drivers/rtc/rtc-ds3232.c

   1 /*
   2  * RTC client/driver for the Maxim/Dallas DS3232 Real-Time Clock over I2C
   3  *
   4  * Copyright (C) 2009-2011 Freescale Semiconductor.
   5  * Author: Jack Lan <jack.lan@freescale.com>
   6  *
   7  * This program is free software; you can redistribute  it and/or modify it
   8  * under  the terms of  the GNU General  Public License as published by the
   9  * Free Software Foundation;  either version 2 of the  License, or (at your
  10  * option) any later version.
  11  */
  12 /*
  13  * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
  14  * recommened in .../Documentation/i2c/writing-clients 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
  29 #define DS3232_REG_SECONDS      0x00
  30 #define DS3232_REG_MINUTES      0x01
  31 #define DS3232_REG_HOURS        0x02
  32 #define DS3232_REG_AMPM         0x02
  33 #define DS3232_REG_DAY          0x03
  34 #define DS3232_REG_DATE         0x04
  35 #define DS3232_REG_MONTH        0x05
  36 #define DS3232_REG_CENTURY      0x05
  37 #define DS3232_REG_YEAR         0x06
  38 #define DS3232_REG_ALARM1         0x07  /* Alarm 1 BASE */
  39 #define DS3232_REG_ALARM2         0x0B  /* Alarm 2 BASE */
  40 #define DS3232_REG_CR           0x0E    /* Control register */
  41 #       define DS3232_REG_CR_nEOSC        0x80
  42 #       define DS3232_REG_CR_INTCN        0x04
  43 #       define DS3232_REG_CR_A2IE        0x02
  44 #       define DS3232_REG_CR_A1IE        0x01
  45
  46 #define DS3232_REG_SR   0x0F    /* control/status register */
  47 #       define DS3232_REG_SR_OSF   0x80
  48 #       define DS3232_REG_SR_BSY   0x04
  49 #       define DS3232_REG_SR_A2F   0x02
  50 #       define DS3232_REG_SR_A1F   0x01
  51
  52 struct ds3232 {
  53         struct i2c_client *client;
  54         struct rtc_device *rtc;
  55         struct work_struct work;
  56
  57         /* The mutex protects alarm operations, and prevents a race
  58          * between the enable_irq() in the workqueue and the free_irq()
  59          * in the remove function.
  60          */
  61         struct mutex mutex;
  62         bool suspended;
  63         int exiting;
  64 };
  65
  66 static struct i2c_driver ds3232_driver;
  67
  68 static int ds3232_check_rtc_status(struct i2c_client *client)
  69 {
  70         int ret = 0;
  71         int control, stat;
  72
  73         stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
  74         if (stat < 0)
  75                 return stat;
  76
  77         if (stat & DS3232_REG_SR_OSF)
  78                 dev_warn(&client->dev,
  79                                 "oscillator discontinuity flagged, "
  80                                 "time unreliable\n");
  81
  82         stat &= ~(DS3232_REG_SR_OSF | DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
  83
  84         ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
  85         if (ret < 0)
  86                 return ret;
  87
  88         /* If the alarm is pending, clear it before requesting
  89          * the interrupt, so an interrupt event isn't reported
  90          * before everything is initialized.
