drivers/rtc/rtc-ds3232.c

   1 /*
   2  * RTC client/driver for the Maxim/Dallas DS3232 Real-Time Clock over I2C
   3  *
   4  * Copyright (C) 2009-2010 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 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/i2c.h>
  22 #include <linux/rtc.h>
  23 #include <linux/bcd.h>
  24 #include <linux/workqueue.h>
  25 #include <linux/slab.h>
  26
  27 #define DS3232_REG_SECONDS      0x00
  28 #define DS3232_REG_MINUTES      0x01
  29 #define DS3232_REG_HOURS        0x02
  30 #define DS3232_REG_AMPM         0x02
  31 #define DS3232_REG_DAY          0x03
  32 #define DS3232_REG_DATE         0x04
  33 #define DS3232_REG_MONTH        0x05
  34 #define DS3232_REG_CENTURY      0x05
  35 #define DS3232_REG_YEAR         0x06
  36 #define DS3232_REG_ALARM1         0x07  /* Alarm 1 BASE */
  37 #define DS3232_REG_ALARM2         0x0B  /* Alarm 2 BASE */
  38 #define DS3232_REG_CR           0x0E    /* Control register */
  39 #       define DS3232_REG_CR_nEOSC        0x80
  40 #       define DS3232_REG_CR_INTCN        0x04
  41 #       define DS3232_REG_CR_A2IE        0x02
  42 #       define DS3232_REG_CR_A1IE        0x01
  43
  44 #define DS3232_REG_SR   0x0F    /* control/status register */
  45 #       define DS3232_REG_SR_OSF   0x80
  46 #       define DS3232_REG_SR_BSY   0x04
  47 #       define DS3232_REG_SR_A2F   0x02
  48 #       define DS3232_REG_SR_A1F   0x01
  49
  50 struct ds3232 {
  51         struct i2c_client *client;
  52         struct rtc_device *rtc;
  53         struct work_struct work;
  54
  55         /* The mutex protects alarm operations, and prevents a race
  56          * between the enable_irq() in the workqueue and the free_irq()
  57          * in the remove function.
  58          */
  59         struct mutex mutex;
  60         int exiting;
  61 };
  62
  63 static struct i2c_driver ds3232_driver;
  64
  65 static int ds3232_check_rtc_status(struct i2c_client *client)
  66 {
  67         int ret = 0;
  68         int control, stat;
  69
  70         stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
  71         if (stat < 0)
  72                 return stat;
  73
  74         if (stat & DS3232_REG_SR_OSF)
  75                 dev_warn(&client->dev,
  76                                 "oscillator discontinuity flagged, "
  77                                 "time unreliable\n");
  78
  79         stat &= ~(DS3232_REG_SR_OSF | DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
  80
  81         ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
  82         if (ret < 0)
  83                 return ret;
  84
  85         /* If the alarm is pending, clear it before requesting
  86          * the interrupt, so an interrupt event isn't reported
  87          * before everything is initialized.
  88          */
  89
  90         control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
  91         if (control < 0)
  92                 return control;
  93
  94         control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
  95         control |= DS3232_REG_CR_INTCN;
  96
  97         return i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
  98 }
  99
 100 static int ds3232_read_time(struct device *dev, struct rtc_time *time)
 101 {
 102         struct i2c_client *client = to_i2c_client(dev);
 103         int ret;
 104         u8 buf[7];
 105         unsigned int year, month, day, hour, minute, second;
 106         unsigned int week, twelve_hr, am_pm;
 107         unsigned int century, add_century = 0;
 108
 109         ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_SECONDS, 7, buf);
 110
 111         if (ret < 0)
 112                 return ret;
 113         if (ret < 7)
 114                 return -EIO;
 115
 116         second = buf[0];
 117         minute = buf[1];
 118         hour = buf[2];
 119         week = buf[3];
 120         day = buf[4];
 121         month = buf[5];
 122         year = buf[6];
 123
 124         /* Extract additional information for AM/PM and century */
 125
 126         twelve_hr = hour & 0x40;
 127         am_pm = hour & 0x20;
 128         century = month & 0x80;
 129
 130         /* Write to rtc_time structure */
 131
 132         time->tm_sec = bcd2bin(second);
 133         time->tm_min = bcd2bin(minute);
