drivers/iio/potentiometer/mcp4131.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Industrial I/O driver for Microchip digital potentiometers
   4  *
   5  * Copyright (c) 2016 Slawomir Stepien
   6  * Based on: Peter Rosin's code from mcp4531.c
   7  *
   8  * Datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/22060b.pdf
   9  *
  10  * DEVID        #Wipers #Positions      Resistor Opts (kOhm)
  11  * mcp4131      1       129             5, 10, 50, 100
  12  * mcp4132      1       129             5, 10, 50, 100
  13  * mcp4141      1       129             5, 10, 50, 100
  14  * mcp4142      1       129             5, 10, 50, 100
  15  * mcp4151      1       257             5, 10, 50, 100
  16  * mcp4152      1       257             5, 10, 50, 100
  17  * mcp4161      1       257             5, 10, 50, 100
  18  * mcp4162      1       257             5, 10, 50, 100
  19  * mcp4231      2       129             5, 10, 50, 100
  20  * mcp4232      2       129             5, 10, 50, 100
  21  * mcp4241      2       129             5, 10, 50, 100
  22  * mcp4242      2       129             5, 10, 50, 100
  23  * mcp4251      2       257             5, 10, 50, 100
  24  * mcp4252      2       257             5, 10, 50, 100
  25  * mcp4261      2       257             5, 10, 50, 100
  26  * mcp4262      2       257             5, 10, 50, 100
  27  */
  28
  29 /*
  30  * TODO:
  31  * 1. Write wiper setting to EEPROM for EEPROM capable models.
  32  */
  33
  34 #include <linux/cache.h>
  35 #include <linux/err.h>
  36 #include <linux/export.h>
  37 #include <linux/iio/iio.h>
  38 #include <linux/iio/types.h>
  39 #include <linux/module.h>
  40 #include <linux/mod_devicetable.h>
  41 #include <linux/mutex.h>
  42 #include <linux/property.h>
  43 #include <linux/spi/spi.h>
  44
  45 #define MCP4131_WRITE           (0x00 << 2)
  46 #define MCP4131_READ            (0x03 << 2)
  47
  48 #define MCP4131_WIPER_SHIFT     4
  49 #define MCP4131_CMDERR(r)       ((r[0]) & 0x02)
  50 #define MCP4131_RAW(r)          ((r[0]) == 0xff ? 0x100 : (r[1]))
  51
  52 struct mcp4131_cfg {
  53         int wipers;
  54         int max_pos;
  55         int kohms;
  56 };
  57
  58 enum mcp4131_type {
  59         MCP413x_502 = 0,
  60         MCP413x_103,
  61         MCP413x_503,
  62         MCP413x_104,
  63         MCP414x_502,
  64         MCP414x_103,
  65         MCP414x_503,
  66         MCP414x_104,
  67         MCP415x_502,
  68         MCP415x_103,
  69         MCP415x_503,
  70         MCP415x_104,
  71         MCP416x_502,
  72         MCP416x_103,
  73         MCP416x_503,
  74         MCP416x_104,
  75         MCP423x_502,
  76         MCP423x_103,
  77         MCP423x_503,
  78         MCP423x_104,
  79         MCP424x_502,
  80         MCP424x_103,
  81         MCP424x_503,
  82         MCP424x_104,
  83         MCP425x_502,
  84         MCP425x_103,
  85         MCP425x_503,
  86         MCP425x_104,
  87         MCP426x_502,
  88         MCP426x_103,
  89         MCP426x_503,
  90         MCP426x_104,
  91 };
  92
  93 static const struct mcp4131_cfg mcp4131_cfg[] = {
  94         [MCP413x_502] = { .wipers = 1, .max_pos = 128, .kohms =   5, },
  95         [MCP413x_103] = { .wipers = 1, .max_pos = 128, .kohms =  10, },
  96         [MCP413x_503] = { .wipers = 1, .max_pos = 128, .kohms =  50, },
  97         [MCP413x_104] = { .wipers = 1, .max_pos = 128, .kohms = 100, },
  98         [MCP414x_502] = { .wipers = 1, .max_pos = 128, .kohms =   5, },
  99         [MCP414x_103] = { .wipers = 1, .max_pos = 128, .kohms =  10, },
