1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Linear Technology LTC4306 and LTC4305 I2C multiplexer/switch
4  *
5  * Copyright (C) 2017 Analog Devices Inc.
6  *
7  * Based on: i2c-mux-pca954x.c
8  *
9  * Datasheet: http://cds.linear.com/docs/en/datasheet/4306.pdf
10  */
11 
12 #include <linux/gpio/consumer.h>
13 #include <linux/gpio/driver.h>
14 #include <linux/i2c-mux.h>
15 #include <linux/i2c.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 #include <linux/of_device.h>
19 #include <linux/property.h>
20 #include <linux/regmap.h>
21 #include <linux/slab.h>
22 
23 #define LTC4305_MAX_NCHANS 2
24 #define LTC4306_MAX_NCHANS 4
25 
26 #define LTC_REG_STATUS	0x0
27 #define LTC_REG_CONFIG	0x1
28 #define LTC_REG_MODE	0x2
29 #define LTC_REG_SWITCH	0x3
30 
31 #define LTC_DOWNSTREAM_ACCL_EN	BIT(6)
32 #define LTC_UPSTREAM_ACCL_EN	BIT(7)
33 
34 #define LTC_GPIO_ALL_INPUT	0xC0
35 #define LTC_SWITCH_MASK		0xF0
36 
37 enum ltc_type {
38 	ltc_4305,
39 	ltc_4306,
40 };
41 
42 struct chip_desc {
43 	u8 nchans;
44 	u8 num_gpios;
45 };
46 
47 struct ltc4306 {
48 	struct regmap *regmap;
49 	struct gpio_chip gpiochip;
50 	const struct chip_desc *chip;
51 };
52 
53 static const struct chip_desc chips[] = {
54 	[ltc_4305] = {
55 		.nchans = LTC4305_MAX_NCHANS,
56 	},
57 	[ltc_4306] = {
58 		.nchans = LTC4306_MAX_NCHANS,
59 		.num_gpios = 2,
60 	},
61 };
62 
63 static bool ltc4306_is_volatile_reg(struct device *dev, unsigned int reg)
64 {
65 	return (reg == LTC_REG_CONFIG) ? true : false;
66 }
67 
68 static const struct regmap_config ltc4306_regmap_config = {
69 	.reg_bits = 8,
70 	.val_bits = 8,
71 	.max_register = LTC_REG_SWITCH,
72 	.volatile_reg = ltc4306_is_volatile_reg,
73 	.cache_type = REGCACHE_FLAT,
74 };
75 
76 static int ltc4306_gpio_get(struct gpio_chip *chip, unsigned int offset)
77 {
78 	struct ltc4306 *data = gpiochip_get_data(chip);
79 	unsigned int val;
80 	int ret;
81 
82 	ret = regmap_read(data->regmap, LTC_REG_CONFIG, &val);
83 	if (ret < 0)
84 		return ret;
85 
86 	return !!(val & BIT(1 - offset));
87 }
88 
89 static void ltc4306_gpio_set(struct gpio_chip *chip, unsigned int offset,
90 			     int value)
91 {
92 	struct ltc4306 *data = gpiochip_get_data(chip);
93 
94 	regmap_update_bits(data->regmap, LTC_REG_CONFIG, BIT(5 - offset),
95 			   value ? BIT(5 - offset) : 0);
96 }
97 
98 static int ltc4306_gpio_get_direction(struct gpio_chip *chip,
99 				      unsigned int offset)
100 {
101 	struct ltc4306 *data = gpiochip_get_data(chip);
102 	unsigned int val;
103 	int ret;
104 
105 	ret = regmap_read(data->regmap, LTC_REG_MODE, &val);
106 	if (ret < 0)
107 		return ret;
108 
109 	return !!(val & BIT(7 - offset));
110 }
111 
112 static int ltc4306_gpio_direction_input(struct gpio_chip *chip,
113 					unsigned int offset)
114 {
115 	struct ltc4306 *data = gpiochip_get_data(chip);
116 
117 	return regmap_update_bits(data->regmap, LTC_REG_MODE,
118 				  BIT(7 - offset), BIT(7 - offset));
119 }
120 
