drivers/iio/dac/ad5421.c

   1 /*
   2  * AD5421 Digital to analog converters  driver
   3  *
   4  * Copyright 2011 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2.
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/delay.h>
  11 #include <linux/err.h>
  12 #include <linux/module.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/kernel.h>
  15 #include <linux/spi/spi.h>
  16 #include <linux/slab.h>
  17 #include <linux/sysfs.h>
  18
  19 #include <linux/iio/iio.h>
  20 #include <linux/iio/sysfs.h>
  21 #include <linux/iio/events.h>
  22 #include <linux/iio/dac/ad5421.h>
  23
  24
  25 #define AD5421_REG_DAC_DATA             0x1
  26 #define AD5421_REG_CTRL                 0x2
  27 #define AD5421_REG_OFFSET               0x3
  28 #define AD5421_REG_GAIN                 0x4
  29 /* load dac and fault shared the same register number. Writing to it will cause
  30  * a dac load command, reading from it will return the fault status register */
  31 #define AD5421_REG_LOAD_DAC             0x5
  32 #define AD5421_REG_FAULT                0x5
  33 #define AD5421_REG_FORCE_ALARM_CURRENT  0x6
  34 #define AD5421_REG_RESET                0x7
  35 #define AD5421_REG_START_CONVERSION     0x8
  36 #define AD5421_REG_NOOP                 0x9
  37
  38 #define AD5421_CTRL_WATCHDOG_DISABLE    BIT(12)
  39 #define AD5421_CTRL_AUTO_FAULT_READBACK BIT(11)
  40 #define AD5421_CTRL_MIN_CURRENT         BIT(9)
  41 #define AD5421_CTRL_ADC_SOURCE_TEMP     BIT(8)
  42 #define AD5421_CTRL_ADC_ENABLE          BIT(7)
  43 #define AD5421_CTRL_PWR_DOWN_INT_VREF   BIT(6)
  44
  45 #define AD5421_FAULT_SPI                        BIT(15)
  46 #define AD5421_FAULT_PEC                        BIT(14)
  47 #define AD5421_FAULT_OVER_CURRENT               BIT(13)
  48 #define AD5421_FAULT_UNDER_CURRENT              BIT(12)
  49 #define AD5421_FAULT_TEMP_OVER_140              BIT(11)
  50 #define AD5421_FAULT_TEMP_OVER_100              BIT(10)
  51 #define AD5421_FAULT_UNDER_VOLTAGE_6V           BIT(9)
  52 #define AD5421_FAULT_UNDER_VOLTAGE_12V          BIT(8)
  53
  54 /* These bits will cause the fault pin to go high */
  55 #define AD5421_FAULT_TRIGGER_IRQ \
  56         (AD5421_FAULT_SPI | AD5421_FAULT_PEC | AD5421_FAULT_OVER_CURRENT | \
  57         AD5421_FAULT_UNDER_CURRENT | AD5421_FAULT_TEMP_OVER_140)
  58
  59 /**
  60  * struct ad5421_state - driver instance specific data
  61  * @spi:                spi_device
  62  * @ctrl:               control register cache
  63  * @current_range:      current range which the device is configured for
  64  * @data:               spi transfer buffers
  65  * @fault_mask:         software masking of events
  66  */
  67 struct ad5421_state {
  68         struct spi_device               *spi;
  69         unsigned int                    ctrl;
  70         enum ad5421_current_range       current_range;
  71         unsigned int                    fault_mask;
  72
  73         /*
  74          * DMA (thus cache coherency maintenance) requires the
  75          * transfer buffers to live in their own cache lines.
