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 #include <linux/pm.h>
  29
  30 #define DS1374_REG_TOD0         0x00 /* Time of Day */
  31 #define DS1374_REG_TOD1         0x01
  32 #define DS1374_REG_TOD2         0x02
  33 #define DS1374_REG_TOD3         0x03
  34 #define DS1374_REG_WDALM0       0x04 /* Watchdog/Alarm */
  35 #define DS1374_REG_WDALM1       0x05
  36 #define DS1374_REG_WDALM2       0x06
  37 #define DS1374_REG_CR           0x07 /* Control */
  38 #define DS1374_REG_CR_AIE       0x01 /* Alarm Int. Enable */
  39 #define DS1374_REG_CR_WDALM     0x20 /* 1=Watchdog, 0=Alarm */
  40 #define DS1374_REG_CR_WACE      0x40 /* WD/Alarm counter enable */
  41 #define DS1374_REG_SR           0x08 /* Status */
  42 #define DS1374_REG_SR_OSF       0x80 /* Oscillator Stop Flag */
  43 #define DS1374_REG_SR_AF        0x01 /* Alarm Flag */
  44 #define DS1374_REG_TCR          0x09 /* Trickle Charge */
  45
  46 static const struct i2c_device_id ds1374_id[] = {
  47         { "ds1374", 0 },
  48         { }
  49 };
  50 MODULE_DEVICE_TABLE(i2c, ds1374_id);
  51
  52 struct ds1374 {
  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         int exiting;
  63 };
  64
  65 static struct i2c_driver ds1374_driver;
  66
  67 static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
  68                            int reg, int nbytes)
  69 {
  70         u8 buf[4];
  71         int ret;
  72         int i;
  73
  74         if (nbytes > 4) {
  75                 WARN_ON(1);
  76                 return -EINVAL;
  77         }
  78
  79         ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
  80
  81         if (ret < 0)
  82                 return ret;
  83         if (ret < nbytes)
  84                 return -EIO;
  85
  86         for (i = nbytes - 1, *time = 0; i >= 0; i--)
  87                 *time = (*time << 8) | buf[i];
  88
  89         return 0;
  90 }
  91
  92 static int ds1374_write_rtc(struct i2c_client *client, u32 time,
  93                             int reg, int nbytes)
  94 {
  95         u8 buf[4];
  96         int i;
  97
  98         if (nbytes > 4) {
  99                 WARN_ON(1);
 100                 return -EINVAL;
 101         }
 102
 103         for (i = 0; i < nbytes; i++) {
 104                 buf[i] = time & 0xff;
 105                 time >>= 8;
 106         }
 107
 108         return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
 109 }
 110
 111 static int ds1374_check_rtc_status(struct i2c_client *client)
 112 {
 113         int ret = 0;
 114         int control, stat;
 115
 116         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 117         if (stat < 0)
 118                 return stat;
 119
 120         if (stat & DS1374_REG_SR_OSF)
 121                 dev_warn(&client->dev,
 122                          "oscillator discontinuity flagged, "
 123                          "time unreliable\n");
 124
 125         stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
 126
 127         ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
 128         if (ret < 0)
 129                 return ret;
 130
 131         /* If the alarm is pending, clear it before requesting
 132          * the interrupt, so an interrupt event isn't reported
 133          * before everything is initialized.
 134          */
 135
 136         control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 137         if (control < 0)
 138                 return control;
 139
 140         control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
 141         return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
 142 }
 143
 144 static int ds1374_read_time(struct device *dev, struct rtc_time *time)
 145 {
 146         struct i2c_client *client = to_i2c_client(dev);
 147         u32 itime;
 148         int ret;
 149
 150         ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
 151         if (!ret)
 152                 rtc_time_to_tm(itime, time);
 153
 154         return ret;
 155 }
 156
 157 static int ds1374_set_time(struct device *dev, struct rtc_time *time)
 158 {
 159         struct i2c_client *client = to_i2c_client(dev);
 160         unsigned long itime;
 161
 162         rtc_tm_to_time(time, &itime);
 163         return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
 164 }
 165
 166 /* The ds1374 has a decrementer for an alarm, rather than a comparator.
 167  * If the time of day is changed, then the alarm will need to be
 168  * reset.