121 static int ltc4306_gpio_direction_output(struct gpio_chip *chip,
122 					 unsigned int offset, int value)
123 {
124 	struct ltc4306 *data = gpiochip_get_data(chip);
125 
126 	ltc4306_gpio_set(chip, offset, value);
127 	return regmap_update_bits(data->regmap, LTC_REG_MODE,
128 				  BIT(7 - offset), 0);
129 }
130 
131 static int ltc4306_gpio_set_config(struct gpio_chip *chip,
132 				   unsigned int offset, unsigned long config)
133 {
134 	struct ltc4306 *data = gpiochip_get_data(chip);
135 	unsigned int val;
136 
137 	switch (pinconf_to_config_param(config)) {
138 	case PIN_CONFIG_DRIVE_OPEN_DRAIN:
139 		val = 0;
140 		break;
141 	case PIN_CONFIG_DRIVE_PUSH_PULL:
142 		val = BIT(4 - offset);
143 		break;
144 	default:
145 		return -ENOTSUPP;
146 	}
147 
148 	return regmap_update_bits(data->regmap, LTC_REG_MODE,
149 				  BIT(4 - offset), val);
150 }
151 
152 static int ltc4306_gpio_init(struct ltc4306 *data)
153 {
154 	struct device *dev = regmap_get_device(data->regmap);
155 
156 	if (!data->chip->num_gpios)
157 		return 0;
158 
159 	data->gpiochip.label = dev_name(dev);
160 	data->gpiochip.base = -1;
161 	data->gpiochip.ngpio = data->chip->num_gpios;
162 	data->gpiochip.parent = dev;
163 	data->gpiochip.can_sleep = true;
164 	data->gpiochip.get_direction = ltc4306_gpio_get_direction;
165 	data->gpiochip.direction_input = ltc4306_gpio_direction_input;
166 	data->gpiochip.direction_output = ltc4306_gpio_direction_output;
167 	data->gpiochip.get = ltc4306_gpio_get;
168 	data->gpiochip.set = ltc4306_gpio_set;
169 	data->gpiochip.set_config = ltc4306_gpio_set_config;
170 	data->gpiochip.owner = THIS_MODULE;
171 
172 	/* gpiolib assumes all GPIOs default input */
173 	regmap_write(data->regmap, LTC_REG_MODE, LTC_GPIO_ALL_INPUT);
174 
175 	return devm_gpiochip_add_data(dev, &data->gpiochip, data);
176 }
177 
178 static int ltc4306_select_mux(struct i2c_mux_core *muxc, u32 chan)
179 {
180 	struct ltc4306 *data = i2c_mux_priv(muxc);
181 
182 	return regmap_update_bits(data->regmap, LTC_REG_SWITCH,
183 				  LTC_SWITCH_MASK, BIT(7 - chan));
184 }
185 
186 static int ltc4306_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
187 {
188 	struct ltc4306 *data = i2c_mux_priv(muxc);
189 
190 	return regmap_update_bits(data->regmap, LTC_REG_SWITCH,
191 				  LTC_SWITCH_MASK, 0);
192 }
193 
194 static const struct i2c_device_id ltc4306_id[] = {
195 	{ "ltc4305", ltc_4305 },
196 	{ "ltc4306", ltc_4306 },
197 	{ }
198 };
199 MODULE_DEVICE_TABLE(i2c, ltc4306_id);
200 
201 static const struct of_device_id ltc4306_of_match[] = {
202 	{ .compatible = "lltc,ltc4305", .data = &chips[ltc_4305] },
203 	{ .compatible = "lltc,ltc4306", .data = &chips[ltc_4306] },
204 	{ }
205 };
206 MODULE_DEVICE_TABLE(of, ltc4306_of_match);
207 
208 static int ltc4306_probe(struct i2c_client *client)
209 {
210 	struct i2c_adapter *adap = client->adapter;
211 	const struct chip_desc *chip;
212 	struct i2c_mux_core *muxc;
213 	struct ltc4306 *data;
214 	struct gpio_desc *gpio;
