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
36enum ltc_type {
37 ltc_4305,
38 ltc_4306,
39};
40
41struct chip_desc {
42 u8 nchans;
43 u8 num_gpios;
44};
45
46struct ltc4306 {
47 struct regmap *regmap;
48 struct gpio_chip gpiochip;
49 const struct chip_desc *chip;
50};
51
52static 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
62static bool ltc4306_is_volatile_reg(struct device *dev, unsigned int reg)
63{
64 return reg == LTC_REG_CONFIG;
65}
66
67static 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
75static int ltc4306_gpio_get(struct gpio_chip *chip, unsigned int offset)
76{
77 struct ltc4306 *data = gpiochip_get_data(gc: chip);
78 unsigned int val;
79 int ret;
80
81 ret = regmap_read(map: data->regmap, LTC_REG_CONFIG, val: &val);
82 if (ret < 0)
83 return ret;
84
85 return !!(val & BIT(1 - offset));
86}
87
88static void ltc4306_gpio_set(struct gpio_chip *chip, unsigned int offset,
89 int value)
90{
91 struct ltc4306 *data = gpiochip_get_data(gc: chip);
92
93 regmap_update_bits(map: data->regmap, LTC_REG_CONFIG, BIT(5 - offset),
94 val: value ? BIT(5 - offset) : 0);
95}
96
97static int ltc4306_gpio_get_direction(struct gpio_chip *chip,
98 unsigned int offset)
99{
100 struct ltc4306 *data = gpiochip_get_data(gc: chip);
101 unsigned int val;
102 int ret;
103
104 ret = regmap_read(map: data->regmap, LTC_REG_MODE, val: &val);
105 if (ret < 0)
106 return ret;
107
108 return !!(val & BIT(7 - offset));
109}
110
111static int ltc4306_gpio_direction_input(struct gpio_chip *chip,
112 unsigned int offset)
113{
114 struct ltc4306 *data = gpiochip_get_data(gc: chip);
115
116 return regmap_update_bits(map: data->regmap, LTC_REG_MODE,
117 BIT(7 - offset), BIT(7 - offset));
118}
119
120static int ltc4306_gpio_direction_output(struct gpio_chip *chip,
121 unsigned int offset, int value)
122{
123 struct ltc4306 *data = gpiochip_get_data(gc: chip);
124
125 ltc4306_gpio_set(chip, offset, value);
126 return regmap_update_bits(map: data->regmap, LTC_REG_MODE,
127 BIT(7 - offset), val: 0);
128}
129
130static int ltc4306_gpio_set_config(struct gpio_chip *chip,
131 unsigned int offset, unsigned long config)
132{
133 struct ltc4306 *data = gpiochip_get_data(gc: 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(map: data->regmap, LTC_REG_MODE,
148 BIT(4 - offset), val);
149}
150
151static int ltc4306_gpio_init(struct ltc4306 *data)
152{
153 struct device *dev = regmap_get_device(map: 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(map: data->regmap, LTC_REG_MODE, LTC_GPIO_ALL_INPUT);
173
174 return devm_gpiochip_add_data(dev, &data->gpiochip, data);
175}
176
177static 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(map: data->regmap, LTC_REG_SWITCH,
182 LTC_SWITCH_MASK, BIT(7 - chan));
183}
184
185static 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(map: data->regmap, LTC_REG_SWITCH,
190 LTC_SWITCH_MASK, val: 0);
191}
192
193static const struct i2c_device_id ltc4306_id[] = {
194 { "ltc4305", ltc_4305 },
195 { "ltc4306", ltc_4306 },
196 { }
197};
198MODULE_DEVICE_TABLE(i2c, ltc4306_id);
199
200static 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};
205MODULE_DEVICE_TABLE(of, ltc4306_of_match);
206
207static 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(dev: &client->dev);
219
220 if (!chip)
221 chip = &chips[i2c_match_id(id: ltc4306_id, client)->driver_data];
222
223 idle_disc = device_property_read_bool(dev: &client->dev,
224 propname: "i2c-mux-idle-disconnect");
225
226 muxc = i2c_mux_alloc(parent: adap, dev: &client->dev,
227 max_adapters: chip->nchans, sizeof_priv: sizeof(*data),
228 I2C_MUX_LOCKED, select: ltc4306_select_mux,
229 deselect: 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, data: muxc);
236
237 data->regmap = devm_regmap_init_i2c(client, &ltc4306_regmap_config);
238 if (IS_ERR(ptr: data->regmap)) {
239 ret = PTR_ERR(ptr: 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(dev: &client->dev, con_id: "enable", flags: GPIOD_OUT_LOW);
247 if (IS_ERR(ptr: gpio))
248 return PTR_ERR(ptr: gpio);
249
250 if (gpio) {
251 udelay(1);
252 gpiod_set_value(desc: gpio, value: 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(map: data->regmap, LTC_REG_SWITCH, val: 0) < 0) {
261 dev_warn(&client->dev, "probe failed\n");
262 return -ENODEV;
263 }
264
265 if (device_property_read_bool(dev: &client->dev,
266 propname: "ltc,downstream-accelerators-enable"))
267 val |= LTC_DOWNSTREAM_ACCL_EN;
268
269 if (device_property_read_bool(dev: &client->dev,
270 propname: "ltc,upstream-accelerators-enable"))
271 val |= LTC_UPSTREAM_ACCL_EN;
272
273 if (regmap_write(map: 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, force_nr: 0, chan_id: num, class: 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
296static 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
303static 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
313module_i2c_driver(ltc4306_driver);
314
315MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
316MODULE_DESCRIPTION("Linear Technology LTC4306, LTC4305 I2C mux/switch driver");
317MODULE_LICENSE("GPL v2");
318

source code of linux/drivers/i2c/muxes/i2c-mux-ltc4306.c