drivers/rtc/rtc-ab8500.c

   1 /*
   2  * Copyright (C) ST-Ericsson SA 2010
   3  *
   4  * License terms: GNU General Public License (GPL) version 2
   5  * Author: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
   6  *
   7  * RTC clock driver for the RTC part of the AB8500 Power management chip.
   8  * Based on RTC clock driver for the AB3100 Analog Baseband Chip by
   9  * Linus Walleij <linus.walleij@stericsson.com>
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/kernel.h>
  14 #include <linux/init.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/rtc.h>
  17 #include <linux/mfd/abx500.h>
  18 #include <linux/mfd/abx500/ab8500.h>
  19 #include <linux/delay.h>
  20 #include <linux/of.h>
  21
  22 #define AB8500_RTC_SOFF_STAT_REG        0x00
  23 #define AB8500_RTC_CC_CONF_REG          0x01
  24 #define AB8500_RTC_READ_REQ_REG         0x02
  25 #define AB8500_RTC_WATCH_TSECMID_REG    0x03
  26 #define AB8500_RTC_WATCH_TSECHI_REG     0x04
  27 #define AB8500_RTC_WATCH_TMIN_LOW_REG   0x05
  28 #define AB8500_RTC_WATCH_TMIN_MID_REG   0x06
  29 #define AB8500_RTC_WATCH_TMIN_HI_REG    0x07
  30 #define AB8500_RTC_ALRM_MIN_LOW_REG     0x08
  31 #define AB8500_RTC_ALRM_MIN_MID_REG     0x09
  32 #define AB8500_RTC_ALRM_MIN_HI_REG      0x0A
  33 #define AB8500_RTC_STAT_REG             0x0B
  34 #define AB8500_RTC_BKUP_CHG_REG         0x0C
  35 #define AB8500_RTC_FORCE_BKUP_REG       0x0D
  36 #define AB8500_RTC_CALIB_REG            0x0E
  37 #define AB8500_RTC_SWITCH_STAT_REG      0x0F
  38
  39 /* RtcReadRequest bits */
  40 #define RTC_READ_REQUEST                0x01
  41 #define RTC_WRITE_REQUEST               0x02
  42
  43 /* RtcCtrl bits */
  44 #define RTC_ALARM_ENA                   0x04
  45 #define RTC_STATUS_DATA                 0x01
  46
  47 #define COUNTS_PER_SEC                  (0xF000 / 60)
  48 #define AB8500_RTC_EPOCH                2000
  49
  50 static const u8 ab8500_rtc_time_regs[] = {
  51         AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
  52         AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
  53         AB8500_RTC_WATCH_TSECMID_REG
  54 };
  55
  56 static const u8 ab8500_rtc_alarm_regs[] = {
  57         AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
  58         AB8500_RTC_ALRM_MIN_LOW_REG
  59 };
  60
  61 /* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
  62 static unsigned long get_elapsed_seconds(int year)
  63 {
  64         unsigned long secs;
  65         struct rtc_time tm = {
  66                 .tm_year = year - 1900,
  67                 .tm_mday = 1,
  68         };
  69
  70         /*
  71          * This function calculates secs from 1970 and not from
  72          * 1900, even if we supply the offset from year 1900.
