root/drivers/iio/dac/ad5421.c

DEFINITIONS

1. ad5421_write_unlocked
2. ad5421_write
3. ad5421_read
4. ad5421_update_ctrl
5. ad5421_fault_handler
6. ad5421_get_current_min_max
7. ad5421_get_offset
8. ad5421_read_raw
9. ad5421_write_raw
10. ad5421_write_event_config
11. ad5421_read_event_config
12. ad5421_read_event_value
13. ad5421_probe

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * AD5421 Digital to analog converters  driver
   4  *
   5  * Copyright 2011 Analog Devices Inc.
   6  */
   7 
   8 #include <linux/device.h>
   9 #include <linux/delay.h>
  10 #include <linux/err.h>
  11 #include <linux/module.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/kernel.h>
  14 #include <linux/spi/spi.h>
  15 #include <linux/slab.h>
  16 #include <linux/sysfs.h>
  17 
  18 #include <linux/iio/iio.h>
  19 #include <linux/iio/sysfs.h>
  20 #include <linux/iio/events.h>
  21 #include <linux/iio/dac/ad5421.h>
  22 
  23 
  24 #define AD5421_REG_DAC_DATA             0x1
  25 #define AD5421_REG_CTRL                 0x2
  26 #define AD5421_REG_OFFSET               0x3
  27 #define AD5421_REG_GAIN                 0x4
  28 /* load dac and fault shared the same register number. Writing to it will cause
  29  * a dac load command, reading from it will return the fault status register */
  30 #define AD5421_REG_LOAD_DAC             0x5
  31 #define AD5421_REG_FAULT                0x5
  32 #define AD5421_REG_FORCE_ALARM_CURRENT  0x6
  33 #define AD5421_REG_RESET                0x7
  34 #define AD5421_REG_START_CONVERSION     0x8
  35 #define AD5421_REG_NOOP                 0x9
  36 
  37 #define AD5421_CTRL_WATCHDOG_DISABLE    BIT(12)
  38 #define AD5421_CTRL_AUTO_FAULT_READBACK BIT(11)
  39 #define AD5421_CTRL_MIN_CURRENT         BIT(9)
  40 #define AD5421_CTRL_ADC_SOURCE_TEMP     BIT(8)
  41 #define AD5421_CTRL_ADC_ENABLE          BIT(7)
  42 #define AD5421_CTRL_PWR_DOWN_INT_VREF   BIT(6)
  43 
  44 #define AD5421_FAULT_SPI                        BIT(15)
  45 #define AD5421_FAULT_PEC                        BIT(14)
  46 #define AD5421_FAULT_OVER_CURRENT               BIT(13)
  47 #define AD5421_FAULT_UNDER_CURRENT              BIT(12)
  48 #define AD5421_FAULT_TEMP_OVER_140              BIT(11)
  49 #define AD5421_FAULT_TEMP_OVER_100              BIT(10)
  50 #define AD5421_FAULT_UNDER_VOLTAGE_6V           BIT(9)
  51 #define AD5421_FAULT_UNDER_VOLTAGE_12V          BIT(8)
  52 
  53 /* These bits will cause the fault pin to go high */
  54 #define AD5421_FAULT_TRIGGER_IRQ \
  55         (AD5421_FAULT_SPI | AD5421_FAULT_PEC | AD5421_FAULT_OVER_CURRENT | \
  56         AD5421_FAULT_UNDER_CURRENT | AD5421_FAULT_TEMP_OVER_140)
  57 
  58 /**
  59  * struct ad5421_state - driver instance specific data
  60  * @spi:                spi_device
  61  * @ctrl:               control register cache
  62  * @current_range:      current range which the device is configured for
  63  * @data:               spi transfer buffers
  64  * @fault_mask:         software masking of events
  65  */
  66 struct ad5421_state {
  67         struct spi_device               *spi;
  68         unsigned int                    ctrl;
  69         enum ad5421_current_range       current_range;
  70         unsigned int                    fault_mask;
  71 
  72         /*
  73          * DMA (thus cache coherency maintenance) requires the
  74          * transfer buffers to live in their own cache lines.
