drivers/iio/adc/ti-adc12138.c

   1 /*
   2  * ADC12130/ADC12132/ADC12138 12-bit plus sign ADC driver
   3  *
   4  * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
   5  *
   6  * This file is subject to the terms and conditions of version 2 of
   7  * the GNU General Public License.  See the file COPYING in the main
   8  * directory of this archive for more details.
   9  *
  10  * Datasheet: http://www.ti.com/lit/ds/symlink/adc12138.pdf
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/completion.h>
  16 #include <linux/clk.h>
  17 #include <linux/spi/spi.h>
  18 #include <linux/iio/iio.h>
  19 #include <linux/iio/buffer.h>
  20 #include <linux/iio/trigger.h>
  21 #include <linux/iio/triggered_buffer.h>
  22 #include <linux/iio/trigger_consumer.h>
  23 #include <linux/regulator/consumer.h>
  24
  25 #define ADC12138_MODE_AUTO_CAL                  0x08
  26 #define ADC12138_MODE_READ_STATUS               0x0c
  27 #define ADC12138_MODE_ACQUISITION_TIME_6        0x0e
  28 #define ADC12138_MODE_ACQUISITION_TIME_10       0x4e
  29 #define ADC12138_MODE_ACQUISITION_TIME_18       0x8e
  30 #define ADC12138_MODE_ACQUISITION_TIME_34       0xce
  31
  32 #define ADC12138_STATUS_CAL                     BIT(6)
  33
  34 enum {
  35         adc12130,
  36         adc12132,
  37         adc12138,
  38 };
  39
  40 struct adc12138 {
  41         struct spi_device *spi;
  42         unsigned int id;
  43         /* conversion clock */
  44         struct clk *cclk;
  45         /* positive analog voltage reference */
  46         struct regulator *vref_p;
  47         /* negative analog voltage reference */
  48         struct regulator *vref_n;
  49         struct mutex lock;
  50         struct completion complete;
  51         /* The number of cclk periods for the S/H's acquisition time */
  52         unsigned int acquisition_time;
  53
  54         u8 tx_buf[2] ____cacheline_aligned;
  55         u8 rx_buf[2];
  56 };
  57
  58 #define ADC12138_VOLTAGE_CHANNEL(chan)                                  \
  59         {                                                               \
  60                 .type = IIO_VOLTAGE,                                    \
  61                 .indexed = 1,                                           \
  62                 .channel = chan,                                        \
  63                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  64                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)    \
  65                                         | BIT(IIO_CHAN_INFO_OFFSET),    \
  66                 .scan_index = chan,                                     \
  67                 .scan_type = {                                          \
  68                         .sign = 's',                                    \
  69                         .realbits = 13,                                 \
  70                         .storagebits = 16,                              \
  71                         .shift = 3,                                     \
  72                         .endianness = IIO_BE,                           \
  73                 },                                                      \
  74         }
  75
  76 #define ADC12138_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si)                 \
  77         {                                                               \
  78                 .type = IIO_VOLTAGE,                                    \
  79                 .indexed = 1,                                           \
  80                 .channel = (chan1),                                     \
  81                 .channel2 = (chan2),                                    \
  82                 .differential = 1,                                      \
  83                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  84                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)    \
  85                                         | BIT(IIO_CHAN_INFO_OFFSET),    \
  86                 .scan_index = si,                                       \
  87                 .scan_type = {                                          \
  88                         .sign = 's',                                    \
  89                         .realbits = 13,                                 \
