drivers/rtc/rtc-ds1374.c

   1 /*
   2  * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C
   3  *
   4  * Based on code by Randy Vinson <[email protected]>,
   5  * which was based on the m41t00.c by Mark Greer <[email protected]>.
   6  *
   7  * Copyright (C) 2014 Rose Technology
   8  * Copyright (C) 2006-2007 Freescale Semiconductor
   9  *
  10  * 2005 (c) MontaVista Software, Inc. This file is licensed under
  11  * the terms of the GNU General Public License version 2. This program
  12  * is licensed "as is" without any warranty of any kind, whether express
  13  * or implied.
  14  */
  15 /*
  16  * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
  17  * recommended in .../Documentation/i2c/writing-clients.rst section
  18  * "Sending and receiving", using SMBus level communication is preferred.
  19  */
  20
  21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  22
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/i2c.h>
  27 #include <linux/rtc.h>
  28 #include <linux/bcd.h>
  29 #include <linux/workqueue.h>
  30 #include <linux/slab.h>
  31 #include <linux/pm.h>
  32 #ifdef CONFIG_RTC_DRV_DS1374_WDT
  33 #include <linux/fs.h>
  34 #include <linux/ioctl.h>
  35 #include <linux/miscdevice.h>
  36 #include <linux/reboot.h>
  37 #include <linux/watchdog.h>
  38 #endif
  39
  40 #define DS1374_REG_TOD0         0x00 /* Time of Day */
  41 #define DS1374_REG_TOD1         0x01
  42 #define DS1374_REG_TOD2         0x02
  43 #define DS1374_REG_TOD3         0x03
  44 #define DS1374_REG_WDALM0       0x04 /* Watchdog/Alarm */
  45 #define DS1374_REG_WDALM1       0x05
  46 #define DS1374_REG_WDALM2       0x06
  47 #define DS1374_REG_CR           0x07 /* Control */
  48 #define DS1374_REG_CR_AIE       0x01 /* Alarm Int. Enable */
  49 #define DS1374_REG_CR_WDSTR     0x08 /* 1=INT, 0=RST */
  50 #define DS1374_REG_CR_WDALM     0x20 /* 1=Watchdog, 0=Alarm */
  51 #define DS1374_REG_CR_WACE      0x40 /* WD/Alarm counter enable */
  52 #define DS1374_REG_SR           0x08 /* Status */
  53 #define DS1374_REG_SR_OSF       0x80 /* Oscillator Stop Flag */
  54 #define DS1374_REG_SR_AF        0x01 /* Alarm Flag */
  55 #define DS1374_REG_TCR          0x09 /* Trickle Charge */
  56
  57 static const struct i2c_device_id ds1374_id[] = {
  58         { "ds1374", 0 },
  59         { }
  60 };
  61 MODULE_DEVICE_TABLE(i2c, ds1374_id);
  62
  63 #ifdef CONFIG_OF
  64 static const struct of_device_id ds1374_of_match[] = {
  65         { .compatible = "dallas,ds1374" },
  66         { }
  67 };
  68 MODULE_DEVICE_TABLE(of, ds1374_of_match);
  69 #endif
  70
  71 struct ds1374 {
  72         struct i2c_client *client;
  73         struct rtc_device *rtc;
  74         struct work_struct work;
  75 #ifdef CONFIG_RTC_DRV_DS1374_WDT
  76         struct watchdog_device wdt;
  77 #endif
  78         /* The mutex protects alarm operations, and prevents a race
  79          * between the enable_irq() in the workqueue and the free_irq()
  80          * in the remove function.
  81          */
  82         struct mutex mutex;
  83         int exiting;
  84 };
  85
  86 static struct i2c_driver ds1374_driver;
  87
  88 static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
  89                            int reg, int nbytes)
  90 {
  91         u8 buf[4];
  92         int ret;
  93         int i;
  94
  95         if (WARN_ON(nbytes > 4))
  96                 return -EINVAL;
  97
  98         ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
  99
 100         if (ret < 0)
 101                 return ret;
 102         if (ret < nbytes)
 103                 return -EIO;
 104
 105         for (i = nbytes - 1, *time = 0; i >= 0; i--)
 106                 *time = (*time << 8) | buf[i];
 107
 108         return 0;
 109 }
 110
 111 static int ds1374_write_rtc(struct i2c_client *client, u32 time,
 112                             int reg, int nbytes)
 113 {
 114         u8 buf[4];
 115         int i;
 116
 117         if (nbytes > 4) {
 118                 WARN_ON(1);
 119                 return -EINVAL;
 120         }
 121
 122         for (i = 0; i < nbytes; i++) {
 123                 buf[i] = time & 0xff;
 124                 time >>= 8;
 125         }
 126
 127         return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
 128 }
 129
 130 static int ds1374_check_rtc_status(struct i2c_client *client)
 131 {
 132         int ret = 0;
 133         int control, stat;
 134
 135         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 136         if (stat < 0)
 137                 return stat;
 138
 139         if (stat & DS1374_REG_SR_OSF)
 140                 dev_warn(&client->dev,
 141                          "oscillator discontinuity flagged, time unreliable\n");
 142
 143         stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
 144
 145         ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
 146         if (ret < 0)
 147                 return ret;
 148
 149         /* If the alarm is pending, clear it before requesting
 150          * the interrupt, so an interrupt event isn't reported
 151          * before everything is initialized.