  76          */
  77         union {
  78                 __be32 d32;
  79                 u8 d8[4];
  80         } data[2] ____cacheline_aligned;
  81 };
  82
  83 static const struct iio_event_spec ad5421_current_event[] = {
  84         {
  85                 .type = IIO_EV_TYPE_THRESH,
  86                 .dir = IIO_EV_DIR_RISING,
  87                 .mask_separate = BIT(IIO_EV_INFO_VALUE) |
  88                         BIT(IIO_EV_INFO_ENABLE),
  89         }, {
  90                 .type = IIO_EV_TYPE_THRESH,
  91                 .dir = IIO_EV_DIR_FALLING,
  92                 .mask_separate = BIT(IIO_EV_INFO_VALUE) |
  93                         BIT(IIO_EV_INFO_ENABLE),
  94         },
  95 };
  96
  97 static const struct iio_event_spec ad5421_temp_event[] = {
  98         {
  99                 .type = IIO_EV_TYPE_THRESH,
 100                 .dir = IIO_EV_DIR_RISING,
 101                 .mask_separate = BIT(IIO_EV_INFO_VALUE) |
 102                         BIT(IIO_EV_INFO_ENABLE),
 103         },
 104 };
 105
 106 static const struct iio_chan_spec ad5421_channels[] = {
 107         {
 108                 .type = IIO_CURRENT,
 109                 .indexed = 1,
 110                 .output = 1,
 111                 .channel = 0,
 112                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 113                         BIT(IIO_CHAN_INFO_CALIBSCALE) |
 114                         BIT(IIO_CHAN_INFO_CALIBBIAS),
 115                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
 116                         BIT(IIO_CHAN_INFO_OFFSET),
 117                 .scan_type = {
 118                         .sign = 'u',
 119                         .realbits = 16,
 120                         .storagebits = 16,
 121                 },
 122                 .event_spec = ad5421_current_event,
 123                 .num_event_specs = ARRAY_SIZE(ad5421_current_event),
 124         },
 125         {
 126                 .type = IIO_TEMP,
 127                 .channel = -1,
 128                 .event_spec = ad5421_temp_event,
 129                 .num_event_specs = ARRAY_SIZE(ad5421_temp_event),
 130         },
 131 };
 132
 133 static int ad5421_write_unlocked(struct iio_dev *indio_dev,
 134         unsigned int reg, unsigned int val)
 135 {
 136         struct ad5421_state *st = iio_priv(indio_dev);
 137
 138         st->data[0].d32 = cpu_to_be32((reg << 16) | val);
 139
 140         return spi_write(st->spi, &st->data[0].d8[1], 3);
 141 }
 142
 143 static int ad5421_write(struct iio_dev *indio_dev, unsigned int reg,
 144         unsigned int val)
 145 {
 146         int ret;
 147
 148         mutex_lock(&indio_dev->mlock);
 149         ret = ad5421_write_unlocked(indio_dev, reg, val);
 150         mutex_unlock(&indio_dev->mlock);
 151
 152         return ret;
 153 }
 154
 155 static int ad5421_read(struct iio_dev *indio_dev, unsigned int reg)
 156 {
 157         struct ad5421_state *st = iio_priv(indio_dev);
 158         int ret;
 159         struct spi_transfer t[] = {
 160                 {
 161                         .tx_buf = &st->data[0].d8[1],
 162                         .len = 3,
 163                         .cs_change = 1,
 164                 }, {
 165                         .rx_buf = &st->data[1].d8[1],
 166                         .len = 3,
 167                 },
 168         };
 169
 170         mutex_lock(&indio_dev->mlock);
 171
 172         st->data[0].d32 = cpu_to_be32((1 << 23) | (reg << 16));
 173
 174         ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
 175         if (ret >= 0)
 176                 ret = be32_to_cpu(st->data[1].d32) & 0xffff;
 177
 178         mutex_unlock(&indio_dev->mlock);
 179
 180         return ret;
 181 }
 182
 183 static int ad5421_update_ctrl(struct iio_dev *indio_dev, unsigned int set,
 184         unsigned int clr)
 185 {
 186         struct ad5421_state *st = iio_priv(indio_dev);
 187         unsigned int ret;
 188
 189         mutex_lock(&indio_dev->mlock);
 190
 191         st->ctrl &= ~clr;
 192         st->ctrl |= set;
 193
 194         ret = ad5421_write_unlocked(indio_dev, AD5421_REG_CTRL, st->ctrl);
 195
 196         mutex_unlock(&indio_dev->mlock);
 197
 198         return ret;
 199 }
 200
 201 static irqreturn_t ad5421_fault_handler(int irq, void *data)
 202 {
 203         struct iio_dev *indio_dev = data;
 204         struct ad5421_state *st = iio_priv(indio_dev);
 205         unsigned int fault;
 206         unsigned int old_fault = 0;
 207         unsigned int events;
 208
 209         fault = ad5421_read(indio_dev, AD5421_REG_FAULT);
 210         if (!fault)
 211                 return IRQ_NONE;
 212
 213         /* If we had a fault, this might mean that the DAC has lost its state
 214          * and has been reset. Make sure that the control register actually
 215          * contains what we expect it to contain. Otherwise the watchdog might
 216          * be enabled and we get watchdog timeout faults, which will render the
 217          * DAC unusable. */
 218         ad5421_update_ctrl(indio_dev, 0, 0);
 219
 220
 221         /* The fault pin stays high as long as a fault condition is present and
 222          * it is not possible to mask fault conditions. For certain fault
 223          * conditions for example like over-temperature it takes some time
 224          * until the fault condition disappears. If we would exit the interrupt
 225          * handler immediately after handling the event it would be entered
 226          * again instantly. Thus we fall back to polling in case we detect that
 227          * a interrupt condition is still present.