 134         if (twelve_hr) {
 135                 /* Convert to 24 hr */
 136                 if (am_pm)
 137                         time->tm_hour = bcd2bin(hour & 0x1F) + 12;
 138                 else
 139                         time->tm_hour = bcd2bin(hour & 0x1F);
 140         } else {
 141                 time->tm_hour = bcd2bin(hour);
 142         }
 143
 144         time->tm_wday = bcd2bin(week);
 145         time->tm_mday = bcd2bin(day);
 146         time->tm_mon = bcd2bin(month & 0x7F);
 147         if (century)
 148                 add_century = 100;
 149
 150         time->tm_year = bcd2bin(year) + add_century;
 151
 152         return rtc_valid_tm(time);
 153 }
 154
 155 static int ds3232_set_time(struct device *dev, struct rtc_time *time)
 156 {
 157         struct i2c_client *client = to_i2c_client(dev);
 158         u8 buf[7];
 159
 160         /* Extract time from rtc_time and load into ds3232*/
 161
 162         buf[0] = bin2bcd(time->tm_sec);
 163         buf[1] = bin2bcd(time->tm_min);
 164         buf[2] = bin2bcd(time->tm_hour);
 165         buf[3] = bin2bcd(time->tm_wday); /* Day of the week */
 166         buf[4] = bin2bcd(time->tm_mday); /* Date */
 167         buf[5] = bin2bcd(time->tm_mon);
 168         if (time->tm_year >= 100) {
 169                 buf[5] |= 0x80;
 170                 buf[6] = bin2bcd(time->tm_year - 100);
 171         } else {
 172                 buf[6] = bin2bcd(time->tm_year);
 173         }
 174
 175         return i2c_smbus_write_i2c_block_data(client,
 176                                               DS3232_REG_SECONDS, 7, buf);
 177 }
 178
 179 /*
 180  * DS3232 has two alarm, we only use alarm1
 181  * According to linux specification, only support one-shot alarm
 182  * no periodic alarm mode
 183  */
 184 static int ds3232_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 185 {
 186         struct i2c_client *client = to_i2c_client(dev);
 187         struct ds3232 *ds3232 = i2c_get_clientdata(client);
 188         int control, stat;
 189         int ret;
 190         u8 buf[4];
 191
 192         mutex_lock(&ds3232->mutex);
 193
 194         ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
 195         if (ret < 0)
 196                 goto out;
 197         stat = ret;
 198         ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
 199         if (ret < 0)
 200                 goto out;
 201         control = ret;
 202         ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
 203         if (ret < 0)
 204                 goto out;
 205
 206         alarm->time.tm_sec = bcd2bin(buf[0] & 0x7F);
 207         alarm->time.tm_min = bcd2bin(buf[1] & 0x7F);
 208         alarm->time.tm_hour = bcd2bin(buf[2] & 0x7F);
 209         alarm->time.tm_mday = bcd2bin(buf[3] & 0x7F);
 210
 211         alarm->time.tm_mon = -1;
 212         alarm->time.tm_year = -1;
 213         alarm->time.tm_wday = -1;
 214         alarm->time.tm_yday = -1;
 215         alarm->time.tm_isdst = -1;
 216
 217         alarm->enabled = !!(control & DS3232_REG_CR_A1IE);
 218         alarm->pending = !!(stat & DS3232_REG_SR_A1F);
 219
 220         ret = 0;
 221 out:
 222         mutex_unlock(&ds3232->mutex);
 223         return ret;
 224 }
 225
 226 /*
 227  * linux rtc-module does not support wday alarm
 228  * and only 24h time mode supported indeed
 229  */
 230 static int ds3232_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 231 {
 232         struct i2c_client *client = to_i2c_client(dev);
 233         struct ds3232 *ds3232 = i2c_get_clientdata(client);
 234         int control, stat;
 235         int ret;
 236         u8 buf[4];
 237
 238         if (client->irq <= 0)
 239                 return -EINVAL;
 240
 241         mutex_lock(&ds3232->mutex);
 242
 243         buf[0] = bin2bcd(alarm->time.tm_sec);
 244         buf[1] = bin2bcd(alarm->time.tm_min);
 245         buf[2] = bin2bcd(alarm->time.tm_hour);
 246         buf[3] = bin2bcd(alarm->time.tm_mday);
 247
 248         /* clear alarm interrupt enable bit */
 249         ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
 250         if (ret < 0)
 251                 goto out;
 252         control = ret;
 253         control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
 254         ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
