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 * @lock lock to protect the data buffer during SPI ops 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 struct mutex lock; 73 74 /* 75 * DMA (thus cache coherency maintenance) requires the 76 * transfer buffers to live in their own cache lines. 77 */ 78 union { 79 __be32 d32; 80 u8 d8[4]; 81 } data[2] ____cacheline_aligned; 82 }; 83 84 static const struct iio_event_spec ad5421_current_event[] = { 85 { 86 .type = IIO_EV_TYPE_THRESH, 87 .dir = IIO_EV_DIR_RISING, 88 .mask_separate = BIT(IIO_EV_INFO_VALUE) | 89 BIT(IIO_EV_INFO_ENABLE), 90 }, { 91 .type = IIO_EV_TYPE_THRESH, 92 .dir = IIO_EV_DIR_FALLING, 93 .mask_separate = BIT(IIO_EV_INFO_VALUE) | 94 BIT(IIO_EV_INFO_ENABLE), 95 }, 96 }; 97 98 static const struct iio_event_spec ad5421_temp_event[] = { 99 { 100 .type = IIO_EV_TYPE_THRESH, 101 .dir = IIO_EV_DIR_RISING, 102 .mask_separate = BIT(IIO_EV_INFO_VALUE) | 103 BIT(IIO_EV_INFO_ENABLE), 104 }, 105 }; 106 107 static const struct iio_chan_spec ad5421_channels[] = { 108 { 109 .type = IIO_CURRENT, 110 .indexed = 1, 111 .output = 1, 112 .channel = 0, 113 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | 114 BIT(IIO_CHAN_INFO_CALIBSCALE) | 115 BIT(IIO_CHAN_INFO_CALIBBIAS), 116 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | 117 BIT(IIO_CHAN_INFO_OFFSET), 118 .scan_type = { 119 .sign = 'u', 120 .realbits = 16, 121 .storagebits = 16, 122 }, 123 .event_spec = ad5421_current_event, 124 .num_event_specs = ARRAY_SIZE(ad5421_current_event), 125 }, 126 { 127 .type = IIO_TEMP, 128 .channel = -1, 129 .event_spec = ad5421_temp_event, 130 .num_event_specs = ARRAY_SIZE(ad5421_temp_event), 131 }, 132 }; 133 134 static int ad5421_write_unlocked(struct iio_dev *indio_dev, 135 unsigned int reg, unsigned int val) 136 { 137 struct ad5421_state *st = iio_priv(indio_dev); 138 139 st->data[0].d32 = cpu_to_be32((reg << 16) | val); 140 141 return spi_write(st->spi, &st->data[0].d8[1], 3); 142 } 143 144 static int ad5421_write(struct iio_dev *indio_dev, unsigned int reg, 145 unsigned int val) 146 { 147 struct ad5421_state *st = iio_priv(indio_dev); 148 int ret; 149 150 mutex_lock(&st->lock); 151 ret = ad5421_write_unlocked(indio_dev, reg, val); 152 mutex_unlock(&st->lock); 153 154 return ret; 155 } 156 157 static int ad5421_read(struct iio_dev *indio_dev, unsigned int reg) 158 { 159 struct ad5421_state *st = iio_priv(indio_dev); 160 int ret; 161 struct spi_transfer t[] = { 162 { 163 .tx_buf = &st->data[0].d8[1], 164 .len = 3, 165 .cs_change = 1, 166 }, { 167 .rx_buf = &st->data[1].d8[1], 168 .len = 3, 169 }, 170 }; 171 172 mutex_lock(&st->lock); 173 174 st->data[0].d32 = cpu_to_be32((1 << 23) | (reg << 16)); 175 176 ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t)); 177 if (ret >= 0) 178 ret = be32_to_cpu(st->data[1].d32) & 0xffff; 179 180 mutex_unlock(&st->lock); 181 182 return ret; 183 } 184 185 static int ad5421_update_ctrl(struct iio_dev *indio_dev, unsigned int set, 186 unsigned int clr) 187 { 188 struct ad5421_state *st = iio_priv(indio_dev); 189 unsigned