drivers/gpio/gpio-max3191x.c

   1 /*
   2  * gpio-max3191x.c - GPIO driver for Maxim MAX3191x industrial serializer
   3  *
   4  * Copyright (C) 2017 KUNBUS GmbH
   5  *
   6  * The MAX3191x makes 8 digital 24V inputs available via SPI.
   7  * Multiple chips can be daisy-chained, the spec does not impose
   8  * a limit on the number of chips and neither does this driver.
   9  *
  10  * Either of two modes is selectable: In 8-bit mode, only the state
  11  * of the inputs is clocked out to achieve high readout speeds;
  12  * In 16-bit mode, an additional status byte is clocked out with
  13  * a CRC and indicator bits for undervoltage and overtemperature.
  14  * The driver returns an error instead of potentially bogus data
  15  * if any of these fault conditions occur.  However it does allow
  16  * readout of non-faulting chips in the same daisy-chain.
  17  *
  18  * MAX3191x supports four debounce settings and the driver is
  19  * capable of configuring these differently for each chip in the
  20  * daisy-chain.
  21  *
  22  * If the chips are hardwired to 8-bit mode ("modesel" pulled high),
  23  * gpio-pisosr.c can be used alternatively to this driver.
  24  *
  25  * https://datasheets.maximintegrated.com/en/ds/MAX31910.pdf
  26  * https://datasheets.maximintegrated.com/en/ds/MAX31911.pdf
  27  * https://datasheets.maximintegrated.com/en/ds/MAX31912.pdf
  28  * https://datasheets.maximintegrated.com/en/ds/MAX31913.pdf
  29  * https://datasheets.maximintegrated.com/en/ds/MAX31953-MAX31963.pdf
  30  *
  31  * This program is free software; you can redistribute it and/or modify
  32  * it under the terms of the GNU General Public License (version 2) as
  33  * published by the Free Software Foundation.
  34  */
  35
  36 #include <linux/bitmap.h>
  37 #include <linux/crc8.h>
  38 #include <linux/gpio/consumer.h>
  39 #include <linux/gpio/driver.h>
  40 #include <linux/module.h>
  41 #include <linux/spi/spi.h>
  42
  43 enum max3191x_mode {
  44         STATUS_BYTE_ENABLED,
  45         STATUS_BYTE_DISABLED,
  46 };
  47
  48 /**
  49  * struct max3191x_chip - max3191x daisy-chain
  50  * @gpio: GPIO controller struct
  51  * @lock: protects read sequences
  52  * @nchips: number of chips in the daisy-chain
  53  * @mode: current mode, 0 for 16-bit, 1 for 8-bit;
  54  *      for simplicity, all chips in the daisy-chain are assumed
  55  *      to use the same mode
  56  * @modesel_pins: GPIO pins to configure modesel of each chip
  57  * @fault_pins: GPIO pins to detect fault of each chip
  58  * @db0_pins: GPIO pins to configure debounce of each chip
  59  * @db1_pins: GPIO pins to configure debounce of each chip
  60  * @mesg: SPI message to perform a readout
  61  * @xfer: SPI transfer used by @mesg
  62  * @crc_error: bitmap signaling CRC error for each chip
  63  * @overtemp: bitmap signaling overtemperature alarm for each chip
  64  * @undervolt1: bitmap signaling undervoltage alarm for each chip
  65  * @undervolt2: bitmap signaling undervoltage warning for each chip
  66  * @fault: bitmap signaling assertion of @fault_pins for each chip
  67  * @ignore_uv: whether to ignore undervoltage alarms;
  68  *      set by a device property if the chips are powered through
  69  *      5VOUT instead of VCC24V, in which case they will constantly
  70  *      signal undervoltage;
  71  *      for simplicity, all chips in the daisy-chain are assumed
  72  *      to be powered the same way
  73  */
  74 struct max3191x_chip {
  75         struct gpio_chip gpio;
  76         struct mutex lock;
  77         u32 nchips;
  78         enum max3191x_mode mode;
  79         struct gpio_descs *modesel_pins;
  80         struct gpio_descs *fault_pins;
  81         struct gpio_descs *db0_pins;
  82         struct gpio_descs *db1_pins;
  83         struct spi_message mesg;
  84         struct spi_transfer xfer;
  85         unsigned long *crc_error;
  86         unsigned long *overtemp;
  87         unsigned long *undervolt1;
  88         unsigned long *undervolt2;
  89         unsigned long *fault;
  90         bool ignore_uv;
  91 };
  92
  93 #define MAX3191X_NGPIO 8
