drivers/iio/amplifiers/ada4250.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * ADA4250 driver
   4  *
   5  * Copyright 2022 Analog Devices Inc.
   6  */
   7
   8 #include <linux/bitfield.h>
   9 #include <linux/bits.h>
  10 #include <linux/device.h>
  11 #include <linux/iio/iio.h>
  12 #include <linux/module.h>
  13 #include <linux/regmap.h>
  14 #include <linux/regulator/consumer.h>
  15 #include <linux/spi/spi.h>
  16
  17 #include <linux/unaligned.h>
  18
  19 /* ADA4250 Register Map */
  20 #define ADA4250_REG_GAIN_MUX        0x00
  21 #define ADA4250_REG_REFBUF_EN       0x01
  22 #define ADA4250_REG_RESET           0x02
  23 #define ADA4250_REG_SNSR_CAL_VAL    0x04
  24 #define ADA4250_REG_SNSR_CAL_CNFG   0x05
  25 #define ADA4250_REG_DIE_REV         0x18
  26 #define ADA4250_REG_CHIP_ID         0x19
  27
  28 /* ADA4250_REG_GAIN_MUX Map */
  29 #define ADA4250_GAIN_MUX_MSK        GENMASK(2, 0)
  30
  31 /* ADA4250_REG_REFBUF Map */
  32 #define ADA4250_REFBUF_MSK          BIT(0)
  33
  34 /* ADA4250_REG_RESET Map */
  35 #define ADA4250_RESET_MSK           BIT(0)
  36
  37 /* ADA4250_REG_SNSR_CAL_VAL Map */
  38 #define ADA4250_CAL_CFG_BIAS_MSK    GENMASK(7, 0)
  39
  40 /* ADA4250_REG_SNSR_CAL_CNFG Bit Definition */
  41 #define ADA4250_BIAS_SET_MSK        GENMASK(3, 2)
  42 #define ADA4250_RANGE_SET_MSK       GENMASK(1, 0)
  43
  44 /* Miscellaneous definitions */
  45 #define ADA4250_CHIP_ID             0x4250
  46 #define ADA4250_RANGE1              0
  47 #define ADA4250_RANGE4              3
  48
  49 /* ADA4250 current bias set */
  50 enum ada4250_current_bias {
  51         ADA4250_BIAS_DISABLED,
  52         ADA4250_BIAS_BANDGAP,
  53         ADA4250_BIAS_AVDD,
  54 };
  55
  56 struct ada4250_state {
  57         struct spi_device       *spi;
  58         struct regmap           *regmap;
  59         struct regulator        *reg;
  60         /* Protect against concurrent accesses to the device and data content */
  61         struct mutex            lock;
  62         u8                      bias;
  63         u8                      gain;
  64         int                     offset_uv;
  65         bool                    refbuf_en;
  66 };
  67
  68 /* ADA4250 Current Bias Source Settings: Disabled, Bandgap Reference, AVDD */
  69 static const int calibbias_table[] = {0, 1, 2};
  70
  71 /* ADA4250 Gain (V/V) values: 1, 2, 4, 8, 16, 32, 64, 128 */
  72 static const int hwgain_table[] = {1, 2, 4, 8, 16, 32, 64, 128};
  73
  74 static const struct regmap_config ada4250_regmap_config = {
  75         .reg_bits = 8,
  76         .val_bits = 8,
  77         .read_flag_mask = BIT(7),
  78         .max_register = 0x1A,
  79 };
  80
  81 static int ada4250_set_offset_uv(struct iio_dev *indio_dev,
  82                                  const struct iio_chan_spec *chan,
  83                                  int offset_uv)
  84 {
  85         struct ada4250_state *st = iio_priv(indio_dev);
