drivers/iio/amplifiers/hmc425a.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * HMC425A and similar Gain Amplifiers
   4  *
   5  * Copyright 2020, 2024 Analog Devices Inc.
   6  */
   7
   8 #include <linux/bits.h>
   9 #include <linux/bitops.h>
  10 #include <linux/device.h>
  11 #include <linux/err.h>
  12 #include <linux/gpio/consumer.h>
  13 #include <linux/iio/iio.h>
  14 #include <linux/iio/sysfs.h>
  15 #include <linux/kernel.h>
  16 #include <linux/math.h>
  17 #include <linux/mod_devicetable.h>
  18 #include <linux/module.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/property.h>
  21 #include <linux/slab.h>
  22 #include <linux/regulator/consumer.h>
  23 #include <linux/sysfs.h>
  24
  25 /*
  26  * The LTC6373 amplifier supports configuring gain using GPIO's with the following
  27  *  values (OUTPUT_V / INPUT_V): 0(shutdown), 0.25, 0.5, 1, 2, 4, 8, 16
  28  *
  29  * Except for the shutdown value, all can be converted to dB using 20 * log10(x)
  30  * From here, it is observed that all values are multiples of the '2' gain setting,
  31  *  with the correspondent of 6.020dB.
  32  */
  33 #define LTC6373_CONVERSION_CONSTANT     6020
  34 #define LTC6373_MIN_GAIN_CODE           0x6
  35 #define LTC6373_CONVERSION_MASK         GENMASK(2, 0)
  36 #define LTC6373_SHUTDOWN                GENMASK(2, 0)
  37
  38 enum hmc425a_type {
  39         ID_HMC425A,
  40         ID_HMC540S,
  41         ID_ADRF5740,
  42         ID_LTC6373,
  43 };
  44
  45 struct hmc425a_chip_info {
  46         const char                      *name;
  47         const struct iio_chan_spec      *channels;
  48         unsigned int                    num_channels;
  49         unsigned int                    num_gpios;
  50         int                             gain_min;
  51         int                             gain_max;
  52         int                             default_gain;
  53         int                             powerdown_val;
  54         bool                            has_powerdown;
  55
  56         int                             (*gain_dB_to_code)(int gain, int *code);
  57         int                             (*code_to_gain_dB)(int code, int *val, int *val2);
  58 };
  59
  60 struct hmc425a_state {
  61         struct  mutex lock; /* protect sensor state */
  62         const struct    hmc425a_chip_info *chip_info;
  63         struct  gpio_descs *gpios;
  64         u32     gain;
  65         bool    powerdown;
  66 };
  67
  68 static int gain_dB_to_code(struct hmc425a_state *st, int val, int val2, int *code)
  69 {
  70         const struct hmc425a_chip_info *inf = st->chip_info;
  71         int gain;
  72
  73         if (val < 0)
  74                 gain = (val * 1000) - (val2 / 1000);
  75         else
  76                 gain = (val * 1000) + (val2 / 1000);
  77
  78         if (gain > inf->gain_max || gain < inf->gain_min)
  79                 return -EINVAL;
  80         if (st->powerdown)
  81                 return -EPERM;
  82
  83         return st->chip_info->gain_dB_to_code(gain, code);
  84 }
  85
  86 static int hmc425a_gain_dB_to_code(int gain, int *code)
  87 {
  88         *code = ~((abs(gain) / 500) & 0x3F);
  89         return 0;
  90 }
  91
  92 static int hmc540s_gain_dB_to_code(int gain, int *code)
  93 {
  94         *code = ~((abs(gain) / 1000) & 0xF);
  95         return 0;
  96 }
  97
  98 static int adrf5740_gain_dB_to_code(int gain, int *code)
  99 {
 100         int temp = (abs(gain) / 2000) & 0xF;
 101
 102         /* Bit [0-3]: 2dB 4dB 8dB 8dB */
 103         *code = temp & BIT(3) ? temp | BIT(2) : temp;
 104         return 0;
 105 }
 106
 107 static int ltc6373_gain_dB_to_code(int gain, int *code)
 108 {
 109         *code = ~(DIV_ROUND_CLOSEST(gain, LTC6373_CONVERSION_CONSTANT) + 3)
 110                 & LTC6373_CONVERSION_MASK;
 111         return 0;
 112 }
 113
 114 static int code_to_gain_dB(struct hmc425a_state *st, int *val, int *val2)
 115 {
 116         if (st->powerdown)
 117                 return -EPERM;
