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 <rvinson@mvista.com>,
   5  * which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>.
   6  *
   7  * Copyright (C) 2006-2007 Freescale Semiconductor
   8  *
   9  * 2005 (c) MontaVista Software, Inc. This file is licensed under
  10  * the terms of the GNU General Public License version 2. This program
  11  * is licensed "as is" without any warranty of any kind, whether express
  12  * or implied.
  13  */
  14 /*
  15  * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
  16  * recommened in .../Documentation/i2c/writing-clients section
  17  * "Sending and receiving", using SMBus level communication is preferred.
  18  */
  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 DS1374_REG_TOD0         0x00 /* Time of Day */
  30 #define DS1374_REG_TOD1         0x01
  31 #define DS1374_REG_TOD2         0x02
  32 #define DS1374_REG_TOD3         0x03
  33 #define DS1374_REG_WDALM0       0x04 /* Watchdog/Alarm */
  34 #define DS1374_REG_WDALM1       0x05
  35 #define DS1374_REG_WDALM2       0x06
  36 #define DS1374_REG_CR           0x07 /* Control */
  37 #define DS1374_REG_CR_AIE       0x01 /* Alarm Int. Enable */
  38 #define DS1374_REG_CR_WDALM     0x20 /* 1=Watchdog, 0=Alarm */
  39 #define DS1374_REG_CR_WACE      0x40 /* WD/Alarm counter enable */
  40 #define DS1374_REG_SR           0x08 /* Status */
  41 #define DS1374_REG_SR_OSF       0x80 /* Oscillator Stop Flag */
  42 #define DS1374_REG_SR_AF        0x01 /* Alarm Flag */
  43 #define DS1374_REG_TCR          0x09 /* Trickle Charge */
  44
  45 static const struct i2c_device_id ds1374_id[] = {
  46         { "ds1374", 0 },
  47         { }
  48 };
  49 MODULE_DEVICE_TABLE(i2c, ds1374_id);
  50
  51 struct ds1374 {
  52         struct i2c_client *client;
  53         struct rtc_device *rtc;
  54         struct work_struct work;
  55
  56         /* The mutex protects alarm operations, and prevents a race
  57          * between the enable_irq() in the workqueue and the free_irq()
  58          * in the remove function.
  59          */
  60         struct mutex mutex;
  61         int exiting;
  62 };
  63
  64 static struct i2c_driver ds1374_driver;
  65
  66 static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
  67                            int reg, int nbytes)
  68 {
  69         u8 buf[4];
  70         int ret;
  71         int i;
  72
  73         if (nbytes > 4) {
  74                 WARN_ON(1);
  75                 return -EINVAL;
  76         }
  77
  78         ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
  79
  80         if (ret < 0)
  81                 return ret;
  82         if (ret < nbytes)
  83                 return -EIO;
  84
  85         for (i = nbytes - 1, *time = 0; i >= 0; i--)
  86                 *time = (*time << 8) | buf[i];
  87
  88         return 0;
  89 }
  90
  91 static int ds1374_write_rtc(struct i2c_client *client, u32 time,
  92                             int reg, int nbytes)
  93 {
  94         u8 buf[4];
  95         int i;
  96
  97         if (nbytes > 4) {
  98                 WARN_ON(1);
  99                 return -EINVAL;
 100         }
 101
 102         for (i = 0; i < nbytes; i++) {
 103                 buf[i] = time & 0xff;
 104                 time >>= 8;
 105         }
 106
 107         return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
 108 }
 109
 110 static int ds1374_check_rtc_status(struct i2c_client *client)
 111 {
 112         int ret = 0;
 113         int control, stat;
 114
 115         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 116         if (stat < 0)
 117                 return stat;
 118
 119         if (stat & DS1374_REG_SR_OSF)
 120                 dev_warn(&client->dev,
 121                          "oscillator discontinuity flagged, "
 122                          "time unreliable\n");
 123
 124         stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
 125
 126         ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
 127         if (ret < 0)
 128                 return ret;
 129
 130         /* If the alarm is pending, clear it before requesting
 131          * the interrupt, so an interrupt event isn't reported
 132          * before everything is initialized.