int ret; 190 191 mutex_lock(&st->lock); 192 193 st->ctrl &= ~clr; 194 st->ctrl |= set; 195 196 ret = ad5421_write_unlocked(indio_dev, AD5421_REG_CTRL, st->ctrl); 197 198 mutex_unlock(&st->lock); 199 200 return ret; 201 } 202 203 static irqreturn_t ad5421_fault_handler(int irq, void *data) 204 { 205 struct iio_dev *indio_dev = data; 206 struct ad5421_state *st = iio_priv(indio_dev); 207 unsigned int fault; 208 unsigned int old_fault = 0; 209 unsigned int events; 210 211 fault = ad5421_read(indio_dev, AD5421_REG_FAULT); 212 if (!fault) 213 return IRQ_NONE; 214 215 /* If we had a fault, this might mean that the DAC has lost its state 216 * and has been reset. Make sure that the control register actually 217 * contains what we expect it to contain. Otherwise the watchdog might 218 * be enabled and we get watchdog timeout faults, which will render the 219 * DAC unusable. */ 220 ad5421_update_ctrl(indio_dev, 0, 0); 221 222 223 /* The fault pin stays high as long as a fault condition is present and 224 * it is not possible to mask fault conditions. For certain fault 225 * conditions for example like over-temperature it takes some time 226 * until the fault condition disappears. If we would exit the interrupt 227 * handler immediately after handling the event it would be entered 228 * again instantly. Thus we fall back to polling in case we detect that 229 * a interrupt condition is still present. 230 */ 231 do { 232 /* 0xffff is a invalid value for the register and will only be 233 * read if there has been a communication error */ 234 if (fault == 0xffff) 235 fault = 0; 236 237 /* we are only interested in new events */ 238 events = (old_fault ^ fault) & fault; 239 events &= st->fault_mask; 240 241 if (events & AD5421_FAULT_OVER_CURRENT) { 242 iio_push_event(indio_dev, 243 IIO_UNMOD_EVENT_CODE(IIO_CURRENT, 244 0, 245 IIO_EV_TYPE_THRESH, 246 IIO_EV_DIR_RISING), 247 iio_get_time_ns(indio_dev)); 248 } 249 250 if (events & AD5421_FAULT_UNDER_CURRENT) { 251 iio_push_event(indio_dev, 252 IIO_UNMOD_EVENT_CODE(IIO_CURRENT, 253 0, 254 IIO_EV_TYPE_THRESH, 255 IIO_EV_DIR_FALLING), 256 iio_get_time_ns(indio_dev)); 257 } 258 259 if (events & AD5421_FAULT_TEMP_OVER_140) { 260 iio_push_event(indio_dev, 261 IIO_UNMOD_EVENT_CODE(IIO_TEMP, 262 0, 263 IIO_EV_TYPE_MAG, 264 IIO_EV_DIR_RISING), 265 iio_get_time_ns(indio_dev)); 266 } 267 268 old_fault = fault; 269 fault = ad5421_read(indio_dev, AD5421_REG_FAULT); 270 271 /* still active? go to sleep for some time */ 272 if (fault & AD5421_FAULT_TRIGGER_IRQ) 273 msleep(1000); 274 275 } while (fault & AD5421_FAULT_TRIGGER_IRQ); 276 277 278 return IRQ_HANDLED; 279 } 280 281 static void ad5421_get_current_min_max(struct ad5421_state *st, 282 unsigned int *min, unsigned int *max) 283 { 284 /* The current range is configured using external pins, which are 285 * usually hard-wired and not run-time switchable. */ 286 switch (st->current_range) { 287 case AD5421_CURRENT_RANGE_4mA_20mA: 288 *min = 4000; 289 *max = 20000; 290 break; 291 case AD5421_CURRENT_RANGE_3mA8_21mA: 292 *min = 3800; 293 *max = 21000; 294 break; 295 case AD5421_CURRENT_RANGE_3mA2_24mA: 296 *min = 3200; 297 *max = 24000; 298 break; 299 default: 300 *min = 0; 301 *max = 1; 302 break; 303 } 304 } 305 306 static inline unsigned int ad5421_get_offset(struct ad5421_state *st) 307 { 308 unsigned int min, max; 309 310 ad5421_get_current_min_max(st, &min, &max); 311 return (min * (1 << 16)) / (max - min); 312 } 313 314 static int ad5421_read_raw(struct iio_dev *indio_dev, 315 struct iio_chan_spec const *chan, int *val, int *val2, long m) 316 { 317 struct ad5421_state *st = iio_priv(indio_dev); 318 unsigned int min, max; 319 int ret; 320 321 if (chan->type != IIO_CURRENT) 322 return -EINVAL; 323 324 switch (m) { 325 case IIO_CHAN_INFO_RAW: 326 ret = ad5421_read(indio_dev, AD5421_REG_DAC_DATA); 327 if (ret < 0) 328 return ret; 329 *val = ret; 330 return IIO_VAL_INT; 331 case IIO_CHAN_INFO_SCALE: 332 ad5421_get_current_min_max(st, &min, &max); 333 *val = max - min; 334 *val2 = (1 << 16) * 1000; 335 return IIO_VAL_FRACTIONAL; 336 case IIO_CHAN_INFO_OFFSET: 337 *val = ad5421_get_offset(st); 338 return IIO_VAL_INT; 339 case IIO_CHAN_INFO_CALIBBIAS: 340 ret = ad5421_read(indio_dev, AD5421_REG_OFFSET); 341 if (ret < 0) 342 return ret; 343 *val = ret - 32768; 344 return IIO_VAL_INT; 345 case IIO_CHAN_INFO_CALIBSCALE: 346 ret = ad5421_read(indio_dev, AD5421_REG_GAIN); 347 if (ret < 0) 348 return ret; 349 *val = ret; 350 return IIO_VAL_INT; 351 } 352 353 return -EINVAL; 354 } 355 356 static int ad5421_write_raw(struct iio_dev *indio_dev, 357 struct iio_chan_spec const *chan, int val, int val2, long mask) 358 { 359 const unsigned int max_val = 1 << 16; 360 361 switch (mask) { 362 case IIO_CHAN_INFO_RAW: 363 if (val >= max_val || val < 0) 364 return -EINVAL; 365 366 return ad5421_write(indio_dev, AD5421_REG_DAC_DATA, val); 367 case IIO_CHAN_INFO_CALIBBIAS: 368 val += 32768; 369 if (val >= max_val || val < 0) 370 return -EINVAL; 371 372 return ad5421_write(indio_dev, AD5421_REG_OFFSET, val); 373 case IIO_CHAN_INFO_CALIBSCALE: 374 if (val >= max_val || val < 0) 375 return -EINVAL; 376 377 return ad5421_write(indio_dev, AD5421_REG_GAIN, val); 378 default: 379 break; 380 } 381 382 return -EINVAL; 383 } 384 385 static int ad5421_write_event_config(struct iio_dev *indio_dev, 386 const struct iio_chan_spec *chan, enum iio_event_type type, 387 enum iio_event_direction dir, int state) 388 { 389 struct ad5421_state *st = iio_priv(indio_dev); 390 unsigned int mask; 391 392 switch (chan->type) { 393 case IIO_CURRENT: 394 if (dir == IIO_EV_DIR_RISING) 395 mask = AD5421_FAULT_OVER_CURRENT; 396 else 397 mask = AD5421_FAULT_UNDER_CURRENT; 398 break; 399 case IIO_TEMP: 400 mask = AD5421_FAULT_TEMP_OVER_140; 401 break; 402 default: 403 return -EINVAL; 404 } 405 406 mutex_lock(&st->lock); 407 if (state) 408 st->fault_mask |= mask; 409 else 410 st->fault_mask &= ~mask; 411 mutex_unlock(&st->lock); 412 413 return 0; 414 } 415 416 static int ad5421_read_event_config(struct iio_dev *indio_dev, 417 const struct iio_chan_spec *chan, enum iio_event_type type, 418 enum