe(struct platform_device * pdev)107 static int i2c_mux_gpio_probe(struct platform_device *pdev)
108 {
109 struct i2c_mux_core *muxc;
110 struct gpiomux *mux;
111 struct i2c_adapter *parent;
112 struct i2c_adapter *root;
113 unsigned initial_state;
114 int i, ngpios, ret;
115
116 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
117 if (!mux)
118 return -ENOMEM;
119
120 if (!dev_get_platdata(&pdev->dev)) {
121 ret = i2c_mux_gpio_probe_dt(mux, pdev);
122 if (ret < 0)
123 return ret;
124 } else {
125 memcpy(&mux->data, dev_get_platdata(&pdev->dev),
126 sizeof(mux->data));
127 }
128
129 ngpios = gpiod_count(&pdev->dev, "mux");
130 if (ngpios <= 0) {
131 dev_err(&pdev->dev, "no valid gpios provided\n");
132 return ngpios ?: -EINVAL;
133 }
134 mux->ngpios = ngpios;
135
136 parent = i2c_get_adapter(mux->data.parent);
137 if (!parent)
138 return -EPROBE_DEFER;
139
140 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
141 ngpios * sizeof(*mux->gpios), 0,
142 i2c_mux_gpio_select, NULL);
143 if (!muxc) {
144 ret = -ENOMEM;
145 goto alloc_failed;
146 }
147 mux->gpios = muxc->priv;
148 muxc->priv = mux;
149
150 platform_set_drvdata(pdev, muxc);
151
152 root = i2c_root_adapter(&parent->dev);
153
154 muxc->mux_locked = true;
155
156 if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
157 initial_state = mux->data.idle;
158 muxc->deselect = i2c_mux_gpio_deselect;
159 } else {
160 initial_state = mux->data.values[0];
161 }
162
163 for (i = 0; i < ngpios; i++) {
164 struct device *gpio_dev;
165 struct gpio_desc *gpiod;
166 enum gpiod_flags flag;
167
168 if (initial_state & BIT(i))
169 flag = GPIOD_OUT_HIGH;
170 else
171 flag = GPIOD_OUT_LOW;
172 gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
173 if (IS_ERR(gpiod)) {
174 ret = PTR_ERR(gpiod);
175 goto alloc_failed;
176 }
177
178 mux->gpios[i] = gpiod;
179
180 if (!muxc->mux_locked)
181 continue;
182
183 /* FIXME: find a proper way to access the GPIO device */
184 gpio_dev = &gpiod->gdev->dev;
185 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
186 }
187
188 if (muxc->mux_locked)
189 dev_info(&pdev->dev, "mux-locked i2c mux\n");
190
191 for (i = 0; i < mux->data.n_values; i++) {
192 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
193 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
194
195 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
196 if (ret)
197 goto add_adapter_failed;
198 }
199
200 dev_info(&pdev->dev, "%d port mux on %s adapter\n",
201 mux->data.n_values, parent->name);
202
203 return 0;
204
205 add_adapter_failed:
206 i2c_mux_del_adapters(muxc);
207 alloc_failed:
208 i2c_put_adapter(parent);
209
210 return ret;
211 }
212
i2c_mux_gpio_remove(struct platform_device * pdev)213 static int i2c_mux_gpio_remove(struct platform_device *pdev)
214 {
215 struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
216
217 i2c_mux_del_adapters(muxc);
218 i2c_put_adapter(muxc->parent);
219
220 return 0;
221 }
222
223 static const struct of_device_id i2c_mux_gpio_of_match[] = {
224 { .compatible = "i2c-mux-gpio", },
225 {},
226 };
227 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
228
229 static struct platform_driver i2c_mux_gpio_driver = {
230 .probe = i2c_mux_gpio_probe,
231 .remove = i2c_mux_gpio_remove,
232 .driver = {
233 .name = "i2c-mux-gpio",
234 .of_match_table = i2c_mux_gpio_of_match,
235 },
236 };
237
238 module_platform_driver(i2c_mux_gpio_driver);
239
240 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
241 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
242 MODULE_LICENSE("GPL");
243 MODULE_ALIAS("platform:i2c-mux-gpio");
244