  86
  87         int i, ret, x[8], max_vos, min_vos, voltage_v, vlsb = 0;
  88         u8 offset_raw, range = ADA4250_RANGE1;
  89         u32 lsb_coeff[6] = {1333, 2301, 4283, 8289, 16311, 31599};
  90
  91         if (st->bias == 0 || st->bias == 3)
  92                 return -EINVAL;
  93
  94         voltage_v = regulator_get_voltage(st->reg);
  95         voltage_v = DIV_ROUND_CLOSEST(voltage_v, 1000000);
  96
  97         if (st->bias == ADA4250_BIAS_AVDD)
  98                 x[0] = voltage_v;
  99         else
 100                 x[0] = 5;
 101
 102         x[1] = 126 * (x[0] - 1);
 103
 104         for (i = 0; i < 6; i++)
 105                 x[i + 2] = DIV_ROUND_CLOSEST(x[1] * 1000, lsb_coeff[i]);
 106
 107         if (st->gain == 0)
 108                 return -EINVAL;
 109
 110         /*
 111          * Compute Range and Voltage per LSB for the Sensor Offset Calibration
 112          * Example of computation for Range 1 and Range 2 (Curren Bias Set = AVDD):
 113          *                     Range 1                            Range 2
 114          *   Gain   | Max Vos(mV) |   LSB(mV)        |  Max Vos(mV)  | LSB(mV) |
 115          *    2     |    X1*127   | X1=0.126(AVDD-1) |   X1*3*127    |  X1*3   |
 116          *    4     |    X2*127   | X2=X1/1.3333     |   X2*3*127    |  X2*3   |
 117          *    8     |    X3*127   | X3=X1/2.301      |   X3*3*127    |  X3*3   |
 118          *    16    |    X4*127   | X4=X1/4.283      |   X4*3*127    |  X4*3   |
 119          *    32    |    X5*127   | X5=X1/8.289      |   X5*3*127    |  X5*3   |
 120          *    64    |    X6*127   | X6=X1/16.311     |   X6*3*127    |  X6*3   |
 121          *    128   |    X7*127   | X7=X1/31.599     |   X7*3*127    |  X7*3   |
 122          */
 123         for (i = ADA4250_RANGE1; i <= ADA4250_RANGE4; i++) {
 124                 max_vos = x[st->gain] *  127 * ((1 << (i + 1)) - 1);
 125                 min_vos = -1 * max_vos;
 126                 if (offset_uv > min_vos && offset_uv < max_vos) {
 127                         range = i;
 128                         vlsb = x[st->gain] * ((1 << (i + 1)) - 1);
 129                         break;
 130                 }
 131         }
 132
 133         if (vlsb <= 0)
 134                 return -EINVAL;
 135
 136         offset_raw = DIV_ROUND_CLOSEST(abs(offset_uv), vlsb);
 137
 138         mutex_lock(&st->lock);
 139         ret = regmap_update_bits(st->regmap, ADA4250_REG_SNSR_CAL_CNFG,
 140                                  ADA4250_RANGE_SET_MSK,
 141                                  FIELD_PREP(ADA4250_RANGE_SET_MSK, range));
 142         if (ret)
 143                 goto exit;
 144
 145         st->offset_uv = offset_raw * vlsb;
 146
 147         /*
 148          * To set the offset calibration value, use bits [6:0] and bit 7 as the
 149          * polarity bit (set to "0" for a negative offset and "1" for a positive
 150          * offset).