  94 #define MAX3191X_CRC8_POLYNOMIAL 0xa8 /* (x^5) + x^4 + x^2 + x^0 */
  95
  96 DECLARE_CRC8_TABLE(max3191x_crc8);
  97
  98 static int max3191x_get_direction(struct gpio_chip *gpio, unsigned int offset)
  99 {
 100         return 1; /* always in */
 101 }
 102
 103 static int max3191x_direction_input(struct gpio_chip *gpio, unsigned int offset)
 104 {
 105         return 0;
 106 }
 107
 108 static int max3191x_direction_output(struct gpio_chip *gpio,
 109                                      unsigned int offset, int value)
 110 {
 111         return -EINVAL;
 112 }
 113
 114 static void max3191x_set(struct gpio_chip *gpio, unsigned int offset, int value)
 115 { }
 116
 117 static void max3191x_set_multiple(struct gpio_chip *gpio, unsigned long *mask,
 118                                   unsigned long *bits)
 119 { }
 120
 121 static unsigned int max3191x_wordlen(struct max3191x_chip *max3191x)
 122 {
 123         return max3191x->mode == STATUS_BYTE_ENABLED ? 2 : 1;
 124 }
 125
 126 static int max3191x_readout_locked(struct max3191x_chip *max3191x)
 127 {
 128         struct device *dev = max3191x->gpio.parent;
 129         struct spi_device *spi = to_spi_device(dev);
 130         int val, i, ot = 0, uv1 = 0;
 131
 132         val = spi_sync(spi, &max3191x->mesg);
 133         if (val) {
 134                 dev_err_ratelimited(dev, "SPI receive error %d\n", val);
 135                 return val;
 136         }
 137
 138         for (i = 0; i < max3191x->nchips; i++) {
 139                 if (max3191x->mode == STATUS_BYTE_ENABLED) {
 140                         u8 in     = ((u8 *)max3191x->xfer.rx_buf)[i * 2];
 141                         u8 status = ((u8 *)max3191x->xfer.rx_buf)[i * 2 + 1];
 142
 143                         val = (status & 0xf8) != crc8(max3191x_crc8, &in, 1, 0);
 144                         __assign_bit(i, max3191x->crc_error, val);
 145                         if (val)
 146                                 dev_err_ratelimited(dev,
 147                                         "chip %d: CRC error\n", i);
 148
 149                         ot  = (status >> 1) & 1;
 150                         __assign_bit(i, max3191x->overtemp, ot);
 151                         if (ot)
 152                                 dev_err_ratelimited(dev,
 153                                         "chip %d: overtemperature\n", i);
 154
 155                         if (!max3191x->ignore_uv) {
 156                                 uv1 = !((status >> 2) & 1);
 157                                 __assign_bit(i, max3191x->undervolt1, uv1);
 158                                 if (uv1)
 159                                         dev_err_ratelimited(dev,
 160                                                 "chip %d: undervoltage\n", i);
 161
 162                                 val = !(status & 1);
 163                                 __assign_bit(i, max3191x->undervolt2, val);
 164                                 if (val && !uv1)
 165                                         dev_warn_ratelimited(dev,
 166                                                 "chip %d: voltage warn\n", i);
 167                         }
 168                 }
 169
 170                 if (max3191x->fault_pins && !max3191x->ignore_uv) {
 171                         /* fault pin shared by all chips or per chip */
 172                         struct gpio_desc *fault_pin =
 173                                 (max3191x->fault_pins->ndescs == 1)
 174                                         ? max3191x->fault_pins->desc[0]
 175                                         : max3191x->fault_pins->desc[i];
 176
 177                         val = gpiod_get_value_cansleep(fault_pin);
 178                         if (val < 0) {
 179                                 dev_err_ratelimited(dev,
 180                                         "GPIO read error %d\n", val);
 181                                 return val;
 182                         }
 183                         __assign_bit(i, max3191x->fault, val);
 184                         if (val && !uv1 && !ot)
 185                                 dev_err_ratelimited(dev,
