drivers/rtc/rtc-pcf2127.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * An I2C and SPI driver for the NXP PCF2127/29 RTC
   4  * Copyright 2013 Til-Technologies
   5  *
   6  * Author: Renaud Cerrato <r.cerrato@til-technologies.fr>
   7  *
   8  * Watchdog and tamper functions
   9  * Author: Bruno Thomsen <bruno.thomsen@gmail.com>
  10  *
  11  * based on the other drivers in this same directory.
  12  *
  13  * Datasheet: http://cache.nxp.com/documents/data_sheet/PCF2127.pdf
  14  */
  15
  16 #include <linux/i2c.h>
  17 #include <linux/spi/spi.h>
  18 #include <linux/bcd.h>
  19 #include <linux/rtc.h>
  20 #include <linux/slab.h>
  21 #include <linux/module.h>
  22 #include <linux/of.h>
  23 #include <linux/regmap.h>
  24 #include <linux/watchdog.h>
  25
  26 /* Control register 1 */
  27 #define PCF2127_REG_CTRL1               0x00
  28 /* Control register 2 */
  29 #define PCF2127_REG_CTRL2               0x01
  30 /* Control register 3 */
  31 #define PCF2127_REG_CTRL3               0x02
  32 #define PCF2127_BIT_CTRL3_BLF                   BIT(2)
  33 /* Time and date registers */
  34 #define PCF2127_REG_SC                  0x03
  35 #define PCF2127_BIT_SC_OSF                      BIT(7)
  36 #define PCF2127_REG_MN                  0x04
  37 #define PCF2127_REG_HR                  0x05
  38 #define PCF2127_REG_DM                  0x06
  39 #define PCF2127_REG_DW                  0x07
  40 #define PCF2127_REG_MO                  0x08
  41 #define PCF2127_REG_YR                  0x09
  42 /* Watchdog registers */
  43 #define PCF2127_REG_WD_CTL              0x10
  44 #define PCF2127_BIT_WD_CTL_TF0                  BIT(0)
  45 #define PCF2127_BIT_WD_CTL_TF1                  BIT(1)
  46 #define PCF2127_BIT_WD_CTL_CD0                  BIT(6)
  47 #define PCF2127_BIT_WD_CTL_CD1                  BIT(7)
  48 #define PCF2127_REG_WD_VAL              0x11
  49 /*
  50  * RAM registers
  51  * PCF2127 has 512 bytes general-purpose static RAM (SRAM) that is
  52  * battery backed and can survive a power outage.
  53  * PCF2129 doesn't have this feature.
  54  */
  55 #define PCF2127_REG_RAM_ADDR_MSB        0x1A
  56 #define PCF2127_REG_RAM_WRT_CMD         0x1C
  57 #define PCF2127_REG_RAM_RD_CMD          0x1D
  58
  59 /* Watchdog timer value constants */
  60 #define PCF2127_WD_VAL_STOP             0
  61 #define PCF2127_WD_VAL_MIN              2
  62 #define PCF2127_WD_VAL_MAX              255
  63 #define PCF2127_WD_VAL_DEFAULT          60
  64
  65 struct pcf2127 {
  66         struct rtc_device *rtc;
  67         struct watchdog_device wdd;
  68         struct regmap *regmap;
  69 };
  70
  71 /*
  72  * In the routines that deal directly with the pcf2127 hardware, we use
  73  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  74  */
  75 static int pcf2127_rtc_read_time(struct device *dev, struct rtc_time *tm)
  76 {
  77         struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
  78         unsigned char buf[10];
  79         int ret;
  80
  81         /*
  82          * Avoid reading CTRL2 register as it causes WD_VAL register
  83          * value to reset to 0 which means watchdog is stopped.
