drivers/rtc/rtc-ds1374.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C
   4  *
   5  * Based on code by Randy Vinson <rvinson@mvista.com>,
   6  * which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>.
   7  *
   8  * Copyright (C) 2014 Rose Technology
   9  * Copyright (C) 2006-2007 Freescale Semiconductor
  10  * Copyright (c) 2005 MontaVista Software, Inc.
  11  */
  12 /*
  13  * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
  14  * recommended in .../Documentation/i2c/writing-clients.rst section
  15  * "Sending and receiving", using SMBus level communication is preferred.
  16  */
  17
  18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/i2c.h>
  24 #include <linux/rtc.h>
  25 #include <linux/bcd.h>
  26 #include <linux/workqueue.h>
  27 #include <linux/slab.h>
  28 #include <linux/pm.h>
  29 #ifdef CONFIG_RTC_DRV_DS1374_WDT
  30 #include <linux/fs.h>
  31 #include <linux/ioctl.h>
  32 #include <linux/miscdevice.h>
  33 #include <linux/reboot.h>
  34 #include <linux/watchdog.h>
  35 #endif
  36
  37 #define DS1374_REG_TOD0         0x00 /* Time of Day */
  38 #define DS1374_REG_TOD1         0x01
  39 #define DS1374_REG_TOD2         0x02
  40 #define DS1374_REG_TOD3         0x03
  41 #define DS1374_REG_WDALM0       0x04 /* Watchdog/Alarm */
  42 #define DS1374_REG_WDALM1       0x05
  43 #define DS1374_REG_WDALM2       0x06
  44 #define DS1374_REG_CR           0x07 /* Control */
  45 #define DS1374_REG_CR_AIE       0x01 /* Alarm Int. Enable */
  46 #define DS1374_REG_CR_WDSTR     0x08 /* 1=INT, 0=RST */
  47 #define DS1374_REG_CR_WDALM     0x20 /* 1=Watchdog, 0=Alarm */
  48 #define DS1374_REG_CR_WACE      0x40 /* WD/Alarm counter enable */
  49 #define DS1374_REG_SR           0x08 /* Status */
  50 #define DS1374_REG_SR_OSF       0x80 /* Oscillator Stop Flag */
  51 #define DS1374_REG_SR_AF        0x01 /* Alarm Flag */
  52 #define DS1374_REG_TCR          0x09 /* Trickle Charge */
  53
  54 static const struct i2c_device_id ds1374_id[] = {
  55         { "ds1374", 0 },
  56         { }
  57 };
  58 MODULE_DEVICE_TABLE(i2c, ds1374_id);
  59
  60 #ifdef CONFIG_OF
  61 static const struct of_device_id ds1374_of_match[] = {
  62         { .compatible = "dallas,ds1374" },
  63         { }
  64 };
  65 MODULE_DEVICE_TABLE(of, ds1374_of_match);
  66 #endif
  67
  68 struct ds1374 {
  69         struct i2c_client *client;
  70         struct rtc_device *rtc;
  71         struct work_struct work;
  72 #ifdef CONFIG_RTC_DRV_DS1374_WDT
  73         struct watchdog_device wdt;
  74 #endif
  75         /* The mutex protects alarm operations, and prevents a race
  76          * between the enable_irq() in the workqueue and the free_irq()
  77          * in the remove function.
  78          */
  79         struct mutex mutex;
  80         int exiting;
  81 };
  82
  83 static struct i2c_driver ds1374_driver;
  84
  85 static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
  86                            int reg, int nbytes)
  87 {
  88         u8 buf[4];
  89         int ret;
  90         int i;
  91
  92         if (WARN_ON(nbytes > 4))
  93                 return -EINVAL;
  94
  95         ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
  96
  97         if (ret < 0)
  98                 return ret;
  99         if (ret < nbytes)
 100                 return -EIO;
 101
 102         for (i = nbytes - 1, *time = 0; i >= 0; i--)
 103                 *time = (*time << 8) | buf[i];
 104
 105         return 0;
 106 }
 107
 108 static int ds1374_write_rtc(struct i2c_client *client, u32 time,
 109                             int reg, int nbytes)
 110 {
 111         u8 buf[4];
 112         int i;
 113
 114         if (nbytes > 4) {
 115                 WARN_ON(1);
 116                 return -EINVAL;
 117         }
 118
 119         for (i = 0; i < nbytes; i++) {
 120                 buf[i] = time & 0xff;
 121                 time >>= 8;
 122         }
 123
 124         return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
 125 }
 126
 127 static int ds1374_check_rtc_status(struct i2c_client *client)
 128 {
 129         int ret = 0;
 130         int control, stat;
 131
 132         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 133         if (stat < 0)
 134                 return stat;
 135
 136         if (stat & DS1374_REG_SR_OSF)
 137                 dev_warn(&client->dev,
 138                          "oscillator discontinuity flagged, time unreliable\n");
 139
 140         stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
 141
 142         ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
 143         if (ret < 0)
 144                 return ret;
 145
 146         /* If the alarm is pending, clear it before requesting
 147          * the interrupt, so an interrupt event isn't reported
 148          * before everything is initialized.