 228          */
 229         do {
 230                 /* 0xffff is a invalid value for the register and will only be
 231                  * read if there has been a communication error */
 232                 if (fault == 0xffff)
 233                         fault = 0;
 234
 235                 /* we are only interested in new events */
 236                 events = (old_fault ^ fault) & fault;
 237                 events &= st->fault_mask;
 238
 239                 if (events & AD5421_FAULT_OVER_CURRENT) {
 240                         iio_push_event(indio_dev,
 241                                 IIO_UNMOD_EVENT_CODE(IIO_CURRENT,
 242                                         0,
 243                                         IIO_EV_TYPE_THRESH,
 244                                         IIO_EV_DIR_RISING),
 245                         iio_get_time_ns(indio_dev));
 246                 }
 247
 248                 if (events & AD5421_FAULT_UNDER_CURRENT) {
 249                         iio_push_event(indio_dev,
 250                                 IIO_UNMOD_EVENT_CODE(IIO_CURRENT,
 251                                         0,
 252                                         IIO_EV_TYPE_THRESH,
 253                                         IIO_EV_DIR_FALLING),
 254                                 iio_get_time_ns(indio_dev));
 255                 }
 256
 257                 if (events & AD5421_FAULT_TEMP_OVER_140) {
 258                         iio_push_event(indio_dev,
 259                                 IIO_UNMOD_EVENT_CODE(IIO_TEMP,
 260                                         0,
 261                                         IIO_EV_TYPE_MAG,
 262                                         IIO_EV_DIR_RISING),
 263                                 iio_get_time_ns(indio_dev));
 264                 }
 265
 266                 old_fault = fault;
 267                 fault = ad5421_read(indio_dev, AD5421_REG_FAULT);
 268
 269                 /* still active? go to sleep for some time */
 270                 if (fault & AD5421_FAULT_TRIGGER_IRQ)
 271                         msleep(1000);
 272
 273         } while (fault & AD5421_FAULT_TRIGGER_IRQ);
 274
 275
 276         return IRQ_HANDLED;
 277 }
 278
 279 static void ad5421_get_current_min_max(struct ad5421_state *st,
 280         unsigned int *min, unsigned int *max)
 281 {
 282         /* The current range is configured using external pins, which are
 283          * usually hard-wired and not run-time switchable. */
 284         switch (st->current_range) {
 285         case AD5421_CURRENT_RANGE_4mA_20mA:
 286                 *min = 4000;
 287                 *max = 20000;
 288                 break;
 289         case AD5421_CURRENT_RANGE_3mA8_21mA:
 290                 *min = 3800;
 291                 *max = 21000;
 292                 break;
 293         case AD5421_CURRENT_RANGE_3mA2_24mA:
 294                 *min = 3200;
 295                 *max = 24000;
 296                 break;
 297         default:
 298                 *min = 0;
 299                 *max = 1;
 300                 break;
 301         }
 302 }
 303
 304 static inline unsigned int ad5421_get_offset(struct ad5421_state *st)
 305 {
 306         unsigned int min, max;
 307
 308         ad5421_get_current_min_max(st, &min, &max);
 309         return (min * (1 << 16)) / (max - min);
 310 }
 311
 312 static int ad5421_read_raw(struct iio_dev *indio_dev,
 313         struct iio_chan_spec const *chan, int *val, int *val2, long m)
 314 {
 315         struct ad5421_state *st = iio_priv(indio_dev);
 316         unsigned int min, max;
 317         int ret;
 318
 319         if (chan->type != IIO_CURRENT)
 320                 return -EINVAL;
 321
 322         switch (m) {
 323         case IIO_CHAN_INFO_RAW:
 324                 ret = ad5421_read(indio_dev, AD5421_REG_DAC_DATA);
