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	of_node_put(adapter_np);
80	if (!adapter)
81		return -EPROBE_DEFER;
82
83	mux->data.parent = i2c_adapter_id(adapter);
84	put_device(&adapter->dev);
85
86	mux->data.n_values = of_get_child_count(np);
87
88	values = devm_kzalloc(&pdev->dev,
89			      sizeof(*mux->data.values) * mux->data.n_values,
90			      GFP_KERNEL);
91	if (!values) {
92		dev_err(&pdev->dev, "Cannot allocate values array");
93		return -ENOMEM;
94	}
95
96	for_each_child_of_node(np, child) {
97		of_property_read_u32(child, "reg", values + i);
98		i++;
99	}
100	mux->data.values = values;
101
102	if (of_property_read_u32(np, "idle-state", &mux->data.idle))
103		mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
104
105	mux->data.n_gpios = of_gpio_named_count(np, "mux-gpios");
106	if (mux->data.n_gpios < 0) {
107		dev_err(&pdev->dev, "Missing mux-gpios property in the DT.\n");
108		return -EINVAL;
109	}
110
111	gpios = devm_kzalloc(&pdev->dev,
112			     sizeof(*mux->data.gpios) * mux->data.n_gpios, GFP_KERNEL);
113	if (!gpios) {
114		dev_err(&pdev->dev, "Cannot allocate gpios array");
115		return -ENOMEM;
116	}
117
118	for (i = 0; i < mux->data.n_gpios; i++) {
119		ret = of_get_named_gpio(np, "mux-gpios", i);
120		if (ret < 0)
121			return ret;
122		gpios[i] = ret;
123	}
124
125	mux->data.gpios = gpios;
126
127	return 0;
128}
129#else
130static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
131					struct platform_device *pdev)
132{
133	return 0;
134}
135#endif
136
137static int i2c_mux_gpio_probe(struct platform_device *pdev)
138{
139	struct gpiomux *mux;
140	struct i2c_adapter *parent;
141	int (*deselect) (struct i2c_adapter *, void *, u32);
142	unsigned initial_state, gpio_base;
143	int i, ret;
144
145	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
146	if (!mux) {
147		dev_err(&pdev->dev, "Cannot allocate gpiomux structure");
148		return -ENOMEM;
149	}
150
151	platform_set_drvdata(pdev, mux);
152
153	if (!dev_get_platdata(&pdev->dev)) {
154		ret = i2c_mux_gpio_probe_dt(mux, pdev);
155		if (ret < 0)
156			return ret;
157	} else {
158		memcpy(&mux->data, dev_get_platdata(&pdev->dev),
159			sizeof(mux->data));
160	}
161
162	/*
163	 * If a GPIO chip name is provided, the GPIO pin numbers provided are
164	 * relative to its base GPIO number. Otherwise they are absolute.
165	 */
166	if (mux->data.gpio_chip) {
167		struct gpio_chip *gpio;
168
169		gpio = gpiochip_find(mux->data.gpio_chip,
170				     match_gpio_chip_by_label);
171		if (!gpio)
172			return -EPROBE_DEFER;
173
174		gpio_base = gpio->base;
175	} else {
176		gpio_base = 0;
177	}
178
179	parent = i2c_get_adapter(mux->data.parent);
180	if (!parent)
181		return -EPROBE_DEFER;
182
183	mux->parent = parent;
184	mux->gpio_base = gpio_base;
185
186	mux->adap = devm_kzalloc(&pdev->dev,
187				 sizeof(*mux->adap) * mux->data.n_values,
188				 GFP_KERNEL);
189	if (!mux->adap) {
190		dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
191		ret = -ENOMEM;
192		goto alloc_failed;
193	}
194
195	if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
196		initial_state = mux->data.idle;
197		deselect = i2c_mux_gpio_deselect;
198	} else {
199		initial_state = mux->data.values[0];
200		deselect = NULL;
201	}
202
203	for (i = 0; i < mux->data.n_gpios; i++) {
204		ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
205		if (ret) {
206			dev_err(&pdev->dev, "Failed to request GPIO %d\n",
207				mux->data.gpios[i]);
208			goto err_request_gpio;
209		}
210
211		ret = gpio_direction_output(gpio_base + mux->data.gpios[i],
212					    initial_state & (1 << i));
213		if (ret) {
214			dev_err(&pdev->dev,
215				"Failed to set direction of GPIO %d to output\n",
216				mux->data.gpios[i]);
217			i++;	/* gpio_request above succeeded, so must free */
218			goto err_request_gpio;
219		}
220	}
221
222	for (i = 0; i < mux->data.n_values; i++) {
223		u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
224		unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
225
226		mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr,
227						   mux->data.values[i], class,
228						   i2c_mux_gpio_select, deselect);
229		if (!mux->adap[i]) {
230			ret = -ENODEV;
231			dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
232			goto add_adapter_failed;
233		}
234	}
235
236	dev_info(&pdev->dev, "%d port mux on %s adapter\n",
237		 mux->data.n_values, parent->name);
238
239	return 0;
240
241add_adapter_failed:
242	for (; i > 0; i--)
243		i2c_del_mux_adapter(mux->adap[i - 1]);
244	i = mux->data.n_gpios;
245err_request_gpio:
246	for (; i > 0; i--)
247		gpio_free(gpio_base + mux->data.gpios[i - 1]);
248alloc_failed:
249	i2c_put_adapter(parent);
250
251	return ret;
252}
253
254static int i2c_mux_gpio_remove(struct platform_device *pdev)
255{
256	struct gpiomux *mux = platform_get_drvdata(pdev);
257	int i;
258
259	for (i = 0; i < mux->data.n_values; i++)
260		i2c_del_mux_adapter(mux->adap[i]);
261
262	for (i = 0; i < mux->data.n_gpios; i++)
263		gpio_free(mux->gpio_base + mux->data.gpios[i]);
264
265	i2c_put_adapter(mux->parent);
266
267	return 0;
268}
269
270static const struct of_device_id i2c_mux_gpio_of_match[] = {
271	{ .compatible = "i2c-mux-gpio", },
272	{},
273};
274MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
275
276static struct platform_driver i2c_mux_gpio_driver = {
277	.probe	= i2c_mux_gpio_probe,
278	.remove	= i2c_mux_gpio_remove,
279	.driver	= {
280		.name	= "i2c-mux-gpio",
281		.of_match_table = i2c_mux_gpio_of_match,
282	},
283};
284
285module_platform_driver(i2c_mux_gpio_driver);
286
287MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
288MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
289MODULE_LICENSE("GPL");
290MODULE_ALIAS("platform:i2c-mux-gpio");
291