 152          */
 153
 154         control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 155         if (control < 0)
 156                 return control;
 157
 158         control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
 159         return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
 160 }
 161
 162 static int ds1374_read_time(struct device *dev, struct rtc_time *time)
 163 {
 164         struct i2c_client *client = to_i2c_client(dev);
 165         u32 itime;
 166         int ret;
 167
 168         ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
 169         if (!ret)
 170                 rtc_time64_to_tm(itime, time);
 171
 172         return ret;
 173 }
 174
 175 static int ds1374_set_time(struct device *dev, struct rtc_time *time)
 176 {
 177         struct i2c_client *client = to_i2c_client(dev);
 178         unsigned long itime = rtc_tm_to_time64(time);
 179
 180         return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
 181 }
 182
 183 #ifndef CONFIG_RTC_DRV_DS1374_WDT
 184 /* The ds1374 has a decrementer for an alarm, rather than a comparator.
 185  * If the time of day is changed, then the alarm will need to be
 186  * reset.
 187  */
 188 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 189 {
 190         struct i2c_client *client = to_i2c_client(dev);
 191         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 192         u32 now, cur_alarm;
 193         int cr, sr;
 194         int ret = 0;
 195
 196         if (client->irq <= 0)
 197                 return -EINVAL;
 198
 199         mutex_lock(&ds1374->mutex);
 200
 201         cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 202         if (ret < 0)
 203                 goto out;
 204
 205         sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 206         if (ret < 0)
 207                 goto out;
 208
 209         ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
 210         if (ret)
 211                 goto out;
 212
 213         ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
 214         if (ret)
 215                 goto out;
 216
 217         rtc_time64_to_tm(now + cur_alarm, &alarm->time);
 218         alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
 219         alarm->pending = !!(sr & DS1374_REG_SR_AF);
 220
 221 out:
 222         mutex_unlock(&ds1374->mutex);
 223         return ret;
 224 }
 225
 226 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 227 {
 228         struct i2c_client *client = to_i2c_client(dev);
 229         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 230         struct rtc_time now;
 231         unsigned long new_alarm, itime;
 232         int cr;
 233         int ret = 0;
 234
 235         if (client->irq <= 0)
 236                 return -EINVAL;
 237
 238         ret = ds1374_read_time(dev, &now);
 239         if (ret < 0)
 240                 return ret;
 241
 242         new_alarm = rtc_tm_to_time64(&alarm->time);
 243         itime = rtc_tm_to_time64(&now);
 244
 245         /* This can happen due to races, in addition to dates that are
 246          * truly in the past.  To avoid requiring the caller to check for
 247          * races, dates in the past are assumed to be in the recent past
 248          * (i.e. not something that we'd rather the caller know about via
 249          * an error), and the alarm is set to go off as soon as possible.
 250          */
 251         if (time_before_eq(new_alarm, itime))
 252                 new_alarm = 1;
 253         else
 254                 new_alarm -= itime;
 255
 256         mutex_lock(&ds1374->mutex);
 257
 258         ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 259         if (ret < 0)
 260                 goto out;
 261
 262         /* Disable any existing alarm before setting the new one
 263          * (or lack thereof). */
 264         cr &= ~DS1374_REG_CR_WACE;
 265
 266         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 267         if (ret < 0)
 268                 goto out;
 269
 270         ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
 271         if (ret)
 272                 goto out;
 273
 274         if (alarm->enabled) {
 275                 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
 276                 cr &= ~DS1374_REG_CR_WDALM;
 277
 278                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 279         }
 280
 281 out:
 282         mutex_unlock(&ds1374->mutex);
 283         return ret;
 284 }
 285 #endif
 286
 287 static irqreturn_t ds1374_irq(int irq, void *dev_id)
 288 {
 289         struct i2c_client *client = dev_id;
 290         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 291
 292         disable_irq_nosync(irq);
 293         schedule_work(&ds1374->work);
 294         return IRQ_HANDLED;
 295 }
 296
 297 static void ds1374_work(struct work_struct *work)
 298 {
 299         struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
 300         struct i2c_client *client = ds1374->client;
