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 #define AB8540_RTC_ALRM_SEC             0x22
  39 #define AB8540_RTC_ALRM_MIN_LOW_REG     0x23
  40 #define AB8540_RTC_ALRM_MIN_MID_REG     0x24
  41 #define AB8540_RTC_ALRM_MIN_HI_REG      0x25
  42
  43 /* RtcReadRequest bits */
  44 #define RTC_READ_REQUEST                0x01
  45 #define RTC_WRITE_REQUEST               0x02
  46
  47 /* RtcCtrl bits */
  48 #define RTC_ALARM_ENA                   0x04
  49 #define RTC_STATUS_DATA                 0x01
  50
  51 #define COUNTS_PER_SEC                  (0xF000 / 60)
  52 #define AB8500_RTC_EPOCH                2000
  53
  54 static const u8 ab8500_rtc_time_regs[] = {
  55         AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
  56         AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
  57         AB8500_RTC_WATCH_TSECMID_REG
  58 };
  59
  60 static const u8 ab8500_rtc_alarm_regs[] = {
  61         AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
  62         AB8500_RTC_ALRM_MIN_LOW_REG
  63 };
  64
  65 static const u8 ab8540_rtc_alarm_regs[] = {
  66         AB8540_RTC_ALRM_MIN_HI_REG, AB8540_RTC_ALRM_MIN_MID_REG,
  67         AB8540_RTC_ALRM_MIN_LOW_REG, AB8540_RTC_ALRM_SEC
  68 };
  69
  70 /* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
  71 static unsigned long get_elapsed_seconds(int year)
  72 {
  73         unsigned long secs;
  74         struct rtc_time tm = {
  75                 .tm_year = year - 1900,
  76                 .tm_mday = 1,
  77         };
  78
  79         /*
  80          * This function calculates secs from 1970 and not from
  81          * 1900, even if we supply the offset from year 1900.
  82          */
  83         rtc_tm_to_time(&tm, &secs);
  84         return secs;
  85 }
  86
  87 static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
  88 {
  89         unsigned long timeout = jiffies + HZ;
  90         int retval, i;
  91         unsigned long mins, secs;
  92         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
  93         u8 value;
  94
  95         /* Request a data read */
  96         retval = abx500_set_register_interruptible(dev,
  97                 AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
  98         if (retval < 0)
  99                 return retval;
 100
 101         /* Wait for some cycles after enabling the rtc read in ab8500 */
 102         while (time_before(jiffies, timeout)) {
 103                 retval = abx500_get_register_interruptible(dev,
 104                         AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
 105                 if (retval < 0)
 106                         return retval;
 107
 108                 if (!(value & RTC_READ_REQUEST))
 109                         break;
 110
 111                 usleep_range(1000, 5000);
 112         }
 113
 114         /* Read the Watchtime registers */
 115         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 116                 retval = abx500_get_register_interruptible(dev,
 117                         AB8500_RTC, ab8500_rtc_time_regs[i], &value);
 118                 if (retval < 0)
 119                         return retval;
 120                 buf[i] = value;
 121         }
 122
 123         mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
 124
 125         secs =  (buf[3] << 8) | buf[4];
 126         secs =  secs / COUNTS_PER_SEC;
 127         secs =  secs + (mins * 60);
 128
 129         /* Add back the initially subtracted number of seconds */
 130         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 131
 132         rtc_time_to_tm(secs, tm);
 133         return rtc_valid_tm(tm);
 134 }
 135
 136 static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
 137 {
 138         int retval, i;
 139         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 140         unsigned long no_secs, no_mins, secs = 0;
 141
 142         if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
 143                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 144                                 AB8500_RTC_EPOCH);
 145                 return -EINVAL;
 146         }
 147
 148         /* Get the number of seconds since 1970 */
 149         rtc_tm_to_time(tm, &secs);
 150
 151         /*
 152          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 153          * we only have a small counter in the RTC.
