drivers/iio/adc/ad7266.c

   1 /*
   2  * AD7266/65 SPI ADC driver
   3  *
   4  * Copyright 2012 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2.
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/kernel.h>
  11 #include <linux/slab.h>
  12 #include <linux/spi/spi.h>
  13 #include <linux/regulator/consumer.h>
  14 #include <linux/err.h>
  15 #include <linux/gpio.h>
  16 #include <linux/module.h>
  17
  18 #include <linux/interrupt.h>
  19
  20 #include <linux/iio/iio.h>
  21 #include <linux/iio/buffer.h>
  22 #include <linux/iio/trigger_consumer.h>
  23 #include <linux/iio/triggered_buffer.h>
  24
  25 #include <linux/platform_data/ad7266.h>
  26
  27 struct ad7266_state {
  28         struct spi_device       *spi;
  29         struct regulator        *reg;
  30         unsigned long           vref_mv;
  31
  32         struct spi_transfer     single_xfer[3];
  33         struct spi_message      single_msg;
  34
  35         enum ad7266_range       range;
  36         enum ad7266_mode        mode;
  37         bool                    fixed_addr;
  38         struct gpio             gpios[3];
  39
  40         /*
  41          * DMA (thus cache coherency maintenance) requires the
  42          * transfer buffers to live in their own cache lines.
  43          * The buffer needs to be large enough to hold two samples (4 bytes) and
  44          * the naturally aligned timestamp (8 bytes).
  45          */
  46         struct {
  47                 __be16 sample[2];
  48                 s64 timestamp;
  49         } data ____cacheline_aligned;
  50 };
  51
  52 static int ad7266_wakeup(struct ad7266_state *st)
  53 {
  54         /* Any read with >= 2 bytes will wake the device */
  55         return spi_read(st->spi, &st->data.sample[0], 2);
  56 }
  57
  58 static int ad7266_powerdown(struct ad7266_state *st)
  59 {
  60         /* Any read with < 2 bytes will powerdown the device */
  61         return spi_read(st->spi, &st->data.sample[0], 1);
  62 }
  63
  64 static int ad7266_preenable(struct iio_dev *indio_dev)
  65 {
  66         struct ad7266_state *st = iio_priv(indio_dev);
  67         return ad7266_wakeup(st);
  68 }
  69
  70 static int ad7266_postdisable(struct iio_dev *indio_dev)
  71 {
  72         struct ad7266_state *st = iio_priv(indio_dev);
  73         return ad7266_powerdown(st);
  74 }
  75
  76 static const struct iio_buffer_setup_ops iio_triggered_buffer_setup_ops = {
  77         .preenable = &ad7266_preenable,
  78         .postenable = &iio_triggered_buffer_postenable,
  79         .predisable = &iio_triggered_buffer_predisable,
  80         .postdisable = &ad7266_postdisable,
  81 };
  82
  83 static irqreturn_t ad7266_trigger_handler(int irq, void *p)
  84 {
  85         struct iio_poll_func *pf = p;
  86         struct iio_dev *indio_dev = pf->indio_dev;
  87         struct ad7266_state *st = iio_priv(indio_dev);
  88         int ret;
  89
  90         ret = spi_read(st->spi, st->data.sample, 4);
  91         if (ret == 0) {
  92                 iio_push_to_buffers_with_timestamp(indio_dev, &st->data,
  93                             pf->timestamp);
  94         }
  95
  96         iio_trigger_notify_done(indio_dev->trig);
  97
  98         return IRQ_HANDLED;
  99 }
 100
 101 static void ad7266_select_input(struct ad7266_state *st, unsigned int nr)
 102 {
 103         unsigned int i;
 104
 105         if (st->fixed_addr)
 106                 return;
 107
 108         switch (st->mode) {
 109         case AD7266_MODE_SINGLE_ENDED:
 110                 nr >>= 1;
 111                 break;
 112         case AD7266_MODE_PSEUDO_DIFF:
 113                 nr |= 1;
 114                 break;
 115         case AD7266_MODE_DIFF:
 116                 nr &= ~1;
 117                 break;
 118         }
 119
 120         for (i = 0; i < 3; ++i)
 121                 gpio_set_value(st->gpios[i].gpio, (bool)(nr & BIT(i)));
 122 }
 123
 124 static int ad7266_update_scan_mode(struct iio_dev *indio_dev,