 133          */
 134
 135         control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 136         if (control < 0)
 137                 return control;
 138
 139         control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
 140         return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
 141 }
 142
 143 static int ds1374_read_time(struct device *dev, struct rtc_time *time)
 144 {
 145         struct i2c_client *client = to_i2c_client(dev);
 146         u32 itime;
 147         int ret;
 148
 149         ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
 150         if (!ret)
 151                 rtc_time_to_tm(itime, time);
 152
 153         return ret;
 154 }
 155
 156 static int ds1374_set_time(struct device *dev, struct rtc_time *time)
 157 {
 158         struct i2c_client *client = to_i2c_client(dev);
 159         unsigned long itime;
 160
 161         rtc_tm_to_time(time, &itime);
 162         return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
 163 }
 164
 165 /* The ds1374 has a decrementer for an alarm, rather than a comparator.
 166  * If the time of day is changed, then the alarm will need to be
 167  * reset.
 168  */
 169 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 170 {
 171         struct i2c_client *client = to_i2c_client(dev);
 172         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 173         u32 now, cur_alarm;
 174         int cr, sr;
 175         int ret = 0;
 176
 177         if (client->irq <= 0)
 178                 return -EINVAL;
 179
 180         mutex_lock(&ds1374->mutex);
 181
 182         cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 183         if (ret < 0)
 184                 goto out;
 185
 186         sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 187         if (ret < 0)
 188                 goto out;
 189
 190         ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
 191         if (ret)
 192                 goto out;
 193
 194         ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
 195         if (ret)
 196                 goto out;
 197
 198         rtc_time_to_tm(now + cur_alarm, &alarm->time);
 199         alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
 200         alarm->pending = !!(sr & DS1374_REG_SR_AF);
 201
 202 out:
 203         mutex_unlock(&ds1374->mutex);
 204         return ret;
 205 }
 206
 207 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 208 {
 209         struct i2c_client *client = to_i2c_client(dev);
 210         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 211         struct rtc_time now;
 212         unsigned long new_alarm, itime;
 213         int cr;
 214         int ret = 0;
 215
 216         if (client->irq <= 0)
 217                 return -EINVAL;
 218
 219         ret = ds1374_read_time(dev, &now);
 220         if (ret < 0)
 221                 return ret;
 222
 223         rtc_tm_to_time(&alarm->time, &new_alarm);
 224         rtc_tm_to_time(&now, &itime);
 225
 226         /* This can happen due to races, in addition to dates that are
 227          * truly in the past.  To avoid requiring the caller to check for
 228          * races, dates in the past are assumed to be in the recent past
 229          * (i.e. not something that we'd rather the caller know about via
 230          * an error), and the alarm is set to go off as soon as possible.
 231          */
 232         if (time_before_eq(new_alarm, itime))
 233                 new_alarm = 1;
 234         else
 235                 new_alarm -= itime;
 236
 237         mutex_lock(&ds1374->mutex);
 238
 239         ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 240         if (ret < 0)
 241                 goto out;
 242
 243         /* Disable any existing alarm before setting the new one
 244          * (or lack thereof). */
 245         cr &= ~DS1374_REG_CR_WACE;
 246
 247         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 248         if (ret < 0)
 249                 goto out;
 250
 251         ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
 252         if (ret)
 253                 goto out;
 254
 255         if (alarm->enabled) {
 256                 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
 257                 cr &= ~DS1374_REG_CR_WDALM;
 258
 259                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 260         }
 261
 262 out:
 263         mutex_unlock(&ds1374->mutex);
 264         return ret;
 265 }
 266
 267 static irqreturn_t ds1374_irq(int irq, void *dev_id)
 268 {
 269         struct i2c_client *client = dev_id;
 270         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 271
 272         disable_irq_nosync(irq);
 273         schedule_work(&ds1374->work);
 274         return IRQ_HANDLED;
 275 }
 276
 277 static void ds1374_work(struct work_struct *work)
 278 {
 279         struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
 280         struct i2c_client *client = ds1374->client;
 281         int stat, control;
 282
 283         mutex_lock(&ds1374->mutex);
 284
 285         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 286         if (stat < 0)
 287                 goto unlock;
 288
 289         if (stat & DS1374_REG_SR_AF) {
 290                 stat &= ~DS1374_REG_SR_AF;
 291                 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