 169  */
 170 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 171 {
 172         struct i2c_client *client = to_i2c_client(dev);
 173         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 174         u32 now, cur_alarm;
 175         int cr, sr;
 176         int ret = 0;
 177
 178         if (client->irq <= 0)
 179                 return -EINVAL;
 180
 181         mutex_lock(&ds1374->mutex);
 182
 183         cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 184         if (ret < 0)
 185                 goto out;
 186
 187         sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 188         if (ret < 0)
 189                 goto out;
 190
 191         ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
 192         if (ret)
 193                 goto out;
 194
 195         ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
 196         if (ret)
 197                 goto out;
 198
 199         rtc_time_to_tm(now + cur_alarm, &alarm->time);
 200         alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
 201         alarm->pending = !!(sr & DS1374_REG_SR_AF);
 202
 203 out:
 204         mutex_unlock(&ds1374->mutex);
 205         return ret;
 206 }
 207
 208 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 209 {
 210         struct i2c_client *client = to_i2c_client(dev);
 211         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 212         struct rtc_time now;
 213         unsigned long new_alarm, itime;
 214         int cr;
 215         int ret = 0;
 216
 217         if (client->irq <= 0)
 218                 return -EINVAL;
 219
 220         ret = ds1374_read_time(dev, &now);
 221         if (ret < 0)
 222                 return ret;
 223
 224         rtc_tm_to_time(&alarm->time, &new_alarm);
 225         rtc_tm_to_time(&now, &itime);
 226
 227         /* This can happen due to races, in addition to dates that are
 228          * truly in the past.  To avoid requiring the caller to check for
 229          * races, dates in the past are assumed to be in the recent past
 230          * (i.e. not something that we'd rather the caller know about via
 231          * an error), and the alarm is set to go off as soon as possible.
 232          */
 233         if (time_before_eq(new_alarm, itime))
 234                 new_alarm = 1;
 235         else
 236                 new_alarm -= itime;
 237
 238         mutex_lock(&ds1374->mutex);
 239
 240         ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 241         if (ret < 0)
 242                 goto out;
 243
 244         /* Disable any existing alarm before setting the new one
 245          * (or lack thereof). */
 246         cr &= ~DS1374_REG_CR_WACE;
 247
 248         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 249         if (ret < 0)
 250                 goto out;
 251
 252         ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
 253         if (ret)
 254                 goto out;
 255
 256         if (alarm->enabled) {
 257                 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
 258                 cr &= ~DS1374_REG_CR_WDALM;
 259
 260                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 261         }
 262
 263 out:
 264         mutex_unlock(&ds1374->mutex);
 265         return ret;
 266 }
 267
 268 static irqreturn_t ds1374_irq(int irq, void *dev_id)
 269 {
 270         struct i2c_client *client = dev_id;
 271         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 272
 273         disable_irq_nosync(irq);
 274         schedule_work(&ds1374->work);
 275         return IRQ_HANDLED;
 276 }
 277
 278 static void ds1374_work(struct work_struct *work)
 279 {
 280         struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
 281         struct i2c_client *client = ds1374->client;
 282         int stat, control;
 283
 284         mutex_lock(&ds1374->mutex);
 285
 286         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 287         if (stat < 0)
 288                 goto unlock;
 289
 290         if (stat & DS1374_REG_SR_AF) {
 291                 stat &= ~DS1374_REG_SR_AF;
 292                 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
 293
 294                 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 295                 if (control < 0)
 296                         goto out;
 297
 298                 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
 299                 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
 300
 301                 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
 302         }
 303
 304 out:
 305         if (!ds1374->exiting)
 306                 enable_irq(client->irq);
 307 unlock:
 308         mutex_unlock(&ds1374->mutex);
 309 }
 310
 311 static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled)
