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 #include <linux/pm_wakeirq.h>
  22
  23 #define AB8500_RTC_SOFF_STAT_REG        0x00
  24 #define AB8500_RTC_CC_CONF_REG          0x01
  25 #define AB8500_RTC_READ_REQ_REG         0x02
  26 #define AB8500_RTC_WATCH_TSECMID_REG    0x03
  27 #define AB8500_RTC_WATCH_TSECHI_REG     0x04
  28 #define AB8500_RTC_WATCH_TMIN_LOW_REG   0x05
  29 #define AB8500_RTC_WATCH_TMIN_MID_REG   0x06
  30 #define AB8500_RTC_WATCH_TMIN_HI_REG    0x07
  31 #define AB8500_RTC_ALRM_MIN_LOW_REG     0x08
  32 #define AB8500_RTC_ALRM_MIN_MID_REG     0x09
  33 #define AB8500_RTC_ALRM_MIN_HI_REG      0x0A
  34 #define AB8500_RTC_STAT_REG             0x0B
  35 #define AB8500_RTC_BKUP_CHG_REG         0x0C
  36 #define AB8500_RTC_FORCE_BKUP_REG       0x0D
  37 #define AB8500_RTC_CALIB_REG            0x0E
  38 #define AB8500_RTC_SWITCH_STAT_REG      0x0F
  39 #define AB8540_RTC_ALRM_SEC             0x22
  40 #define AB8540_RTC_ALRM_MIN_LOW_REG     0x23
  41 #define AB8540_RTC_ALRM_MIN_MID_REG     0x24
  42 #define AB8540_RTC_ALRM_MIN_HI_REG      0x25
  43
  44 /* RtcReadRequest bits */
  45 #define RTC_READ_REQUEST                0x01
  46 #define RTC_WRITE_REQUEST               0x02
  47
  48 /* RtcCtrl bits */
  49 #define RTC_ALARM_ENA                   0x04
  50 #define RTC_STATUS_DATA                 0x01
  51
  52 #define COUNTS_PER_SEC                  (0xF000 / 60)
  53 #define AB8500_RTC_EPOCH                2000
  54
  55 static const u8 ab8500_rtc_time_regs[] = {
  56         AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
  57         AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
  58         AB8500_RTC_WATCH_TSECMID_REG
  59 };
  60
  61 static const u8 ab8500_rtc_alarm_regs[] = {
  62         AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
  63         AB8500_RTC_ALRM_MIN_LOW_REG
  64 };
  65
  66 static const u8 ab8540_rtc_alarm_regs[] = {
  67         AB8540_RTC_ALRM_MIN_HI_REG, AB8540_RTC_ALRM_MIN_MID_REG,
  68         AB8540_RTC_ALRM_MIN_LOW_REG, AB8540_RTC_ALRM_SEC
  69 };
  70
  71 /* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
  72 static unsigned long get_elapsed_seconds(int year)
  73 {
  74         unsigned long secs;
  75         struct rtc_time tm = {
  76                 .tm_year = year - 1900,
  77                 .tm_mday = 1,
  78         };
  79
  80         /*
  81          * This function calculates secs from 1970 and not from
  82          * 1900, even if we supply the offset from year 1900.
  83          */
  84         rtc_tm_to_time(&tm, &secs);
  85         return secs;
  86 }
  87
  88 static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
  89 {
  90         unsigned long timeout = jiffies + HZ;
  91         int retval, i;
  92         unsigned long mins, secs;
  93         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
  94         u8 value;
  95
  96         /* Request a data read */
  97         retval = abx500_set_register_interruptible(dev,
  98                 AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
  99         if (retval < 0)
 100                 return retval;
 101
 102         /* Wait for some cycles after enabling the rtc read in ab8500 */
 103         while (time_before(jiffies, timeout)) {
 104                 retval = abx500_get_register_interruptible(dev,
 105                         AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
 106                 if (retval < 0)
 107                         return retval;
 108
 109                 if (!(value & RTC_READ_REQUEST))
 110                         break;
 111
 112                 usleep_range(1000, 5000);
 113         }
 114
 115         /* Read the Watchtime registers */
 116         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 117                 retval = abx500_get_register_interruptible(dev,
 118                         AB8500_RTC, ab8500_rtc_time_regs[i], &value);
 119                 if (retval < 0)
 120                         return retval;
 121                 buf[i] = value;
 122         }
 123
 124         mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
 125
 126         secs =  (buf[3] << 8) | buf[4];
 127         secs =  secs / COUNTS_PER_SEC;
 128         secs =  secs + (mins * 60);
 129
 130         /* Add back the initially subtracted number of seconds */
 131         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 132
 133         rtc_time_to_tm(secs, tm);
 134         return rtc_valid_tm(tm);
 135 }
 136
 137 static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
 138 {
 139         int retval, i;
 140         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 141         unsigned long no_secs, no_mins, secs = 0;
 142
 143         if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
 144                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 145                                 AB8500_RTC_EPOCH);
 146                 return -EINVAL;
 147         }
 148
 149         /* Get the number of seconds since 1970 */
 150         rtc_tm_to_time(tm, &secs);
 151
 152         /*
 153          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 154          * we only have a small counter in the RTC.