 100         [MCP414x_503] = { .wipers = 1, .max_pos = 128, .kohms =  50, },
 101         [MCP414x_104] = { .wipers = 1, .max_pos = 128, .kohms = 100, },
 102         [MCP415x_502] = { .wipers = 1, .max_pos = 256, .kohms =   5, },
 103         [MCP415x_103] = { .wipers = 1, .max_pos = 256, .kohms =  10, },
 104         [MCP415x_503] = { .wipers = 1, .max_pos = 256, .kohms =  50, },
 105         [MCP415x_104] = { .wipers = 1, .max_pos = 256, .kohms = 100, },
 106         [MCP416x_502] = { .wipers = 1, .max_pos = 256, .kohms =   5, },
 107         [MCP416x_103] = { .wipers = 1, .max_pos = 256, .kohms =  10, },
 108         [MCP416x_503] = { .wipers = 1, .max_pos = 256, .kohms =  50, },
 109         [MCP416x_104] = { .wipers = 1, .max_pos = 256, .kohms = 100, },
 110         [MCP423x_502] = { .wipers = 2, .max_pos = 128, .kohms =   5, },
 111         [MCP423x_103] = { .wipers = 2, .max_pos = 128, .kohms =  10, },
 112         [MCP423x_503] = { .wipers = 2, .max_pos = 128, .kohms =  50, },
 113         [MCP423x_104] = { .wipers = 2, .max_pos = 128, .kohms = 100, },
 114         [MCP424x_502] = { .wipers = 2, .max_pos = 128, .kohms =   5, },
 115         [MCP424x_103] = { .wipers = 2, .max_pos = 128, .kohms =  10, },
 116         [MCP424x_503] = { .wipers = 2, .max_pos = 128, .kohms =  50, },
 117         [MCP424x_104] = { .wipers = 2, .max_pos = 128, .kohms = 100, },
 118         [MCP425x_502] = { .wipers = 2, .max_pos = 256, .kohms =   5, },
 119         [MCP425x_103] = { .wipers = 2, .max_pos = 256, .kohms =  10, },
 120         [MCP425x_503] = { .wipers = 2, .max_pos = 256, .kohms =  50, },
 121         [MCP425x_104] = { .wipers = 2, .max_pos = 256, .kohms = 100, },
 122         [MCP426x_502] = { .wipers = 2, .max_pos = 256, .kohms =   5, },
 123         [MCP426x_103] = { .wipers = 2, .max_pos = 256, .kohms =  10, },
 124         [MCP426x_503] = { .wipers = 2, .max_pos = 256, .kohms =  50, },
 125         [MCP426x_104] = { .wipers = 2, .max_pos = 256, .kohms = 100, },
 126 };
 127
 128 struct mcp4131_data {
 129         struct spi_device *spi;
 130         const struct mcp4131_cfg *cfg;
 131         struct mutex lock;
 132         u8 buf[2] ____cacheline_aligned;
 133 };
 134
 135 #define MCP4131_CHANNEL(ch) {                                   \
 136         .type = IIO_RESISTANCE,                                 \
 137         .indexed = 1,                                           \
 138         .output = 1,                                            \
 139         .channel = (ch),                                        \
 140         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
 141         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
 142 }
 143
 144 static const struct iio_chan_spec mcp4131_channels[] = {
 145         MCP4131_CHANNEL(0),
 146         MCP4131_CHANNEL(1),
 147 };
 148
 149 static int mcp4131_read(struct spi_device *spi, void *buf, size_t len)
 150 {
 151         struct spi_transfer t = {
 152                 .tx_buf = buf, /* We need to send addr, cmd and 12 bits */
 153                 .rx_buf = buf,
 154                 .len = len,
 155         };
 156         struct spi_message m;
 157
 158         spi_message_init(&m);
 159         spi_message_add_tail(&t, &m);
 160
 161         return spi_sync(spi, &m);
 162 }
 163
 164 static int mcp4131_read_raw(struct iio_dev *indio_dev,
 165                             struct iio_chan_spec const *chan,
 166                             int *val, int *val2, long mask)
 167 {
 168         int err;
 169         struct mcp4131_data *data = iio_priv(indio_dev);