 154          */
 155         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 156
 157         no_mins = secs / 60;
 158
 159         no_secs = secs % 60;
 160         /* Make the seconds count as per the RTC resolution */
 161         no_secs = no_secs * COUNTS_PER_SEC;
 162
 163         buf[4] = no_secs & 0xFF;
 164         buf[3] = (no_secs >> 8) & 0xFF;
 165
 166         buf[2] = no_mins & 0xFF;
 167         buf[1] = (no_mins >> 8) & 0xFF;
 168         buf[0] = (no_mins >> 16) & 0xFF;
 169
 170         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 171                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 172                         ab8500_rtc_time_regs[i], buf[i]);
 173                 if (retval < 0)
 174                         return retval;
 175         }
 176
 177         /* Request a data write */
 178         return abx500_set_register_interruptible(dev, AB8500_RTC,
 179                 AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
 180 }
 181
 182 static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 183 {
 184         int retval, i;
 185         u8 rtc_ctrl, value;
 186         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 187         unsigned long secs, mins;
 188
 189         /* Check if the alarm is enabled or not */
 190         retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 191                 AB8500_RTC_STAT_REG, &rtc_ctrl);
 192         if (retval < 0)
 193                 return retval;
 194
 195         if (rtc_ctrl & RTC_ALARM_ENA)
 196                 alarm->enabled = 1;
 197         else
 198                 alarm->enabled = 0;
 199
 200         alarm->pending = 0;
 201
 202         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 203                 retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 204                         ab8500_rtc_alarm_regs[i], &value);
 205                 if (retval < 0)
 206                         return retval;
 207                 buf[i] = value;
 208         }
 209
 210         mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
 211         secs = mins * 60;
 212
 213         /* Add back the initially subtracted number of seconds */
 214         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 215
 216         rtc_time_to_tm(secs, &alarm->time);
 217
 218         return rtc_valid_tm(&alarm->time);
 219 }
 220
 221 static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
 222 {
 223         return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
 224                 AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
 225                 enabled ? RTC_ALARM_ENA : 0);
 226 }
 227
 228 static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 229 {
 230         int retval, i;
 231         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 232         unsigned long mins, secs = 0, cursec = 0;
 233         struct rtc_time curtm;
 234
 235         if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 236                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 237                                 AB8500_RTC_EPOCH);
 238                 return -EINVAL;
 239         }
 240
 241         /* Get the number of seconds since 1970 */
 242         rtc_tm_to_time(&alarm->time, &secs);
 243
 244         /*
 245          * Check whether alarm is set less than 1min.
 246          * Since our RTC doesn't support alarm resolution less than 1min,
 247          * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
 248          */
 249         ab8500_rtc_read_time(dev, &curtm); /* Read current time */
 250         rtc_tm_to_time(&curtm, &cursec);
 251         if ((secs - cursec) < 59) {
 252                 dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
 253                 return -EINVAL;
 254         }
 255
 256         /*
 257          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 258          * we only have a small counter in the RTC.
 259          */
 260         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 261
 262         mins = secs / 60;
 263
 264         buf[2] = mins & 0xFF;
 265         buf[1] = (mins >> 8) & 0xFF;
 266         buf[0] = (mins >> 16) & 0xFF;
 267
 268         /* Set the alarm time */
 269         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 270                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 271                         ab8500_rtc_alarm_regs[i], buf[i]);
 272                 if (retval < 0)
 273                         return retval;
 274         }
 275
 276         return ab8500_rtc_irq_enable(dev, alarm->enabled);
 277 }
 278
 279 static int ab8540_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 280 {
 281         int retval, i;
 282         unsigned char buf[ARRAY_SIZE(ab8540_rtc_alarm_regs)];
 283         unsigned long mins, secs = 0;
 284
 285         if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 286                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 287                                 AB8500_RTC_EPOCH);
 288                 return -EINVAL;
 289         }
 290
 291         /* Get the number of seconds since 1970 */
 292         rtc_tm_to_time(&alarm->time, &secs);
 293
 294         /*
 295          * Convert it to the number of seconds since 01-01-2000 00:00:00
 296          */
 297         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 298         mins = secs / 60;
 299
 300         buf[3] = secs % 60;
 301         buf[2] = mins & 0xFF;
 302         buf[1] = (mins >> 8) & 0xFF;
 303         buf[0] = (mins >> 16) & 0xFF;
 304
 305         /* Set the alarm time */
 306         for (i = 0; i < ARRAY_SIZE(ab8540_rtc_alarm_regs); i++) {
 307                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 308                         ab8540_rtc_alarm_regs[i], buf[i]);
 309                 if (retval < 0)
 310                         return retval;
 311         }
 312
 313         return ab8500_rtc_irq_enable(dev, alarm->enabled);
 314 }
 315
 316 static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
 317 {
 318         int retval;
 319         u8  rtccal = 0;
 320
 321         /*
 322          * Check that the calibration value (which is in units of 0.5
 323          * parts-per-million) is in the AB8500's range for RtcCalibration
 324          * register. -128 (0x80) is not permitted because the AB8500 uses
 325          * a sign-bit rather than two's complement, so 0x80 is just another
 326          * representation of zero.