 155          */
 156         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 157
 158         no_mins = secs / 60;
 159
 160         no_secs = secs % 60;
 161         /* Make the seconds count as per the RTC resolution */
 162         no_secs = no_secs * COUNTS_PER_SEC;
 163
 164         buf[4] = no_secs & 0xFF;
 165         buf[3] = (no_secs >> 8) & 0xFF;
 166
 167         buf[2] = no_mins & 0xFF;
 168         buf[1] = (no_mins >> 8) & 0xFF;
 169         buf[0] = (no_mins >> 16) & 0xFF;
 170
 171         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 172                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 173                         ab8500_rtc_time_regs[i], buf[i]);
 174                 if (retval < 0)
 175                         return retval;
 176         }
 177
 178         /* Request a data write */
 179         return abx500_set_register_interruptible(dev, AB8500_RTC,
 180                 AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
 181 }
 182
 183 static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 184 {
 185         int retval, i;
 186         u8 rtc_ctrl, value;
 187         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 188         unsigned long secs, mins;
 189
 190         /* Check if the alarm is enabled or not */
 191         retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 192                 AB8500_RTC_STAT_REG, &rtc_ctrl);
 193         if (retval < 0)
 194                 return retval;
 195
 196         if (rtc_ctrl & RTC_ALARM_ENA)
 197                 alarm->enabled = 1;
 198         else
 199                 alarm->enabled = 0;
 200
 201         alarm->pending = 0;
 202
 203         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 204                 retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 205                         ab8500_rtc_alarm_regs[i], &value);
 206                 if (retval < 0)
 207                         return retval;
 208                 buf[i] = value;
 209         }
 210
 211         mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
 212         secs = mins * 60;
 213
 214         /* Add back the initially subtracted number of seconds */
 215         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 216
 217         rtc_time_to_tm(secs, &alarm->time);
 218
 219         return rtc_valid_tm(&alarm->time);
 220 }
 221
 222 static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
 223 {
 224         return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
 225                 AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
 226                 enabled ? RTC_ALARM_ENA : 0);
 227 }
 228
 229 static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 230 {
 231         int retval, i;
 232         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 233         unsigned long mins, secs = 0, cursec = 0;
 234         struct rtc_time curtm;
 235
 236         if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 237                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 238                                 AB8500_RTC_EPOCH);
 239                 return -EINVAL;
 240         }
 241
 242         /* Get the number of seconds since 1970 */
 243         rtc_tm_to_time(&alarm->time, &secs);
 244
 245         /*
 246          * Check whether alarm is set less than 1min.
 247          * Since our RTC doesn't support alarm resolution less than 1min,
 248          * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
 249          */
 250         ab8500_rtc_read_time(dev, &curtm); /* Read current time */
 251         rtc_tm_to_time(&curtm, &cursec);
 252         if ((secs - cursec) < 59) {
 253                 dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
 254                 return -EINVAL;
 255         }
 256
 257         /*
 258          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 259          * we only have a small counter in the RTC.
 260          */
 261         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 262
 263         mins = secs / 60;
 264
 265         buf[2] = mins & 0xFF;
 266         buf[1] = (mins >> 8) & 0xFF;
 267         buf[0] = (mins >> 16) & 0xFF;
 268
 269         /* Set the alarm time */
 270         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 271                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 272                         ab8500_rtc_alarm_regs[i], buf[i]);
 273                 if (retval < 0)
 274                         return retval;
 275         }
 276
 277         return ab8500_rtc_irq_enable(dev, alarm->enabled);
 278 }
 279
 280 static int ab8540_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 281 {
 282         int retval, i;
 283         unsigned char buf[ARRAY_SIZE(ab8540_rtc_alarm_regs)];
 284         unsigned long mins, secs = 0;
 285
 286         if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 287                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 288                                 AB8500_RTC_EPOCH);
 289                 return -EINVAL;
 290         }
 291
 292         /* Get the number of seconds since 1970 */
 293         rtc_tm_to_time(&alarm->time, &secs);
 294
 295         /*
 296          * Convert it to the number of seconds since 01-01-2000 00:00:00
 297          */
 298         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 299         mins = secs / 60;
 300
 301         buf[3] = secs % 60;
 302         buf[2] = mins & 0xFF;
 303         buf[1] = (mins >> 8) & 0xFF;
 304         buf[0] = (mins >> 16) & 0xFF;
 305
 306         /* Set the alarm time */
 307         for (i = 0; i < ARRAY_SIZE(ab8540_rtc_alarm_regs); i++) {
 308                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 309                         ab8540_rtc_alarm_regs[i], buf[i]);
 310                 if (retval < 0)
 311                         return retval;
 312         }
 313
 314         return ab8500_rtc_irq_enable(dev, alarm->enabled);
 315 }
 316
 317 static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
 318 {
 319         int retval;
 320         u8  rtccal = 0;
 321
 322         /*
 323          * Check that the calibration value (which is in units of 0.5
 324          * parts-per-million) is in the AB8500's range for RtcCalibration
 325          * register. -128 (0x80) is not permitted because the AB8500 uses
 326          * a sign-bit rather than two's complement, so 0x80 is just another
 327          * representation of zero.