  84          */
  85         ret = regmap_bulk_read(pcf2127->regmap, PCF2127_REG_CTRL3,
  86                                (buf + PCF2127_REG_CTRL3),
  87                                ARRAY_SIZE(buf) - PCF2127_REG_CTRL3);
  88         if (ret) {
  89                 dev_err(dev, "%s: read error\n", __func__);
  90                 return ret;
  91         }
  92
  93         if (buf[PCF2127_REG_CTRL3] & PCF2127_BIT_CTRL3_BLF)
  94                 dev_info(dev,
  95                         "low voltage detected, check/replace RTC battery.\n");
  96
  97         /* Clock integrity is not guaranteed when OSF flag is set. */
  98         if (buf[PCF2127_REG_SC] & PCF2127_BIT_SC_OSF) {
  99                 /*
 100                  * no need clear the flag here,
 101                  * it will be cleared once the new date is saved
 102                  */
 103                 dev_warn(dev,
 104                          "oscillator stop detected, date/time is not reliable\n");
 105                 return -EINVAL;
 106         }
 107
 108         dev_dbg(dev,
 109                 "%s: raw data is cr3=%02x, sec=%02x, min=%02x, hr=%02x, "
 110                 "mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
 111                 __func__, buf[PCF2127_REG_CTRL3], buf[PCF2127_REG_SC],
 112                 buf[PCF2127_REG_MN], buf[PCF2127_REG_HR],
 113                 buf[PCF2127_REG_DM], buf[PCF2127_REG_DW],
 114                 buf[PCF2127_REG_MO], buf[PCF2127_REG_YR]);
 115
 116         tm->tm_sec = bcd2bin(buf[PCF2127_REG_SC] & 0x7F);
 117         tm->tm_min = bcd2bin(buf[PCF2127_REG_MN] & 0x7F);
 118         tm->tm_hour = bcd2bin(buf[PCF2127_REG_HR] & 0x3F); /* rtc hr 0-23 */
 119         tm->tm_mday = bcd2bin(buf[PCF2127_REG_DM] & 0x3F);
 120         tm->tm_wday = buf[PCF2127_REG_DW] & 0x07;
 121         tm->tm_mon = bcd2bin(buf[PCF2127_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
 122         tm->tm_year = bcd2bin(buf[PCF2127_REG_YR]);
 123         if (tm->tm_year < 70)
 124                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
 125
 126         dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 127                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 128                 __func__,
 129                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 130                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 131
 132         return 0;
 133 }
 134
 135 static int pcf2127_rtc_set_time(struct device *dev, struct rtc_time *tm)
 136 {
 137         struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
 138         unsigned char buf[7];
 139         int i = 0, err;
 140
 141         dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
 142                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 143                 __func__,
 144                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 145                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 146
 147         /* hours, minutes and seconds */
 148         buf[i++] = bin2bcd(tm->tm_sec); /* this will also clear OSF flag */
 149         buf[i++] = bin2bcd(tm->tm_min);
 150         buf[i++] = bin2bcd(tm->tm_hour);
 151         buf[i++] = bin2bcd(tm->tm_mday);
 152         buf[i++] = tm->tm_wday & 0x07;
 153
 154         /* month, 1 - 12 */
 155         buf[i++] = bin2bcd(tm->tm_mon + 1);
 156
 157         /* year */
 158         buf[i++] = bin2bcd(tm->tm_year % 100);
 159
 160         /* write register's data */
 161         err = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_SC, buf, i);
 162         if (err) {
 163                 dev_err(dev,
 164                         "%s: err=%d", __func__, err);
 165                 return err;