 149          */
 150
 151         control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 152         if (control < 0)
 153                 return control;
 154
 155         control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
 156         return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
 157 }
 158
 159 static int ds1374_read_time(struct device *dev, struct rtc_time *time)
 160 {
 161         struct i2c_client *client = to_i2c_client(dev);
 162         u32 itime;
 163         int ret;
 164
 165         ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
 166         if (!ret)
 167                 rtc_time64_to_tm(itime, time);
 168
 169         return ret;
 170 }
 171
 172 static int ds1374_set_time(struct device *dev, struct rtc_time *time)
 173 {
 174         struct i2c_client *client = to_i2c_client(dev);
 175         unsigned long itime = rtc_tm_to_time64(time);
 176
 177         return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
 178 }
 179
 180 #ifndef CONFIG_RTC_DRV_DS1374_WDT
 181 /* The ds1374 has a decrementer for an alarm, rather than a comparator.
 182  * If the time of day is changed, then the alarm will need to be
 183  * reset.
 184  */
 185 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 186 {
 187         struct i2c_client *client = to_i2c_client(dev);
 188         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 189         u32 now, cur_alarm;
 190         int cr, sr;
 191         int ret = 0;
 192
 193         if (client->irq <= 0)
 194                 return -EINVAL;
 195
 196         mutex_lock(&ds1374->mutex);
 197
 198         cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 199         if (ret < 0)
 200                 goto out;
 201
 202         sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 203         if (ret < 0)
 204                 goto out;
 205
 206         ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
 207         if (ret)
 208                 goto out;
 209
 210         ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
 211         if (ret)
 212                 goto out;
 213
 214         rtc_time64_to_tm(now + cur_alarm, &alarm->time);
 215         alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
 216         alarm->pending = !!(sr & DS1374_REG_SR_AF);
 217
 218 out:
 219         mutex_unlock(&ds1374->mutex);
 220         return ret;
 221 }
 222
 223 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 224 {
 225         struct i2c_client *client = to_i2c_client(dev);
 226         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 227         struct rtc_time now;
 228         unsigned long new_alarm, itime;
 229         int cr;
 230         int ret = 0;
 231
 232         if (client->irq <= 0)
 233                 return -EINVAL;
 234
 235         ret = ds1374_read_time(dev, &now);
 236         if (ret < 0)
 237                 return ret;
 238
 239         new_alarm = rtc_tm_to_time64(&alarm->time);
 240         itime = rtc_tm_to_time64(&now);
 241
 242         /* This can happen due to races, in addition to dates that are
 243          * truly in the past.  To avoid requiring the caller to check for
 244          * races, dates in the past are assumed to be in the recent past
 245          * (i.e. not something that we'd rather the caller know about via
 246          * an error), and the alarm is set to go off as soon as possible.
 247          */
 248         if (time_before_eq(new_alarm, itime))
 249                 new_alarm = 1;
 250         else
 251                 new_alarm -= itime;
 252
 253         mutex_lock(&ds1374->mutex);
 254
 255         ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 256         if (ret < 0)
 257                 goto out;
 258
 259         /* Disable any existing alarm before setting the new one
 260          * (or lack thereof). */
 261         cr &= ~DS1374_REG_CR_WACE;
 262
 263         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 264         if (ret < 0)
 265                 goto out;
 266
 267         ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
 268         if (ret)
 269                 goto out;
 270
 271         if (alarm->enabled) {
 272                 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
 273                 cr &= ~DS1374_REG_CR_WDALM;
 274
 275                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 276         }
 277
 278 out:
 279         mutex_unlock(&ds1374->mutex);
 280         return ret;
 281 }
 282 #endif
 283
 284 static irqreturn_t ds1374_irq(int irq, void *dev_id)
 285 {
 286         struct i2c_client *client = dev_id;
 287         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 288
 289         disable_irq_nosync(irq);
 290         schedule_work(&ds1374->work);
 291         return IRQ_HANDLED;
 292 }
 293
 294 static void ds1374_work(struct work_struct *work)
 295 {
 296         struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
