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          * Maximum size needed: 16x 2 bytes ADC data + 8 bytes timestamp.
  55          * Less may be need if not all channels are enabled, as long as
  56          * the 8 byte alignment of the timestamp is maintained.
  57          */
  58         __be16 data[20] __aligned(8);
  59
  60         u8 tx_buf[2] ____cacheline_aligned;
  61         u8 rx_buf[2];
  62 };
  63
  64 #define ADC12138_VOLTAGE_CHANNEL(chan)                                  \
  65         {                                                               \
  66                 .type = IIO_VOLTAGE,                                    \
  67                 .indexed = 1,                                           \
  68                 .channel = chan,                                        \
  69                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  70                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)    \
  71                                         | BIT(IIO_CHAN_INFO_OFFSET),    \
  72                 .scan_index = chan,                                     \
  73                 .scan_type = {                                          \
  74                         .sign = 's',                                    \
  75                         .realbits = 13,                                 \
  76                         .storagebits = 16,                              \
  77                         .shift = 3,                                     \
  78                         .endianness = IIO_BE,                           \
  79                 },                                                      \
  80         }
  81
  82 #define ADC12138_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si)                 \
  83         {                                                               \
  84                 .type = IIO_VOLTAGE,                                    \
  85                 .indexed = 1,                                           \
  86                 .channel = (chan1),                                     \
  87                 .channel2 = (chan2),                                    \
  88                 .differential = 1,                                      \
  89                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
  90                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)    \
  91                                         | BIT(IIO_CHAN_INFO_OFFSET),    \
  92                 .scan_index = si,                                       \
  93                 .scan_type = {                                          \
  94                         .sign = 's',                                    \
  95                         .realbits = 13,                                 \
  96                         .storagebits = 16,                              \
  97                         .shift = 3,                                     \
  98                         .endianness = IIO_BE,                           \
  99                 },                                                      \
 100         }
 101
 102 static const struct iio_chan_spec adc12132_channels[] = {
 103         ADC12138_VOLTAGE_CHANNEL(0),
 104         ADC12138_VOLTAGE_CHANNEL(1),
 105         ADC12138_VOLTAGE_CHANNEL_DIFF(0, 1, 2),
 106         ADC12138_VOLTAGE_CHANNEL_DIFF(1, 0, 3),
 107         IIO_CHAN_SOFT_TIMESTAMP(4),
 108 };
 109
 110 static const struct iio_chan_spec adc12138_channels[] = {
 111         ADC12138_VOLTAGE_CHANNEL(0),
 112         ADC12138_VOLTAGE_CHANNEL(1),
 113         ADC12138_VOLTAGE_CHANNEL(2),
 114         ADC12138_VOLTAGE_CHANNEL(3),
 115         ADC12138_VOLTAGE_CHANNEL(4),
 116         ADC12138_VOLTAGE_CHANNEL(5),
 117         ADC12138_VOLTAGE_CHANNEL(6),
 118         ADC12138_VOLTAGE_CHANNEL(7),
 119         ADC12138_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
 120         ADC12138_VOLTAGE_CHANNEL_DIFF(1, 0, 9),
 121         ADC12138_VOLTAGE_CHANNEL_DIFF(2, 3, 10),
 122         ADC12138_VOLTAGE_CHANNEL_DIFF(3, 2, 11),
 123         ADC12138_VOLTAGE_CHANNEL_DIFF(4, 5, 12),
 124         ADC12138_VOLTAGE_CHANNEL_DIFF(5, 4, 13),
 125         ADC12138_VOLTAGE_CHANNEL_DIFF(6, 7, 14),
 126         ADC12138_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
 127         IIO_CHAN_SOFT_TIMESTAMP(16),
 128 };
 129
 130 static int adc12138_mode_programming(struct adc12138 *adc, u8 mode,
 131                                      void *rx_buf, int len)
 132 {
 133         struct spi_transfer xfer = {
 134                 .tx_buf = adc->tx_buf,
 135                 .rx_buf = adc->rx_buf,
 136                 .len = len,
 137         };
 138         int ret;
 139
 140         /* Skip unused bits for ADC12130 and ADC12132 */
 141         if (adc->id != adc12138)
 142                 mode = (mode & 0xc0) | ((mode & 0x0f) << 2);
 143
 144         adc->tx_buf[0] = mode;
 145
 146         ret = spi_sync_transfer(adc->spi, &xfer, 1);
 147         if (ret)
 148                 return ret;
 149
 150         memcpy(rx_buf, adc->rx_buf, len);
 151
 152         return 0;
 153 }
 154
 155 static int adc12138_read_status(struct adc12138 *adc)
 156 {
 157         u8 rx_buf[2];
 158         int ret;