 325                 if (ret < 0)
 326                         return ret;
 327                 *val = ret;
 328                 return IIO_VAL_INT;
 329         case IIO_CHAN_INFO_SCALE:
 330                 ad5421_get_current_min_max(st, &min, &max);
 331                 *val = max - min;
 332                 *val2 = (1 << 16) * 1000;
 333                 return IIO_VAL_FRACTIONAL;
 334         case IIO_CHAN_INFO_OFFSET:
 335                 *val = ad5421_get_offset(st);
 336                 return IIO_VAL_INT;
 337         case IIO_CHAN_INFO_CALIBBIAS:
 338                 ret = ad5421_read(indio_dev, AD5421_REG_OFFSET);
 339                 if (ret < 0)
 340                         return ret;
 341                 *val = ret - 32768;
 342                 return IIO_VAL_INT;
 343         case IIO_CHAN_INFO_CALIBSCALE:
 344                 ret = ad5421_read(indio_dev, AD5421_REG_GAIN);
 345                 if (ret < 0)
 346                         return ret;
 347                 *val = ret;
 348                 return IIO_VAL_INT;
 349         }
 350
 351         return -EINVAL;
 352 }
 353
 354 static int ad5421_write_raw(struct iio_dev *indio_dev,
 355         struct iio_chan_spec const *chan, int val, int val2, long mask)
 356 {
 357         const unsigned int max_val = 1 << 16;
 358
 359         switch (mask) {
 360         case IIO_CHAN_INFO_RAW:
 361                 if (val >= max_val || val < 0)
 362                         return -EINVAL;
 363
 364                 return ad5421_write(indio_dev, AD5421_REG_DAC_DATA, val);
 365         case IIO_CHAN_INFO_CALIBBIAS:
 366                 val += 32768;
 367                 if (val >= max_val || val < 0)
 368                         return -EINVAL;
 369
 370                 return ad5421_write(indio_dev, AD5421_REG_OFFSET, val);
 371         case IIO_CHAN_INFO_CALIBSCALE:
 372                 if (val >= max_val || val < 0)
 373                         return -EINVAL;
 374
 375                 return ad5421_write(indio_dev, AD5421_REG_GAIN, val);
 376         default:
 377                 break;
 378         }
 379
 380         return -EINVAL;
 381 }
 382
 383 static int ad5421_write_event_config(struct iio_dev *indio_dev,
 384         const struct iio_chan_spec *chan, enum iio_event_type type,
 385         enum iio_event_direction dir, int state)
 386 {
 387         struct ad5421_state *st = iio_priv(indio_dev);
 388         unsigned int mask;
 389
 390         switch (chan->type) {
 391         case IIO_CURRENT:
 392                 if (dir == IIO_EV_DIR_RISING)
 393                         mask = AD5421_FAULT_OVER_CURRENT;
 394                 else
 395                         mask = AD5421_FAULT_UNDER_CURRENT;
 396                 break;
 397         case IIO_TEMP:
 398                 mask = AD5421_FAULT_TEMP_OVER_140;
 399                 break;
 400         default:
 401                 return -EINVAL;
 402         }
 403
 404         mutex_lock(&indio_dev->mlock);
 405         if (state)
 406                 st->fault_mask |= mask;
 407         else
 408                 st->fault_mask &= ~mask;
 409         mutex_unlock(&indio_dev->mlock);
 410
 411         return 0;
 412 }
 413
 414 static int ad5421_read_event_config(struct iio_dev *indio_dev,
 415         const struct iio_chan_spec *chan, enum iio_event_type type,
 416         enum iio_event_direction dir)
 417 {
 418         struct ad5421_state *st = iio_priv(indio_dev);
 419         unsigned int mask;
 420
 421         switch (chan->type) {
 422         case IIO_CURRENT:
 423                 if (dir == IIO_EV_DIR_RISING)
 424                         mask = AD5421_FAULT_OVER_CURRENT;
 425                 else
 426                         mask = AD5421_FAULT_UNDER_CURRENT;
 427                 break;
 428         case IIO_TEMP:
 429                 mask = AD5421_FAULT_TEMP_OVER_140;