 255         if (ret < 0)
 256                 goto out;
 257
 258         /* clear any pending alarm flag */
 259         ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
 260         if (ret < 0)
 261                 goto out;
 262         stat = ret;
 263         stat &= ~(DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
 264         ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
 265         if (ret < 0)
 266                 goto out;
 267
 268         ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
 269
 270         if (alarm->enabled) {
 271                 control |= DS3232_REG_CR_A1IE;
 272                 ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
 273         }
 274 out:
 275         mutex_unlock(&ds3232->mutex);
 276         return ret;
 277 }
 278
 279 static void ds3232_update_alarm(struct i2c_client *client)
 280 {
 281         struct ds3232 *ds3232 = i2c_get_clientdata(client);
 282         int control;
 283         int ret;
 284         u8 buf[4];
 285
 286         mutex_lock(&ds3232->mutex);
 287
 288         ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
 289         if (ret < 0)
 290                 goto unlock;
 291
 292         buf[0] = bcd2bin(buf[0]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
 293                                                                 0x80 : buf[0];
 294         buf[1] = bcd2bin(buf[1]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
 295                                                                 0x80 : buf[1];
 296         buf[2] = bcd2bin(buf[2]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
 297                                                                 0x80 : buf[2];
 298         buf[3] = bcd2bin(buf[3]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
 299                                                                 0x80 : buf[3];
 300
 301         ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
 302         if (ret < 0)
 303                 goto unlock;
 304
 305         control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
 306         if (control < 0)
 307                 goto unlock;
 308
 309         if (ds3232->rtc->irq_data & (RTC_AF | RTC_UF))
 310                 /* enable alarm1 interrupt */
 311                 control |= DS3232_REG_CR_A1IE;
 312         else
 313                 /* disable alarm1 interrupt */
 314                 control &= ~(DS3232_REG_CR_A1IE);
 315         i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
 316
 317 unlock:
 318         mutex_unlock(&ds3232->mutex);
 319 }
 320
 321 static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled)
 322 {
 323         struct i2c_client *client = to_i2c_client(dev);
 324         struct ds3232 *ds3232 = i2c_get_clientdata(client);
 325
 326         if (client->irq <= 0)
 327                 return -EINVAL;
 328
 329         if (enabled)
 330                 ds3232->rtc->irq_data |= RTC_AF;
 331         else
 332                 ds3232->rtc->irq_data &= ~RTC_AF;
 333
 334         ds3232_update_alarm(client);
 335         return 0;
 336 }
 337
 338 static int ds3232_update_irq_enable(struct device *dev, unsigned int enabled)
 339 {
 340         struct i2c_client *client = to_i2c_client(dev);
 341         struct ds3232 *ds3232 = i2c_get_clientdata(client);
 342
 343         if (client->irq <= 0)
 344                 return -EINVAL;
 345
 346         if (enabled)
 347                 ds3232->rtc->irq_data |= RTC_UF;
 348         else
 349                 ds3232->rtc->irq_data &= ~RTC_UF;
 350
 351         ds3232_update_alarm(client);
 352         return 0;
 353 }
 354
 355 static irqreturn_t ds3232_irq(int irq, void *dev_id)
 356 {
 357         struct i2c_client *client = dev_id;
 358         struct ds3232 *ds3232 = i2c_get_clientdata(client);
 359
 360         disable_irq_nosync(irq);
 361         schedule_work(&ds3232->work);
 362         return IRQ_HANDLED;
 363 }
 364
 365 static void ds3232_work(struct work_struct *work)
 366 {
 367         struct ds3232 *ds3232 = container_of(work, struct ds3232, work);
 368         struct i2c_client *client = ds3232->client;
 369         int stat, control;
 370
 371         mutex_lock(&ds3232->mutex);
 372
 373         stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