  91          */
  92
  93         control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
  94         if (control < 0)
  95                 return control;
  96
  97         control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
  98         control |= DS3232_REG_CR_INTCN;
  99
 100         return i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
 101 }
 102
 103 static int ds3232_read_time(struct device *dev, struct rtc_time *time)
 104 {
 105         struct i2c_client *client = to_i2c_client(dev);
 106         int ret;
 107         u8 buf[7];
 108         unsigned int year, month, day, hour, minute, second;
 109         unsigned int week, twelve_hr, am_pm;
 110         unsigned int century, add_century = 0;
 111
 112         ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_SECONDS, 7, buf);
 113
 114         if (ret < 0)
 115                 return ret;
 116         if (ret < 7)
 117                 return -EIO;
 118
 119         second = buf[0];
 120         minute = buf[1];
 121         hour = buf[2];
 122         week = buf[3];
 123         day = buf[4];
 124         month = buf[5];
 125         year = buf[6];
 126
 127         /* Extract additional information for AM/PM and century */
 128
 129         twelve_hr = hour & 0x40;
 130         am_pm = hour & 0x20;
 131         century = month & 0x80;
 132
 133         /* Write to rtc_time structure */
 134
 135         time->tm_sec = bcd2bin(second);
 136         time->tm_min = bcd2bin(minute);
 137         if (twelve_hr) {
 138                 /* Convert to 24 hr */
 139                 if (am_pm)
 140                         time->tm_hour = bcd2bin(hour & 0x1F) + 12;
 141                 else
 142                         time->tm_hour = bcd2bin(hour & 0x1F);
 143         } else {
 144                 time->tm_hour = bcd2bin(hour);
 145         }
 146
 147         /* Day of the week in linux range is 0~6 while 1~7 in RTC chip */
 148         time->tm_wday = bcd2bin(week) - 1;
 149         time->tm_mday = bcd2bin(day);
 150         /* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */
 151         time->tm_mon = bcd2bin(month & 0x7F) - 1;
 152         if (century)
 153                 add_century = 100;
 154
 155         time->tm_year = bcd2bin(year) + add_century;
 156
 157         return rtc_valid_tm(time);
 158 }
 159
 160 static int ds3232_set_time(struct device *dev, struct rtc_time *time)
 161 {
 162         struct i2c_client *client = to_i2c_client(dev);
 163         u8 buf[7];
 164
 165         /* Extract time from rtc_time and load into ds3232*/
 166
 167         buf[0] = bin2bcd(time->tm_sec);
 168         buf[1] = bin2bcd(time->tm_min);
 169         buf[2] = bin2bcd(time->tm_hour);
 170         /* Day of the week in linux range is 0~6 while 1~7 in RTC chip */
 171         buf[3] = bin2bcd(time->tm_wday + 1);
 172         buf[4] = bin2bcd(time->tm_mday); /* Date */
 173         /* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */
 174         buf[5] = bin2bcd(time->tm_mon + 1);
 175         if (time->tm_year >= 100) {
 176                 buf[5] |= 0x80;
 177                 buf[6] = bin2bcd(time->tm_year - 100);
 178         } else {
 179                 buf[6] = bin2bcd(time->tm_year);
 180         }
 181
 182         return i2c_smbus_write_i2c_block_data(client,
 183                                               DS3232_REG_SECONDS, 7, buf);
 184 }
 185
 186 /*
 187  * DS3232 has two alarm, we only use alarm1
 188  * According to linux specification, only support one-shot alarm
 189  * no periodic alarm mode
 190  */
 191 static int ds3232_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 192 {
 193         struct i2c_client *client = to_i2c_client(dev);
 194         struct ds3232 *ds3232 = i2c_get_clientdata(client);
 195         int control, stat;
 196         int ret;
 197         u8 buf[4];
 198
 199         mutex_lock(&ds3232->mutex);
 200
 201         ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
 202         if (ret < 0)
 203                 goto out;
 204         stat = ret;
 205         ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
 206         if (ret < 0)
 207                 goto out;
 208         control = ret;
 209         ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
 210         if (ret < 0)
 211                 goto out;
 212
 213         alarm->time.tm_sec = bcd2bin(buf[0] & 0x7F);
 214         alarm->time.tm_min = bcd2bin(buf[1] & 0x7F);
 215         alarm->time.tm_hour = bcd2bin(buf[2] & 0x7F);
 216         alarm->time.tm_mday = bcd2bin(buf[3] & 0x7F);
 217
 218         alarm->time.tm_mon = -1;
 219         alarm->time.tm_year = -1;
 220         alarm->time.tm_wday = -1;
 221         alarm->time.tm_yday = -1;
 222         alarm->time.tm_isdst = -1;
 223
 224         alarm->enabled = !!(control & DS3232_REG_CR_A1IE);
 225         alarm->pending = !!(stat & DS3232_REG_SR_A1F);
 226
 227         ret = 0;
 228 out:
 229         mutex_unlock(&ds3232->mutex);
 230         return ret;
 231 }
 232
 233 /*
 234  * linux rtc-module does not support wday alarm
