1/*
2 * I2C multiplexer using GPIO API
3 *
4 * Peter Korsgaard <peter.korsgaard@barco.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <linux/i2c.h>
12#include <linux/i2c-mux.h>
13#include <linux/i2c-mux-gpio.h>
14#include <linux/platform_device.h>
15#include <linux/module.h>
16#include <linux/slab.h>
17#include <linux/gpio.h>
18#include <linux/of_gpio.h>
19
20struct gpiomux {
21	struct i2c_adapter *parent;
22	struct i2c_adapter **adap; /* child busses */
23	struct i2c_mux_gpio_platform_data data;
24	unsigned gpio_base;
25};
26
27static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
28{
29	int i;
30
31	for (i = 0; i < mux->data.n_gpios; i++)
32		gpio_set_value_cansleep(mux->gpio_base + mux->data.gpios[i],
33					val & (1 << i));
34}
35
36static int i2c_mux_gpio_select(struct i2c_adapter *adap, void *data, u32 chan)
37{
38	struct gpiomux *mux = data;
39
40	i2c_mux_gpio_set(mux, chan);
41
42	return 0;
43}
44
45static int i2c_mux_gpio_deselect(struct i2c_adapter *adap, void *data, u32 chan)
46{
47	struct gpiomux *mux = data;
48
49	i2c_mux_gpio_set(mux, mux->data.idle);
50
51	return 0;
52}
53
54static int match_gpio_chip_by_label(struct gpio_chip *chip,
55					      void *data)
56{
57	return !strcmp(chip->label, data);
58}
59
60#ifdef CONFIG_OF
61static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
62					struct platform_device *pdev)
63{
64	struct device_node *np = pdev->dev.of_node;
65	struct device_node *adapter_np, *child;
66	struct i2c_adapter *adapter;
67	unsigned *values, *gpios;
68	int i = 0, ret;
69
70	if (!np)
71		return -ENODEV;
72
73	adapter_np = of_parse_phandle(np, "i2c-parent", 0);
74	if (!adapter_np) {
75		dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
76		return -ENODEV;
77	}
78	adapter = of_find_i2c_adapter_by_node(adapter_np);
79	if (!adapter)
80		return -EPROBE_DEFER;
81
82	mux->data.parent = i2c_adapter_id(adapter);
83	put_device(&adapter->dev);
84
85	mux->data.n_values = of_get_child_count(np);
86
87	values = devm_kzalloc(&pdev->dev,
88			      sizeof(*mux->data.values) * mux->data.n_values,
89			      GFP_KERNEL);
90	if (!values) {
91		dev_err(&pdev->dev, "Cannot allocate values array");
92		return -ENOMEM;
93	}
94
95	for_each_child_of_node(np, child) {
96		of_property_read_u32(child, "reg", values + i);
97		i++;
98	}
99	mux->data.values = values;
100
101	if (of_property_read_u32(np, "idle-state", &mux->data.idle))
102		mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
103
104	mux->data.n_gpios = of_gpio_named_count(np, "mux-gpios");
105	if (mux->data.n_gpios < 0) {
106		dev_err(&pdev->dev, "Missing mux-gpios property in the DT.\n");
107		return -EINVAL;
108	}
109
110	gpios = devm_kzalloc(&pdev->dev,
111			     sizeof(*mux->data.gpios) * mux->data.n_gpios, GFP_KERNEL);
112	if (!gpios) {
113		dev_err(&pdev->dev, "Cannot allocate gpios array");
114		return -ENOMEM;
115	}
116
117	for (i = 0; i < mux->data.n_gpios; i++) {
118		ret = of_get_named_gpio(np, "mux-gpios", i);
119		if (ret < 0)
120			return ret;
121		gpios[i] = ret;
122	}
123
124	mux->data.gpios = gpios;
125
126	return 0;
127}
128#else
129static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
130					struct platform_device *pdev)
131{
132	return 0;
133}
134#endif
135
136static int i2c_mux_gpio_probe(struct platform_device *pdev)
137{
138	struct gpiomux *mux;
139	struct i2c_adapter *parent;
140	int (*deselect) (struct i2c_adapter *, void *, u32);
141	unsigned initial_state, gpio_base;
142	int i, ret;
143
144	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
145	if (!mux) {
146		dev_err(&pdev->dev, "Cannot allocate gpiomux structure");
147		return -ENOMEM;
148	}
149
150	platform_set_drvdata(pdev, mux);
151
152	if (!dev_get_platdata(&pdev->dev)) {
153		ret = i2c_mux_gpio_probe_dt(mux, pdev);
154		if (ret < 0)
155			return ret;
156	} else {
157		memcpy(&mux->data, dev_get_platdata(&pdev->dev),
158			sizeof(mux->data));
159	}
160
161	/*
162	 * If a GPIO chip name is provided, the GPIO pin numbers provided are
163	 * relative to its base GPIO number. Otherwise they are absolute.