iio_event_direction dir) 419 { 420 struct ad5421_state *st = iio_priv(indio_dev); 421 unsigned int mask; 422 423 switch (chan->type) { 424 case IIO_CURRENT: 425 if (dir == IIO_EV_DIR_RISING) 426 mask = AD5421_FAULT_OVER_CURRENT; 427 else 428 mask = AD5421_FAULT_UNDER_CURRENT; 429 break; 430 case IIO_TEMP: 431 mask = AD5421_FAULT_TEMP_OVER_140; 432 break; 433 default: 434 return -EINVAL; 435 } 436 437 return (bool)(st->fault_mask & mask); 438 } 439 440 static int ad5421_read_event_value(struct iio_dev *indio_dev, 441 const struct iio_chan_spec *chan, enum iio_event_type type, 442 enum iio_event_direction dir, enum iio_event_info info, int *val, 443 int *val2) 444 { 445 int ret; 446 447 switch (chan->type) { 448 case IIO_CURRENT: 449 ret = ad5421_read(indio_dev, AD5421_REG_DAC_DATA); 450 if (ret < 0) 451 return ret; 452 *val = ret; 453 break; 454 case IIO_TEMP: 455 *val = 140000; 456 break; 457 default: 458 return -EINVAL; 459 } 460 461 return IIO_VAL_INT; 462 } 463 464 static const struct iio_info ad5421_info = { 465 .read_raw = ad5421_read_raw, 466 .write_raw = ad5421_write_raw, 467 .read_event_config = ad5421_read_event_config, 468 .write_event_config = ad5421_write_event_config, 469 .read_event_value = ad5421_read_event_value, 470 }; 471 472 static int ad5421_probe(struct spi_device *spi) 473 { 474 struct ad5421_platform_data *pdata = dev_get_platdata(&spi->dev); 475 struct iio_dev *indio_dev; 476 struct ad5421_state *st; 477 int ret; 478 479 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st)); 480 if (indio_dev == NULL) { 481 dev_err(&spi->dev, "Failed to allocate iio device\n"); 482 return -ENOMEM; 483 } 484 485 st = iio_priv(indio_dev); 486 spi_set_drvdata(spi, indio_dev); 487 488 st->spi = spi; 489 490 indio_dev->dev.parent = &spi->dev; 491 indio_dev->name = "ad5421"; 492 indio_dev->info = &ad5421_info; 493 indio_dev->modes = INDIO_DIRECT_MODE; 494 indio_dev->channels = ad5421_channels; 495 indio_dev->num_channels = ARRAY_SIZE(ad5421_channels); 496 497 mutex_init(&st->lock); 498 499 st->ctrl = AD5421_CTRL_WATCHDOG_DISABLE | 500 AD5421_CTRL_AUTO_FAULT_READBACK; 501 502 if (pdata) { 503 st->current_range = pdata->current_range; 504 if (pdata->external_vref) 505 st->ctrl |= AD5421_CTRL_PWR_DOWN_INT_VREF; 506 } else { 507 st->current_range = AD5421_CURRENT_RANGE_4mA_20mA; 508 } 509 510 /* write initial ctrl register value */ 511 ad5421_update_ctrl(indio_dev, 0, 0); 512 513 if (spi->irq) { 514 ret = devm_request_threaded_irq(&spi->dev, spi->irq, 515 NULL, 516 ad5421_fault_handler, 517 IRQF_TRIGGER_HIGH | IRQF_ONESHOT, 518 "ad5421 fault", 519 indio_dev); 520 if (ret) 521 return ret; 522 } 523 524 return devm_iio_device_register(&spi->dev, indio_dev); 525 } 526 527 static struct spi_driver ad5421_driver = { 528 .driver = { 529 .name = "ad5421", 530 }, 531 .probe = ad5421_probe, 532 }; 533 module_spi_driver(ad5421_driver); 534 535 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>"); 536 MODULE_DESCRIPTION("Analog Devices AD5421 DAC"); 537 MODULE_LICENSE("GPL v2"); 538 MODULE_ALIAS("spi:ad5421"); 539