  75          */
  76         union {
  77                 __be32 d32;
  78                 u8 d8[4];
  79         } data[2] ____cacheline_aligned;
  80 };
  81 
  82 static const struct iio_event_spec ad5421_current_event[] = {
  83         {
  84                 .type = IIO_EV_TYPE_THRESH,
  85                 .dir = IIO_EV_DIR_RISING,
  86                 .mask_separate = BIT(IIO_EV_INFO_VALUE) |
  87                         BIT(IIO_EV_INFO_ENABLE),
  88         }, {
  89                 .type = IIO_EV_TYPE_THRESH,
  90                 .dir = IIO_EV_DIR_FALLING,
  91                 .mask_separate = BIT(IIO_EV_INFO_VALUE) |
  92                         BIT(IIO_EV_INFO_ENABLE),
  93         },
  94 };
  95 
  96 static const struct iio_event_spec ad5421_temp_event[] = {
  97         {
  98                 .type = IIO_EV_TYPE_THRESH,
  99                 .dir = IIO_EV_DIR_RISING,
 100                 .mask_separate = BIT(IIO_EV_INFO_VALUE) |
 101                         BIT(IIO_EV_INFO_ENABLE),
 102         },
 103 };
 104 
 105 static const struct iio_chan_spec ad5421_channels[] = {
 106         {
 107                 .type = IIO_CURRENT,
 108                 .indexed = 1,
 109                 .output = 1,
 110                 .channel = 0,
 111                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 112                         BIT(IIO_CHAN_INFO_CALIBSCALE) |
 113                         BIT(IIO_CHAN_INFO_CALIBBIAS),
 114                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
 115                         BIT(IIO_CHAN_INFO_OFFSET),
 116                 .scan_type = {
 117                         .sign = 'u',
 118                         .realbits = 16,
 119                         .storagebits = 16,
 120                 },
 121                 .event_spec = ad5421_current_event,
 122                 .num_event_specs = ARRAY_SIZE(ad5421_current_event),
 123         },
 124         {
 125                 .type = IIO_TEMP,
 126                 .channel = -1,
 127                 .event_spec = ad5421_temp_event,
 128                 .num_event_specs = ARRAY_SIZE(ad5421_temp_event),
 129         },
 130 };
 131 
 132 static int ad5421_write_unlocked(struct iio_dev *indio_dev,
 133         unsigned int reg, unsigned int val)
 134 {
 135         struct ad5421_state *st = iio_priv(indio_dev);
 136 
 137         st->data[0].d32 = cpu_to_be32((reg << 16) | val);
 138 
 139         return spi_write(st->spi, &st->data[0].d8[1], 3);
 140 }
 141 
 142 static int ad5421_write(struct iio_dev *indio_dev, unsigned int reg,
 143         unsigned int val)
 144 {
 145         int ret;
 146 
 147         mutex_lock(&indio_dev->mlock);
 148         ret = ad5421_write_unlocked(indio_dev, reg, val);
 149         mutex_unlock(&indio_dev->mlock);
 150 
 151         return ret;
 152 }
 153 
 154 static int ad5421_read(struct iio_dev *indio_dev, unsigned int reg)
 155 {
 156         struct ad5421_state *st = iio_priv(indio_dev);
 157         int ret;
 158         struct spi_transfer t[] = {
 159                 {
 160                         .tx_buf = &st->data[0].d8[1],
 161                         .len = 3,
 162                         .cs_change = 1,
 163                 }, {
 164                         .rx_buf = &st->data[1].d8[1],
 165                         .len = 3,
 166                 },
 167         };
 168 
 169         mutex_lock(&indio_dev->mlock);
 170 
 171         st->data[0].d32 = cpu_to_be32((1 << 23) | (reg << 16));
 172 
 173         ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
 174         if (ret >= 0)
 175                 ret = be32_to_cpu(st->data[1].d32) & 0xffff;
 176 
 177         mutex_unlock(&indio_dev->mlock);
 178 
 179         return ret;
 180 }
 181 
 182 static int ad5421_update_ctrl(struct iio_dev *indio_dev, unsigned int set,
 183         unsigned int clr)
 184 {
 185         struct ad5421_state *st = iio_priv(indio_dev);
 186         unsigned int ret;
 187 
 188         mutex_lock(&indio_dev->mlock);
 189 
 190         st->ctrl &= ~clr;
 191         st->ctrl |= set;
 192 
 193         ret = ad5421_write_unlocked(indio_dev, AD5421_REG_CTRL, st->ctrl);
 194 
 195         mutex_unlock(&indio_dev->mlock);
 196 
 197         return ret;
 198 }
 199 
 200 static irqreturn_t ad5421_fault_handler(int irq, void *data)
 201 {
 202         struct iio_dev *indio_dev = data;
 203         struct ad5421_state *st = iio_priv(indio_dev);
 204         unsigned int fault;
 205         unsigned int old_fault = 0;
 206         unsigned int events;
 207 
 208         fault = ad5421_read(indio_dev, AD5421_REG_FAULT);
 209         if (!fault)
 210                 return IRQ_NONE;
 211 
 212         /* If we had a fault, this might mean that the DAC has lost its state
 213          * and has been reset. Make sure that the control register actually
 214          * contains what we expect it to contain. Otherwise the watchdog might
 215          * be enabled and we get watchdog timeout faults, which will render the
 216          * DAC unusable. */
 217         ad5421_update_ctrl(indio_dev, 0, 0);
 218 
 219 
 220         /* The fault pin stays high as long as a fault condition is present and
 221          * it is not possible to mask fault conditions. For certain fault
 222          * conditions for example like over-temperature it takes some time
 223          * until the fault condition disappears. If we would exit the interrupt
 224          * handler immediately after handling the event it would be entered
 225          * again instantly. Thus we fall back to polling in case we detect that
 226          * a interrupt condition is still present.