 166         }
 167
 168         return 0;
 169 }
 170
 171 #ifdef CONFIG_RTC_INTF_DEV
 172 static int pcf2127_rtc_ioctl(struct device *dev,
 173                                 unsigned int cmd, unsigned long arg)
 174 {
 175         struct pcf2127 *pcf2127 = dev_get_drvdata(dev);
 176         int touser;
 177         int ret;
 178
 179         switch (cmd) {
 180         case RTC_VL_READ:
 181                 ret = regmap_read(pcf2127->regmap, PCF2127_REG_CTRL3, &touser);
 182                 if (ret)
 183                         return ret;
 184
 185                 touser = touser & PCF2127_BIT_CTRL3_BLF ? 1 : 0;
 186
 187                 if (copy_to_user((void __user *)arg, &touser, sizeof(int)))
 188                         return -EFAULT;
 189                 return 0;
 190         default:
 191                 return -ENOIOCTLCMD;
 192         }
 193 }
 194 #else
 195 #define pcf2127_rtc_ioctl NULL
 196 #endif
 197
 198 static const struct rtc_class_ops pcf2127_rtc_ops = {
 199         .ioctl          = pcf2127_rtc_ioctl,
 200         .read_time      = pcf2127_rtc_read_time,
 201         .set_time       = pcf2127_rtc_set_time,
 202 };
 203
 204 static int pcf2127_nvmem_read(void *priv, unsigned int offset,
 205                               void *val, size_t bytes)
 206 {
 207         struct pcf2127 *pcf2127 = priv;
 208         int ret;
 209         unsigned char offsetbuf[] = { offset >> 8, offset };
 210
 211         ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_ADDR_MSB,
 212                                 offsetbuf, 2);
 213         if (ret)
 214                 return ret;
 215
 216         ret = regmap_bulk_read(pcf2127->regmap, PCF2127_REG_RAM_RD_CMD,
 217                                val, bytes);
 218
 219         return ret ?: bytes;
 220 }
 221
 222 static int pcf2127_nvmem_write(void *priv, unsigned int offset,
 223                                void *val, size_t bytes)
 224 {
 225         struct pcf2127 *pcf2127 = priv;
 226         int ret;
 227         unsigned char offsetbuf[] = { offset >> 8, offset };
 228
 229         ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_ADDR_MSB,
 230                                 offsetbuf, 2);
 231         if (ret)
 232                 return ret;
 233
 234         ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_WRT_CMD,
 235                                 val, bytes);
 236
 237         return ret ?: bytes;
 238 }
 239
 240 /* watchdog driver */
 241
 242 static int pcf2127_wdt_ping(struct watchdog_device *wdd)
 243 {
 244         struct pcf2127 *pcf2127 = watchdog_get_drvdata(wdd);
 245
 246         return regmap_write(pcf2127->regmap, PCF2127_REG_WD_VAL, wdd->timeout);
 247 }
 248
 249 /*
 250  * Restart watchdog timer if feature is active.
 251  *
 252  * Note: Reading CTRL2 register causes watchdog to stop which is unfortunate,
 253  * since register also contain control/status flags for other features.
 254  * Always call this function after reading CTRL2 register.
 255  */
 256 static int pcf2127_wdt_active_ping(struct watchdog_device *wdd)
 257 {
 258         int ret = 0;
 259
 260         if (watchdog_active(wdd)) {
 261                 ret = pcf2127_wdt_ping(wdd);
 262                 if (ret)
 263                         dev_err(wdd->parent,
 264                                 "%s: watchdog restart failed, ret=%d\n",
 265                                 __func__, ret);
 266         }
 267
 268         return ret;
 269 }
 270
 271 static int pcf2127_wdt_start(struct watchdog_device *wdd)
 272 {
 273         return pcf2127_wdt_ping(wdd);
 274 }
 275
 276 static int pcf2127_wdt_stop(struct watchdog_device *wdd)
 277 {
 278         struct pcf2127 *pcf2127 = watchdog_get_drvdata(wdd);
 279