 186                                         "chip %d: fault\n", i);
 187                 }
 188         }
 189
 190         return 0;
 191 }
 192
 193 static bool max3191x_chip_is_faulting(struct max3191x_chip *max3191x,
 194                                       unsigned int chipnum)
 195 {
 196         /* without status byte the only diagnostic is the fault pin */
 197         if (!max3191x->ignore_uv && test_bit(chipnum, max3191x->fault))
 198                 return true;
 199
 200         if (max3191x->mode == STATUS_BYTE_DISABLED)
 201                 return false;
 202
 203         return test_bit(chipnum, max3191x->crc_error) ||
 204                test_bit(chipnum, max3191x->overtemp)  ||
 205                (!max3191x->ignore_uv &&
 206                 test_bit(chipnum, max3191x->undervolt1));
 207 }
 208
 209 static int max3191x_get(struct gpio_chip *gpio, unsigned int offset)
 210 {
 211         struct max3191x_chip *max3191x = gpiochip_get_data(gpio);
 212         int ret, chipnum, wordlen = max3191x_wordlen(max3191x);
 213         u8 in;
 214
 215         mutex_lock(&max3191x->lock);
 216         ret = max3191x_readout_locked(max3191x);
 217         if (ret)
 218                 goto out_unlock;
 219
 220         chipnum = offset / MAX3191X_NGPIO;
 221         if (max3191x_chip_is_faulting(max3191x, chipnum)) {
 222                 ret = -EIO;
 223                 goto out_unlock;
 224         }
 225
 226         in = ((u8 *)max3191x->xfer.rx_buf)[chipnum * wordlen];
 227         ret = (in >> (offset % MAX3191X_NGPIO)) & 1;
 228
 229 out_unlock:
 230         mutex_unlock(&max3191x->lock);
 231         return ret;
 232 }
 233
 234 static int max3191x_get_multiple(struct gpio_chip *gpio, unsigned long *mask,
 235                                  unsigned long *bits)
 236 {
 237         struct max3191x_chip *max3191x = gpiochip_get_data(gpio);
 238         int ret, bit = 0, wordlen = max3191x_wordlen(max3191x);
 239
 240         mutex_lock(&max3191x->lock);
 241         ret = max3191x_readout_locked(max3191x);
 242         if (ret)
 243                 goto out_unlock;
 244
 245         while ((bit = find_next_bit(mask, gpio->ngpio, bit)) != gpio->ngpio) {
 246                 unsigned int chipnum = bit / MAX3191X_NGPIO;
 247                 unsigned long in, shift, index;
 248
 249                 if (max3191x_chip_is_faulting(max3191x, chipnum)) {
 250                         ret = -EIO;
 251                         goto out_unlock;
 252                 }
 253
 254                 in = ((u8 *)max3191x->xfer.rx_buf)[chipnum * wordlen];
 255                 shift = round_down(bit % BITS_PER_LONG, MAX3191X_NGPIO);
 256                 index = bit / BITS_PER_LONG;
 257                 bits[index] &= ~(mask[index] & (0xff << shift));
 258                 bits[index] |= mask[index] & (in << shift); /* copy bits */
 259
 260                 bit = (chipnum + 1) * MAX3191X_NGPIO; /* go to next chip */
 261         }
 262
 263 out_unlock:
 264         mutex_unlock(&max3191x->lock);
 265         return ret;
 266 }
 267
 268 static int max3191x_set_config(struct gpio_chip *gpio, unsigned int offset,
 269                                unsigned long config)
 270 {
 271         struct max3191x_chip *max3191x = gpiochip_get_data(gpio);
 272         u32 debounce, chipnum, db0_val, db1_val;
 273
 274         if (pinconf_to_config_param(config) != PIN_CONFIG_INPUT_DEBOUNCE)
 275                 return -ENOTSUPP;
 276
 277         if (!max3191x->db0_pins || !max3191x->db1_pins)
 278                 return -EINVAL;
 279
 280         debounce = pinconf_to_config_argument(config);
 281         switch (debounce) {
 282         case 0:
 283                 db0_val = 0;
 284                 db1_val = 0;
 285                 break;
 286         case 1 ... 25:
 287                 db0_val = 0;
 288                 db1_val = 1;
 289                 break;
 290         case 26 ... 750:
 291                 db0_val = 1;
 292                 db1_val = 0;
 293                 break;
 294         case 751 ... 3000:
 295                 db0_val = 1;
 296                 db1_val = 1;
 297                 break;