  90                         .storagebits = 16,                              \
  91                         .shift = 3,                                     \
  92                         .endianness = IIO_BE,                           \
  93                 },                                                      \
  94         }
  95
  96 static const struct iio_chan_spec adc12132_channels[] = {
  97         ADC12138_VOLTAGE_CHANNEL(0),
  98         ADC12138_VOLTAGE_CHANNEL(1),
  99         ADC12138_VOLTAGE_CHANNEL_DIFF(0, 1, 2),
 100         ADC12138_VOLTAGE_CHANNEL_DIFF(1, 0, 3),
 101         IIO_CHAN_SOFT_TIMESTAMP(4),
 102 };
 103
 104 static const struct iio_chan_spec adc12138_channels[] = {
 105         ADC12138_VOLTAGE_CHANNEL(0),
 106         ADC12138_VOLTAGE_CHANNEL(1),
 107         ADC12138_VOLTAGE_CHANNEL(2),
 108         ADC12138_VOLTAGE_CHANNEL(3),
 109         ADC12138_VOLTAGE_CHANNEL(4),
 110         ADC12138_VOLTAGE_CHANNEL(5),
 111         ADC12138_VOLTAGE_CHANNEL(6),
 112         ADC12138_VOLTAGE_CHANNEL(7),
 113         ADC12138_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
 114         ADC12138_VOLTAGE_CHANNEL_DIFF(1, 0, 9),
 115         ADC12138_VOLTAGE_CHANNEL_DIFF(2, 3, 10),
 116         ADC12138_VOLTAGE_CHANNEL_DIFF(3, 2, 11),
 117         ADC12138_VOLTAGE_CHANNEL_DIFF(4, 5, 12),
 118         ADC12138_VOLTAGE_CHANNEL_DIFF(5, 4, 13),
 119         ADC12138_VOLTAGE_CHANNEL_DIFF(6, 7, 14),
 120         ADC12138_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
 121         IIO_CHAN_SOFT_TIMESTAMP(16),
 122 };
 123
 124 static int adc12138_mode_programming(struct adc12138 *adc, u8 mode,
 125                                      void *rx_buf, int len)
 126 {
 127         struct spi_transfer xfer = {
 128                 .tx_buf = adc->tx_buf,
 129                 .rx_buf = adc->rx_buf,
 130                 .len = len,
 131         };
 132         int ret;
 133
 134         /* Skip unused bits for ADC12130 and ADC12132 */
 135         if (adc->id != adc12138)
 136                 mode = (mode & 0xc0) | ((mode & 0x0f) << 2);
 137
 138         adc->tx_buf[0] = mode;
 139
 140         ret = spi_sync_transfer(adc->spi, &xfer, 1);
 141         if (ret)
 142                 return ret;
 143
 144         memcpy(rx_buf, adc->rx_buf, len);
 145
 146         return 0;
 147 }
 148
 149 static int adc12138_read_status(struct adc12138 *adc)
 150 {
 151         u8 rx_buf[2];
 152         int ret;
 153
 154         ret = adc12138_mode_programming(adc, ADC12138_MODE_READ_STATUS,
 155                                         rx_buf, 2);
 156         if (ret)
 157                 return ret;
 158
 159         return (rx_buf[0] << 1) | (rx_buf[1] >> 7);
 160 }
 161
 162 static int __adc12138_start_conv(struct adc12138 *adc,
 163                                  struct iio_chan_spec const *channel,
 164                                  void *data, int len)
 165
 166 {
 167         const u8 ch_to_mux[] = { 0, 4, 1, 5, 2, 6, 3, 7 };
 168         u8 mode = (ch_to_mux[channel->channel] << 4) |
 169                   (channel->differential ? 0 : 0x80);
 170
 171         return adc12138_mode_programming(adc, mode, data, len);
 172 }
 173
 174 static int adc12138_start_conv(struct adc12138 *adc,
 175                                struct iio_chan_spec const *channel)
 176 {
 177         u8 trash;
 178
 179         return __adc12138_start_conv(adc, channel, &trash, 1);
 180 }
 181
 182 static int adc12138_start_and_read_conv(struct adc12138 *adc,
 183                                         struct iio_chan_spec const *channel,
 184                                         __be16 *data)
 185 {
 186         return __adc12138_start_conv(adc, channel, data, 2);
 187 }
 188
 189 static int adc12138_read_conv_data(struct adc12138 *adc, __be16 *value)
 190 {
 191         /* Issue a read status instruction and read previous conversion data */
 192         return adc12138_mode_programming(adc, ADC12138_MODE_READ_STATUS,
 193                                          value, sizeof(*value));
 194 }
 195
 196 static int adc12138_wait_eoc(struct adc12138 *adc, unsigned long timeout)
 197 {
 198         if (!wait_for_completion_timeout(&adc->complete, timeout))
 199                 return -ETIMEDOUT;
 200
 201         return 0;
 202 }
 203
 204 static int adc12138_adc_conversion(struct adc12138 *adc,