 118         return st->chip_info->code_to_gain_dB(st->gain, val, val2);
 119 }
 120
 121 static int hmc425a_code_to_gain_dB(int code, int *val, int *val2)
 122 {
 123         *val = (~code * -500) / 1000;
 124         *val2 = ((~code * -500) % 1000) * 1000;
 125         return 0;
 126 }
 127
 128 static int hmc540s_code_to_gain_dB(int code, int *val, int *val2)
 129 {
 130         *val = (~code * -1000) / 1000;
 131         *val2 = ((~code * -1000) % 1000) * 1000;
 132         return 0;
 133 }
 134
 135 static int adrf5740_code_to_gain_dB(int code, int *val, int *val2)
 136 {
 137         /*
 138          * Bit [0-3]: 2dB 4dB 8dB 8dB
 139          * When BIT(3) is set, unset BIT(2) and use 3 as double the place value
 140          */
 141         code = code & BIT(3) ? code & ~BIT(2) : code;
 142         *val = (code * -2000) / 1000;
 143         *val2 = ((code * -2000) % 1000) * 1000;
 144         return 0;
 145 }
 146
 147 static int ltc6373_code_to_gain_dB(int code, int *val, int *val2)
 148 {
 149         int gain = ((~code & LTC6373_CONVERSION_MASK) - 3) *
 150                    LTC6373_CONVERSION_CONSTANT;
 151
 152         *val = gain / 1000;
 153         *val2 = (gain % 1000) * 1000;
 154         return 0;
 155 }
 156
 157 static int hmc425a_write(struct iio_dev *indio_dev, u32 value)
 158 {
 159         struct hmc425a_state *st = iio_priv(indio_dev);
 160         DECLARE_BITMAP(values, BITS_PER_TYPE(value));
 161
 162         values[0] = value;
 163
 164         gpiod_set_array_value_cansleep(st->gpios->ndescs, st->gpios->desc,
 165                                        NULL, values);
 166         return 0;
 167 }
 168
 169 static int hmc425a_read_raw(struct iio_dev *indio_dev,
 170                             struct iio_chan_spec const *chan, int *val,
 171                             int *val2, long m)
 172 {
 173         struct hmc425a_state *st = iio_priv(indio_dev);
 174         int ret;
 175
 176         mutex_lock(&st->lock);
 177         switch (m) {
 178         case IIO_CHAN_INFO_HARDWAREGAIN:
 179                 ret = code_to_gain_dB(st, val, val2);
 180                 if (ret)
 181                         break;
 182                 ret = IIO_VAL_INT_PLUS_MICRO_DB;
 183                 break;
 184         default:
 185                 ret = -EINVAL;
 186         }
 187         mutex_unlock(&st->lock);
 188
 189         return ret;
 190 };
 191
 192 static int hmc425a_write_raw(struct iio_dev *indio_dev,
 193                              struct iio_chan_spec const *chan, int val,
 194                              int val2, long mask)
 195 {
 196         struct hmc425a_state *st = iio_priv(indio_dev);
 197         int code = 0, ret;
 198
 199         mutex_lock(&st->lock);
 200         switch (mask) {
 201         case IIO_CHAN_INFO_HARDWAREGAIN:
 202                 ret = gain_dB_to_code(st, val, val2, &code);
 203                 if (ret)
 204                         break;
 205                 st->gain = code;
 206
 207                 ret = hmc425a_write(indio_dev, st->gain);
 208                 break;
 209         default:
 210                 ret = -EINVAL;
 211         }
 212         mutex_unlock(&st->lock);
 213
 214         return ret;
 215 }
 216
 217 static int hmc425a_write_raw_get_fmt(struct iio_dev *indio_dev,
 218                                      struct iio_chan_spec const *chan,
 219                                      long mask)
 220 {
 221         switch (mask) {
 222         case IIO_CHAN_INFO_HARDWAREGAIN:
 223                 return IIO_VAL_INT_PLUS_MICRO_DB;
 224         default:
 225                 return -EINVAL;
 226         }
 227 }
 228
 229 static const struct iio_info hmc425a_info = {
 230         .read_raw = &hmc425a_read_raw,
 231         .write_raw = &hmc425a_write_raw,
 232         .write_raw_get_fmt = &hmc425a_write_raw_get_fmt,
 233 };
 234
 235 static ssize_t ltc6373_read_powerdown(struct iio_dev *indio_dev,
 236                                       uintptr_t private,