 374         if (stat < 0)
 375                 goto unlock;
 376
 377         if (stat & DS3232_REG_SR_A1F) {
 378                 control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
 379                 if (control < 0)
 380                         goto out;
 381                 /* disable alarm1 interrupt */
 382                 control &= ~(DS3232_REG_CR_A1IE);
 383                 i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
 384
 385                 /* clear the alarm pend flag */
 386                 stat &= ~DS3232_REG_SR_A1F;
 387                 i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
 388
 389                 rtc_update_irq(ds3232->rtc, 1, RTC_AF | RTC_IRQF);
 390         }
 391
 392 out:
 393         if (!ds3232->exiting)
 394                 enable_irq(client->irq);
 395 unlock:
 396         mutex_unlock(&ds3232->mutex);
 397 }
 398
 399 static const struct rtc_class_ops ds3232_rtc_ops = {
 400         .read_time = ds3232_read_time,
 401         .set_time = ds3232_set_time,
 402         .read_alarm = ds3232_read_alarm,
 403         .set_alarm = ds3232_set_alarm,
 404         .alarm_irq_enable = ds3232_alarm_irq_enable,
 405         .update_irq_enable = ds3232_update_irq_enable,
 406 };
 407
 408 static int __devinit ds3232_probe(struct i2c_client *client,
 409                 const struct i2c_device_id *id)
 410 {
 411         struct ds3232 *ds3232;
 412         int ret;
 413
 414         ds3232 = kzalloc(sizeof(struct ds3232), GFP_KERNEL);
 415         if (!ds3232)
 416                 return -ENOMEM;
 417
 418         ds3232->client = client;
 419         i2c_set_clientdata(client, ds3232);
 420
 421         INIT_WORK(&ds3232->work, ds3232_work);
 422         mutex_init(&ds3232->mutex);
 423
 424         ret = ds3232_check_rtc_status(client);
 425         if (ret)
 426                 goto out_free;
 427
 428         ds3232->rtc = rtc_device_register(client->name, &client->dev,
 429                                           &ds3232_rtc_ops, THIS_MODULE);
 430         if (IS_ERR(ds3232->rtc)) {
 431                 ret = PTR_ERR(ds3232->rtc);
 432                 dev_err(&client->dev, "unable to register the class device\n");
 433                 goto out_irq;
 434         }
 435
 436         if (client->irq >= 0) {
 437                 ret = request_irq(client->irq, ds3232_irq, 0,
 438                                  "ds3232", client);
 439                 if (ret) {
 440                         dev_err(&client->dev, "unable to request IRQ\n");
 441                         goto out_free;
 442                 }
 443         }
 444
 445         return 0;
 446
 447 out_irq:
 448         if (client->irq >= 0)
 449                 free_irq(client->irq, client);
 450
 451 out_free:
 452         kfree(ds3232);
 453         return ret;
 454 }
 455
 456 static int __devexit ds3232_remove(struct i2c_client *client)
 457 {
 458         struct ds3232 *ds3232 = i2c_get_clientdata(client);
 459
 460         if (client->irq >= 0) {
 461                 mutex_lock(&ds3232->mutex);
 462                 ds3232->exiting = 1;
 463                 mutex_unlock(&ds3232->mutex);
 464
 465                 free_irq(client->irq, client);
 466                 flush_scheduled_work();
 467         }
 468
 469         rtc_device_unregister(ds3232->rtc);
 470         kfree(ds3232);
 471         return 0;
 472 }
 473
 474 static const struct i2c_device_id ds3232_id[] = {
 475         { "ds3232", 0 },
 476         { }
 477 };
 478 MODULE_DEVICE_TABLE(i2c, ds3232_id);
 479
 480 static struct i2c_driver ds3232_driver = {
 481         .driver = {
 482                 .name = "rtc-ds3232",
 483                 .owner = THIS_MODULE,
 484         },
 485         .probe = ds3232_probe,
 486         .remove = __devexit_p(ds3232_remove),
 487         .id_table = ds3232_id,
 488 };
 489
 490 static int __init ds3232_init(void)
 491 {
 492         return i2c_add_driver(&ds3232_driver);
 493 }
 494
 495 static void __exit ds3232_exit(void)
 496 {
 497         i2c_del_driver(&ds3232_driver);
 498 }
 499
 500 module_init(ds3232_init);
 501 module_exit(ds3232_exit);
 502
 503 MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>");
 504 MODULE_DESCRIPTION("Maxim/Dallas DS3232 RTC Driver");
 505 MODULE_LICENSE("GPL");