 125         const unsigned long *scan_mask)
 126 {
 127         struct ad7266_state *st = iio_priv(indio_dev);
 128         unsigned int nr = find_first_bit(scan_mask, indio_dev->masklength);
 129
 130         ad7266_select_input(st, nr);
 131
 132         return 0;
 133 }
 134
 135 static int ad7266_read_single(struct ad7266_state *st, int *val,
 136         unsigned int address)
 137 {
 138         int ret;
 139
 140         ad7266_select_input(st, address);
 141
 142         ret = spi_sync(st->spi, &st->single_msg);
 143         *val = be16_to_cpu(st->data.sample[address % 2]);
 144
 145         return ret;
 146 }
 147
 148 static int ad7266_read_raw(struct iio_dev *indio_dev,
 149         struct iio_chan_spec const *chan, int *val, int *val2, long m)
 150 {
 151         struct ad7266_state *st = iio_priv(indio_dev);
 152         unsigned long scale_mv;
 153         int ret;
 154
 155         switch (m) {
 156         case IIO_CHAN_INFO_RAW:
 157                 if (iio_buffer_enabled(indio_dev))
 158                         return -EBUSY;
 159
 160                 ret = ad7266_read_single(st, val, chan->address);
 161                 if (ret)
 162                         return ret;
 163
 164                 *val = (*val >> 2) & 0xfff;
 165                 if (chan->scan_type.sign == 's')
 166                         *val = sign_extend32(*val, 11);
 167
 168                 return IIO_VAL_INT;
 169         case IIO_CHAN_INFO_SCALE:
 170                 scale_mv = st->vref_mv;
 171                 if (st->mode == AD7266_MODE_DIFF)
 172                         scale_mv *= 2;
 173                 if (st->range == AD7266_RANGE_2VREF)
 174                         scale_mv *= 2;
 175
 176                 *val = scale_mv;
 177                 *val2 = chan->scan_type.realbits;
 178                 return IIO_VAL_FRACTIONAL_LOG2;
 179         case IIO_CHAN_INFO_OFFSET:
 180                 if (st->range == AD7266_RANGE_2VREF &&
 181                         st->mode != AD7266_MODE_DIFF)
 182                         *val = 2048;
 183                 else
 184                         *val = 0;
 185                 return IIO_VAL_INT;
 186         }
 187         return -EINVAL;
 188 }
 189
 190 #define AD7266_CHAN(_chan, _sign) {                     \
 191         .type = IIO_VOLTAGE,                            \
 192         .indexed = 1,                                   \
 193         .channel = (_chan),                             \
 194         .address = (_chan),                             \
 195         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
 196         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
 197                 | BIT(IIO_CHAN_INFO_OFFSET),                    \
 198         .scan_index = (_chan),                          \
 199         .scan_type = {                                  \
 200                 .sign = (_sign),                        \
 201                 .realbits = 12,                         \
 202                 .storagebits = 16,                      \
 203                 .shift = 2,                             \
 204                 .endianness = IIO_BE,                   \
 205         },                                              \
 206 }
 207
 208 #define AD7266_DECLARE_SINGLE_ENDED_CHANNELS(_name, _sign) \
 209 const struct iio_chan_spec ad7266_channels_##_name[] = { \
 210         AD7266_CHAN(0, (_sign)), \
 211         AD7266_CHAN(1, (_sign)), \
 212         AD7266_CHAN(2, (_sign)), \
 213         AD7266_CHAN(3, (_sign)), \
 214         AD7266_CHAN(4, (_sign)), \
 215         AD7266_CHAN(5, (_sign)), \
 216         AD7266_CHAN(6, (_sign)), \
 217         AD7266_CHAN(7, (_sign)), \
 218         AD7266_CHAN(8, (_sign)), \
 219         AD7266_CHAN(9, (_sign)), \
 220         AD7266_CHAN(10, (_sign)), \
 221         AD7266_CHAN(11, (_sign)), \
 222         IIO_CHAN_SOFT_TIMESTAMP(13), \
 223 }
 224
 225 #define AD7266_DECLARE_SINGLE_ENDED_CHANNELS_FIXED(_name, _sign) \