  73          */
  74         rtc_tm_to_time(&tm, &secs);
  75         return secs;
  76 }
  77
  78 static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
  79 {
  80         unsigned long timeout = jiffies + HZ;
  81         int retval, i;
  82         unsigned long mins, secs;
  83         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
  84         u8 value;
  85
  86         /* Request a data read */
  87         retval = abx500_set_register_interruptible(dev,
  88                 AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
  89         if (retval < 0)
  90                 return retval;
  91
  92         /* Wait for some cycles after enabling the rtc read in ab8500 */
  93         while (time_before(jiffies, timeout)) {
  94                 retval = abx500_get_register_interruptible(dev,
  95                         AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
  96                 if (retval < 0)
  97                         return retval;
  98
  99                 if (!(value & RTC_READ_REQUEST))
 100                         break;
 101
 102                 usleep_range(1000, 5000);
 103         }
 104
 105         /* Read the Watchtime registers */
 106         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 107                 retval = abx500_get_register_interruptible(dev,
 108                         AB8500_RTC, ab8500_rtc_time_regs[i], &value);
 109                 if (retval < 0)
 110                         return retval;
 111                 buf[i] = value;
 112         }
 113
 114         mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
 115
 116         secs =  (buf[3] << 8) | buf[4];
 117         secs =  secs / COUNTS_PER_SEC;
 118         secs =  secs + (mins * 60);
 119
 120         /* Add back the initially subtracted number of seconds */
 121         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 122
 123         rtc_time_to_tm(secs, tm);
 124         return rtc_valid_tm(tm);
 125 }
 126
 127 static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
 128 {
 129         int retval, i;
 130         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 131         unsigned long no_secs, no_mins, secs = 0;
 132
 133         if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
 134                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 135                                 AB8500_RTC_EPOCH);
 136                 return -EINVAL;
 137         }
 138
 139         /* Get the number of seconds since 1970 */
 140         rtc_tm_to_time(tm, &secs);
 141
 142         /*
 143          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 144          * we only have a small counter in the RTC.
 145          */
 146         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 147
 148         no_mins = secs / 60;
 149
 150         no_secs = secs % 60;
 151         /* Make the seconds count as per the RTC resolution */
 152         no_secs = no_secs * COUNTS_PER_SEC;
 153
 154         buf[4] = no_secs & 0xFF;
 155         buf[3] = (no_secs >> 8) & 0xFF;
 156
 157         buf[2] = no_mins & 0xFF;
 158         buf[1] = (no_mins >> 8) & 0xFF;
 159         buf[0] = (no_mins >> 16) & 0xFF;
 160
 161         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 162                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 163                         ab8500_rtc_time_regs[i], buf[i]);
 164                 if (retval < 0)
 165                         return retval;
 166         }
 167
 168         /* Request a data write */
 169         return abx500_set_register_interruptible(dev, AB8500_RTC,
 170                 AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
 171 }
 172
 173 static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 174 {
 175         int retval, i;
 176         u8 rtc_ctrl, value;
 177         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 178         unsigned long secs, mins;
 179
 180         /* Check if the alarm is enabled or not */
 181         retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 182                 AB8500_RTC_STAT_REG, &rtc_ctrl);
 183         if (retval < 0)
 184                 return retval;
 185
 186         if (rtc_ctrl & RTC_ALARM_ENA)
 187                 alarm->enabled = 1;
 188         else
 189                 alarm->enabled = 0;
 190
 191         alarm->pending = 0;
 192
 193         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 194                 retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 195                         ab8500_rtc_alarm_regs[i], &value);
 196                 if (retval < 0)
 197                         return retval;
 198                 buf[i] = value;
 199         }
 200
 201         mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
 202         secs = mins * 60;
 203
 204         /* Add back the initially subtracted number of seconds */
 205         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 206
 207         rtc_time_to_tm(secs, &alarm->time);
 208
 209         return rtc_valid_tm(&alarm->time);
 210 }
 211
 212 static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
 213 {
 214         return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
 215                 AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
 216                 enabled ? RTC_ALARM_ENA : 0);
 217 }
 218
 219 static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 220 {
 221         int retval, i;
 222         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 223         unsigned long mins, secs = 0, cursec = 0;
 224         struct rtc_time curtm;
 225
 226         if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 227                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 228                                 AB8500_RTC_EPOCH);
 229                 return -EINVAL;
 230         }
 231
 232         /* Get the number of seconds since 1970 */
 233         rtc_tm_to_time(&alarm->time, &secs);
 234
 235         /*
 236          * Check whether alarm is set less than 1min.