 237                                       const struct iio_chan_spec *chan,
 238                                       char *buf)
 239 {
 240         struct hmc425a_state *st = iio_priv(indio_dev);
 241
 242         return sysfs_emit(buf, "%d\n", st->powerdown);
 243 }
 244
 245 static ssize_t ltc6373_write_powerdown(struct iio_dev *indio_dev,
 246                                        uintptr_t private,
 247                                        const struct iio_chan_spec *chan,
 248                                        const char *buf,
 249                                        size_t len)
 250 {
 251         struct hmc425a_state *st = iio_priv(indio_dev);
 252         bool powerdown;
 253         int code, ret;
 254
 255         ret = kstrtobool(buf, &powerdown);
 256         if (ret)
 257                 return ret;
 258
 259         mutex_lock(&st->lock);
 260         st->powerdown = powerdown;
 261         code = (powerdown) ? LTC6373_SHUTDOWN : st->gain;
 262         hmc425a_write(indio_dev, code);
 263         mutex_unlock(&st->lock);
 264         return len;
 265 }
 266
 267 static const struct iio_chan_spec_ext_info ltc6373_ext_info[] = {
 268         {
 269                 .name = "powerdown",
 270                 .read = ltc6373_read_powerdown,
 271                 .write = ltc6373_write_powerdown,
 272                 .shared = IIO_SEPARATE,
 273         },
 274         {}
 275 };
 276
 277 #define HMC425A_CHAN(_channel)                                          \
 278 {                                                                       \
 279         .type = IIO_VOLTAGE,                                            \
 280         .output = 1,                                                    \
 281         .indexed = 1,                                                   \
 282         .channel = _channel,                                            \
 283         .info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),          \
 284 }
 285
 286 #define LTC6373_CHAN(_channel)                                          \
 287 {                                                                       \
 288         .type = IIO_VOLTAGE,                                            \
 289         .output = 1,                                                    \
 290         .indexed = 1,                                                   \
 291         .channel = _channel,                                            \
 292         .info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),          \
 293         .ext_info = ltc6373_ext_info,                                   \
 294 }
 295
 296 static const struct iio_chan_spec hmc425a_channels[] = {
 297         HMC425A_CHAN(0),
 298 };
 299
 300 static const struct iio_chan_spec ltc6373_channels[] = {
 301         LTC6373_CHAN(0),
 302 };
 303
 304 static const struct hmc425a_chip_info hmc425a_chip_info_tbl[] = {
 305         [ID_HMC425A] = {
 306                 .name = "hmc425a",
 307                 .channels = hmc425a_channels,
 308                 .num_channels = ARRAY_SIZE(hmc425a_channels),
 309                 .num_gpios = 6,
 310                 .gain_min = -31500,
 311                 .gain_max = 0,
 312                 .default_gain = -0x40, /* set default gain -31.5db*/
 313                 .gain_dB_to_code = hmc425a_gain_dB_to_code,
 314                 .code_to_gain_dB = hmc425a_code_to_gain_dB,
 315         },
 316         [ID_HMC540S] = {
 317                 .name = "hmc540s",
 318                 .channels = hmc425a_channels,
 319                 .num_channels = ARRAY_SIZE(hmc425a_channels),
 320                 .num_gpios = 4,
 321                 .gain_min = -15000,
 322                 .gain_max = 0,
 323                 .default_gain = -0x10, /* set default gain -15.0db*/
 324                 .gain_dB_to_code = hmc540s_gain_dB_to_code,
 325                 .code_to_gain_dB = hmc540s_code_to_gain_dB,
 326         },
 327         [ID_ADRF5740] = {
 328                 .name = "adrf5740",