 430                 break;
 431         default:
 432                 return -EINVAL;
 433         }
 434
 435         return (bool)(st->fault_mask & mask);
 436 }
 437
 438 static int ad5421_read_event_value(struct iio_dev *indio_dev,
 439         const struct iio_chan_spec *chan, enum iio_event_type type,
 440         enum iio_event_direction dir, enum iio_event_info info, int *val,
 441         int *val2)
 442 {
 443         int ret;
 444
 445         switch (chan->type) {
 446         case IIO_CURRENT:
 447                 ret = ad5421_read(indio_dev, AD5421_REG_DAC_DATA);
 448                 if (ret < 0)
 449                         return ret;
 450                 *val = ret;
 451                 break;
 452         case IIO_TEMP:
 453                 *val = 140000;
 454                 break;
 455         default:
 456                 return -EINVAL;
 457         }
 458
 459         return IIO_VAL_INT;
 460 }
 461
 462 static const struct iio_info ad5421_info = {
 463         .read_raw =             ad5421_read_raw,
 464         .write_raw =            ad5421_write_raw,
 465         .read_event_config =    ad5421_read_event_config,
 466         .write_event_config =   ad5421_write_event_config,
 467         .read_event_value =     ad5421_read_event_value,
 468         .driver_module =        THIS_MODULE,
 469 };
 470
 471 static int ad5421_probe(struct spi_device *spi)
 472 {
 473         struct ad5421_platform_data *pdata = dev_get_platdata(&spi->dev);
 474         struct iio_dev *indio_dev;
 475         struct ad5421_state *st;
 476         int ret;
 477
 478         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 479         if (indio_dev == NULL) {
 480                 dev_err(&spi->dev, "Failed to allocate iio device\n");
 481                 return  -ENOMEM;
 482         }
 483
 484         st = iio_priv(indio_dev);
 485         spi_set_drvdata(spi, indio_dev);
 486
 487         st->spi = spi;
 488
 489         indio_dev->dev.parent = &spi->dev;
 490         indio_dev->name = "ad5421";
 491         indio_dev->info = &ad5421_info;
 492         indio_dev->modes = INDIO_DIRECT_MODE;
 493         indio_dev->channels = ad5421_channels;
 494         indio_dev->num_channels = ARRAY_SIZE(ad5421_channels);
 495
 496         st->ctrl = AD5421_CTRL_WATCHDOG_DISABLE |
 497                         AD5421_CTRL_AUTO_FAULT_READBACK;
 498
 499         if (pdata) {
 500                 st->current_range = pdata->current_range;
 501                 if (pdata->external_vref)
 502                         st->ctrl |= AD5421_CTRL_PWR_DOWN_INT_VREF;
 503         } else {
 504                 st->current_range = AD5421_CURRENT_RANGE_4mA_20mA;
 505         }
 506
 507         /* write initial ctrl register value */
 508         ad5421_update_ctrl(indio_dev, 0, 0);
 509
 510         if (spi->irq) {
 511                 ret = devm_request_threaded_irq(&spi->dev, spi->irq,
 512                                            NULL,
 513                                            ad5421_fault_handler,
 514                                            IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
 515                                            "ad5421 fault",
 516                                            indio_dev);
 517                 if (ret)
 518                         return ret;
 519         }
 520
 521         return devm_iio_device_register(&spi->dev, indio_dev);
 522 }
 523
 524 static struct spi_driver ad5421_driver = {
 525         .driver = {
 526                    .name = "ad5421",
 527         },
 528         .probe = ad5421_probe,
 529 };
 530 module_spi_driver(ad5421_driver);
 531
 532 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 533 MODULE_DESCRIPTION("Analog Devices AD5421 DAC");
 534 MODULE_LICENSE("GPL v2");
 535 MODULE_ALIAS("spi:ad5421");