 297         struct i2c_client *client = ds1374->client;
 298         int stat, control;
 299
 300         mutex_lock(&ds1374->mutex);
 301
 302         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 303         if (stat < 0)
 304                 goto unlock;
 305
 306         if (stat & DS1374_REG_SR_AF) {
 307                 stat &= ~DS1374_REG_SR_AF;
 308                 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
 309
 310                 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 311                 if (control < 0)
 312                         goto out;
 313
 314                 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
 315                 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
 316
 317                 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
 318         }
 319
 320 out:
 321         if (!ds1374->exiting)
 322                 enable_irq(client->irq);
 323 unlock:
 324         mutex_unlock(&ds1374->mutex);
 325 }
 326
 327 #ifndef CONFIG_RTC_DRV_DS1374_WDT
 328 static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled)
 329 {
 330         struct i2c_client *client = to_i2c_client(dev);
 331         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 332         int ret;
 333
 334         mutex_lock(&ds1374->mutex);
 335
 336         ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 337         if (ret < 0)
 338                 goto out;
 339
 340         if (enabled) {
 341                 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
 342                 ret &= ~DS1374_REG_CR_WDALM;
 343         } else {
 344                 ret &= ~DS1374_REG_CR_WACE;
 345         }
 346         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
 347
 348 out:
 349         mutex_unlock(&ds1374->mutex);
 350         return ret;
 351 }
 352 #endif
 353
 354 static const struct rtc_class_ops ds1374_rtc_ops = {
 355         .read_time = ds1374_read_time,
 356         .set_time = ds1374_set_time,
 357 #ifndef CONFIG_RTC_DRV_DS1374_WDT
 358         .read_alarm = ds1374_read_alarm,
 359         .set_alarm = ds1374_set_alarm,
 360         .alarm_irq_enable = ds1374_alarm_irq_enable,
 361 #endif
 362 };
 363
 364 #ifdef CONFIG_RTC_DRV_DS1374_WDT
 365 /*
 366  *****************************************************************************
 367  *
 368  * Watchdog Driver
 369  *
 370  *****************************************************************************
 371  */
 372 /* Default margin */
 373 #define TIMER_MARGIN_DEFAULT    32
 374 #define TIMER_MARGIN_MIN        1
 375 #define TIMER_MARGIN_MAX        4095 /* 24-bit value */
 376
 377 static int wdt_margin;
 378 module_param(wdt_margin, int, 0);
 379 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 32s)");
 380
 381 static bool nowayout = WATCHDOG_NOWAYOUT;
 382 module_param(nowayout, bool, 0);
 383 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default ="
 384                 __MODULE_STRING(WATCHDOG_NOWAYOUT)")");
 385
 386 static const struct watchdog_info ds1374_wdt_info = {
 387         .identity       = "DS1374 Watchdog",
 388         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 389                                                 WDIOF_MAGICCLOSE,
 390 };
 391
 392 static int ds1374_wdt_settimeout(struct watchdog_device *wdt, unsigned int timeout)
 393 {
 394         struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
 395         struct i2c_client *client = ds1374->client;
 396         int ret, cr;
 397
 398         wdt->timeout = timeout;
 399
 400         cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 401         if (cr < 0)
 402                 return cr;
 403
 404         /* Disable any existing watchdog/alarm before setting the new one */
 405         cr &= ~DS1374_REG_CR_WACE;
 406
 407         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 408         if (ret < 0)
 409                 return ret;
 410
 411         /* Set new watchdog time */
 412         timeout = timeout * 4096;
 413         ret = ds1374_write_rtc(client, timeout, DS1374_REG_WDALM0, 3);
 414         if (ret)
 415                 return ret;
 416
 417         /* Enable watchdog timer */
 418         cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_WDALM;
 419         cr &= ~DS1374_REG_CR_WDSTR;/* for RST PIN */
 420         cr &= ~DS1374_REG_CR_AIE;
 421
 422         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 423         if (ret < 0)
 424                 return ret;
 425
 426         return 0;
 427 }
 428
 429 /*
 430  * Reload the watchdog timer.  (ie, pat the watchdog)
 431  */
 432 static int ds1374_wdt_start(struct watchdog_device *wdt)
 433 {
 434         struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
 435         u32 val;
 436
 437         return ds1374_read_rtc(ds1374->client, &val, DS1374_REG_WDALM0, 3);
 438 }
 439
 440 static int ds1374_wdt_stop(struct watchdog_device *wdt)
 441 {