 226 const struct iio_chan_spec ad7266_channels_##_name##_fixed[] = { \
 227         AD7266_CHAN(0, (_sign)), \
 228         AD7266_CHAN(1, (_sign)), \
 229         IIO_CHAN_SOFT_TIMESTAMP(2), \
 230 }
 231
 232 static AD7266_DECLARE_SINGLE_ENDED_CHANNELS(u, 'u');
 233 static AD7266_DECLARE_SINGLE_ENDED_CHANNELS(s, 's');
 234 static AD7266_DECLARE_SINGLE_ENDED_CHANNELS_FIXED(u, 'u');
 235 static AD7266_DECLARE_SINGLE_ENDED_CHANNELS_FIXED(s, 's');
 236
 237 #define AD7266_CHAN_DIFF(_chan, _sign) {                        \
 238         .type = IIO_VOLTAGE,                            \
 239         .indexed = 1,                                   \
 240         .channel = (_chan) * 2,                         \
 241         .channel2 = (_chan) * 2 + 1,                    \
 242         .address = (_chan),                             \
 243         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
 244         .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)    \
 245                 | BIT(IIO_CHAN_INFO_OFFSET),                    \
 246         .scan_index = (_chan),                          \
 247         .scan_type = {                                  \
 248                 .sign = _sign,                  \
 249                 .realbits = 12,                         \
 250                 .storagebits = 16,                      \
 251                 .shift = 2,                             \
 252                 .endianness = IIO_BE,                   \
 253         },                                              \
 254         .differential = 1,                              \
 255 }
 256
 257 #define AD7266_DECLARE_DIFF_CHANNELS(_name, _sign) \
 258 const struct iio_chan_spec ad7266_channels_diff_##_name[] = { \
 259         AD7266_CHAN_DIFF(0, (_sign)), \
 260         AD7266_CHAN_DIFF(1, (_sign)), \
 261         AD7266_CHAN_DIFF(2, (_sign)), \
 262         AD7266_CHAN_DIFF(3, (_sign)), \
 263         AD7266_CHAN_DIFF(4, (_sign)), \
 264         AD7266_CHAN_DIFF(5, (_sign)), \
 265         IIO_CHAN_SOFT_TIMESTAMP(6), \
 266 }
 267
 268 static AD7266_DECLARE_DIFF_CHANNELS(s, 's');
 269 static AD7266_DECLARE_DIFF_CHANNELS(u, 'u');
 270
 271 #define AD7266_DECLARE_DIFF_CHANNELS_FIXED(_name, _sign) \
 272 const struct iio_chan_spec ad7266_channels_diff_fixed_##_name[] = { \
 273         AD7266_CHAN_DIFF(0, (_sign)), \
 274         AD7266_CHAN_DIFF(1, (_sign)), \
 275         IIO_CHAN_SOFT_TIMESTAMP(2), \
 276 }
 277
 278 static AD7266_DECLARE_DIFF_CHANNELS_FIXED(s, 's');
 279 static AD7266_DECLARE_DIFF_CHANNELS_FIXED(u, 'u');
 280
 281 static const struct iio_info ad7266_info = {
 282         .read_raw = &ad7266_read_raw,
 283         .update_scan_mode = &ad7266_update_scan_mode,
 284         .driver_module = THIS_MODULE,
 285 };
 286
 287 static const unsigned long ad7266_available_scan_masks[] = {
 288         0x003,
 289         0x00c,
 290         0x030,
 291         0x0c0,
 292         0x300,
 293         0xc00,
 294         0x000,
 295 };
 296
 297 static const unsigned long ad7266_available_scan_masks_diff[] = {
 298         0x003,
 299         0x00c,
 300         0x030,
 301         0x000,
 302 };
 303
 304 static const unsigned long ad7266_available_scan_masks_fixed[] = {
 305         0x003,
 306         0x000,
 307 };
 308
 309 struct ad7266_chan_info {
 310         const struct iio_chan_spec *channels;
 311         unsigned int num_channels;
 312         const unsigned long *scan_masks;
 313 };
 314
 315 #define AD7266_CHAN_INFO_INDEX(_differential, _signed, _fixed) \
 316         (((_differential) << 2) | ((_signed) << 1) | ((_fixed) << 0))
 317
 318 static const struct ad7266_chan_info ad7266_chan_infos[] = {
 319         [AD7266_CHAN_INFO_INDEX(0, 0, 0)] = {
 320                 .channels = ad7266_channels_u,
 321                 .num_channels = ARRAY_SIZE(ad7266_channels_u),
 322                 .scan_masks = ad7266_available_scan_masks,
 323         },
 324         [AD7266_CHAN_INFO_INDEX(0, 0, 1)] = {