 235  * and only 24h time mode supported indeed
 236  */
 237 static int ds3232_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 238 {
 239         struct i2c_client *client = to_i2c_client(dev);
 240         struct ds3232 *ds3232 = i2c_get_clientdata(client);
 241         int control, stat;
 242         int ret;
 243         u8 buf[4];
 244
 245         if (client->irq <= 0)
 246                 return -EINVAL;
 247
 248         mutex_lock(&ds3232->mutex);
 249
 250         buf[0] = bin2bcd(alarm->time.tm_sec);
 251         buf[1] = bin2bcd(alarm->time.tm_min);
 252         buf[2] = bin2bcd(alarm->time.tm_hour);
 253         buf[3] = bin2bcd(alarm->time.tm_mday);
 254
 255         /* clear alarm interrupt enable bit */
 256         ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
 257         if (ret < 0)
 258                 goto out;
 259         control = ret;
 260         control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
 261         ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
 262         if (ret < 0)
 263                 goto out;
 264
 265         /* clear any pending alarm flag */
 266         ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
 267         if (ret < 0)
 268                 goto out;
 269         stat = ret;
 270         stat &= ~(DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
 271         ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
 272         if (ret < 0)
 273                 goto out;
 274
 275         ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
 276
 277         if (alarm->enabled) {
 278                 control |= DS3232_REG_CR_A1IE;
 279                 ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
 280         }
 281 out:
 282         mutex_unlock(&ds3232->mutex);
 283         return ret;
 284 }
 285
 286 static void ds3232_update_alarm(struct i2c_client *client)
 287 {
 288         struct ds3232 *ds3232 = i2c_get_clientdata(client);
 289         int control;
 290         int ret;
 291         u8 buf[4];
 292
 293         mutex_lock(&ds3232->mutex);
 294
 295         ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
 296         if (ret < 0)
 297                 goto unlock;
 298
 299         buf[0] = bcd2bin(buf[0]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
 300                                                                 0x80 : buf[0];
 301         buf[1] = bcd2bin(buf[1]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
 302                                                                 0x80 : buf[1];
 303         buf[2] = bcd2bin(buf[2]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
 304                                                                 0x80 : buf[2];
 305         buf[3] = bcd2bin(buf[3]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
 306                                                                 0x80 : buf[3];
 307
 308         ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
 309         if (ret < 0)
 310                 goto unlock;
 311
 312         control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
 313         if (control < 0)
 314                 goto unlock;
 315
 316         if (ds3232->rtc->irq_data & (RTC_AF | RTC_UF))
 317                 /* enable alarm1 interrupt */
 318                 control |= DS3232_REG_CR_A1IE;
 319         else
 320                 /* disable alarm1 interrupt */
 321                 control &= ~(DS3232_REG_CR_A1IE);
 322         i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
 323
 324 unlock:
 325         mutex_unlock(&ds3232->mutex);
 326 }
 327
 328 static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled)
 329 {
 330         struct i2c_client *client = to_i2c_client(dev);
 331         struct ds3232 *ds3232 = i2c_get_clientdata(client);
 332
 333         if (client->irq <= 0)
 334                 return -EINVAL;
 335
 336         if (enabled)
 337                 ds3232->rtc->irq_data |= RTC_AF;
 338         else
 339                 ds3232->rtc->irq_data &= ~RTC_AF;
 340
 341         ds3232_update_alarm(client);
 342         return 0;
 343 }
 344
 345 static irqreturn_t ds3232_irq(int irq, void *dev_id)
 346 {
 347         struct i2c_client *client = dev_id;
 348         struct ds3232 *ds3232 = i2c_get_clientdata(client);
 349
 350         disable_irq_nosync(irq);
 351
 352         /*
 353          * If rtc as a wakeup source, can't schedule the work
 354          * at system resume flow, because at this time the i2c bus
 355          * has not been resumed.
 356          */
 357         if (!ds3232->suspended)
 358                 schedule_work(&ds3232->work);
 359
 360         return IRQ_HANDLED;
 361 }
 362
 363 static void ds3232_work(struct work_struct *work)
 364 {
 365         struct ds3232 *ds3232 = container_of(work, struct ds3232, work);
 366         struct i2c_client *client = ds3232->client;
 367         int stat, control;
 368
 369         mutex_lock(&ds3232->mutex);
 370
 371         stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
 372         if (stat < 0)