 159
 160         ret = adc12138_mode_programming(adc, ADC12138_MODE_READ_STATUS,
 161                                         rx_buf, 2);
 162         if (ret)
 163                 return ret;
 164
 165         return (rx_buf[0] << 1) | (rx_buf[1] >> 7);
 166 }
 167
 168 static int __adc12138_start_conv(struct adc12138 *adc,
 169                                  struct iio_chan_spec const *channel,
 170                                  void *data, int len)
 171
 172 {
 173         const u8 ch_to_mux[] = { 0, 4, 1, 5, 2, 6, 3, 7 };
 174         u8 mode = (ch_to_mux[channel->channel] << 4) |
 175                   (channel->differential ? 0 : 0x80);
 176
 177         return adc12138_mode_programming(adc, mode, data, len);
 178 }
 179
 180 static int adc12138_start_conv(struct adc12138 *adc,
 181                                struct iio_chan_spec const *channel)
 182 {
 183         u8 trash;
 184
 185         return __adc12138_start_conv(adc, channel, &trash, 1);
 186 }
 187
 188 static int adc12138_start_and_read_conv(struct adc12138 *adc,
 189                                         struct iio_chan_spec const *channel,
 190                                         __be16 *data)
 191 {
 192         return __adc12138_start_conv(adc, channel, data, 2);
 193 }
 194
 195 static int adc12138_read_conv_data(struct adc12138 *adc, __be16 *value)
 196 {
 197         /* Issue a read status instruction and read previous conversion data */
 198         return adc12138_mode_programming(adc, ADC12138_MODE_READ_STATUS,
 199                                          value, sizeof(*value));
 200 }
 201
 202 static int adc12138_wait_eoc(struct adc12138 *adc, unsigned long timeout)
 203 {
 204         if (!wait_for_completion_timeout(&adc->complete, timeout))
 205                 return -ETIMEDOUT;
 206
 207         return 0;
 208 }
 209
 210 static int adc12138_adc_conversion(struct adc12138 *adc,
 211                                    struct iio_chan_spec const *channel,
 212                                    __be16 *value)
 213 {
 214         int ret;
 215
 216         reinit_completion(&adc->complete);
 217
 218         ret = adc12138_start_conv(adc, channel);
 219         if (ret)
 220                 return ret;
 221
 222         ret = adc12138_wait_eoc(adc, msecs_to_jiffies(100));
 223         if (ret)
 224                 return ret;
 225
 226         return adc12138_read_conv_data(adc, value);
 227 }
 228
 229 static int adc12138_read_raw(struct iio_dev *iio,
 230                              struct iio_chan_spec const *channel, int *value,
 231                              int *shift, long mask)
 232 {
 233         struct adc12138 *adc = iio_priv(iio);
 234         int ret;
 235         __be16 data;
 236
 237         switch (mask) {
 238         case IIO_CHAN_INFO_RAW:
 239                 mutex_lock(&adc->lock);
 240                 ret = adc12138_adc_conversion(adc, channel, &data);
 241                 mutex_unlock(&adc->lock);
 242                 if (ret)
 243                         return ret;
 244
 245                 *value = sign_extend32(be16_to_cpu(data) >> 3, 12);
 246
 247                 return IIO_VAL_INT;
 248         case IIO_CHAN_INFO_SCALE:
 249                 ret = regulator_get_voltage(adc->vref_p);
 250                 if (ret < 0)
 251                         return ret;
 252                 *value = ret;
 253
 254                 if (!IS_ERR(adc->vref_n)) {
 255                         ret = regulator_get_voltage(adc->vref_n);
 256                         if (ret < 0)
 257                                 return ret;
 258                         *value -= ret;
 259                 }
 260
 261                 /* convert regulator output voltage to mV */
 262                 *value /= 1000;
 263                 *shift = channel->scan_type.realbits - 1;
 264
 265                 return IIO_VAL_FRACTIONAL_LOG2;
 266         case IIO_CHAN_INFO_OFFSET:
 267                 if (!IS_ERR(adc->vref_n)) {
 268                         *value = regulator_get_voltage(adc->vref_n);
 269                         if (*value < 0)
 270                                 return *value;
 271                 } else {
 272                         *value = 0;
 273                 }
 274
 275                 /* convert regulator output voltage to mV */
 276                 *value /= 1000;
 277
 278                 return IIO_VAL_INT;
 279         }
 280
 281         return -EINVAL;
 282 }
 283
 284 static const struct iio_info adc12138_info = {
 285         .read_raw = adc12138_read_raw,
 286         .driver_module = THIS_MODULE,
 287 };
 288
 289 static int adc12138_init(struct adc12138 *adc)
 290 {
 291         int ret;
 292         int status;
 293         u8 mode;
 294         u8 trash;
 295
 296         reinit_completion(&adc->complete);
 297
 298         ret = adc12138_mode_programming(adc, ADC12138_MODE_AUTO_CAL, &trash, 1);
 299         if (ret)
 300                 return ret;
 301
 302         /* data output at this time has no significance */
 303         status = adc12138_read_status(adc);
 304         if (status < 0)
 305                 return status;
 306
 307         adc12138_wait_eoc(adc, msecs_to_jiffies(100));
 308
 309         status = adc12138_read_status(adc);