 151          */
 152         if (offset_uv < 0) {
 153                 offset_raw |= BIT(7);
 154                 st->offset_uv *= (-1);
 155         }
 156
 157         ret = regmap_write(st->regmap, ADA4250_REG_SNSR_CAL_VAL, offset_raw);
 158
 159 exit:
 160         mutex_unlock(&st->lock);
 161
 162         return ret;
 163 }
 164
 165 static int ada4250_read_raw(struct iio_dev *indio_dev,
 166                             struct iio_chan_spec const *chan,
 167                             int *val, int *val2, long info)
 168 {
 169         struct ada4250_state *st = iio_priv(indio_dev);
 170         int ret;
 171
 172         switch (info) {
 173         case IIO_CHAN_INFO_HARDWAREGAIN:
 174                 ret = regmap_read(st->regmap, ADA4250_REG_GAIN_MUX, val);
 175                 if (ret)
 176                         return ret;
 177
 178                 *val = BIT(*val);
 179
 180                 return IIO_VAL_INT;
 181         case IIO_CHAN_INFO_OFFSET:
 182                 *val = st->offset_uv;
 183
 184                 return IIO_VAL_INT;
 185         case IIO_CHAN_INFO_CALIBBIAS:
 186                 ret = regmap_read(st->regmap, ADA4250_REG_SNSR_CAL_CNFG, val);
 187                 if (ret)
 188                         return ret;
 189
 190                 *val = FIELD_GET(ADA4250_BIAS_SET_MSK, *val);
 191
 192                 return IIO_VAL_INT;
 193         case IIO_CHAN_INFO_SCALE:
 194                 *val = 1;
 195                 *val2 = 1000000;
 196
 197                 return IIO_VAL_FRACTIONAL;
 198         default:
 199                 return -EINVAL;
 200         }
 201 }
 202
 203 static int ada4250_write_raw(struct iio_dev *indio_dev,
 204                              struct iio_chan_spec const *chan,
 205                              int val, int val2, long info)
 206 {
 207         struct ada4250_state *st = iio_priv(indio_dev);
 208         int ret;
 209
 210         switch (info) {
 211         case IIO_CHAN_INFO_HARDWAREGAIN:
 212                 ret = regmap_write(st->regmap, ADA4250_REG_GAIN_MUX,
 213                                    FIELD_PREP(ADA4250_GAIN_MUX_MSK, ilog2(val)));
 214                 if (ret)
 215                         return ret;
 216
 217                 st->gain = ilog2(val);
 218
 219                 return ret;
 220         case IIO_CHAN_INFO_OFFSET:
 221                 return ada4250_set_offset_uv(indio_dev, chan, val);
 222         case IIO_CHAN_INFO_CALIBBIAS:
 223                 ret = regmap_update_bits(st->regmap, ADA4250_REG_SNSR_CAL_CNFG,
 224                                          ADA4250_BIAS_SET_MSK,
 225                                          FIELD_PREP(ADA4250_BIAS_SET_MSK, val));
 226                 if (ret)
 227                         return ret;
 228
 229                 st->bias = val;
 230
 231                 return ret;
 232         default:
 233                 return -EINVAL;
 234         }
 235 }
 236
 237 static int ada4250_read_avail(struct iio_dev *indio_dev,
 238                               struct iio_chan_spec const *chan,
 239                               const int **vals, int *type, int *length,
 240                               long mask)
 241 {
 242         switch (mask) {
 243         case IIO_CHAN_INFO_CALIBBIAS:
 244                 *vals = calibbias_table;
 245                 *type = IIO_VAL_INT;
 246                 *length = ARRAY_SIZE(calibbias_table);
 247
 248                 return IIO_AVAIL_LIST;
 249         case IIO_CHAN_INFO_HARDWAREGAIN:
 250                 *vals = hwgain_table;
 251                 *type = IIO_VAL_INT;
 252                 *length = ARRAY_SIZE(hwgain_table);
 253
 254                 return IIO_AVAIL_LIST;
 255         default:
 256                 return -EINVAL;
 257         }
 258 }
 259
 260 static int ada4250_reg_access(struct iio_dev *indio_dev,
 261                               unsigned int reg,
 262                               unsigned int write_val,
 263                               unsigned int *read_val)
 264 {
 265         struct ada4250_state *st = iio_priv(indio_dev);
 266
 267         if (read_val)
 268                 return regmap_read(st->regmap, reg, read_val);
 269         else
 270                 return regmap_write(st->regmap, reg, write_val);
 271 }
 272
 273 static const struct iio_info ada4250_info = {
 274         .read_raw = ada4250_read_raw,
 275         .write_raw = ada4250_write_raw,
