drivers/i2c/muxes/i2c-mux-ltc4306.c

   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
  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
  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
  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
  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
 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
 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
 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
 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
 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
 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
 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);
 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
 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");