 373                 goto unlock;
 374
 375         if (stat & DS3232_REG_SR_A1F) {
 376                 control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
 377                 if (control < 0) {
 378                         pr_warn("Read Control Register error - Disable IRQ%d\n",
 379                                 client->irq);
 380                 } else {
 381                         /* disable alarm1 interrupt */
 382                         control &= ~(DS3232_REG_CR_A1IE);
 383                         i2c_smbus_write_byte_data(client, DS3232_REG_CR,
 384                                                 control);
 385
 386                         /* clear the alarm pend flag */
 387                         stat &= ~DS3232_REG_SR_A1F;
 388                         i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
 389
 390                         rtc_update_irq(ds3232->rtc, 1, RTC_AF | RTC_IRQF);
 391
 392                         if (!ds3232->exiting)
 393                                 enable_irq(client->irq);
 394                 }
 395         }
 396
 397 unlock:
 398         mutex_unlock(&ds3232->mutex);
 399 }
 400
 401 static const struct rtc_class_ops ds3232_rtc_ops = {
 402         .read_time = ds3232_read_time,
 403         .set_time = ds3232_set_time,
 404         .read_alarm = ds3232_read_alarm,
 405         .set_alarm = ds3232_set_alarm,
 406         .alarm_irq_enable = ds3232_alarm_irq_enable,
 407 };
 408
 409 static int ds3232_probe(struct i2c_client *client,
 410                         const struct i2c_device_id *id)
 411 {
 412         struct ds3232 *ds3232;
 413         int ret;
 414
 415         ds3232 = devm_kzalloc(&client->dev, sizeof(struct ds3232), GFP_KERNEL);
 416         if (!ds3232)
 417                 return -ENOMEM;
 418
 419         ds3232->client = client;
 420         i2c_set_clientdata(client, ds3232);
 421
 422         INIT_WORK(&ds3232->work, ds3232_work);
 423         mutex_init(&ds3232->mutex);
 424
 425         ret = ds3232_check_rtc_status(client);
 426         if (ret)
 427                 return ret;
 428
 429         if (client->irq > 0) {
 430                 ret = devm_request_irq(&client->dev, client->irq, ds3232_irq,
 431                                        IRQF_SHARED, "ds3232", client);
 432                 if (ret) {
 433                         dev_err(&client->dev, "unable to request IRQ\n");
 434                 }
 435                 device_init_wakeup(&client->dev, 1);
 436         }
 437         ds3232->rtc = devm_rtc_device_register(&client->dev, client->name,
 438                                           &ds3232_rtc_ops, THIS_MODULE);
 439         return PTR_ERR_OR_ZERO(ds3232->rtc);
 440 }
 441
 442 static int ds3232_remove(struct i2c_client *client)
 443 {
 444         struct ds3232 *ds3232 = i2c_get_clientdata(client);
 445
 446         if (client->irq > 0) {
 447                 mutex_lock(&ds3232->mutex);
 448                 ds3232->exiting = 1;
 449                 mutex_unlock(&ds3232->mutex);
 450
 451                 devm_free_irq(&client->dev, client->irq, client);
 452                 cancel_work_sync(&ds3232->work);
 453         }
 454
 455         return 0;
 456 }
 457
 458 #ifdef CONFIG_PM_SLEEP
 459 static int ds3232_suspend(struct device *dev)
 460 {
 461         struct ds3232 *ds3232 = dev_get_drvdata(dev);
 462         struct i2c_client *client = to_i2c_client(dev);
 463
 464         if (device_can_wakeup(dev)) {
 465                 ds3232->suspended = true;
 466                 if (irq_set_irq_wake(client->irq, 1)) {
 467                         dev_warn_once(dev, "Cannot set wakeup source\n");
 468                         ds3232->suspended = false;
 469                 }
 470         }
 471
 472         return 0;
 473 }
 474
 475 static int ds3232_resume(struct device *dev)
 476 {
 477         struct ds3232 *ds3232 = dev_get_drvdata(dev);
 478         struct i2c_client *client = to_i2c_client(dev);
 479
 480         if (ds3232->suspended) {
 481                 ds3232->suspended = false;
 482
 483                 /* Clear the hardware alarm pend flag */
 484                 schedule_work(&ds3232->work);
 485
 486                 irq_set_irq_wake(client->irq, 0);
 487         }
 488
 489         return 0;
 490 }
 491 #endif
 492
 493 static const struct dev_pm_ops ds3232_pm_ops = {
 494         SET_SYSTEM_SLEEP_PM_OPS(ds3232_suspend, ds3232_resume)
 495 };
 496
 497 static const struct i2c_device_id ds3232_id[] = {
 498         { "ds3232", 0 },
 499         { }
 500 };
 501 MODULE_DEVICE_TABLE(i2c, ds3232_id);
 502
 503 static struct i2c_driver ds3232_driver = {
 504         .driver = {
 505                 .name = "rtc-ds3232",
 506                 .pm     = &ds3232_pm_ops,
 507         },
 508         .probe = ds3232_probe,
 509         .remove = ds3232_remove,
 510         .id_table = ds3232_id,
 511 };
 512
 513 module_i2c_driver(ds3232_driver);
 514
 515 MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>");
 516 MODULE_DESCRIPTION("Maxim/Dallas DS3232 RTC Driver");
 517 MODULE_LICENSE("GPL");