 237          * Since our RTC doesn't support alarm resolution less than 1min,
 238          * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
 239          */
 240         ab8500_rtc_read_time(dev, &curtm); /* Read current time */
 241         rtc_tm_to_time(&curtm, &cursec);
 242         if ((secs - cursec) < 59) {
 243                 dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
 244                 return -EINVAL;
 245         }
 246
 247         /*
 248          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 249          * we only have a small counter in the RTC.
 250          */
 251         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 252
 253         mins = secs / 60;
 254
 255         buf[2] = mins & 0xFF;
 256         buf[1] = (mins >> 8) & 0xFF;
 257         buf[0] = (mins >> 16) & 0xFF;
 258
 259         /* Set the alarm time */
 260         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 261                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 262                         ab8500_rtc_alarm_regs[i], buf[i]);
 263                 if (retval < 0)
 264                         return retval;
 265         }
 266
 267         return ab8500_rtc_irq_enable(dev, alarm->enabled);
 268 }
 269
 270
 271 static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
 272 {
 273         int retval;
 274         u8  rtccal = 0;
 275
 276         /*
 277          * Check that the calibration value (which is in units of 0.5
 278          * parts-per-million) is in the AB8500's range for RtcCalibration
 279          * register. -128 (0x80) is not permitted because the AB8500 uses
 280          * a sign-bit rather than two's complement, so 0x80 is just another
 281          * representation of zero.
 282          */
 283         if ((calibration < -127) || (calibration > 127)) {
 284                 dev_err(dev, "RtcCalibration value outside permitted range\n");
 285                 return -EINVAL;
 286         }
 287
 288         /*
 289          * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 290          * so need to convert to this sort of representation before writing
 291          * into RtcCalibration register...
 292          */
 293         if (calibration >= 0)
 294                 rtccal = 0x7F & calibration;
 295         else
 296                 rtccal = ~(calibration - 1) | 0x80;
 297
 298         retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 299                         AB8500_RTC_CALIB_REG, rtccal);
 300
 301         return retval;
 302 }
 303
 304 static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
 305 {
 306         int retval;
 307         u8  rtccal = 0;
 308
 309         retval =  abx500_get_register_interruptible(dev, AB8500_RTC,
 310                         AB8500_RTC_CALIB_REG, &rtccal);
 311         if (retval >= 0) {
 312                 /*
 313                  * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 314                  * so need to convert value from RtcCalibration register into
 315                  * a two's complement signed value...
 316                  */
 317                 if (rtccal & 0x80)
 318                         *calibration = 0 - (rtccal & 0x7F);
 319                 else
 320                         *calibration = 0x7F & rtccal;
 321         }
 322
 323         return retval;
 324 }
 325
 326 static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
 327                                 struct device_attribute *attr,
 328                                 const char *buf, size_t count)
 329 {
 330         int retval;
 331         int calibration = 0;
 332
 333         if (sscanf(buf, " %i ", &calibration) != 1) {
 334                 dev_err(dev, "Failed to store RTC calibration attribute\n");
 335                 return -EINVAL;
 336         }
 337
 338         retval = ab8500_rtc_set_calibration(dev, calibration);
 339
 340         return retval ? retval : count;
 341 }
 342
 343 static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
 344                                 struct device_attribute *attr, char *buf)
 345 {
 346         int  retval = 0;
 347         int  calibration = 0;
 348
 349         retval = ab8500_rtc_get_calibration(dev, &calibration);
 350         if (retval < 0) {