 205                                    struct iio_chan_spec const *channel,
 206                                    __be16 *value)
 207 {
 208         int ret;
 209
 210         reinit_completion(&adc->complete);
 211
 212         ret = adc12138_start_conv(adc, channel);
 213         if (ret)
 214                 return ret;
 215
 216         ret = adc12138_wait_eoc(adc, msecs_to_jiffies(100));
 217         if (ret)
 218                 return ret;
 219
 220         return adc12138_read_conv_data(adc, value);
 221 }
 222
 223 static int adc12138_read_raw(struct iio_dev *iio,
 224                              struct iio_chan_spec const *channel, int *value,
 225                              int *shift, long mask)
 226 {
 227         struct adc12138 *adc = iio_priv(iio);
 228         int ret;
 229         __be16 data;
 230
 231         switch (mask) {
 232         case IIO_CHAN_INFO_RAW:
 233                 mutex_lock(&adc->lock);
 234                 ret = adc12138_adc_conversion(adc, channel, &data);
 235                 mutex_unlock(&adc->lock);
 236                 if (ret)
 237                         return ret;
 238
 239                 *value = sign_extend32(be16_to_cpu(data) >> 3, 12);
 240
 241                 return IIO_VAL_INT;
 242         case IIO_CHAN_INFO_SCALE:
 243                 ret = regulator_get_voltage(adc->vref_p);
 244                 if (ret < 0)
 245                         return ret;
 246                 *value = ret;
 247
 248                 if (!IS_ERR(adc->vref_n)) {
 249                         ret = regulator_get_voltage(adc->vref_n);
 250                         if (ret < 0)
 251                                 return ret;
 252                         *value -= ret;
 253                 }
 254
 255                 /* convert regulator output voltage to mV */
 256                 *value /= 1000;
 257                 *shift = channel->scan_type.realbits - 1;
 258
 259                 return IIO_VAL_FRACTIONAL_LOG2;
 260         case IIO_CHAN_INFO_OFFSET:
 261                 if (!IS_ERR(adc->vref_n)) {
 262                         *value = regulator_get_voltage(adc->vref_n);
 263                         if (*value < 0)
 264                                 return *value;
 265                 } else {
 266                         *value = 0;
 267                 }
 268
 269                 /* convert regulator output voltage to mV */
 270                 *value /= 1000;
 271
 272                 return IIO_VAL_INT;
 273         }
 274
 275         return -EINVAL;
 276 }
 277
 278 static const struct iio_info adc12138_info = {
 279         .read_raw = adc12138_read_raw,
 280         .driver_module = THIS_MODULE,
 281 };
 282
 283 static int adc12138_init(struct adc12138 *adc)
 284 {
 285         int ret;
 286         int status;
 287         u8 mode;
 288         u8 trash;
 289
 290         reinit_completion(&adc->complete);
 291
 292         ret = adc12138_mode_programming(adc, ADC12138_MODE_AUTO_CAL, &trash, 1);
 293         if (ret)
 294                 return ret;
 295
 296         /* data output at this time has no significance */
 297         status = adc12138_read_status(adc);
 298         if (status < 0)
 299                 return status;
 300
 301         adc12138_wait_eoc(adc, msecs_to_jiffies(100));
 302
 303         status = adc12138_read_status(adc);
 304         if (status & ADC12138_STATUS_CAL) {
 305                 dev_warn(&adc->spi->dev,
 306                         "Auto Cal sequence is still in progress: %#x\n",
 307                         status);
 308                 return -EIO;
 309         }
 310
 311         switch (adc->acquisition_time) {
 312         case 6:
 313                 mode = ADC12138_MODE_ACQUISITION_TIME_6;
 314                 break;
 315         case 10:
 316                 mode = ADC12138_MODE_ACQUISITION_TIME_10;
 317                 break;
 318         case 18:
 319                 mode = ADC12138_MODE_ACQUISITION_TIME_18;
 320                 break;
 321         case 34:
 322                 mode = ADC12138_MODE_ACQUISITION_TIME_34;
 323                 break;
 324         default:
 325                 return -EINVAL;
 326         }
 327
 328         return adc12138_mode_programming(adc, mode, &trash, 1);
 329 }
 330
 331 static irqreturn_t adc12138_trigger_handler(int irq, void *p)
 332 {