164	 */
165	if (mux->data.gpio_chip) {
166		struct gpio_chip *gpio;
167
168		gpio = gpiochip_find(mux->data.gpio_chip,
169				     match_gpio_chip_by_label);
170		if (!gpio)
171			return -EPROBE_DEFER;
172
173		gpio_base = gpio->base;
174	} else {
175		gpio_base = 0;
176	}
177
178	parent = i2c_get_adapter(mux->data.parent);
179	if (!parent)
180		return -EPROBE_DEFER;
181
182	mux->parent = parent;
183	mux->gpio_base = gpio_base;
184
185	mux->adap = devm_kzalloc(&pdev->dev,
186				 sizeof(*mux->adap) * mux->data.n_values,
187				 GFP_KERNEL);
188	if (!mux->adap) {
189		dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
190		ret = -ENOMEM;
191		goto alloc_failed;
192	}
193
194	if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
195		initial_state = mux->data.idle;
196		deselect = i2c_mux_gpio_deselect;
197	} else {
198		initial_state = mux->data.values[0];
199		deselect = NULL;
200	}
201
202	for (i = 0; i < mux->data.n_gpios; i++) {
203		ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
204		if (ret) {
205			dev_err(&pdev->dev, "Failed to request GPIO %d\n",
206				mux->data.gpios[i]);
207			goto err_request_gpio;
208		}
209
210		ret = gpio_direction_output(gpio_base + mux->data.gpios[i],
211					    initial_state & (1 << i));
212		if (ret) {
213			dev_err(&pdev->dev,
214				"Failed to set direction of GPIO %d to output\n",
215				mux->data.gpios[i]);
216			i++;	/* gpio_request above succeeded, so must free */
217			goto err_request_gpio;
218		}
219	}
220
221	for (i = 0; i < mux->data.n_values; i++) {
222		u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
223		unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
224
225		mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr,
226						   mux->data.values[i], class,
227						   i2c_mux_gpio_select, deselect);
228		if (!mux->adap[i]) {
229			ret = -ENODEV;
230			dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
231			goto add_adapter_failed;
232		}
233	}
234
235	dev_info(&pdev->dev, "%d port mux on %s adapter\n",
236		 mux->data.n_values, parent->name);
237
238	return 0;
239
240add_adapter_failed:
241	for (; i > 0; i--)
242		i2c_del_mux_adapter(mux->adap[i - 1]);
243	i = mux->data.n_gpios;
244err_request_gpio:
245	for (; i > 0; i--)
246		gpio_free(gpio_base + mux->data.gpios[i - 1]);
247alloc_failed:
248	i2c_put_adapter(parent);
249
250	return ret;
251}
252
253static int i2c_mux_gpio_remove(struct platform_device *pdev)
254{
255	struct gpiomux *mux = platform_get_drvdata(pdev);
256	int i;
257
258	for (i = 0; i < mux->data.n_values; i++)
259		i2c_del_mux_adapter(mux->adap[i]);
260
261	for (i = 0; i < mux->data.n_gpios; i++)
262		gpio_free(mux->gpio_base + mux->data.gpios[i]);
263
264	i2c_put_adapter(mux->parent);
265
266	return 0;
267}
268
269static const struct of_device_id i2c_mux_gpio_of_match[] = {
270	{ .compatible = "i2c-mux-gpio", },
271	{},
272};
273MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
274
275static struct platform_driver i2c_mux_gpio_driver = {
276	.probe	= i2c_mux_gpio_probe,
277	.remove	= i2c_mux_gpio_remove,
278	.driver	= {
279		.name	= "i2c-mux-gpio",
280		.of_match_table = i2c_mux_gpio_of_match,
281	},
282};
283
284module_platform_driver(i2c_mux_gpio_driver);
285
286MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
287MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
288MODULE_LICENSE("GPL");
289MODULE_ALIAS("platform:i2c-mux-gpio");
290