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