 227          */
 228         do {
 229                 /* 0xffff is a invalid value for the register and will only be
 230                  * read if there has been a communication error */
 231                 if (fault == 0xffff)
 232                         fault = 0;
 233 
 234                 /* we are only interested in new events */
 235                 events = (old_fault ^ fault) & fault;
 236                 events &= st->fault_mask;
 237 
 238                 if (events & AD5421_FAULT_OVER_CURRENT) {
 239                         iio_push_event(indio_dev,
 240                                 IIO_UNMOD_EVENT_CODE(IIO_CURRENT,
 241                                         0,
 242                                         IIO_EV_TYPE_THRESH,
 243                                         IIO_EV_DIR_RISING),
 244                         iio_get_time_ns(indio_dev));
 245                 }
 246 
 247                 if (events & AD5421_FAULT_UNDER_CURRENT) {
 248                         iio_push_event(indio_dev,
 249                                 IIO_UNMOD_EVENT_CODE(IIO_CURRENT,
 250                                         0,
 251                                         IIO_EV_TYPE_THRESH,
 252                                         IIO_EV_DIR_FALLING),
 253                                 iio_get_time_ns(indio_dev));
 254                 }
 255 
 256                 if (events & AD5421_FAULT_TEMP_OVER_140) {
 257                         iio_push_event(indio_dev,
 258                                 IIO_UNMOD_EVENT_CODE(IIO_TEMP,
 259                                         0,
 260                                         IIO_EV_TYPE_MAG,
 261                                         IIO_EV_DIR_RISING),
 262                                 iio_get_time_ns(indio_dev));
 263                 }
 264 
 265                 old_fault = fault;
 266                 fault = ad5421_read(indio_dev, AD5421_REG_FAULT);
 267 
 268                 /* still active? go to sleep for some time */
 269                 if (fault & AD5421_FAULT_TRIGGER_IRQ)
 270                         msleep(1000);
 271 
 272         } while (fault & AD5421_FAULT_TRIGGER_IRQ);
 273 
 274 
 275         return IRQ_HANDLED;
 276 }
 277 
 278 static void ad5421_get_current_min_max(struct ad5421_state *st,
 279         unsigned int *min, unsigned int *max)
 280 {
 281         /* The current range is configured using external pins, which are
 282          * usually hard-wired and not run-time switchable. */
 283         switch (st->current_range) {
 284         case AD5421_CURRENT_RANGE_4mA_20mA:
 285                 *min = 4000;
 286                 *max = 20000;
 287                 break;
 288         case AD5421_CURRENT_RANGE_3mA8_21mA:
 289                 *min = 3800;
 290                 *max = 21000;
 291                 break;
 292         case AD5421_CURRENT_RANGE_3mA2_24mA:
 293                 *min = 3200;
 294                 *max = 24000;
 295                 break;
 296         default:
 297                 *min = 0;
 298                 *max = 1;
 299                 break;
 300         }
 301 }
 302 
 303 static inline unsigned int ad5421_get_offset(struct ad5421_state *st)
 304 {
 305         unsigned int min, max;
 306 
 307         ad5421_get_current_min_max(st, &min, &max);
 308         return (min * (1 << 16)) / (max - min);
 309 }
 310 
 311 static int ad5421_read_raw(struct iio_dev *indio_dev,
 312         struct iio_chan_spec const *chan, int *val, int *val2, long m)
 313 {
 314         struct ad5421_state *st = iio_priv(indio_dev);
 315         unsigned int min, max;
 316         int ret;
 317 
 318         if (chan->type != IIO_CURRENT)
 319                 return -EINVAL;
 320 
 321         switch (m) {
 322         case IIO_CHAN_INFO_RAW:
 323                 ret = ad5421_read(indio_dev, AD5421_REG_DAC_DATA);