 327          */
 328         if ((calibration < -127) || (calibration > 127)) {
 329                 dev_err(dev, "RtcCalibration value outside permitted range\n");
 330                 return -EINVAL;
 331         }
 332
 333         /*
 334          * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 335          * so need to convert to this sort of representation before writing
 336          * into RtcCalibration register...
 337          */
 338         if (calibration >= 0)
 339                 rtccal = 0x7F & calibration;
 340         else
 341                 rtccal = ~(calibration - 1) | 0x80;
 342
 343         retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 344                         AB8500_RTC_CALIB_REG, rtccal);
 345
 346         return retval;
 347 }
 348
 349 static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
 350 {
 351         int retval;
 352         u8  rtccal = 0;
 353
 354         retval =  abx500_get_register_interruptible(dev, AB8500_RTC,
 355                         AB8500_RTC_CALIB_REG, &rtccal);
 356         if (retval >= 0) {
 357                 /*
 358                  * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 359                  * so need to convert value from RtcCalibration register into
 360                  * a two's complement signed value...
 361                  */
 362                 if (rtccal & 0x80)
 363                         *calibration = 0 - (rtccal & 0x7F);
 364                 else
 365                         *calibration = 0x7F & rtccal;
 366         }
 367
 368         return retval;
 369 }
 370
 371 static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
 372                                 struct device_attribute *attr,
 373                                 const char *buf, size_t count)
 374 {
 375         int retval;
 376         int calibration = 0;
 377
 378         if (sscanf(buf, " %i ", &calibration) != 1) {
 379                 dev_err(dev, "Failed to store RTC calibration attribute\n");
 380                 return -EINVAL;
 381         }
 382
 383         retval = ab8500_rtc_set_calibration(dev, calibration);
 384
 385         return retval ? retval : count;
 386 }
 387
 388 static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
 389                                 struct device_attribute *attr, char *buf)
 390 {
 391         int  retval = 0;
 392         int  calibration = 0;
 393
 394         retval = ab8500_rtc_get_calibration(dev, &calibration);
 395         if (retval < 0) {
 396                 dev_err(dev, "Failed to read RTC calibration attribute\n");
 397                 sprintf(buf, "0\n");
 398                 return retval;
 399         }
 400
 401         return sprintf(buf, "%d\n", calibration);
 402 }
 403
 404 static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
 405                    ab8500_sysfs_show_rtc_calibration,
 406                    ab8500_sysfs_store_rtc_calibration);
 407
 408 static int ab8500_sysfs_rtc_register(struct device *dev)
 409 {
 410         return device_create_file(dev, &dev_attr_rtc_calibration);
 411 }
 412
 413 static void ab8500_sysfs_rtc_unregister(struct device *dev)
 414 {
 415         device_remove_file(dev, &dev_attr_rtc_calibration);
 416 }
 417
 418 static irqreturn_t rtc_alarm_handler(int irq, void *data)
 419 {
 420         struct rtc_device *rtc = data;
 421         unsigned long events = RTC_IRQF | RTC_AF;
 422
 423         dev_dbg(&rtc->dev, "%s\n", __func__);
 424         rtc_update_irq(rtc, 1, events);
 425
 426         return IRQ_HANDLED;
 427 }
 428
 429 static const struct rtc_class_ops ab8500_rtc_ops = {
 430         .read_time              = ab8500_rtc_read_time,