215 	bool idle_disc;
216 	unsigned int val = 0;
217 	int num, ret;
218 
219 	chip = of_device_get_match_data(&client->dev);
220 
221 	if (!chip)
222 		chip = &chips[i2c_match_id(ltc4306_id, client)->driver_data];
223 
224 	idle_disc = device_property_read_bool(&client->dev,
225 					      "i2c-mux-idle-disconnect");
226 
227 	muxc = i2c_mux_alloc(adap, &client->dev,
228 			     chip->nchans, sizeof(*data),
229 			     I2C_MUX_LOCKED, ltc4306_select_mux,
230 			     idle_disc ? ltc4306_deselect_mux : NULL);
231 	if (!muxc)
232 		return -ENOMEM;
233 	data = i2c_mux_priv(muxc);
234 	data->chip = chip;
235 
236 	i2c_set_clientdata(client, muxc);
237 
238 	data->regmap = devm_regmap_init_i2c(client, &ltc4306_regmap_config);
239 	if (IS_ERR(data->regmap)) {
240 		ret = PTR_ERR(data->regmap);
241 		dev_err(&client->dev, "Failed to allocate register map: %d\n",
242 			ret);
243 		return ret;
244 	}
245 
246 	/* Reset and enable the mux if an enable GPIO is specified. */
247 	gpio = devm_gpiod_get_optional(&client->dev, "enable", GPIOD_OUT_LOW);
248 	if (IS_ERR(gpio))
249 		return PTR_ERR(gpio);
250 
251 	if (gpio) {
252 		udelay(1);
253 		gpiod_set_value(gpio, 1);
254 	}
255 
256 	/*
257 	 * Write the mux register at addr to verify
258 	 * that the mux is in fact present. This also
259 	 * initializes the mux to disconnected state.
260 	 */
261 	if (regmap_write(data->regmap, LTC_REG_SWITCH, 0) < 0) {
262 		dev_warn(&client->dev, "probe failed\n");
263 		return -ENODEV;
264 	}
265 
266 	if (device_property_read_bool(&client->dev,
267 				      "ltc,downstream-accelerators-enable"))
268 		val |= LTC_DOWNSTREAM_ACCL_EN;
269 
270 	if (device_property_read_bool(&client->dev,
271 				      "ltc,upstream-accelerators-enable"))
272 		val |= LTC_UPSTREAM_ACCL_EN;
273 
274 	if (regmap_write(data->regmap, LTC_REG_CONFIG, val) < 0)
275 		return -ENODEV;
276 
277 	ret = ltc4306_gpio_init(data);
278 	if (ret < 0)
279 		return ret;
280 
281 	/* Now create an adapter for each channel */
282 	for (num = 0; num < chip->nchans; num++) {
283 		ret = i2c_mux_add_adapter(muxc, 0, num, 0);
284 		if (ret) {
285 			i2c_mux_del_adapters(muxc);
286 			return ret;
287 		}
288 	}
289 
290 	dev_info(&client->dev,
291 		 "registered %d multiplexed busses for I2C switch %s\n",
292 		 num, client->name);
293 
294 	return 0;
295 }
296 
297 static void ltc4306_remove(struct i2c_client *client)
298 {
299 	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
300 
301 	i2c_mux_del_adapters(muxc);
302 }
303 
304 static struct i2c_driver ltc4306_driver = {
305 	.driver		= {
306 		.name	= "ltc4306",
307 		.of_match_table = of_match_ptr(ltc4306_of_match),
308 	},
309 	.probe		= ltc4306_probe,
310 	.remove		= ltc4306_remove,
311 	.id_table	= ltc4306_id,
312 };
313 
314 module_i2c_driver(ltc4306_driver);
315 
316 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
317 MODULE_DESCRIPTION("Linear Technology LTC4306, LTC4305 I2C mux/switch driver");
318 MODULE_LICENSE("GPL v2");
319