 301         int stat, control;
 302
 303         mutex_lock(&ds1374->mutex);
 304
 305         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 306         if (stat < 0)
 307                 goto unlock;
 308
 309         if (stat & DS1374_REG_SR_AF) {
 310                 stat &= ~DS1374_REG_SR_AF;
 311                 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
 312
 313                 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 314                 if (control < 0)
 315                         goto out;
 316
 317                 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
 318                 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
 319
 320                 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
 321         }
 322
 323 out:
 324         if (!ds1374->exiting)
 325                 enable_irq(client->irq);
 326 unlock:
 327         mutex_unlock(&ds1374->mutex);
 328 }
 329
 330 #ifndef CONFIG_RTC_DRV_DS1374_WDT
 331 static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled)
 332 {
 333         struct i2c_client *client = to_i2c_client(dev);
 334         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 335         int ret;
 336
 337         mutex_lock(&ds1374->mutex);
 338
 339         ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 340         if (ret < 0)
 341                 goto out;
 342
 343         if (enabled) {
 344                 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
 345                 ret &= ~DS1374_REG_CR_WDALM;
 346         } else {
 347                 ret &= ~DS1374_REG_CR_WACE;
 348         }
 349         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
 350
 351 out:
 352         mutex_unlock(&ds1374->mutex);
 353         return ret;
 354 }
 355 #endif
 356
 357 static const struct rtc_class_ops ds1374_rtc_ops = {
 358         .read_time = ds1374_read_time,
 359         .set_time = ds1374_set_time,
 360 #ifndef CONFIG_RTC_DRV_DS1374_WDT
 361         .read_alarm = ds1374_read_alarm,
 362         .set_alarm = ds1374_set_alarm,
 363         .alarm_irq_enable = ds1374_alarm_irq_enable,
 364 #endif
 365 };
 366
 367 #ifdef CONFIG_RTC_DRV_DS1374_WDT
 368 /*
 369  *****************************************************************************
 370  *
 371  * Watchdog Driver
 372  *
 373  *****************************************************************************
 374  */
 375 /* Default margin */
 376 #define TIMER_MARGIN_DEFAULT    32
 377 #define TIMER_MARGIN_MIN        1
 378 #define TIMER_MARGIN_MAX        4095 /* 24-bit value */
 379
 380 static int wdt_margin;
 381 module_param(wdt_margin, int, 0);
 382 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 32s)");
 383
 384 static bool nowayout = WATCHDOG_NOWAYOUT;
 385 module_param(nowayout, bool, 0);
 386 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default ="
 387                 __MODULE_STRING(WATCHDOG_NOWAYOUT)")");
 388
 389 static const struct watchdog_info ds1374_wdt_info = {
 390         .identity       = "DS1374 Watchdog",
 391         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 392                                                 WDIOF_MAGICCLOSE,
 393 };
 394
 395 static int ds1374_wdt_settimeout(struct watchdog_device *wdt, unsigned int timeout)
 396 {
 397         struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
 398         struct i2c_client *client = ds1374->client;
 399         int ret, cr;
 400
 401         wdt->timeout = timeout;
 402
 403         cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 404         if (cr < 0)
 405                 return cr;
 406
 407         /* Disable any existing watchdog/alarm before setting the new one */
 408         cr &= ~DS1374_REG_CR_WACE;
 409
 410         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 411         if (ret < 0)
 412                 return ret;
 413
 414         /* Set new watchdog time */
 415         timeout = timeout * 4096;
 416         ret = ds1374_write_rtc(client, timeout, DS1374_REG_WDALM0, 3);
 417         if (ret)
 418                 return ret;
 419
 420         /* Enable watchdog timer */
 421         cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_WDALM;
 422         cr &= ~DS1374_REG_CR_WDSTR;/* for RST PIN */
 423         cr &= ~DS1374_REG_CR_AIE;
 424
 425         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 426         if (ret < 0)
 427                 return ret;
 428
 429         return 0;
 430 }
 431
 432 /*
 433  * Reload the watchdog timer.  (ie, pat the watchdog)
 434  */
 435 static int ds1374_wdt_start(struct watchdog_device *wdt)
 436 {
 437         struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
 438         u32 val;
 439
 440         return ds1374_read_rtc(ds1374->client, &val, DS1374_REG_WDALM0, 3);
 441 }
 442
 443 static int ds1374_wdt_stop(struct watchdog_device *wdt)
 444 {
 445         struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