 280         return regmap_write(pcf2127->regmap, PCF2127_REG_WD_VAL,
 281                             PCF2127_WD_VAL_STOP);
 282 }
 283
 284 static int pcf2127_wdt_set_timeout(struct watchdog_device *wdd,
 285                                    unsigned int new_timeout)
 286 {
 287         dev_dbg(wdd->parent, "new watchdog timeout: %is (old: %is)\n",
 288                 new_timeout, wdd->timeout);
 289
 290         wdd->timeout = new_timeout;
 291
 292         return pcf2127_wdt_active_ping(wdd);
 293 }
 294
 295 static const struct watchdog_info pcf2127_wdt_info = {
 296         .identity = "NXP PCF2127/PCF2129 Watchdog",
 297         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
 298 };
 299
 300 static const struct watchdog_ops pcf2127_watchdog_ops = {
 301         .owner = THIS_MODULE,
 302         .start = pcf2127_wdt_start,
 303         .stop = pcf2127_wdt_stop,
 304         .ping = pcf2127_wdt_ping,
 305         .set_timeout = pcf2127_wdt_set_timeout,
 306 };
 307
 308 static int pcf2127_probe(struct device *dev, struct regmap *regmap,
 309                         const char *name, bool has_nvmem)
 310 {
 311         struct pcf2127 *pcf2127;
 312         int ret = 0;
 313
 314         dev_dbg(dev, "%s\n", __func__);
 315
 316         pcf2127 = devm_kzalloc(dev, sizeof(*pcf2127), GFP_KERNEL);
 317         if (!pcf2127)
 318                 return -ENOMEM;
 319
 320         pcf2127->regmap = regmap;
 321
 322         dev_set_drvdata(dev, pcf2127);
 323
 324         pcf2127->rtc = devm_rtc_allocate_device(dev);
 325         if (IS_ERR(pcf2127->rtc))
 326                 return PTR_ERR(pcf2127->rtc);
 327
 328         pcf2127->rtc->ops = &pcf2127_rtc_ops;
 329
 330         pcf2127->wdd.parent = dev;
 331         pcf2127->wdd.info = &pcf2127_wdt_info;
 332         pcf2127->wdd.ops = &pcf2127_watchdog_ops;
 333         pcf2127->wdd.min_timeout = PCF2127_WD_VAL_MIN;
 334         pcf2127->wdd.max_timeout = PCF2127_WD_VAL_MAX;
 335         pcf2127->wdd.timeout = PCF2127_WD_VAL_DEFAULT;
 336         pcf2127->wdd.min_hw_heartbeat_ms = 500;
 337
 338         watchdog_set_drvdata(&pcf2127->wdd, pcf2127);
 339
 340         if (has_nvmem) {
 341                 struct nvmem_config nvmem_cfg = {
 342                         .priv = pcf2127,
 343                         .reg_read = pcf2127_nvmem_read,
 344                         .reg_write = pcf2127_nvmem_write,
 345                         .size = 512,
 346                 };
 347
 348                 ret = rtc_nvmem_register(pcf2127->rtc, &nvmem_cfg);
 349         }
 350
 351         /*
 352          * Watchdog timer enabled and reset pin /RST activated when timed out.
 353          * Select 1Hz clock source for watchdog timer.
 354          * Timer is not started until WD_VAL is loaded with a valid value.
 355          * Note: Countdown timer disabled and not available.
 356          */
 357         ret = regmap_update_bits(pcf2127->regmap, PCF2127_REG_WD_CTL,
 358                                  PCF2127_BIT_WD_CTL_CD1 |
 359                                  PCF2127_BIT_WD_CTL_CD0 |
 360                                  PCF2127_BIT_WD_CTL_TF1 |
 361                                  PCF2127_BIT_WD_CTL_TF0,
 362                                  PCF2127_BIT_WD_CTL_CD1 |
 363                                  PCF2127_BIT_WD_CTL_CD0 |
 364                                  PCF2127_BIT_WD_CTL_TF1);
 365         if (ret) {
 366                 dev_err(dev, "%s: watchdog config (wd_ctl) failed\n", __func__);
 367                 return ret;
 368         }
 369
 370         ret = devm_watchdog_register_device(dev, &pcf2127->wdd);
 371         if (ret)
 372                 return ret;
 373
 374         return rtc_register_device(pcf2127->rtc);
 375 }