 351                 dev_err(dev, "Failed to read RTC calibration attribute\n");
 352                 sprintf(buf, "0\n");
 353                 return retval;
 354         }
 355
 356         return sprintf(buf, "%d\n", calibration);
 357 }
 358
 359 static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
 360                    ab8500_sysfs_show_rtc_calibration,
 361                    ab8500_sysfs_store_rtc_calibration);
 362
 363 static int ab8500_sysfs_rtc_register(struct device *dev)
 364 {
 365         return device_create_file(dev, &dev_attr_rtc_calibration);
 366 }
 367
 368 static void ab8500_sysfs_rtc_unregister(struct device *dev)
 369 {
 370         device_remove_file(dev, &dev_attr_rtc_calibration);
 371 }
 372
 373 static irqreturn_t rtc_alarm_handler(int irq, void *data)
 374 {
 375         struct rtc_device *rtc = data;
 376         unsigned long events = RTC_IRQF | RTC_AF;
 377
 378         dev_dbg(&rtc->dev, "%s\n", __func__);
 379         rtc_update_irq(rtc, 1, events);
 380
 381         return IRQ_HANDLED;
 382 }
 383
 384 static const struct rtc_class_ops ab8500_rtc_ops = {
 385         .read_time              = ab8500_rtc_read_time,
 386         .set_time               = ab8500_rtc_set_time,
 387         .read_alarm             = ab8500_rtc_read_alarm,
 388         .set_alarm              = ab8500_rtc_set_alarm,
 389         .alarm_irq_enable       = ab8500_rtc_irq_enable,
 390 };
 391
 392 static int ab8500_rtc_probe(struct platform_device *pdev)
 393 {
 394         int err;
 395         struct rtc_device *rtc;
 396         u8 rtc_ctrl;
 397         int irq;
 398
 399         irq = platform_get_irq_byname(pdev, "ALARM");
 400         if (irq < 0)
 401                 return irq;
 402
 403         /* For RTC supply test */
 404         err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
 405                 AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
 406         if (err < 0)
 407                 return err;
 408
 409         /* Wait for reset by the PorRtc */
 410         usleep_range(1000, 5000);
 411
 412         err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
 413                 AB8500_RTC_STAT_REG, &rtc_ctrl);
 414         if (err < 0)
 415                 return err;
 416
 417         /* Check if the RTC Supply fails */
 418         if (!(rtc_ctrl & RTC_STATUS_DATA)) {
 419                 dev_err(&pdev->dev, "RTC supply failure\n");
 420                 return -ENODEV;
 421         }
 422
 423         device_init_wakeup(&pdev->dev, true);
 424
 425         rtc = rtc_device_register("ab8500-rtc", &pdev->dev, &ab8500_rtc_ops,
 426                         THIS_MODULE);
 427         if (IS_ERR(rtc)) {
 428                 dev_err(&pdev->dev, "Registration failed\n");
 429                 err = PTR_ERR(rtc);
 430                 return err;
 431         }
 432
 433         err = request_threaded_irq(irq, NULL, rtc_alarm_handler,
 434                 IRQF_NO_SUSPEND | IRQF_ONESHOT, "ab8500-rtc", rtc);
 435         if (err < 0) {
 436                 rtc_device_unregister(rtc);
 437                 return err;
 438         }
 439
 440         platform_set_drvdata(pdev, rtc);
 441
 442         err = ab8500_sysfs_rtc_register(&pdev->dev);
 443         if (err) {
 444                 dev_err(&pdev->dev, "sysfs RTC failed to register\n");
 445                 return err;
 446         }
 447
 448         return 0;
 449 }
 450
 451 static int ab8500_rtc_remove(struct platform_device *pdev)
 452 {
 453         struct rtc_device *rtc = platform_get_drvdata(pdev);
 454         int irq = platform_get_irq_byname(pdev, "ALARM");
 455
 456         ab8500_sysfs_rtc_unregister(&pdev->dev);
 457
 458         free_irq(irq, rtc);
 459         rtc_device_unregister(rtc);
 460         platform_set_drvdata(pdev, NULL);
 461
 462         return 0;
 463 }
 464
 465 static struct platform_driver ab8500_rtc_driver = {
 466         .driver = {
 467                 .name = "ab8500-rtc",
 468                 .owner = THIS_MODULE,
 469         },
 470         .probe  = ab8500_rtc_probe,
 471         .remove = ab8500_rtc_remove,
 472 };
 473
 474 module_platform_driver(ab8500_rtc_driver);
 475
 476 MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
 477 MODULE_DESCRIPTION("AB8500 RTC Driver");
 478 MODULE_LICENSE("GPL v2");