 170         int address = chan->channel;
 171
 172         switch (mask) {
 173         case IIO_CHAN_INFO_RAW:
 174                 mutex_lock(&data->lock);
 175
 176                 data->buf[0] = (address << MCP4131_WIPER_SHIFT) | MCP4131_READ;
 177                 data->buf[1] = 0;
 178
 179                 err = mcp4131_read(data->spi, data->buf, 2);
 180                 if (err) {
 181                         mutex_unlock(&data->lock);
 182                         return err;
 183                 }
 184
 185                 /* Error, bad address/command combination */
 186                 if (!MCP4131_CMDERR(data->buf)) {
 187                         mutex_unlock(&data->lock);
 188                         return -EIO;
 189                 }
 190
 191                 *val = MCP4131_RAW(data->buf);
 192                 mutex_unlock(&data->lock);
 193
 194                 return IIO_VAL_INT;
 195
 196         case IIO_CHAN_INFO_SCALE:
 197                 *val = 1000 * data->cfg->kohms;
 198                 *val2 = data->cfg->max_pos;
 199                 return IIO_VAL_FRACTIONAL;
 200         }
 201
 202         return -EINVAL;
 203 }
 204
 205 static int mcp4131_write_raw(struct iio_dev *indio_dev,
 206                              struct iio_chan_spec const *chan,
 207                              int val, int val2, long mask)
 208 {
 209         int err;
 210         struct mcp4131_data *data = iio_priv(indio_dev);
 211         int address = chan->channel << MCP4131_WIPER_SHIFT;
 212
 213         switch (mask) {
 214         case IIO_CHAN_INFO_RAW:
 215                 if (val > data->cfg->max_pos || val < 0)
 216                         return -EINVAL;
 217                 break;
 218
 219         default:
 220                 return -EINVAL;
 221         }
 222
 223         mutex_lock(&data->lock);
 224
 225         data->buf[0] = address << MCP4131_WIPER_SHIFT;
 226         data->buf[0] |= MCP4131_WRITE | (val >> 8);
 227         data->buf[1] = val & 0xFF; /* 8 bits here */
 228
 229         err = spi_write(data->spi, data->buf, 2);
 230         mutex_unlock(&data->lock);
 231
 232         return err;
 233 }
 234
 235 static const struct iio_info mcp4131_info = {
 236         .read_raw = mcp4131_read_raw,
 237         .write_raw = mcp4131_write_raw,
 238 };
 239
 240 static int mcp4131_probe(struct spi_device *spi)
 241 {
 242         int err;
 243         struct device *dev = &spi->dev;
 244         unsigned long devid;
 245         struct mcp4131_data *data;
 246         struct iio_dev *indio_dev;
 247
 248         indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 249         if (!indio_dev)
 250                 return -ENOMEM;
 251
 252         data = iio_priv(indio_dev);
 253         spi_set_drvdata(spi, indio_dev);
 254         data->spi = spi;
 255         data->cfg = device_get_match_data(&spi->dev);
 256         if (!data->cfg) {
 257                 devid = spi_get_device_id(spi)->driver_data;
 258                 data->cfg = &mcp4131_cfg[devid];
 259         }
 260
 261         mutex_init(&data->lock);
 262
 263         indio_dev->info = &mcp4131_info;
 264         indio_dev->channels = mcp4131_channels;
 265         indio_dev->num_channels = data->cfg->wipers;
 266         indio_dev->name = spi_get_device_id(spi)->name;
 267
 268         err = devm_iio_device_register(dev, indio_dev);
 269         if (err) {
 270                 dev_info(&spi->dev, "Unable to register %s\n", indio_dev->name);
 271                 return err;
 272         }
 273
 274         return 0;
 275 }
 276