 276         .read_avail = &ada4250_read_avail,
 277         .debugfs_reg_access = &ada4250_reg_access,
 278 };
 279
 280 static const struct iio_chan_spec ada4250_channels[] = {
 281         {
 282                 .type = IIO_VOLTAGE,
 283                 .output = 1,
 284                 .indexed = 1,
 285                 .channel = 0,
 286                 .info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN) |
 287                                 BIT(IIO_CHAN_INFO_OFFSET) |
 288                                 BIT(IIO_CHAN_INFO_CALIBBIAS) |
 289                                 BIT(IIO_CHAN_INFO_SCALE),
 290                 .info_mask_separate_available = BIT(IIO_CHAN_INFO_CALIBBIAS) |
 291                                                 BIT(IIO_CHAN_INFO_HARDWAREGAIN),
 292         }
 293 };
 294
 295 static void ada4250_reg_disable(void *data)
 296 {
 297         regulator_disable(data);
 298 }
 299
 300 static int ada4250_init(struct ada4250_state *st)
 301 {
 302         int ret;
 303         u16 chip_id;
 304         u8 data[2] __aligned(8) = {};
 305         struct spi_device *spi = st->spi;
 306
 307         st->refbuf_en = device_property_read_bool(&spi->dev, "adi,refbuf-enable");
 308
 309         st->reg = devm_regulator_get(&spi->dev, "avdd");
 310         if (IS_ERR(st->reg))
 311                 return dev_err_probe(&spi->dev, PTR_ERR(st->reg),
 312                                      "failed to get the AVDD voltage\n");
 313
 314         ret = regulator_enable(st->reg);
 315         if (ret) {
 316                 dev_err(&spi->dev, "Failed to enable specified AVDD supply\n");
 317                 return ret;
 318         }
 319
 320         ret = devm_add_action_or_reset(&spi->dev, ada4250_reg_disable, st->reg);
 321         if (ret)
 322                 return ret;
 323
 324         ret = regmap_write(st->regmap, ADA4250_REG_RESET,
 325                            FIELD_PREP(ADA4250_RESET_MSK, 1));
 326         if (ret)
 327                 return ret;
 328
 329         ret = regmap_bulk_read(st->regmap, ADA4250_REG_CHIP_ID, data, 2);
 330         if (ret)
 331                 return ret;
 332
 333         chip_id = get_unaligned_le16(data);
 334
 335         if (chip_id != ADA4250_CHIP_ID) {
 336                 dev_err(&spi->dev, "Invalid chip ID.\n");
 337                 return -EINVAL;
 338         }
 339
 340         return regmap_write(st->regmap, ADA4250_REG_REFBUF_EN,
 341                             FIELD_PREP(ADA4250_REFBUF_MSK, st->refbuf_en));
 342 }
 343
 344 static int ada4250_probe(struct spi_device *spi)
 345 {
 346         struct iio_dev *indio_dev;
 347         struct regmap *regmap;
 348         struct ada4250_state *st;
 349         int ret;
 350
 351         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 352         if (!indio_dev)
 353                 return -ENOMEM;
 354
 355         regmap = devm_regmap_init_spi(spi, &ada4250_regmap_config);
 356         if (IS_ERR(regmap))
 357                 return PTR_ERR(regmap);
 358
 359         st = iio_priv(indio_dev);
 360         st->regmap = regmap;
 361         st->spi = spi;
 362
 363         indio_dev->info = &ada4250_info;
 364         indio_dev->name = "ada4250";
 365         indio_dev->channels = ada4250_channels;
 366         indio_dev->num_channels = ARRAY_SIZE(ada4250_channels);
 367
 368         mutex_init(&st->lock);
 369
 370         ret = ada4250_init(st);
 371         if (ret) {
 372                 dev_err(&spi->dev, "ADA4250 init failed\n");
 373                 return ret;
 374         }
 375
 376         return devm_iio_device_register(&spi->dev, indio_dev);
 377 }
 378
 379 static const struct spi_device_id ada4250_id[] = {
 380         { "ada4250", 0 },
 381         {}
 382 };
 383 MODULE_DEVICE_TABLE(spi, ada4250_id);
 384
 385 static const struct of_device_id ada4250_of_match[] = {
 386         { .compatible = "adi,ada4250" },
 387         {},
 388 };
 389 MODULE_DEVICE_TABLE(of, ada4250_of_match);
 390
 391 static struct spi_driver ada4250_driver = {
 392         .driver = {
 393                         .name = "ada4250",
 394                         .of_match_table = ada4250_of_match,
 395                 },
 396         .probe = ada4250_probe,
 397         .id_table = ada4250_id,
 398 };
 399 module_spi_driver(ada4250_driver);
 400
 401 MODULE_AUTHOR("Antoniu Miclaus <antoniu.miclaus@analog.com");
 402 MODULE_DESCRIPTION("Analog Devices ADA4250");
 403 MODULE_LICENSE("GPL v2");