 325                 .channels = ad7266_channels_u_fixed,
 326                 .num_channels = ARRAY_SIZE(ad7266_channels_u_fixed),
 327                 .scan_masks = ad7266_available_scan_masks_fixed,
 328         },
 329         [AD7266_CHAN_INFO_INDEX(0, 1, 0)] = {
 330                 .channels = ad7266_channels_s,
 331                 .num_channels = ARRAY_SIZE(ad7266_channels_s),
 332                 .scan_masks = ad7266_available_scan_masks,
 333         },
 334         [AD7266_CHAN_INFO_INDEX(0, 1, 1)] = {
 335                 .channels = ad7266_channels_s_fixed,
 336                 .num_channels = ARRAY_SIZE(ad7266_channels_s_fixed),
 337                 .scan_masks = ad7266_available_scan_masks_fixed,
 338         },
 339         [AD7266_CHAN_INFO_INDEX(1, 0, 0)] = {
 340                 .channels = ad7266_channels_diff_u,
 341                 .num_channels = ARRAY_SIZE(ad7266_channels_diff_u),
 342                 .scan_masks = ad7266_available_scan_masks_diff,
 343         },
 344         [AD7266_CHAN_INFO_INDEX(1, 0, 1)] = {
 345                 .channels = ad7266_channels_diff_fixed_u,
 346                 .num_channels = ARRAY_SIZE(ad7266_channels_diff_fixed_u),
 347                 .scan_masks = ad7266_available_scan_masks_fixed,
 348         },
 349         [AD7266_CHAN_INFO_INDEX(1, 1, 0)] = {
 350                 .channels = ad7266_channels_diff_s,
 351                 .num_channels = ARRAY_SIZE(ad7266_channels_diff_s),
 352                 .scan_masks = ad7266_available_scan_masks_diff,
 353         },
 354         [AD7266_CHAN_INFO_INDEX(1, 1, 1)] = {
 355                 .channels = ad7266_channels_diff_fixed_s,
 356                 .num_channels = ARRAY_SIZE(ad7266_channels_diff_fixed_s),
 357                 .scan_masks = ad7266_available_scan_masks_fixed,
 358         },
 359 };
 360
 361 static void ad7266_init_channels(struct iio_dev *indio_dev)
 362 {
 363         struct ad7266_state *st = iio_priv(indio_dev);
 364         bool is_differential, is_signed;
 365         const struct ad7266_chan_info *chan_info;
 366         int i;
 367
 368         is_differential = st->mode != AD7266_MODE_SINGLE_ENDED;
 369         is_signed = (st->range == AD7266_RANGE_2VREF) |
 370                     (st->mode == AD7266_MODE_DIFF);
 371
 372         i = AD7266_CHAN_INFO_INDEX(is_differential, is_signed, st->fixed_addr);
 373         chan_info = &ad7266_chan_infos[i];
 374
 375         indio_dev->channels = chan_info->channels;
 376         indio_dev->num_channels = chan_info->num_channels;
 377         indio_dev->available_scan_masks = chan_info->scan_masks;
 378         indio_dev->masklength = chan_info->num_channels - 1;
 379 }
 380
 381 static const char * const ad7266_gpio_labels[] = {
 382         "AD0", "AD1", "AD2",
 383 };
 384
 385 static int ad7266_probe(struct spi_device *spi)
 386 {
 387         struct ad7266_platform_data *pdata = spi->dev.platform_data;
 388         struct iio_dev *indio_dev;
 389         struct ad7266_state *st;
 390         unsigned int i;
 391         int ret;
 392
 393         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 394         if (indio_dev == NULL)
 395                 return -ENOMEM;
 396
 397         st = iio_priv(indio_dev);
 398
 399         st->reg = devm_regulator_get_optional(&spi->dev, "vref");
 400         if (!IS_ERR(st->reg)) {
 401                 ret = regulator_enable(st->reg);
 402                 if (ret)
 403                         return ret;
 404
 405                 ret = regulator_get_voltage(st->reg);
 406                 if (ret < 0)
 407                         goto error_disable_reg;
 408
 409                 st->vref_mv = ret / 1000;
 410         } else {
 411                 /* Any other error indicates that the regulator does exist */
 412                 if (PTR_ERR(st->reg) != -ENODEV)
 413                         return PTR_ERR(st->reg);
 414                 /* Use internal reference */
 415                 st->vref_mv = 2500;
 416         }
 417