 376
 377 #ifdef CONFIG_OF
 378 static const struct of_device_id pcf2127_of_match[] = {
 379         { .compatible = "nxp,pcf2127" },
 380         { .compatible = "nxp,pcf2129" },
 381         {}
 382 };
 383 MODULE_DEVICE_TABLE(of, pcf2127_of_match);
 384 #endif
 385
 386 #if IS_ENABLED(CONFIG_I2C)
 387
 388 static int pcf2127_i2c_write(void *context, const void *data, size_t count)
 389 {
 390         struct device *dev = context;
 391         struct i2c_client *client = to_i2c_client(dev);
 392         int ret;
 393
 394         ret = i2c_master_send(client, data, count);
 395         if (ret != count)
 396                 return ret < 0 ? ret : -EIO;
 397
 398         return 0;
 399 }
 400
 401 static int pcf2127_i2c_gather_write(void *context,
 402                                 const void *reg, size_t reg_size,
 403                                 const void *val, size_t val_size)
 404 {
 405         struct device *dev = context;
 406         struct i2c_client *client = to_i2c_client(dev);
 407         int ret;
 408         void *buf;
 409
 410         if (WARN_ON(reg_size != 1))
 411                 return -EINVAL;
 412
 413         buf = kmalloc(val_size + 1, GFP_KERNEL);
 414         if (!buf)
 415                 return -ENOMEM;
 416
 417         memcpy(buf, reg, 1);
 418         memcpy(buf + 1, val, val_size);
 419
 420         ret = i2c_master_send(client, buf, val_size + 1);
 421
 422         kfree(buf);
 423
 424         if (ret != val_size + 1)
 425                 return ret < 0 ? ret : -EIO;
 426
 427         return 0;
 428 }
 429
 430 static int pcf2127_i2c_read(void *context, const void *reg, size_t reg_size,
 431                                 void *val, size_t val_size)
 432 {
 433         struct device *dev = context;
 434         struct i2c_client *client = to_i2c_client(dev);
 435         int ret;
 436
 437         if (WARN_ON(reg_size != 1))
 438                 return -EINVAL;
 439
 440         ret = i2c_master_send(client, reg, 1);
 441         if (ret != 1)
 442                 return ret < 0 ? ret : -EIO;
 443
 444         ret = i2c_master_recv(client, val, val_size);
 445         if (ret != val_size)
 446                 return ret < 0 ? ret : -EIO;
 447
 448         return 0;
 449 }
 450
 451 /*
 452  * The reason we need this custom regmap_bus instead of using regmap_init_i2c()
 453  * is that the STOP condition is required between set register address and
 454  * read register data when reading from registers.
 455  */
 456 static const struct regmap_bus pcf2127_i2c_regmap = {
 457         .write = pcf2127_i2c_write,
 458         .gather_write = pcf2127_i2c_gather_write,
 459         .read = pcf2127_i2c_read,
 460 };
 461
 462 static struct i2c_driver pcf2127_i2c_driver;
 463
 464 static int pcf2127_i2c_probe(struct i2c_client *client,
 465                                 const struct i2c_device_id *id)
 466 {
 467         struct regmap *regmap;
 468         static const struct regmap_config config = {
 469                 .reg_bits = 8,
 470                 .val_bits = 8,
 471         };
 472
 473         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 474                 return -ENODEV;
 475
 476         regmap = devm_regmap_init(&client->dev, &pcf2127_i2c_regmap,
 477                                         &client->dev, &config);
 478         if (IS_ERR(regmap)) {
 479                 dev_err(&client->dev, "%s: regmap allocation failed: %ld\n",
 480                         __func__, PTR_ERR(regmap));
 481                 return PTR_ERR(regmap);
 482         }
 483
 484         return pcf2127_probe(&client->dev, regmap,
 485                              pcf2127_i2c_driver.driver.name, id->driver_data);
 486 }
 487
 488 static const struct i2c_device_id pcf2127_i2c_id[] = {