 333         struct iio_poll_func *pf = p;
 334         struct iio_dev *indio_dev = pf->indio_dev;
 335         struct adc12138 *adc = iio_priv(indio_dev);
 336         __be16 data[20] = { }; /* 16x 2 bytes ADC data + 8 bytes timestamp */
 337         __be16 trash;
 338         int ret;
 339         int scan_index;
 340         int i = 0;
 341
 342         mutex_lock(&adc->lock);
 343
 344         for_each_set_bit(scan_index, indio_dev->active_scan_mask,
 345                          indio_dev->masklength) {
 346                 const struct iio_chan_spec *scan_chan =
 347                                 &indio_dev->channels[scan_index];
 348
 349                 reinit_completion(&adc->complete);
 350
 351                 ret = adc12138_start_and_read_conv(adc, scan_chan,
 352                                                    i ? &data[i - 1] : &trash);
 353                 if (ret) {
 354                         dev_warn(&adc->spi->dev,
 355                                  "failed to start conversion\n");
 356                         goto out;
 357                 }
 358
 359                 ret = adc12138_wait_eoc(adc, msecs_to_jiffies(100));
 360                 if (ret) {
 361                         dev_warn(&adc->spi->dev, "wait eoc timeout\n");
 362                         goto out;
 363                 }
 364
 365                 i++;
 366         }
 367
 368         if (i) {
 369                 ret = adc12138_read_conv_data(adc, &data[i - 1]);
 370                 if (ret) {
 371                         dev_warn(&adc->spi->dev,
 372                                  "failed to get conversion data\n");
 373                         goto out;
 374                 }
 375         }
 376
 377         iio_push_to_buffers_with_timestamp(indio_dev, data,
 378                                            iio_get_time_ns(indio_dev));
 379 out:
 380         mutex_unlock(&adc->lock);
 381
 382         iio_trigger_notify_done(indio_dev->trig);
 383
 384         return IRQ_HANDLED;
 385 }
 386
 387 static irqreturn_t adc12138_eoc_handler(int irq, void *p)
 388 {
 389         struct iio_dev *indio_dev = p;
 390         struct adc12138 *adc = iio_priv(indio_dev);
 391
 392         complete(&adc->complete);
 393
 394         return IRQ_HANDLED;
 395 }
 396
 397 static int adc12138_probe(struct spi_device *spi)
 398 {
 399         struct iio_dev *indio_dev;
 400         struct adc12138 *adc;
 401         int ret;
 402
 403         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
 404         if (!indio_dev)
 405                 return -ENOMEM;
 406
 407         adc = iio_priv(indio_dev);
 408         adc->spi = spi;
 409         adc->id = spi_get_device_id(spi)->driver_data;
 410         mutex_init(&adc->lock);
 411         init_completion(&adc->complete);
 412
 413         indio_dev->name = spi_get_device_id(spi)->name;
 414         indio_dev->dev.parent = &spi->dev;
 415         indio_dev->info = &adc12138_info;
 416         indio_dev->modes = INDIO_DIRECT_MODE;
 417
 418         switch (adc->id) {
 419         case adc12130:
 420         case adc12132:
 421                 indio_dev->channels = adc12132_channels;
 422                 indio_dev->num_channels = ARRAY_SIZE(adc12132_channels);
 423                 break;
 424         case adc12138:
 425                 indio_dev->channels = adc12138_channels;
 426                 indio_dev->num_channels = ARRAY_SIZE(adc12138_channels);
 427                 break;
 428         default:
 429                 return -EINVAL;
 430         }
 431
 432         ret = of_property_read_u32(spi->dev.of_node, "ti,acquisition-time",
 433                                    &adc->acquisition_time);
 434         if (ret)
 435                 adc->acquisition_time = 10;
 436
 437         adc->cclk = devm_clk_get(&spi->dev, NULL);
 438         if (IS_ERR(adc->cclk))
 439                 return PTR_ERR(adc->cclk);
 440
 441         adc->vref_p = devm_regulator_get(&spi->dev, "vref-p");
 442         if (IS_ERR(adc->vref_p))
 443                 return PTR_ERR(adc->vref_p);
 444
 445         adc->vref_n = devm_regulator_get_optional(&spi->dev, "vref-n");
 446         if (IS_ERR(adc->vref_n)) {
 447                 /*
 448                  * Assume vref_n is 0V if an optional regulator is not
 449                  * specified, otherwise return the error code.