 418         if (pdata) {
 419                 st->fixed_addr = pdata->fixed_addr;
 420                 st->mode = pdata->mode;
 421                 st->range = pdata->range;
 422
 423                 if (!st->fixed_addr) {
 424                         for (i = 0; i < ARRAY_SIZE(st->gpios); ++i) {
 425                                 st->gpios[i].gpio = pdata->addr_gpios[i];
 426                                 st->gpios[i].flags = GPIOF_OUT_INIT_LOW;
 427                                 st->gpios[i].label = ad7266_gpio_labels[i];
 428                         }
 429                         ret = gpio_request_array(st->gpios,
 430                                 ARRAY_SIZE(st->gpios));
 431                         if (ret)
 432                                 goto error_disable_reg;
 433                 }
 434         } else {
 435                 st->fixed_addr = true;
 436                 st->range = AD7266_RANGE_VREF;
 437                 st->mode = AD7266_MODE_DIFF;
 438         }
 439
 440         spi_set_drvdata(spi, indio_dev);
 441         st->spi = spi;
 442
 443         indio_dev->dev.parent = &spi->dev;
 444         indio_dev->name = spi_get_device_id(spi)->name;
 445         indio_dev->modes = INDIO_DIRECT_MODE;
 446         indio_dev->info = &ad7266_info;
 447
 448         ad7266_init_channels(indio_dev);
 449
 450         /* wakeup */
 451         st->single_xfer[0].rx_buf = &st->data.sample[0];
 452         st->single_xfer[0].len = 2;
 453         st->single_xfer[0].cs_change = 1;
 454         /* conversion */
 455         st->single_xfer[1].rx_buf = st->data.sample;
 456         st->single_xfer[1].len = 4;
 457         st->single_xfer[1].cs_change = 1;
 458         /* powerdown */
 459         st->single_xfer[2].tx_buf = &st->data.sample[0];
 460         st->single_xfer[2].len = 1;
 461
 462         spi_message_init(&st->single_msg);
 463         spi_message_add_tail(&st->single_xfer[0], &st->single_msg);
 464         spi_message_add_tail(&st->single_xfer[1], &st->single_msg);
 465         spi_message_add_tail(&st->single_xfer[2], &st->single_msg);
 466
 467         ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
 468                 &ad7266_trigger_handler, &iio_triggered_buffer_setup_ops);
 469         if (ret)
 470                 goto error_free_gpios;
 471
 472         ret = iio_device_register(indio_dev);
 473         if (ret)
 474                 goto error_buffer_cleanup;
 475
 476         return 0;
 477
 478 error_buffer_cleanup:
 479         iio_triggered_buffer_cleanup(indio_dev);
 480 error_free_gpios:
 481         if (!st->fixed_addr)
 482                 gpio_free_array(st->gpios, ARRAY_SIZE(st->gpios));
 483 error_disable_reg:
 484         if (!IS_ERR_OR_NULL(st->reg))
 485                 regulator_disable(st->reg);
 486
 487         return ret;
 488 }
 489
 490 static int ad7266_remove(struct spi_device *spi)
 491 {
 492         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 493         struct ad7266_state *st = iio_priv(indio_dev);
 494
 495         iio_device_unregister(indio_dev);
 496         iio_triggered_buffer_cleanup(indio_dev);
 497         if (!st->fixed_addr)
 498                 gpio_free_array(st->gpios, ARRAY_SIZE(st->gpios));
 499         if (!IS_ERR_OR_NULL(st->reg))
 500                 regulator_disable(st->reg);
 501
 502         return 0;
 503 }
 504
 505 static const struct spi_device_id ad7266_id[] = {
 506         {"ad7265", 0},
 507         {"ad7266", 0},
 508         { }
 509 };
 510 MODULE_DEVICE_TABLE(spi, ad7266_id);
 511
 512 static struct spi_driver ad7266_driver = {
 513         .driver = {
 514                 .name   = "ad7266",
 515         },
 516         .probe          = ad7266_probe,
 517         .remove         = ad7266_remove,
 518         .id_table       = ad7266_id,
 519 };
 520 module_spi_driver(ad7266_driver);
 521
 522 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 523 MODULE_DESCRIPTION("Analog Devices AD7266/65 ADC");
 524 MODULE_LICENSE("GPL v2");