 442         struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
 443         struct i2c_client *client = ds1374->client;
 444         int cr;
 445
 446         cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 447         if (cr < 0)
 448                 return cr;
 449
 450         /* Disable watchdog timer */
 451         cr &= ~DS1374_REG_CR_WACE;
 452
 453         return i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 454 }
 455
 456 static const struct watchdog_ops ds1374_wdt_ops = {
 457         .owner          = THIS_MODULE,
 458         .start          = ds1374_wdt_start,
 459         .stop           = ds1374_wdt_stop,
 460         .set_timeout    = ds1374_wdt_settimeout,
 461 };
 462 #endif /*CONFIG_RTC_DRV_DS1374_WDT*/
 463 /*
 464  *****************************************************************************
 465  *
 466  *      Driver Interface
 467  *
 468  *****************************************************************************
 469  */
 470 static int ds1374_probe(struct i2c_client *client)
 471 {
 472         struct ds1374 *ds1374;
 473         int ret;
 474
 475         ds1374 = devm_kzalloc(&client->dev, sizeof(struct ds1374), GFP_KERNEL);
 476         if (!ds1374)
 477                 return -ENOMEM;
 478
 479         ds1374->rtc = devm_rtc_allocate_device(&client->dev);
 480         if (IS_ERR(ds1374->rtc))
 481                 return PTR_ERR(ds1374->rtc);
 482
 483         ds1374->client = client;
 484         i2c_set_clientdata(client, ds1374);
 485
 486         INIT_WORK(&ds1374->work, ds1374_work);
 487         mutex_init(&ds1374->mutex);
 488
 489         ret = ds1374_check_rtc_status(client);
 490         if (ret)
 491                 return ret;
 492
 493         if (client->irq > 0) {
 494                 ret = devm_request_irq(&client->dev, client->irq, ds1374_irq, 0,
 495                                         "ds1374", client);
 496                 if (ret) {
 497                         dev_err(&client->dev, "unable to request IRQ\n");
 498                         return ret;
 499                 }
 500
 501                 device_set_wakeup_capable(&client->dev, 1);
 502         }
 503
 504         ds1374->rtc->ops = &ds1374_rtc_ops;
 505         ds1374->rtc->range_max = U32_MAX;
 506
 507         ret = devm_rtc_register_device(ds1374->rtc);
 508         if (ret)
 509                 return ret;
 510
 511 #ifdef CONFIG_RTC_DRV_DS1374_WDT
 512         ds1374->wdt.info = &ds1374_wdt_info;
 513         ds1374->wdt.ops = &ds1374_wdt_ops;
 514         ds1374->wdt.timeout = TIMER_MARGIN_DEFAULT;
 515         ds1374->wdt.min_timeout = TIMER_MARGIN_MIN;
 516         ds1374->wdt.max_timeout = TIMER_MARGIN_MAX;
 517
 518         watchdog_init_timeout(&ds1374->wdt, wdt_margin, &client->dev);
 519         watchdog_set_nowayout(&ds1374->wdt, nowayout);
 520         watchdog_stop_on_reboot(&ds1374->wdt);
 521         watchdog_stop_on_unregister(&ds1374->wdt);
 522         watchdog_set_drvdata(&ds1374->wdt, ds1374);
 523         ds1374_wdt_settimeout(&ds1374->wdt, ds1374->wdt.timeout);
 524
 525         ret = devm_watchdog_register_device(&client->dev, &ds1374->wdt);
 526         if (ret)
 527                 return ret;
 528 #endif
 529
 530         return 0;
 531 }
 532
 533 static void ds1374_remove(struct i2c_client *client)
 534 {
 535         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 536
 537         if (client->irq > 0) {
 538                 mutex_lock(&ds1374->mutex);
 539                 ds1374->exiting = 1;
 540                 mutex_unlock(&ds1374->mutex);
 541
 542                 devm_free_irq(&client->dev, client->irq, client);
 543                 cancel_work_sync(&ds1374->work);
 544         }
 545 }
 546
 547 #ifdef CONFIG_PM_SLEEP
 548 static int ds1374_suspend(struct device *dev)
 549 {
 550         struct i2c_client *client = to_i2c_client(dev);
 551
 552         if (client->irq > 0 && device_may_wakeup(&client->dev))
 553                 enable_irq_wake(client->irq);
 554         return 0;
 555 }
 556
 557 static int ds1374_resume(struct device *dev)
 558 {
 559         struct i2c_client *client = to_i2c_client(dev);
 560
 561         if (client->irq > 0 && device_may_wakeup(&client->dev))
 562                 disable_irq_wake(client->irq);
 563         return 0;
 564 }
 565 #endif
 566
 567 static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume);
 568
 569 static struct i2c_driver ds1374_driver = {
 570         .driver = {
 571                 .name = "rtc-ds1374",
 572                 .of_match_table = of_match_ptr(ds1374_of_match),
 573                 .pm = &ds1374_pm,
 574         },
 575         .probe = ds1374_probe,
 576         .remove = ds1374_remove,
 577         .id_table = ds1374_id,
 578 };
 579
 580 module_i2c_driver(ds1374_driver);
 581
 582 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
 583 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
 584 MODULE_LICENSE("GPL");