 277 static const struct of_device_id mcp4131_dt_ids[] = {
 278         { .compatible = "microchip,mcp4131-502",
 279                 .data = &mcp4131_cfg[MCP413x_502] },
 280         { .compatible = "microchip,mcp4131-103",
 281                 .data = &mcp4131_cfg[MCP413x_103] },
 282         { .compatible = "microchip,mcp4131-503",
 283                 .data = &mcp4131_cfg[MCP413x_503] },
 284         { .compatible = "microchip,mcp4131-104",
 285                 .data = &mcp4131_cfg[MCP413x_104] },
 286         { .compatible = "microchip,mcp4132-502",
 287                 .data = &mcp4131_cfg[MCP413x_502] },
 288         { .compatible = "microchip,mcp4132-103",
 289                 .data = &mcp4131_cfg[MCP413x_103] },
 290         { .compatible = "microchip,mcp4132-503",
 291                 .data = &mcp4131_cfg[MCP413x_503] },
 292         { .compatible = "microchip,mcp4132-104",
 293                 .data = &mcp4131_cfg[MCP413x_104] },
 294         { .compatible = "microchip,mcp4141-502",
 295                 .data = &mcp4131_cfg[MCP414x_502] },
 296         { .compatible = "microchip,mcp4141-103",
 297                 .data = &mcp4131_cfg[MCP414x_103] },
 298         { .compatible = "microchip,mcp4141-503",
 299                 .data = &mcp4131_cfg[MCP414x_503] },
 300         { .compatible = "microchip,mcp4141-104",
 301                 .data = &mcp4131_cfg[MCP414x_104] },
 302         { .compatible = "microchip,mcp4142-502",
 303                 .data = &mcp4131_cfg[MCP414x_502] },
 304         { .compatible = "microchip,mcp4142-103",
 305                 .data = &mcp4131_cfg[MCP414x_103] },
 306         { .compatible = "microchip,mcp4142-503",
 307                 .data = &mcp4131_cfg[MCP414x_503] },
 308         { .compatible = "microchip,mcp4142-104",
 309                 .data = &mcp4131_cfg[MCP414x_104] },
 310         { .compatible = "microchip,mcp4151-502",
 311                 .data = &mcp4131_cfg[MCP415x_502] },
 312         { .compatible = "microchip,mcp4151-103",
 313                 .data = &mcp4131_cfg[MCP415x_103] },
 314         { .compatible = "microchip,mcp4151-503",
 315                 .data = &mcp4131_cfg[MCP415x_503] },
 316         { .compatible = "microchip,mcp4151-104",
 317                 .data = &mcp4131_cfg[MCP415x_104] },
 318         { .compatible = "microchip,mcp4152-502",
 319                 .data = &mcp4131_cfg[MCP415x_502] },
 320         { .compatible = "microchip,mcp4152-103",
 321                 .data = &mcp4131_cfg[MCP415x_103] },
 322         { .compatible = "microchip,mcp4152-503",
 323                 .data = &mcp4131_cfg[MCP415x_503] },
 324         { .compatible = "microchip,mcp4152-104",
 325                 .data = &mcp4131_cfg[MCP415x_104] },
 326         { .compatible = "microchip,mcp4161-502",
 327                 .data = &mcp4131_cfg[MCP416x_502] },
 328         { .compatible = "microchip,mcp4161-103",
 329                 .data = &mcp4131_cfg[MCP416x_103] },
 330         { .compatible = "microchip,mcp4161-503",
 331                 .data = &mcp4131_cfg[MCP416x_503] },
 332         { .compatible = "microchip,mcp4161-104",
 333                 .data = &mcp4131_cfg[MCP416x_104] },
 334         { .compatible = "microchip,mcp4162-502",
 335                 .data = &mcp4131_cfg[MCP416x_502] },
 336         { .compatible = "microchip,mcp4162-103",
 337                 .data = &mcp4131_cfg[MCP416x_103] },
 338         { .compatible = "microchip,mcp4162-503",
 339                 .data = &mcp4131_cfg[MCP416x_503] },
 340         { .compatible = "microchip,mcp4162-104",
