summaryrefslogtreecommitdiff
path: root/drivers/i2c/muxes/i2c-mux-ltc4306.c
blob: 83a714605cd67b036d97eb7e2924b546f5b87df2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
/*
 * Linear Technology LTC4306 and LTC4305 I2C multiplexer/switch
 *
 * Copyright (C) 2017 Analog Devices Inc.
 *
 * Licensed under the GPL-2.
 *
 * Based on: i2c-mux-pca954x.c
 *
 * Datasheet: http://cds.linear.com/docs/en/datasheet/4306.pdf
 */

#include <linux/gpio/consumer.h>
#include <linux/gpio/driver.h>
#include <linux/i2c-mux.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/slab.h>

#define LTC4305_MAX_NCHANS 2
#define LTC4306_MAX_NCHANS 4

#define LTC_REG_STATUS	0x0
#define LTC_REG_CONFIG	0x1
#define LTC_REG_MODE	0x2
#define LTC_REG_SWITCH	0x3

#define LTC_DOWNSTREAM_ACCL_EN	BIT(6)
#define LTC_UPSTREAM_ACCL_EN	BIT(7)

#define LTC_GPIO_ALL_INPUT	0xC0
#define LTC_SWITCH_MASK		0xF0

enum ltc_type {
	ltc_4305,
	ltc_4306,
};

struct chip_desc {
	u8 nchans;
	u8 num_gpios;
};

struct ltc4306 {
	struct regmap *regmap;
	struct gpio_chip gpiochip;
	const struct chip_desc *chip;
};

static const struct chip_desc chips[] = {
	[ltc_4305] = {
		.nchans = LTC4305_MAX_NCHANS,
	},
	[ltc_4306] = {
		.nchans = LTC4306_MAX_NCHANS,
		.num_gpios = 2,
	},
};

static bool ltc4306_is_volatile_reg(struct device *dev, unsigned int reg)
{
	return (reg == LTC_REG_CONFIG) ? true : false;
}

static const struct regmap_config ltc4306_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.max_register = LTC_REG_SWITCH,
	.volatile_reg = ltc4306_is_volatile_reg,
	.cache_type = REGCACHE_FLAT,
};

static int ltc4306_gpio_get(struct gpio_chip *chip, unsigned int offset)
{
	struct ltc4306 *data = gpiochip_get_data(chip);
	unsigned int val;
	int ret;

	ret = regmap_read(data->regmap, LTC_REG_CONFIG, &val);
	if (ret < 0)
		return ret;

	return !!(val & BIT(1 - offset));
}

static void ltc4306_gpio_set(struct gpio_chip *chip, unsigned int offset,
			     int value)
{
	struct ltc4306 *data = gpiochip_get_data(chip);

	regmap_update_bits(data->regmap, LTC_REG_CONFIG, BIT(5 - offset),
			   value ? BIT(5 - offset) : 0);
}

static int ltc4306_gpio_get_direction(struct gpio_chip *chip,
				      unsigned int offset)
{
	struct ltc4306 *data = gpiochip_get_data(chip);
	unsigned int val;
	int ret;

	ret = regmap_read(data->regmap, LTC_REG_MODE, &val);
	if (ret < 0)
		return ret;

	return !!(val & BIT(7 - offset));
}

static int ltc4306_gpio_direction_input(struct gpio_chip *chip,
					unsigned int offset)
{
	struct ltc4306 *data = gpiochip_get_data(chip);

	return regmap_update_bits(data->regmap, LTC_REG_MODE,
				  BIT(7 - offset), BIT(7 - offset));
}

static int ltc4306_gpio_direction_output(struct gpio_chip *chip,
					 unsigned int offset, int value)
{
	struct ltc4306 *data = gpiochip_get_data(chip);

	ltc4306_gpio_set(chip, offset, value);
	return regmap_update_bits(data->regmap, LTC_REG_MODE,
				  BIT(7 - offset), 0);
}

static int ltc4306_gpio_set_config(struct gpio_chip *chip,
				   unsigned int offset, unsigned long config)
{
	struct ltc4306 *data = gpiochip_get_data(chip);
	unsigned int val;

	switch (pinconf_to_config_param(config)) {
	case PIN_CONFIG_DRIVE_OPEN_DRAIN:
		val = 0;
		break;
	case PIN_CONFIG_DRIVE_PUSH_PULL:
		val = BIT(4 - offset);
		break;
	default:
		return -ENOTSUPP;
	}

	return regmap_update_bits(data->regmap, LTC_REG_MODE,
				  BIT(4 - offset), val);
}

static int ltc4306_gpio_init(struct ltc4306 *data)
{
	struct device *dev = regmap_get_device(data->regmap);

	if (!data->chip->num_gpios)
		return 0;

	data->gpiochip.label = dev_name(dev);
	data->gpiochip.base = -1;
	data->gpiochip.ngpio = data->chip->num_gpios;
	data->gpiochip.parent = dev;
	data->gpiochip.can_sleep = true;
	data->gpiochip.get_direction = ltc4306_gpio_get_direction;
	data->gpiochip.direction_input = ltc4306_gpio_direction_input;
	data->gpiochip.direction_output = ltc4306_gpio_direction_output;
	data->gpiochip.get = ltc4306_gpio_get;
	data->gpiochip.set = ltc4306_gpio_set;
	data->gpiochip.set_config = ltc4306_gpio_set_config;
	data->gpiochip.owner = THIS_MODULE;