 489         { "pcf2127", 1 },
 490         { "pcf2129", 0 },
 491         { }
 492 };
 493 MODULE_DEVICE_TABLE(i2c, pcf2127_i2c_id);
 494
 495 static struct i2c_driver pcf2127_i2c_driver = {
 496         .driver         = {
 497                 .name   = "rtc-pcf2127-i2c",
 498                 .of_match_table = of_match_ptr(pcf2127_of_match),
 499         },
 500         .probe          = pcf2127_i2c_probe,
 501         .id_table       = pcf2127_i2c_id,
 502 };
 503
 504 static int pcf2127_i2c_register_driver(void)
 505 {
 506         return i2c_add_driver(&pcf2127_i2c_driver);
 507 }
 508
 509 static void pcf2127_i2c_unregister_driver(void)
 510 {
 511         i2c_del_driver(&pcf2127_i2c_driver);
 512 }
 513
 514 #else
 515
 516 static int pcf2127_i2c_register_driver(void)
 517 {
 518         return 0;
 519 }
 520
 521 static void pcf2127_i2c_unregister_driver(void)
 522 {
 523 }
 524
 525 #endif
 526
 527 #if IS_ENABLED(CONFIG_SPI_MASTER)
 528
 529 static struct spi_driver pcf2127_spi_driver;
 530
 531 static int pcf2127_spi_probe(struct spi_device *spi)
 532 {
 533         static const struct regmap_config config = {
 534                 .reg_bits = 8,
 535                 .val_bits = 8,
 536                 .read_flag_mask = 0xa0,
 537                 .write_flag_mask = 0x20,
 538         };
 539         struct regmap *regmap;
 540
 541         regmap = devm_regmap_init_spi(spi, &config);
 542         if (IS_ERR(regmap)) {
 543                 dev_err(&spi->dev, "%s: regmap allocation failed: %ld\n",
 544                         __func__, PTR_ERR(regmap));
 545                 return PTR_ERR(regmap);
 546         }
 547
 548         return pcf2127_probe(&spi->dev, regmap, pcf2127_spi_driver.driver.name,
 549                              spi_get_device_id(spi)->driver_data);
 550 }
 551
 552 static const struct spi_device_id pcf2127_spi_id[] = {
 553         { "pcf2127", 1 },
 554         { "pcf2129", 0 },
 555         { }
 556 };
 557 MODULE_DEVICE_TABLE(spi, pcf2127_spi_id);
 558
 559 static struct spi_driver pcf2127_spi_driver = {
 560         .driver         = {
 561                 .name   = "rtc-pcf2127-spi",
 562                 .of_match_table = of_match_ptr(pcf2127_of_match),
 563         },
 564         .probe          = pcf2127_spi_probe,
 565         .id_table       = pcf2127_spi_id,
 566 };
 567
 568 static int pcf2127_spi_register_driver(void)
 569 {
 570         return spi_register_driver(&pcf2127_spi_driver);
 571 }
 572
 573 static void pcf2127_spi_unregister_driver(void)
 574 {
 575         spi_unregister_driver(&pcf2127_spi_driver);
 576 }
 577
 578 #else
 579
 580 static int pcf2127_spi_register_driver(void)
 581 {
 582         return 0;
 583 }
 584
 585 static void pcf2127_spi_unregister_driver(void)
 586 {
 587 }
 588
 589 #endif
 590
 591 static int __init pcf2127_init(void)
 592 {
 593         int ret;
 594
 595         ret = pcf2127_i2c_register_driver();
 596         if (ret) {
 597                 pr_err("Failed to register pcf2127 i2c driver: %d\n", ret);
 598                 return ret;
 599         }
 600
 601         ret = pcf2127_spi_register_driver();
 602         if (ret) {
 603                 pr_err("Failed to register pcf2127 spi driver: %d\n", ret);
 604                 pcf2127_i2c_unregister_driver();
 605         }
 606
 607         return ret;
 608 }
 609 module_init(pcf2127_init)
 610
 611 static void __exit pcf2127_exit(void)
 612 {
 613         pcf2127_spi_unregister_driver();
 614         pcf2127_i2c_unregister_driver();
 615 }
 616 module_exit(pcf2127_exit)
 617
 618 MODULE_AUTHOR("Renaud Cerrato <r.cerrato@til-technologies.fr>");
 619 MODULE_DESCRIPTION("NXP PCF2127/29 RTC driver");
 620 MODULE_LICENSE("GPL v2");