 450                  */
 451                 ret = PTR_ERR(adc->vref_n);
 452                 if (ret != -ENODEV)
 453                         return ret;
 454         }
 455
 456         ret = devm_request_irq(&spi->dev, spi->irq, adc12138_eoc_handler,
 457                                IRQF_TRIGGER_RISING, indio_dev->name, indio_dev);
 458         if (ret)
 459                 return ret;
 460
 461         ret = clk_prepare_enable(adc->cclk);
 462         if (ret)
 463                 return ret;
 464
 465         ret = regulator_enable(adc->vref_p);
 466         if (ret)
 467                 goto err_clk_disable;
 468
 469         if (!IS_ERR(adc->vref_n)) {
 470                 ret = regulator_enable(adc->vref_n);
 471                 if (ret)
 472                         goto err_vref_p_disable;
 473         }
 474
 475         ret = adc12138_init(adc);
 476         if (ret)
 477                 goto err_vref_n_disable;
 478
 479         spi_set_drvdata(spi, indio_dev);
 480
 481         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 482                                          adc12138_trigger_handler, NULL);
 483         if (ret)
 484                 goto err_vref_n_disable;
 485
 486         ret = iio_device_register(indio_dev);
 487         if (ret)
 488                 goto err_buffer_cleanup;
 489
 490         return 0;
 491 err_buffer_cleanup:
 492         iio_triggered_buffer_cleanup(indio_dev);
 493 err_vref_n_disable:
 494         if (!IS_ERR(adc->vref_n))
 495                 regulator_disable(adc->vref_n);
 496 err_vref_p_disable:
 497         regulator_disable(adc->vref_p);
 498 err_clk_disable:
 499         clk_disable_unprepare(adc->cclk);
 500
 501         return ret;
 502 }
 503
 504 static int adc12138_remove(struct spi_device *spi)
 505 {
 506         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 507         struct adc12138 *adc = iio_priv(indio_dev);
 508
 509         iio_device_unregister(indio_dev);
 510         iio_triggered_buffer_cleanup(indio_dev);
 511         if (!IS_ERR(adc->vref_n))
 512                 regulator_disable(adc->vref_n);
 513         regulator_disable(adc->vref_p);
 514         clk_disable_unprepare(adc->cclk);
 515
 516         return 0;
 517 }
 518
 519 #ifdef CONFIG_OF
 520
 521 static const struct of_device_id adc12138_dt_ids[] = {
 522         { .compatible = "ti,adc12130", },
 523         { .compatible = "ti,adc12132", },
 524         { .compatible = "ti,adc12138", },
 525         {}
 526 };
 527 MODULE_DEVICE_TABLE(of, adc12138_dt_ids);
 528
 529 #endif
 530
 531 static const struct spi_device_id adc12138_id[] = {
 532         { "adc12130", adc12130 },
 533         { "adc12132", adc12132 },
 534         { "adc12138", adc12138 },
 535         {}
 536 };
 537 MODULE_DEVICE_TABLE(spi, adc12138_id);
 538
 539 static struct spi_driver adc12138_driver = {
 540         .driver = {
 541                 .name = "adc12138",
 542                 .of_match_table = of_match_ptr(adc12138_dt_ids),
 543         },
 544         .probe = adc12138_probe,
 545         .remove = adc12138_remove,
 546         .id_table = adc12138_id,
 547 };
 548 module_spi_driver(adc12138_driver);
 549
 550 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 551 MODULE_DESCRIPTION("ADC12130/ADC12132/ADC12138 driver");
 552 MODULE_LICENSE("GPL v2");