 324                 if (ret < 0)
 325                         return ret;
 326                 *val = ret;
 327                 return IIO_VAL_INT;
 328         case IIO_CHAN_INFO_SCALE:
 329                 ad5421_get_current_min_max(st, &min, &max);
 330                 *val = max - min;
 331                 *val2 = (1 << 16) * 1000;
 332                 return IIO_VAL_FRACTIONAL;
 333         case IIO_CHAN_INFO_OFFSET:
 334                 *val = ad5421_get_offset(st);
 335                 return IIO_VAL_INT;
 336         case IIO_CHAN_INFO_CALIBBIAS:
 337                 ret = ad5421_read(indio_dev, AD5421_REG_OFFSET);
 338                 if (ret < 0)
 339                         return ret;
 340                 *val = ret - 32768;
 341                 return IIO_VAL_INT;
 342         case IIO_CHAN_INFO_CALIBSCALE:
 343                 ret = ad5421_read(indio_dev, AD5421_REG_GAIN);
 344                 if (ret < 0)
 345                         return ret;
 346                 *val = ret;
 347                 return IIO_VAL_INT;
 348         }
 349 
 350         return -EINVAL;
 351 }
 352 
 353 static int ad5421_write_raw(struct iio_dev *indio_dev,
 354         struct iio_chan_spec const *chan, int val, int val2, long mask)
 355 {
 356         const unsigned int max_val = 1 << 16;
 357 
 358         switch (mask) {
 359         case IIO_CHAN_INFO_RAW:
 360                 if (val >= max_val || val < 0)
 361                         return -EINVAL;
 362 
 363                 return ad5421_write(indio_dev, AD5421_REG_DAC_DATA, val);
 364         case IIO_CHAN_INFO_CALIBBIAS:
 365                 val += 32768;
 366                 if (val >= max_val || val < 0)
 367                         return -EINVAL;
 368 
 369                 return ad5421_write(indio_dev, AD5421_REG_OFFSET, val);
 370         case IIO_CHAN_INFO_CALIBSCALE:
 371                 if (val >= max_val || val < 0)
 372                         return -EINVAL;
 373 
 374                 return ad5421_write(indio_dev, AD5421_REG_GAIN, val);
 375         default:
 376                 break;
 377         }
 378 
 379         return -EINVAL;
 380 }
 381 
 382 static int ad5421_write_event_config(struct iio_dev *indio_dev,
 383         const struct iio_chan_spec *chan, enum iio_event_type type,
 384         enum iio_event_direction dir, int state)
 385 {
 386         struct ad5421_state *st = iio_priv(indio_dev);
 387         unsigned int mask;
 388 
 389         switch (chan->type) {
 390         case IIO_CURRENT:
 391                 if (dir == IIO_EV_DIR_RISING)
 392                         mask = AD5421_FAULT_OVER_CURRENT;
 393                 else
 394                         mask = AD5421_FAULT_UNDER_CURRENT;
 395                 break;
 396         case IIO_TEMP:
 397                 mask = AD5421_FAULT_TEMP_OVER_140;
 398                 break;
 399         default:
 400                 return -EINVAL;
 401         }
 402 
 403         mutex_lock(&indio_dev->mlock);
 404         if (state)
 405                 st->fault_mask |= mask;
 406         else
 407                 st->fault_mask &= ~mask;
 408         mutex_unlock(&indio_dev->mlock);
 409 
 410         return 0;
 411 }
 412 
 413 static int ad5421_read_event_config(struct iio_dev *indio_dev,
 414         const struct iio_chan_spec *chan, enum iio_event_type type,
 415         enum iio_event_direction dir)
 416 {
 417         struct ad5421_state *st = iio_priv(indio_dev);
 418         unsigned int mask;
 419 
 420         switch (chan->type) {
 421         case IIO_CURRENT:
 422                 if (dir == IIO_EV_DIR_RISING)
 423                         mask = AD5421_FAULT_OVER_CURRENT;
 424                 else
 425                         mask = AD5421_FAULT_UNDER_CURRENT;
 426                 break;
 427         case IIO_TEMP:
 428                 mask = AD5421_FAULT_TEMP_OVER_140;
 429                 break;
 430         default:
 431                 return -EINVAL;
 432         }
 433 
 434         return (bool)(st->fault_mask & mask);
 435 }
 436 
 437 static int ad5421_read_event_value(struct iio_dev *indio_dev,
 438         const struct iio_chan_spec *chan, enum iio_event_type type,
 439         enum iio_event_direction dir, enum iio_event_info info, int *val,
 440         int *val2)
 441 {
 442         int ret;
 443 
 444         switch (chan->type) {
 445         case IIO_CURRENT:
 446                 ret = ad5421_read(indio_dev, AD5421_REG_DAC_DATA);
 447                 if (ret < 0)
 448                         return ret;
 449                 *val = ret;
 450                 break;
 451         case IIO_TEMP:
 452                 *val = 140000;
 453                 break;
 454         default:
 455                 return -EINVAL;
 456         }
 457 
 458         return IIO_VAL_INT;
 459 }
 460 
 461 static const struct iio_info ad5421_info = {
 462         .read_raw =             ad5421_read_raw,
 463         .write_raw =            ad5421_write_raw,
 464         .read_event_config =    ad5421_read_event_config,
 465         .write_event_config =   ad5421_write_event_config,
 466         .read_event_value =     ad5421_read_event_value,
 467 };
 468 
 469 static int ad5421_probe(struct spi_device *spi)
 470 {
 471         struct ad5421_platform_data *pdata = dev_get_platdata(&spi->dev);
 472         struct iio_dev *indio_dev;
 473         struct ad5421_state *st;
 474         int ret;
 475 
 476         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 477         if (indio_dev == NULL) {
 478                 dev_err(&spi->dev, "Failed to allocate iio device\n");
 479                 return  -ENOMEM;
 480         }
 481 
 482         st = iio_priv(indio_dev);
 483         spi_set_drvdata(spi, indio_dev);
 484 
 485         st->spi = spi;
 486 
 487         indio_dev->dev.parent = &spi->dev;
 488         indio_dev->name = "ad5421";
 489         indio_dev->info = &ad5421_info;
 490         indio_dev->modes = INDIO_DIRECT_MODE;
 491         indio_dev->channels = ad5421_channels;
 492         indio_dev->num_channels = ARRAY_SIZE(ad5421_channels);
 493 
 494         st->ctrl = AD5421_CTRL_WATCHDOG_DISABLE |
 495                         AD5421_CTRL_AUTO_FAULT_READBACK;
 496 
 497         if (pdata) {
 498                 st->current_range = pdata->current_range;
 499                 if (pdata->external_vref)
 500                         st->ctrl |= AD5421_CTRL_PWR_DOWN_INT_VREF;
 501         } else {
 502                 st->current_range = AD5421_CURRENT_RANGE_4mA_20mA;
 503         }
 504 
 505         /* write initial ctrl register value */
 506         ad5421_update_ctrl(indio_dev, 0, 0);
 507 
 508         if (spi->irq) {
 509                 ret = devm_request_threaded_irq(&spi->dev, spi->irq,
 510                                            NULL,
 511                                            ad5421_fault_handler,
 512                                            IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
 513                                            "ad5421 fault",
 514                                            indio_dev);
 515                 if (ret)
 516                         return ret;
 517         }
 518 
 519         return devm_iio_device_register(&spi->dev, indio_dev);
 520 }
 521 
 522 static struct spi_driver ad5421_driver = {
 523         .driver = {
 524                    .name = "ad5421",
 525         },
 526         .probe = ad5421_probe,
 527 };
 528 module_spi_driver(ad5421_driver);
 529 
 530 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 531 MODULE_DESCRIPTION("Analog Devices AD5421 DAC");
 532 MODULE_LICENSE("GPL v2");
 533 MODULE_ALIAS("spi:ad5421");