 446         struct i2c_client *client = ds1374->client;
 447         int cr;
 448
 449         cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 450         if (cr < 0)
 451                 return cr;
 452
 453         /* Disable watchdog timer */
 454         cr &= ~DS1374_REG_CR_WACE;
 455
 456         return i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 457 }
 458
 459 static const struct watchdog_ops ds1374_wdt_ops = {
 460         .owner          = THIS_MODULE,
 461         .start          = ds1374_wdt_start,
 462         .stop           = ds1374_wdt_stop,
 463         .set_timeout    = ds1374_wdt_settimeout,
 464 };
 465 #endif /*CONFIG_RTC_DRV_DS1374_WDT*/
 466 /*
 467  *****************************************************************************
 468  *
 469  *      Driver Interface
 470  *
 471  *****************************************************************************
 472  */
 473 static int ds1374_probe(struct i2c_client *client,
 474                         const struct i2c_device_id *id)
 475 {
 476         struct ds1374 *ds1374;
 477         int ret;
 478
 479         ds1374 = devm_kzalloc(&client->dev, sizeof(struct ds1374), GFP_KERNEL);
 480         if (!ds1374)
 481                 return -ENOMEM;
 482
 483         ds1374->rtc = devm_rtc_allocate_device(&client->dev);
 484         if (IS_ERR(ds1374->rtc))
 485                 return PTR_ERR(ds1374->rtc);
 486
 487         ds1374->client = client;
 488         i2c_set_clientdata(client, ds1374);
 489
 490         INIT_WORK(&ds1374->work, ds1374_work);
 491         mutex_init(&ds1374->mutex);
 492
 493         ret = ds1374_check_rtc_status(client);
 494         if (ret)
 495                 return ret;
 496
 497         if (client->irq > 0) {
 498                 ret = devm_request_irq(&client->dev, client->irq, ds1374_irq, 0,
 499                                         "ds1374", client);
 500                 if (ret) {
 501                         dev_err(&client->dev, "unable to request IRQ\n");
 502                         return ret;
 503                 }
 504
 505                 device_set_wakeup_capable(&client->dev, 1);
 506         }
 507
 508         ds1374->rtc->ops = &ds1374_rtc_ops;
 509         ds1374->rtc->range_max = U32_MAX;
 510
 511         ret = devm_rtc_register_device(ds1374->rtc);
 512         if (ret)
 513                 return ret;
 514
 515 #ifdef CONFIG_RTC_DRV_DS1374_WDT
 516         ds1374->wdt.info = &ds1374_wdt_info;
 517         ds1374->wdt.ops = &ds1374_wdt_ops;
 518         ds1374->wdt.timeout = TIMER_MARGIN_DEFAULT;
 519         ds1374->wdt.min_timeout = TIMER_MARGIN_MIN;
 520         ds1374->wdt.max_timeout = TIMER_MARGIN_MAX;
 521
 522         watchdog_init_timeout(&ds1374->wdt, wdt_margin, &client->dev);
 523         watchdog_set_nowayout(&ds1374->wdt, nowayout);
 524         watchdog_stop_on_reboot(&ds1374->wdt);
 525         watchdog_stop_on_unregister(&ds1374->wdt);
 526         watchdog_set_drvdata(&ds1374->wdt, ds1374);
 527         ds1374_wdt_settimeout(&ds1374->wdt, ds1374->wdt.timeout);
 528
 529         ret = devm_watchdog_register_device(&client->dev, &ds1374->wdt);
 530         if (ret)
 531                 return ret;
 532 #endif
 533
 534         return 0;
 535 }
 536
 537 static int ds1374_remove(struct i2c_client *client)
 538 {
 539         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 540
 541         if (client->irq > 0) {
 542                 mutex_lock(&ds1374->mutex);
 543                 ds1374->exiting = 1;
 544                 mutex_unlock(&ds1374->mutex);
 545
 546                 devm_free_irq(&client->dev, client->irq, client);
 547                 cancel_work_sync(&ds1374->work);
 548         }
 549
 550         return 0;
 551 }
 552
 553 #ifdef CONFIG_PM_SLEEP
 554 static int ds1374_suspend(struct device *dev)
 555 {
 556         struct i2c_client *client = to_i2c_client(dev);
 557
 558         if (client->irq > 0 && device_may_wakeup(&client->dev))
 559                 enable_irq_wake(client->irq);
 560         return 0;
 561 }
 562
 563 static int ds1374_resume(struct device *dev)
 564 {
 565         struct i2c_client *client = to_i2c_client(dev);
 566
 567         if (client->irq > 0 && device_may_wakeup(&client->dev))
 568                 disable_irq_wake(client->irq);
 569         return 0;
 570 }
 571 #endif
 572
 573 static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume);
 574
 575 static struct i2c_driver ds1374_driver = {
 576         .driver = {
 577                 .name = "rtc-ds1374",
 578                 .of_match_table = of_match_ptr(ds1374_of_match),
 579                 .pm = &ds1374_pm,
 580         },
 581         .probe = ds1374_probe,
 582         .remove = ds1374_remove,
 583         .id_table = ds1374_id,
 584 };
 585
 586 module_i2c_driver(ds1374_driver);
 587
 588 MODULE_AUTHOR("Scott Wood <[email protected]>");
 589 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
 590 MODULE_LICENSE("GPL");