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
19struct gpiomux {
20	struct i2c_mux_gpio_platform_data data;
21	int ngpios;
22	struct gpio_desc **gpios;
23};
24
25static 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
34static 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
43static 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
53static 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
100static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
101					struct platform_device *pdev)
102{
103	return 0;
104}
105#endif
106
107static 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
205add_adapter_failed:
206	i2c_mux_del_adapters(muxc);
207alloc_failed:
208	i2c_put_adapter(parent);
209
210	return ret;
211}
212
213static 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
223static const struct of_device_id i2c_mux_gpio_of_match[] = {
224	{ .compatible = "i2c-mux-gpio", },
225	{},
226};
227MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
228
229static 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
238module_platform_driver(i2c_mux_gpio_driver);
239
240MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
241MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
242MODULE_LICENSE("GPL");
243MODULE_ALIAS("platform:i2c-mux-gpio");
244