 329                 .channels = hmc425a_channels,
 330                 .num_channels = ARRAY_SIZE(hmc425a_channels),
 331                 .num_gpios = 4,
 332                 .gain_min = -22000,
 333                 .gain_max = 0,
 334                 .default_gain = 0xF, /* set default gain -22.0db*/
 335                 .gain_dB_to_code = adrf5740_gain_dB_to_code,
 336                 .code_to_gain_dB = adrf5740_code_to_gain_dB,
 337         },
 338         [ID_LTC6373] = {
 339                 .name = "ltc6373",
 340                 .channels = ltc6373_channels,
 341                 .num_channels = ARRAY_SIZE(ltc6373_channels),
 342                 .num_gpios = 3,
 343                 .gain_min = -12041, /* gain setting x0.25*/
 344                 .gain_max = 24082,  /* gain setting x16  */
 345                 .default_gain = LTC6373_MIN_GAIN_CODE,
 346                 .powerdown_val = LTC6373_SHUTDOWN,
 347                 .has_powerdown = true,
 348                 .gain_dB_to_code = ltc6373_gain_dB_to_code,
 349                 .code_to_gain_dB = ltc6373_code_to_gain_dB,
 350         },
 351 };
 352
 353 static int hmc425a_probe(struct platform_device *pdev)
 354 {
 355         struct iio_dev *indio_dev;
 356         struct hmc425a_state *st;
 357         int ret;
 358
 359         indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*st));
 360         if (!indio_dev)
 361                 return -ENOMEM;
 362
 363         st = iio_priv(indio_dev);
 364
 365         st->chip_info = device_get_match_data(&pdev->dev);
 366         indio_dev->num_channels = st->chip_info->num_channels;
 367         indio_dev->channels = st->chip_info->channels;
 368         indio_dev->name = st->chip_info->name;
 369         st->gain = st->chip_info->default_gain;
 370
 371         st->gpios = devm_gpiod_get_array(&pdev->dev, "ctrl", GPIOD_OUT_LOW);
 372         if (IS_ERR(st->gpios))
 373                 return dev_err_probe(&pdev->dev, PTR_ERR(st->gpios),
 374                                      "failed to get gpios\n");
 375
 376         if (st->gpios->ndescs != st->chip_info->num_gpios) {
 377                 dev_err(&pdev->dev, "%d GPIOs needed to operate\n",
 378                         st->chip_info->num_gpios);
 379                 return -ENODEV;
 380         }
 381
 382         ret = devm_regulator_get_enable(&pdev->dev, "vcc-supply");
 383         if (ret)
 384                 return ret;
 385
 386         mutex_init(&st->lock);
 387
 388         indio_dev->info = &hmc425a_info;
 389         indio_dev->modes = INDIO_DIRECT_MODE;
 390
 391         if (st->chip_info->has_powerdown) {
 392                 st->powerdown = true;
 393                 hmc425a_write(indio_dev, st->chip_info->powerdown_val);
 394         } else {
 395                 /* Set default gain */
 396                 hmc425a_write(indio_dev, st->gain);
 397         }
 398
 399         return devm_iio_device_register(&pdev->dev, indio_dev);
 400 }
 401
 402 /* Match table for of_platform binding */
 403 static const struct of_device_id hmc425a_of_match[] = {
 404         { .compatible = "adi,hmc425a",
 405           .data = &hmc425a_chip_info_tbl[ID_HMC425A]},
 406         { .compatible = "adi,hmc540s",
 407           .data = &hmc425a_chip_info_tbl[ID_HMC540S]},
 408         { .compatible = "adi,adrf5740",
 409           .data = &hmc425a_chip_info_tbl[ID_ADRF5740]},
 410         { .compatible = "adi,ltc6373",
 411           .data = &hmc425a_chip_info_tbl[ID_LTC6373]},
 412         {}
 413 };
 414 MODULE_DEVICE_TABLE(of, hmc425a_of_match);
 415
 416 static struct platform_driver hmc425a_driver = {
 417         .driver = {
 418                 .name = KBUILD_MODNAME,
 419                 .of_match_table = hmc425a_of_match,
 420         },
 421         .probe = hmc425a_probe,
 422 };
 423 module_platform_driver(hmc425a_driver);
 424
 425 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
 426 MODULE_DESCRIPTION("Analog Devices HMC425A and similar GPIO control Gain Amplifiers");
 427 MODULE_LICENSE("GPL v2");