xref: /openbmc/linux/drivers/i2c/muxes/i2c-mux-gpio.c (revision db6aee60)
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 				fwnode_handle_put(child);
110 				return dev_err_probe(dev, rc, "Cannot get address\n");
111 			}
112 		}
113 
114 		i++;
115 	}
116 	mux->data.values = values;
117 
118 	if (device_property_read_u32(dev, "idle-state", &mux->data.idle))
119 		mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
120 
121 	return 0;
122 }
123 
i2c_mux_gpio_probe(struct platform_device * pdev)124 static int i2c_mux_gpio_probe(struct platform_device *pdev)
125 {
126 	struct i2c_mux_core *muxc;
127 	struct gpiomux *mux;
128 	struct i2c_adapter *parent;
129 	struct i2c_adapter *root;
130 	unsigned initial_state;
131 	int i, ngpios, ret;
132 
133 	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
134 	if (!mux)
135 		return -ENOMEM;
136 
137 	if (!dev_get_platdata(&pdev->dev)) {
138 		ret = i2c_mux_gpio_probe_fw(mux, pdev);
139 		if (ret < 0)
140 			return ret;
141 	} else {
142 		memcpy(&mux->data, dev_get_platdata(&pdev->dev),
143 			sizeof(mux->data));
144 	}
145 
146 	ngpios = gpiod_count(&pdev->dev, "mux");
147 	if (ngpios <= 0) {
148 		dev_err(&pdev->dev, "no valid gpios provided\n");
149 		return ngpios ?: -EINVAL;
150 	}
151 	mux->ngpios = ngpios;
152 
153 	parent = i2c_get_adapter(mux->data.parent);
154 	if (!parent)
155 		return -EPROBE_DEFER;
156 
157 	muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
158 			     array_size(ngpios, sizeof(*mux->gpios)), 0,
159 			     i2c_mux_gpio_select, NULL);
160 	if (!muxc) {
161 		ret = -ENOMEM;
162 		goto alloc_failed;
163 	}
164 	mux->gpios = muxc->priv;
165 	muxc->priv = mux;
166 
167 	platform_set_drvdata(pdev, muxc);
168 
169 	root = i2c_root_adapter(&parent->dev);
170 
171 	muxc->mux_locked = true;
172 
173 	if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
174 		initial_state = mux->data.idle;
175 		muxc->deselect = i2c_mux_gpio_deselect;
176 	} else {
177 		initial_state = mux->data.values[0];
178 	}
179 
180 	for (i = 0; i < ngpios; i++) {
181 		struct device *gpio_dev;
182 		struct gpio_desc *gpiod;
183 		enum gpiod_flags flag;
184 
185 		if (initial_state & BIT(i))
186 			flag = GPIOD_OUT_HIGH;
187 		else
188 			flag = GPIOD_OUT_LOW;
189 		gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
190 		if (IS_ERR(gpiod)) {
191 			ret = PTR_ERR(gpiod);
192 			goto alloc_failed;
193 		}
194 
195 		mux->gpios[i] = gpiod;
196 
197 		if (!muxc->mux_locked)
198 			continue;
199 
200 		/* FIXME: find a proper way to access the GPIO device */
201 		gpio_dev = &gpiod->gdev->dev;
202 		muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
203 	}
204 
205 	if (muxc->mux_locked)
206 		dev_info(&pdev->dev, "mux-locked i2c mux\n");
207 
208 	for (i = 0; i < mux->data.n_values; i++) {
209 		u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
210 		unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
211 
212 		ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
213 		if (ret)
214 			goto add_adapter_failed;
215 	}
216 
217 	dev_info(&pdev->dev, "%d port mux on %s adapter\n",
218 		 mux->data.n_values, parent->name);
219 
220 	return 0;
221 
222 add_adapter_failed:
223 	i2c_mux_del_adapters(muxc);
224 alloc_failed:
225 	i2c_put_adapter(parent);
226 
227 	return ret;
228 }
229 
i2c_mux_gpio_remove(struct platform_device * pdev)230 static void i2c_mux_gpio_remove(struct platform_device *pdev)
231 {
232 	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
233 
234 	i2c_mux_del_adapters(muxc);
235 	i2c_put_adapter(muxc->parent);
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_new = 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