 298         default:
 299                 return -EINVAL;
 300         }
 301
 302         if (max3191x->db0_pins->ndescs == 1)
 303                 chipnum = 0; /* all chips use the same pair of debounce pins */
 304         else
 305                 chipnum = offset / MAX3191X_NGPIO; /* per chip debounce pins */
 306
 307         mutex_lock(&max3191x->lock);
 308         gpiod_set_value_cansleep(max3191x->db0_pins->desc[chipnum], db0_val);
 309         gpiod_set_value_cansleep(max3191x->db1_pins->desc[chipnum], db1_val);
 310         mutex_unlock(&max3191x->lock);
 311         return 0;
 312 }
 313
 314 static void gpiod_set_array_single_value_cansleep(unsigned int ndescs,
 315                                                   struct gpio_desc **desc,
 316                                                   int value)
 317 {
 318         int i, values[ndescs];
 319
 320         for (i = 0; i < ndescs; i++)
 321                 values[i] = value;
 322
 323         gpiod_set_array_value_cansleep(ndescs, desc, values);
 324 }
 325
 326 static struct gpio_descs *devm_gpiod_get_array_optional_count(
 327                                 struct device *dev, const char *con_id,
 328                                 enum gpiod_flags flags, unsigned int expected)
 329 {
 330         struct gpio_descs *descs;
 331         int found = gpiod_count(dev, con_id);
 332
 333         if (found == -ENOENT)
 334                 return NULL;
 335
 336         if (found != expected && found != 1) {
 337                 dev_err(dev, "ignoring %s-gpios: found %d, expected %u or 1\n",
 338                         con_id, found, expected);
 339                 return NULL;
 340         }
 341
 342         descs = devm_gpiod_get_array_optional(dev, con_id, flags);
 343
 344         if (IS_ERR(descs)) {
 345                 dev_err(dev, "failed to get %s-gpios: %ld\n",
 346                         con_id, PTR_ERR(descs));
 347                 return NULL;
 348         }
 349
 350         return descs;
 351 }
 352
 353 static int max3191x_probe(struct spi_device *spi)
 354 {
 355         struct device *dev = &spi->dev;
 356         struct max3191x_chip *max3191x;
 357         int n, ret;
 358
 359         max3191x = devm_kzalloc(dev, sizeof(*max3191x), GFP_KERNEL);
 360         if (!max3191x)
 361                 return -ENOMEM;
 362         spi_set_drvdata(spi, max3191x);
 363
 364         max3191x->nchips = 1;
 365         device_property_read_u32(dev, "#daisy-chained-devices",
 366                                  &max3191x->nchips);
 367
 368         n = BITS_TO_LONGS(max3191x->nchips);
 369         max3191x->crc_error   = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL);
 370         max3191x->undervolt1  = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL);
 371         max3191x->undervolt2  = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL);
 372         max3191x->overtemp    = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL);
 373         max3191x->fault       = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL);
 374         max3191x->xfer.rx_buf = devm_kcalloc(dev, max3191x->nchips,
 375                                                                 2, GFP_KERNEL);
 376         if (!max3191x->crc_error || !max3191x->undervolt1 ||
 377             !max3191x->overtemp  || !max3191x->undervolt2 ||
 378             !max3191x->fault     || !max3191x->xfer.rx_buf)
 379                 return -ENOMEM;
 380
 381         max3191x->modesel_pins = devm_gpiod_get_array_optional_count(dev,
 382                                  "maxim,modesel", GPIOD_ASIS, max3191x->nchips);
 383         max3191x->fault_pins   = devm_gpiod_get_array_optional_count(dev,
 384                                  "maxim,fault", GPIOD_IN, max3191x->nchips);
 385         max3191x->db0_pins     = devm_gpiod_get_array_optional_count(dev,
 386                                  "maxim,db0", GPIOD_OUT_LOW, max3191x->nchips);
 387         max3191x->db1_pins     = devm_gpiod_get_array_optional_count(dev,
 388                                  "maxim,db1", GPIOD_OUT_LOW, max3191x->nchips);
 389