 431         .set_time               = ab8500_rtc_set_time,
 432         .read_alarm             = ab8500_rtc_read_alarm,
 433         .set_alarm              = ab8500_rtc_set_alarm,
 434         .alarm_irq_enable       = ab8500_rtc_irq_enable,
 435 };
 436
 437 static const struct rtc_class_ops ab8540_rtc_ops = {
 438         .read_time              = ab8500_rtc_read_time,
 439         .set_time               = ab8500_rtc_set_time,
 440         .read_alarm             = ab8500_rtc_read_alarm,
 441         .set_alarm              = ab8540_rtc_set_alarm,
 442         .alarm_irq_enable       = ab8500_rtc_irq_enable,
 443 };
 444
 445 static struct platform_device_id ab85xx_rtc_ids[] = {
 446         { "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
 447         { "ab8540-rtc", (kernel_ulong_t)&ab8540_rtc_ops, },
 448 };
 449
 450 static int ab8500_rtc_probe(struct platform_device *pdev)
 451 {
 452         const struct platform_device_id *platid = platform_get_device_id(pdev);
 453         int err;
 454         struct rtc_device *rtc;
 455         u8 rtc_ctrl;
 456         int irq;
 457
 458         irq = platform_get_irq_byname(pdev, "ALARM");
 459         if (irq < 0)
 460                 return irq;
 461
 462         /* For RTC supply test */
 463         err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
 464                 AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
 465         if (err < 0)
 466                 return err;
 467
 468         /* Wait for reset by the PorRtc */
 469         usleep_range(1000, 5000);
 470
 471         err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
 472                 AB8500_RTC_STAT_REG, &rtc_ctrl);
 473         if (err < 0)
 474                 return err;
 475
 476         /* Check if the RTC Supply fails */
 477         if (!(rtc_ctrl & RTC_STATUS_DATA)) {
 478                 dev_err(&pdev->dev, "RTC supply failure\n");
 479                 return -ENODEV;
 480         }
 481
 482         device_init_wakeup(&pdev->dev, true);
 483
 484         rtc = devm_rtc_device_register(&pdev->dev, "ab8500-rtc",
 485                                 (struct rtc_class_ops *)platid->driver_data,
 486                                 THIS_MODULE);
 487         if (IS_ERR(rtc)) {
 488                 dev_err(&pdev->dev, "Registration failed\n");
 489                 err = PTR_ERR(rtc);
 490                 return err;
 491         }
 492
 493         err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
 494                         rtc_alarm_handler, IRQF_NO_SUSPEND | IRQF_ONESHOT,
 495                         "ab8500-rtc", rtc);
 496         if (err < 0)
 497                 return err;
 498
 499         platform_set_drvdata(pdev, rtc);
 500
 501         err = ab8500_sysfs_rtc_register(&pdev->dev);
 502         if (err) {
 503                 dev_err(&pdev->dev, "sysfs RTC failed to register\n");
 504                 return err;
 505         }
 506
 507         return 0;
 508 }
 509
 510 static int ab8500_rtc_remove(struct platform_device *pdev)
 511 {
 512         ab8500_sysfs_rtc_unregister(&pdev->dev);
 513
 514         return 0;
 515 }
 516
 517 static struct platform_driver ab8500_rtc_driver = {
 518         .driver = {
 519                 .name = "ab8500-rtc",
 520                 .owner = THIS_MODULE,
 521         },
 522         .probe  = ab8500_rtc_probe,
 523         .remove = ab8500_rtc_remove,
 524         .id_table = ab85xx_rtc_ids,
 525 };
 526
 527 module_platform_driver(ab8500_rtc_driver);
 528
 529 MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
 530 MODULE_DESCRIPTION("AB8500 RTC Driver");
 531 MODULE_LICENSE("GPL v2");