 292
 293                 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 294                 if (control < 0)
 295                         goto out;
 296
 297                 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
 298                 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
 299
 300                 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
 301         }
 302
 303 out:
 304         if (!ds1374->exiting)
 305                 enable_irq(client->irq);
 306 unlock:
 307         mutex_unlock(&ds1374->mutex);
 308 }
 309
 310 static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled)
 311 {
 312         struct i2c_client *client = to_i2c_client(dev);
 313         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 314         int ret;
 315
 316         mutex_lock(&ds1374->mutex);
 317
 318         ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 319         if (ret < 0)
 320                 goto out;
 321
 322         if (enabled) {
 323                 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
 324                 ret &= ~DS1374_REG_CR_WDALM;
 325         } else {
 326                 ret &= ~DS1374_REG_CR_WACE;
 327         }
 328         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
 329
 330 out:
 331         mutex_unlock(&ds1374->mutex);
 332         return ret;
 333 }
 334
 335 static const struct rtc_class_ops ds1374_rtc_ops = {
 336         .read_time = ds1374_read_time,
 337         .set_time = ds1374_set_time,
 338         .read_alarm = ds1374_read_alarm,
 339         .set_alarm = ds1374_set_alarm,
 340         .alarm_irq_enable = ds1374_alarm_irq_enable,
 341 };
 342
 343 static int ds1374_probe(struct i2c_client *client,
 344                         const struct i2c_device_id *id)
 345 {
 346         struct ds1374 *ds1374;
 347         int ret;
 348
 349         ds1374 = kzalloc(sizeof(struct ds1374), GFP_KERNEL);
 350         if (!ds1374)
 351                 return -ENOMEM;
 352
 353         ds1374->client = client;
 354         i2c_set_clientdata(client, ds1374);
 355
 356         INIT_WORK(&ds1374->work, ds1374_work);
 357         mutex_init(&ds1374->mutex);
 358
 359         ret = ds1374_check_rtc_status(client);
 360         if (ret)
 361                 goto out_free;
 362
 363         if (client->irq > 0) {
 364                 ret = request_irq(client->irq, ds1374_irq, 0,
 365                                   "ds1374", client);
 366                 if (ret) {
 367                         dev_err(&client->dev, "unable to request IRQ\n");
 368                         goto out_free;
 369                 }
 370
 371                 device_set_wakeup_capable(&client->dev, 1);
 372         }
 373
 374         ds1374->rtc = rtc_device_register(client->name, &client->dev,
 375                                           &ds1374_rtc_ops, THIS_MODULE);
 376         if (IS_ERR(ds1374->rtc)) {
 377                 ret = PTR_ERR(ds1374->rtc);
 378                 dev_err(&client->dev, "unable to register the class device\n");
 379                 goto out_irq;
 380         }
 381
 382         return 0;
 383
 384 out_irq:
 385         if (client->irq > 0)
 386                 free_irq(client->irq, client);
 387
 388 out_free:
 389         kfree(ds1374);
 390         return ret;
 391 }
 392
 393 static int __devexit ds1374_remove(struct i2c_client *client)
 394 {
 395         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 396
 397         if (client->irq > 0) {
 398                 mutex_lock(&ds1374->mutex);
 399                 ds1374->exiting = 1;
 400                 mutex_unlock(&ds1374->mutex);
 401
 402                 free_irq(client->irq, client);
 403                 cancel_work_sync(&ds1374->work);
 404         }
 405
 406         rtc_device_unregister(ds1374->rtc);
 407         kfree(ds1374);
 408         return 0;
 409 }
 410
 411 #ifdef CONFIG_PM
 412 static int ds1374_suspend(struct i2c_client *client, pm_message_t state)
 413 {
 414         if (client->irq >= 0 && device_may_wakeup(&client->dev))
 415                 enable_irq_wake(client->irq);
 416         return 0;
 417 }
 418
 419 static int ds1374_resume(struct i2c_client *client)
 420 {
 421         if (client->irq >= 0 && device_may_wakeup(&client->dev))
 422                 disable_irq_wake(client->irq);
 423         return 0;
 424 }
 425 #else
 426 #define ds1374_suspend  NULL
 427 #define ds1374_resume   NULL
 428 #endif
 429
 430 static struct i2c_driver ds1374_driver = {
 431         .driver = {
 432                 .name = "rtc-ds1374",
 433                 .owner = THIS_MODULE,
 434         },
 435         .probe = ds1374_probe,
 436         .suspend = ds1374_suspend,
 437         .resume = ds1374_resume,
 438         .remove = __devexit_p(ds1374_remove),
 439         .id_table = ds1374_id,
 440 };
 441
 442 static int __init ds1374_init(void)
 443 {
 444         return i2c_add_driver(&ds1374_driver);
 445 }
 446
 447 static void __exit ds1374_exit(void)
 448 {
 449         i2c_del_driver(&ds1374_driver);
 450 }
 451
 452 module_init(ds1374_init);
 453 module_exit(ds1374_exit);
 454
 455 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
 456 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
 457 MODULE_LICENSE("GPL");