 390         max3191x->mode = device_property_read_bool(dev, "maxim,modesel-8bit")
 391                                  ? STATUS_BYTE_DISABLED : STATUS_BYTE_ENABLED;
 392         if (max3191x->modesel_pins)
 393                 gpiod_set_array_single_value_cansleep(
 394                                  max3191x->modesel_pins->ndescs,
 395                                  max3191x->modesel_pins->desc, max3191x->mode);
 396
 397         max3191x->ignore_uv = device_property_read_bool(dev,
 398                                                   "maxim,ignore-undervoltage");
 399
 400         if (max3191x->db0_pins && max3191x->db1_pins &&
 401             max3191x->db0_pins->ndescs != max3191x->db1_pins->ndescs) {
 402                 dev_err(dev, "ignoring maxim,db*-gpios: array len mismatch\n");
 403                 devm_gpiod_put_array(dev, max3191x->db0_pins);
 404                 devm_gpiod_put_array(dev, max3191x->db1_pins);
 405                 max3191x->db0_pins = NULL;
 406                 max3191x->db1_pins = NULL;
 407         }
 408
 409         max3191x->xfer.len = max3191x->nchips * max3191x_wordlen(max3191x);
 410         spi_message_init_with_transfers(&max3191x->mesg, &max3191x->xfer, 1);
 411
 412         max3191x->gpio.label = spi->modalias;
 413         max3191x->gpio.owner = THIS_MODULE;
 414         max3191x->gpio.parent = dev;
 415         max3191x->gpio.base = -1;
 416         max3191x->gpio.ngpio = max3191x->nchips * MAX3191X_NGPIO;
 417         max3191x->gpio.can_sleep = true;
 418
 419         max3191x->gpio.get_direction = max3191x_get_direction;
 420         max3191x->gpio.direction_input = max3191x_direction_input;
 421         max3191x->gpio.direction_output = max3191x_direction_output;
 422         max3191x->gpio.set = max3191x_set;
 423         max3191x->gpio.set_multiple = max3191x_set_multiple;
 424         max3191x->gpio.get = max3191x_get;
 425         max3191x->gpio.get_multiple = max3191x_get_multiple;
 426         max3191x->gpio.set_config = max3191x_set_config;
 427
 428         mutex_init(&max3191x->lock);
 429
 430         ret = gpiochip_add_data(&max3191x->gpio, max3191x);
 431         if (ret) {
 432                 mutex_destroy(&max3191x->lock);
 433                 return ret;
 434         }
 435
 436         return 0;
 437 }
 438
 439 static int max3191x_remove(struct spi_device *spi)
 440 {
 441         struct max3191x_chip *max3191x = spi_get_drvdata(spi);
 442
 443         gpiochip_remove(&max3191x->gpio);
 444         mutex_destroy(&max3191x->lock);
 445
 446         return 0;
 447 }
 448
 449 static int __init max3191x_register_driver(struct spi_driver *sdrv)
 450 {
 451         crc8_populate_msb(max3191x_crc8, MAX3191X_CRC8_POLYNOMIAL);
 452         return spi_register_driver(sdrv);
 453 }
 454
 455 #ifdef CONFIG_OF
 456 static const struct of_device_id max3191x_of_id[] = {
 457         { .compatible = "maxim,max31910" },
 458         { .compatible = "maxim,max31911" },
 459         { .compatible = "maxim,max31912" },
 460         { .compatible = "maxim,max31913" },
 461         { .compatible = "maxim,max31953" },
 462         { .compatible = "maxim,max31963" },
 463         { }
 464 };
 465 MODULE_DEVICE_TABLE(of, max3191x_of_id);
 466 #endif
 467
 468 static const struct spi_device_id max3191x_spi_id[] = {
 469         { "max31910" },
 470         { "max31911" },
 471         { "max31912" },
 472         { "max31913" },
 473         { "max31953" },
 474         { "max31963" },
 475         { }
 476 };
 477 MODULE_DEVICE_TABLE(spi, max3191x_spi_id);
 478
 479 static struct spi_driver max3191x_driver = {
 480         .driver = {
 481                 .name           = "max3191x",
 482                 .of_match_table = of_match_ptr(max3191x_of_id),
 483         },
 484         .probe    = max3191x_probe,
 485         .remove   = max3191x_remove,
 486         .id_table = max3191x_spi_id,
 487 };
 488 module_driver(max3191x_driver, max3191x_register_driver, spi_unregister_driver);
 489
 490 MODULE_AUTHOR("Lukas Wunner <lukas@wunner.de>");
 491 MODULE_DESCRIPTION("GPIO driver for Maxim MAX3191x industrial serializer");
 492 MODULE_LICENSE("GPL v2");