 310         if (status & ADC12138_STATUS_CAL) {
 311                 dev_warn(&adc->spi->dev,
 312                         "Auto Cal sequence is still in progress: %#x\n",
 313                         status);
 314                 return -EIO;
 315         }
 316
 317         switch (adc->acquisition_time) {
 318         case 6:
 319                 mode = ADC12138_MODE_ACQUISITION_TIME_6;
 320                 break;
 321         case 10:
 322                 mode = ADC12138_MODE_ACQUISITION_TIME_10;
 323                 break;
 324         case 18:
 325                 mode = ADC12138_MODE_ACQUISITION_TIME_18;
 326                 break;
 327         case 34:
 328                 mode = ADC12138_MODE_ACQUISITION_TIME_34;
 329                 break;
 330         default:
 331                 return -EINVAL;
 332         }
 333
 334         return adc12138_mode_programming(adc, mode, &trash, 1);
 335 }
 336
 337 static irqreturn_t adc12138_trigger_handler(int irq, void *p)
 338 {
 339         struct iio_poll_func *pf = p;
 340         struct iio_dev *indio_dev = pf->indio_dev;
 341         struct adc12138 *adc = iio_priv(indio_dev);
 342         __be16 trash;
 343         int ret;
 344         int scan_index;
 345         int i = 0;
 346
 347         mutex_lock(&adc->lock);
 348
 349         for_each_set_bit(scan_index, indio_dev->active_scan_mask,
 350                          indio_dev->masklength) {
 351                 const struct iio_chan_spec *scan_chan =
 352                                 &indio_dev->channels[scan_index];
 353
 354                 reinit_completion(&adc->complete);
 355
 356                 ret = adc12138_start_and_read_conv(adc, scan_chan,
 357                                         i ? &adc->data[i - 1] : &trash);
 358                 if (ret) {
 359                         dev_warn(&adc->spi->dev,
 360                                  "failed to start conversion\n");
 361                         goto out;
 362                 }
 363
 364                 ret = adc12138_wait_eoc(adc, msecs_to_jiffies(100));
 365                 if (ret) {
 366                         dev_warn(&adc->spi->dev, "wait eoc timeout\n");
 367                         goto out;
 368                 }
 369
 370                 i++;
 371         }
 372
 373         if (i) {
 374                 ret = adc12138_read_conv_data(adc, &adc->data[i - 1]);
 375                 if (ret) {
 376                         dev_warn(&adc->spi->dev,
 377                                  "failed to get conversion data\n");
 378                         goto out;
 379                 }
 380         }
 381
 382         iio_push_to_buffers_with_timestamp(indio_dev, adc->data,
 383                                            iio_get_time_ns(indio_dev));
 384 out:
 385         mutex_unlock(&adc->lock);
 386
 387         iio_trigger_notify_done(indio_dev->trig);
 388
 389         return IRQ_HANDLED;
 390 }
 391
 392 static irqreturn_t adc12138_eoc_handler(int irq, void *p)
 393 {
 394         struct iio_dev *indio_dev = p;
 395         struct adc12138 *adc = iio_priv(indio_dev);
 396
 397         complete(&adc->complete);
 398
 399         return IRQ_HANDLED;
 400 }
 401
 402 static int adc12138_probe(struct spi_device *spi)
 403 {
 404         struct iio_dev *indio_dev;
 405         struct adc12138 *adc;
 406         int ret;
 407
 408         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
 409         if (!indio_dev)
 410                 return -ENOMEM;
 411
 412         adc = iio_priv(indio_dev);
 413         adc->spi = spi;
 414         adc->id = spi_get_device_id(spi)->driver_data;
 415         mutex_init(&adc->lock);
 416         init_completion(&adc->complete);
 417
 418         indio_dev->name = spi_get_device_id(spi)->name;
 419         indio_dev->dev.parent = &spi->dev;
 420         indio_dev->info = &adc12138_info;
 421         indio_dev->modes = INDIO_DIRECT_MODE;
 422
 423         switch (adc->id) {
 424         case adc12130:
 425         case adc12132:
 426                 indio_dev->channels = adc12132_channels;
 427                 indio_dev->num_channels = ARRAY_SIZE(adc12132_channels);
 428                 break;
 429         case adc12138:
 430                 indio_dev->channels = adc12138_channels;
 431                 indio_dev->num_channels = ARRAY_SIZE(adc12138_channels);
 432                 break;
 433         default:
 434                 return -EINVAL;
 435         }
 436
 437         ret = of_property_read_u32(spi->dev.of_node, "ti,acquisition-time",
 438                                    &adc->acquisition_time);
 439         if (ret)
 440                 adc->acquisition_time = 10;
 441
 442         adc->cclk = devm_clk_get(&spi->dev, NULL);
 443         if (IS_ERR(adc->cclk))
 444                 return PTR_ERR(adc->cclk);
 445
 446         adc->vref_p = devm_regulator_get(&spi->dev, "vref-p");
 447         if (IS_ERR(adc->vref_p))
 448                 return PTR_ERR(adc->vref_p);
 449
 450         adc->vref_n = devm_regulator_get_optional(&spi->dev, "vref-n");
 451         if (IS_ERR(adc->vref_n)) {
 452                 /*
 453                  * Assume vref_n is 0V if an optional regulator is not
 454                  * specified, otherwise return the error code.