	/* gpiolib assumes all GPIOs default input */
	regmap_write(data->regmap, LTC_REG_MODE, LTC_GPIO_ALL_INPUT);

	return devm_gpiochip_add_data(dev, &data->gpiochip, data);
}

static int ltc4306_select_mux(struct i2c_mux_core *muxc, u32 chan)
{
	struct ltc4306 *data = i2c_mux_priv(muxc);

	return regmap_update_bits(data->regmap, LTC_REG_SWITCH,
				  LTC_SWITCH_MASK, BIT(7 - chan));
}

static int ltc4306_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
{
	struct ltc4306 *data = i2c_mux_priv(muxc);

	return regmap_update_bits(data->regmap, LTC_REG_SWITCH,
				  LTC_SWITCH_MASK, 0);
}

static const struct i2c_device_id ltc4306_id[] = {
	{ "ltc4305", ltc_4305 },
	{ "ltc4306", ltc_4306 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, ltc4306_id);

static const struct of_device_id ltc4306_of_match[] = {
	{ .compatible = "lltc,ltc4305", .data = &chips[ltc_4305] },
	{ .compatible = "lltc,ltc4306", .data = &chips[ltc_4306] },
	{ }
};
MODULE_DEVICE_TABLE(of, ltc4306_of_match);

static int ltc4306_probe(struct i2c_client *client)
{
	struct i2c_adapter *adap = client->adapter;
	const struct chip_desc *chip;
	struct i2c_mux_core *muxc;
	struct ltc4306 *data;
	struct gpio_desc *gpio;
	bool idle_disc;
	unsigned int val = 0;
	int num, ret;

	chip = of_device_get_match_data(&client->dev);

	if (!chip)
		chip = &chips[i2c_match_id(ltc4306_id, client)->driver_data];

	idle_disc = device_property_read_bool(&client->dev,
					      "i2c-mux-idle-disconnect");

	muxc = i2c_mux_alloc(adap, &client->dev,
			     chip->nchans, sizeof(*data),
			     I2C_MUX_LOCKED, ltc4306_select_mux,
			     idle_disc ? ltc4306_deselect_mux : NULL);
	if (!muxc)
		return -ENOMEM;
	data = i2c_mux_priv(muxc);
	data->chip = chip;

	i2c_set_clientdata(client, muxc);

	data->regmap = devm_regmap_init_i2c(client, &ltc4306_regmap_config);
	if (IS_ERR(data->regmap)) {
		ret = PTR_ERR(data->regmap);
		dev_err(&client->dev, "Failed to allocate register map: %d\n",
			ret);
		return ret;
	}

	/* Reset and enable the mux if an enable GPIO is specified. */
	gpio = devm_gpiod_get_optional(&client->dev, "enable", GPIOD_OUT_LOW);
	if (IS_ERR(gpio))
		return PTR_ERR(gpio);

	if (gpio) {
		udelay(1);
		gpiod_set_value(gpio, 1);
	}

	/*
	 * Write the mux register at addr to verify
	 * that the mux is in fact present. This also
	 * initializes the mux to disconnected state.
	 */
	if (regmap_write(data->regmap, LTC_REG_SWITCH, 0) < 0) {
		dev_warn(&client->dev, "probe failed\n");
		return -ENODEV;
	}

	if (device_property_read_bool(&client->dev,
				      "ltc,downstream-accelerators-enable"))
		val |= LTC_DOWNSTREAM_ACCL_EN;

	if (device_property_read_bool(&client->dev,
				      "ltc,upstream-accelerators-enable"))
		val |= LTC_UPSTREAM_ACCL_EN;

	if (regmap_write(data->regmap, LTC_REG_CONFIG, val) < 0)
		return -ENODEV;

	ret = ltc4306_gpio_init(data);
	if (ret < 0)
		return ret;

	/* Now create an adapter for each channel */
	for (num = 0; num < chip->nchans; num++) {
		ret = i2c_mux_add_adapter(muxc, 0, num, 0);
		if (ret) {
			i2c_mux_del_adapters(muxc);
			return ret;
		}
	}

	dev_info(&client->dev,
		 "registered %d multiplexed busses for I2C switch %s\n",
		 num, client->name);

	return 0;
}

static int ltc4306_remove(struct i2c_client *client)
{
	struct i2c_mux_core *muxc = i2c_get_clientdata(client);

	i2c_mux_del_adapters(muxc);

	return 0;
}

static struct i2c_driver ltc4306_driver = {
	.driver		= {
		.name	= "ltc4306",
		.of_match_table = of_match_ptr(ltc4306_of_match),
	},
	.probe_new	= ltc4306_probe,
	.remove		= ltc4306_remove,
	.id_table	= ltc4306_id,
};

module_i2c_driver(ltc4306_driver);

MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("Linear Technology LTC4306, LTC4305 I2C mux/switch driver");
MODULE_LICENSE("GPL v2");