 312 {
 313         struct i2c_client *client = to_i2c_client(dev);
 314         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 315         int ret;
 316
 317         mutex_lock(&ds1374->mutex);
 318
 319         ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 320         if (ret < 0)
 321                 goto out;
 322
 323         if (enabled) {
 324                 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
 325                 ret &= ~DS1374_REG_CR_WDALM;
 326         } else {
 327                 ret &= ~DS1374_REG_CR_WACE;
 328         }
 329         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
 330
 331 out:
 332         mutex_unlock(&ds1374->mutex);
 333         return ret;
 334 }
 335
 336 static const struct rtc_class_ops ds1374_rtc_ops = {
 337         .read_time = ds1374_read_time,
 338         .set_time = ds1374_set_time,
 339         .read_alarm = ds1374_read_alarm,
 340         .set_alarm = ds1374_set_alarm,
 341         .alarm_irq_enable = ds1374_alarm_irq_enable,
 342 };
 343
 344 static int ds1374_probe(struct i2c_client *client,
 345                         const struct i2c_device_id *id)
 346 {
 347         struct ds1374 *ds1374;
 348         int ret;
 349
 350         ds1374 = kzalloc(sizeof(struct ds1374), GFP_KERNEL);
 351         if (!ds1374)
 352                 return -ENOMEM;
 353
 354         ds1374->client = client;
 355         i2c_set_clientdata(client, ds1374);
 356
 357         INIT_WORK(&ds1374->work, ds1374_work);
 358         mutex_init(&ds1374->mutex);
 359
 360         ret = ds1374_check_rtc_status(client);
 361         if (ret)
 362                 goto out_free;
 363
 364         if (client->irq > 0) {
 365                 ret = request_irq(client->irq, ds1374_irq, 0,
 366                                   "ds1374", client);
 367                 if (ret) {
 368                         dev_err(&client->dev, "unable to request IRQ\n");
 369                         goto out_free;
 370                 }
 371
 372                 device_set_wakeup_capable(&client->dev, 1);
 373         }
 374
 375         ds1374->rtc = rtc_device_register(client->name, &client->dev,
 376                                           &ds1374_rtc_ops, THIS_MODULE);
 377         if (IS_ERR(ds1374->rtc)) {
 378                 ret = PTR_ERR(ds1374->rtc);
 379                 dev_err(&client->dev, "unable to register the class device\n");
 380                 goto out_irq;
 381         }
 382
 383         return 0;
 384
 385 out_irq:
 386         if (client->irq > 0)
 387                 free_irq(client->irq, client);
 388
 389 out_free:
 390         kfree(ds1374);
 391         return ret;
 392 }
 393
 394 static int __devexit ds1374_remove(struct i2c_client *client)
 395 {
 396         struct ds1374 *ds1374 = i2c_get_clientdata(client);
 397
 398         if (client->irq > 0) {
 399                 mutex_lock(&ds1374->mutex);
 400                 ds1374->exiting = 1;
 401                 mutex_unlock(&ds1374->mutex);
 402
 403                 free_irq(client->irq, client);
 404                 cancel_work_sync(&ds1374->work);
 405         }
 406
 407         rtc_device_unregister(ds1374->rtc);
 408         kfree(ds1374);
 409         return 0;
 410 }
 411
 412 #ifdef CONFIG_PM
 413 static int ds1374_suspend(struct device *dev)
 414 {
 415         struct i2c_client *client = to_i2c_client(dev);
 416
 417         if (client->irq >= 0 && device_may_wakeup(&client->dev))
 418                 enable_irq_wake(client->irq);
 419         return 0;
 420 }
 421
 422 static int ds1374_resume(struct device *dev)
 423 {
 424         struct i2c_client *client = to_i2c_client(dev);
 425
 426         if (client->irq >= 0 && device_may_wakeup(&client->dev))
 427                 disable_irq_wake(client->irq);
 428         return 0;
 429 }
 430
 431 static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume);
 432
 433 #define DS1374_PM (&ds1374_pm)
 434 #else
 435 #define DS1374_PM NULL
 436 #endif
 437
 438 static struct i2c_driver ds1374_driver = {
 439         .driver = {
 440                 .name = "rtc-ds1374",
 441                 .owner = THIS_MODULE,
 442                 .pm = DS1374_PM,
 443         },
 444         .probe = ds1374_probe,
 445         .remove = __devexit_p(ds1374_remove),
 446         .id_table = ds1374_id,
 447 };
 448
 449 static int __init ds1374_init(void)
 450 {
 451         return i2c_add_driver(&ds1374_driver);
 452 }
 453
 454 static void __exit ds1374_exit(void)
 455 {
 456         i2c_del_driver(&ds1374_driver);
 457 }
 458
 459 module_init(ds1374_init);
 460 module_exit(ds1374_exit);
 461
 462 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
 463 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
 464 MODULE_LICENSE("GPL");