 341                 .data = &mcp4131_cfg[MCP416x_104] },
 342         { .compatible = "microchip,mcp4231-502",
 343                 .data = &mcp4131_cfg[MCP423x_502] },
 344         { .compatible = "microchip,mcp4231-103",
 345                 .data = &mcp4131_cfg[MCP423x_103] },
 346         { .compatible = "microchip,mcp4231-503",
 347                 .data = &mcp4131_cfg[MCP423x_503] },
 348         { .compatible = "microchip,mcp4231-104",
 349                 .data = &mcp4131_cfg[MCP423x_104] },
 350         { .compatible = "microchip,mcp4232-502",
 351                 .data = &mcp4131_cfg[MCP423x_502] },
 352         { .compatible = "microchip,mcp4232-103",
 353                 .data = &mcp4131_cfg[MCP423x_103] },
 354         { .compatible = "microchip,mcp4232-503",
 355                 .data = &mcp4131_cfg[MCP423x_503] },
 356         { .compatible = "microchip,mcp4232-104",
 357                 .data = &mcp4131_cfg[MCP423x_104] },
 358         { .compatible = "microchip,mcp4241-502",
 359                 .data = &mcp4131_cfg[MCP424x_502] },
 360         { .compatible = "microchip,mcp4241-103",
 361                 .data = &mcp4131_cfg[MCP424x_103] },
 362         { .compatible = "microchip,mcp4241-503",
 363                 .data = &mcp4131_cfg[MCP424x_503] },
 364         { .compatible = "microchip,mcp4241-104",
 365                 .data = &mcp4131_cfg[MCP424x_104] },
 366         { .compatible = "microchip,mcp4242-502",
 367                 .data = &mcp4131_cfg[MCP424x_502] },
 368         { .compatible = "microchip,mcp4242-103",
 369                 .data = &mcp4131_cfg[MCP424x_103] },
 370         { .compatible = "microchip,mcp4242-503",
 371                 .data = &mcp4131_cfg[MCP424x_503] },
 372         { .compatible = "microchip,mcp4242-104",
 373                 .data = &mcp4131_cfg[MCP424x_104] },
 374         { .compatible = "microchip,mcp4251-502",
 375                 .data = &mcp4131_cfg[MCP425x_502] },
 376         { .compatible = "microchip,mcp4251-103",
 377                 .data = &mcp4131_cfg[MCP425x_103] },
 378         { .compatible = "microchip,mcp4251-503",
 379                 .data = &mcp4131_cfg[MCP425x_503] },
 380         { .compatible = "microchip,mcp4251-104",
 381                 .data = &mcp4131_cfg[MCP425x_104] },
 382         { .compatible = "microchip,mcp4252-502",
 383                 .data = &mcp4131_cfg[MCP425x_502] },
 384         { .compatible = "microchip,mcp4252-103",
 385                 .data = &mcp4131_cfg[MCP425x_103] },
 386         { .compatible = "microchip,mcp4252-503",
 387                 .data = &mcp4131_cfg[MCP425x_503] },
 388         { .compatible = "microchip,mcp4252-104",
 389                 .data = &mcp4131_cfg[MCP425x_104] },
 390         { .compatible = "microchip,mcp4261-502",
 391                 .data = &mcp4131_cfg[MCP426x_502] },
 392         { .compatible = "microchip,mcp4261-103",
 393                 .data = &mcp4131_cfg[MCP426x_103] },
 394         { .compatible = "microchip,mcp4261-503",
 395                 .data = &mcp4131_cfg[MCP426x_503] },
 396         { .compatible = "microchip,mcp4261-104",
 397                 .data = &mcp4131_cfg[MCP426x_104] },
 398         { .compatible = "microchip,mcp4262-502",
 399                 .data = &mcp4131_cfg[MCP426x_502] },
 400         { .compatible = "microchip,mcp4262-103",
 401                 .data = &mcp4131_cfg[MCP426x_103] },
 402         { .compatible = "microchip,mcp4262-503",
 403                 .data = &mcp4131_cfg[MCP426x_503] },
 404         { .compatible = "microchip,mcp4262-104",
 405                 .data = &mcp4131_cfg[MCP426x_104] },