 455                  */
 456                 ret = PTR_ERR(adc->vref_n);
 457                 if (ret != -ENODEV)
 458                         return ret;
 459         }
 460
 461         ret = devm_request_irq(&spi->dev, spi->irq, adc12138_eoc_handler,
 462                                IRQF_TRIGGER_RISING, indio_dev->name, indio_dev);
 463         if (ret)
 464                 return ret;
 465
 466         ret = clk_prepare_enable(adc->cclk);
 467         if (ret)
 468                 return ret;
 469
 470         ret = regulator_enable(adc->vref_p);
 471         if (ret)
 472                 goto err_clk_disable;
 473
 474         if (!IS_ERR(adc->vref_n)) {
 475                 ret = regulator_enable(adc->vref_n);
 476                 if (ret)
 477                         goto err_vref_p_disable;
 478         }
 479
 480         ret = adc12138_init(adc);
 481         if (ret)
 482                 goto err_vref_n_disable;
 483
 484         spi_set_drvdata(spi, indio_dev);
 485
 486         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 487                                          adc12138_trigger_handler, NULL);
 488         if (ret)
 489                 goto err_vref_n_disable;
 490
 491         ret = iio_device_register(indio_dev);
 492         if (ret)
 493                 goto err_buffer_cleanup;
 494
 495         return 0;
 496 err_buffer_cleanup:
 497         iio_triggered_buffer_cleanup(indio_dev);
 498 err_vref_n_disable:
 499         if (!IS_ERR(adc->vref_n))
 500                 regulator_disable(adc->vref_n);
 501 err_vref_p_disable:
 502         regulator_disable(adc->vref_p);
 503 err_clk_disable:
 504         clk_disable_unprepare(adc->cclk);
 505
 506         return ret;
 507 }
 508
 509 static int adc12138_remove(struct spi_device *spi)
 510 {
 511         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 512         struct adc12138 *adc = iio_priv(indio_dev);
 513
 514         iio_device_unregister(indio_dev);
 515         iio_triggered_buffer_cleanup(indio_dev);
 516         if (!IS_ERR(adc->vref_n))
 517                 regulator_disable(adc->vref_n);
 518         regulator_disable(adc->vref_p);
 519         clk_disable_unprepare(adc->cclk);
 520
 521         return 0;
 522 }
 523
 524 #ifdef CONFIG_OF
 525
 526 static const struct of_device_id adc12138_dt_ids[] = {
 527         { .compatible = "ti,adc12130", },
 528         { .compatible = "ti,adc12132", },
 529         { .compatible = "ti,adc12138", },
 530         {}
 531 };
 532 MODULE_DEVICE_TABLE(of, adc12138_dt_ids);
 533
 534 #endif
 535
 536 static const struct spi_device_id adc12138_id[] = {
 537         { "adc12130", adc12130 },
 538         { "adc12132", adc12132 },
 539         { "adc12138", adc12138 },
 540         {}
 541 };
 542 MODULE_DEVICE_TABLE(spi, adc12138_id);
 543
 544 static struct spi_driver adc12138_driver = {
 545         .driver = {
 546                 .name = "adc12138",
 547                 .of_match_table = of_match_ptr(adc12138_dt_ids),
 548         },
 549         .probe = adc12138_probe,
 550         .remove = adc12138_remove,
 551         .id_table = adc12138_id,
 552 };
 553 module_spi_driver(adc12138_driver);
 554
 555 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
 556 MODULE_DESCRIPTION("ADC12130/ADC12132/ADC12138 driver");
 557 MODULE_LICENSE("GPL v2");