 406         {}
 407 };
 408 MODULE_DEVICE_TABLE(of, mcp4131_dt_ids);
 409
 410 static const struct spi_device_id mcp4131_id[] = {
 411         { "mcp4131-502", MCP413x_502 },
 412         { "mcp4131-103", MCP413x_103 },
 413         { "mcp4131-503", MCP413x_503 },
 414         { "mcp4131-104", MCP413x_104 },
 415         { "mcp4132-502", MCP413x_502 },
 416         { "mcp4132-103", MCP413x_103 },
 417         { "mcp4132-503", MCP413x_503 },
 418         { "mcp4132-104", MCP413x_104 },
 419         { "mcp4141-502", MCP414x_502 },
 420         { "mcp4141-103", MCP414x_103 },
 421         { "mcp4141-503", MCP414x_503 },
 422         { "mcp4141-104", MCP414x_104 },
 423         { "mcp4142-502", MCP414x_502 },
 424         { "mcp4142-103", MCP414x_103 },
 425         { "mcp4142-503", MCP414x_503 },
 426         { "mcp4142-104", MCP414x_104 },
 427         { "mcp4151-502", MCP415x_502 },
 428         { "mcp4151-103", MCP415x_103 },
 429         { "mcp4151-503", MCP415x_503 },
 430         { "mcp4151-104", MCP415x_104 },
 431         { "mcp4152-502", MCP415x_502 },
 432         { "mcp4152-103", MCP415x_103 },
 433         { "mcp4152-503", MCP415x_503 },
 434         { "mcp4152-104", MCP415x_104 },
 435         { "mcp4161-502", MCP416x_502 },
 436         { "mcp4161-103", MCP416x_103 },
 437         { "mcp4161-503", MCP416x_503 },
 438         { "mcp4161-104", MCP416x_104 },
 439         { "mcp4162-502", MCP416x_502 },
 440         { "mcp4162-103", MCP416x_103 },
 441         { "mcp4162-503", MCP416x_503 },
 442         { "mcp4162-104", MCP416x_104 },
 443         { "mcp4231-502", MCP423x_502 },
 444         { "mcp4231-103", MCP423x_103 },
 445         { "mcp4231-503", MCP423x_503 },
 446         { "mcp4231-104", MCP423x_104 },
 447         { "mcp4232-502", MCP423x_502 },
 448         { "mcp4232-103", MCP423x_103 },
 449         { "mcp4232-503", MCP423x_503 },
 450         { "mcp4232-104", MCP423x_104 },
 451         { "mcp4241-502", MCP424x_502 },
 452         { "mcp4241-103", MCP424x_103 },
 453         { "mcp4241-503", MCP424x_503 },
 454         { "mcp4241-104", MCP424x_104 },
 455         { "mcp4242-502", MCP424x_502 },
 456         { "mcp4242-103", MCP424x_103 },
 457         { "mcp4242-503", MCP424x_503 },
 458         { "mcp4242-104", MCP424x_104 },
 459         { "mcp4251-502", MCP425x_502 },
 460         { "mcp4251-103", MCP425x_103 },
 461         { "mcp4251-503", MCP425x_503 },
 462         { "mcp4251-104", MCP425x_104 },
 463         { "mcp4252-502", MCP425x_502 },
 464         { "mcp4252-103", MCP425x_103 },
 465         { "mcp4252-503", MCP425x_503 },
 466         { "mcp4252-104", MCP425x_104 },
 467         { "mcp4261-502", MCP426x_502 },
 468         { "mcp4261-103", MCP426x_103 },
 469         { "mcp4261-503", MCP426x_503 },
 470         { "mcp4261-104", MCP426x_104 },
 471         { "mcp4262-502", MCP426x_502 },
 472         { "mcp4262-103", MCP426x_103 },
 473         { "mcp4262-503", MCP426x_503 },
 474         { "mcp4262-104", MCP426x_104 },
 475         {}
 476 };
 477 MODULE_DEVICE_TABLE(spi, mcp4131_id);
 478
 479 static struct spi_driver mcp4131_driver = {
 480         .driver = {
 481                 .name   = "mcp4131",
 482                 .of_match_table = mcp4131_dt_ids,
 483         },
 484         .probe          = mcp4131_probe,
 485         .id_table       = mcp4131_id,
 486 };
 487
 488 module_spi_driver(mcp4131_driver);
 489
 490 MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
 491 MODULE_DESCRIPTION("MCP4131 digital potentiometer");
 492 MODULE_LICENSE("GPL v2");