 328          */
 329         if ((calibration < -127) || (calibration > 127)) {
 330                 dev_err(dev, "RtcCalibration value outside permitted range\n");
 331                 return -EINVAL;
 332         }
 333
 334         /*
 335          * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 336          * so need to convert to this sort of representation before writing
 337          * into RtcCalibration register...
 338          */
 339         if (calibration >= 0)
 340                 rtccal = 0x7F & calibration;
 341         else
 342                 rtccal = ~(calibration - 1) | 0x80;
 343
 344         retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 345                         AB8500_RTC_CALIB_REG, rtccal);
 346
 347         return retval;
 348 }
 349
 350 static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
 351 {
 352         int retval;
 353         u8  rtccal = 0;
 354
 355         retval =  abx500_get_register_interruptible(dev, AB8500_RTC,
 356                         AB8500_RTC_CALIB_REG, &rtccal);
 357         if (retval >= 0) {
 358                 /*
 359                  * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 360                  * so need to convert value from RtcCalibration register into
 361                  * a two's complement signed value...
 362                  */
 363                 if (rtccal & 0x80)
 364                         *calibration = 0 - (rtccal & 0x7F);
 365                 else
 366                         *calibration = 0x7F & rtccal;
 367         }
 368
 369         return retval;
 370 }
 371
 372 static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
 373                                 struct device_attribute *attr,
 374                                 const char *buf, size_t count)
 375 {
 376         int retval;
 377         int calibration = 0;
 378
 379         if (sscanf(buf, " %i ", &calibration) != 1) {
 380                 dev_err(dev, "Failed to store RTC calibration attribute\n");
 381                 return -EINVAL;
 382         }
 383
 384         retval = ab8500_rtc_set_calibration(dev, calibration);
 385
 386         return retval ? retval : count;
 387 }
 388
 389 static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
 390                                 struct device_attribute *attr, char *buf)
 391 {
 392         int  retval = 0;
 393         int  calibration = 0;
 394
 395         retval = ab8500_rtc_get_calibration(dev, &calibration);
 396         if (retval < 0) {
 397                 dev_err(dev, "Failed to read RTC calibration attribute\n");
 398                 sprintf(buf, "0\n");
 399                 return retval;
 400         }
 401
 402         return sprintf(buf, "%d\n", calibration);
 403 }
 404
 405 static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
 406                    ab8500_sysfs_show_rtc_calibration,
 407                    ab8500_sysfs_store_rtc_calibration);
 408
 409 static int ab8500_sysfs_rtc_register(struct device *dev)
 410 {
 411         return device_create_file(dev, &dev_attr_rtc_calibration);
 412 }
 413
 414 static void ab8500_sysfs_rtc_unregister(struct device *dev)
 415 {
 416         device_remove_file(dev, &dev_attr_rtc_calibration);
 417 }
 418
 419 static irqreturn_t rtc_alarm_handler(int irq, void *data)
 420 {
 421         struct rtc_device *rtc = data;
 422         unsigned long events = RTC_IRQF | RTC_AF;
 423
 424         dev_dbg(&rtc->dev, "%s\n", __func__);
 425         rtc_update_irq(rtc, 1, events);
 426
 427         return IRQ_HANDLED;
 428 }
 429
 430 static const struct rtc_class_ops ab8500_rtc_ops = {
 431         .read_time              = ab8500_rtc_read_time,
 432         .set_time               = ab8500_rtc_set_time,
 433         .read_alarm             = ab8500_rtc_read_alarm,
 434         .set_alarm              = ab8500_rtc_set_alarm,
 435         .alarm_irq_enable       = ab8500_rtc_irq_enable,
 436 };
 437
 438 static const struct rtc_class_ops ab8540_rtc_ops = {
 439         .read_time              = ab8500_rtc_read_time,
 440         .set_time               = ab8500_rtc_set_time,
 441         .read_alarm             = ab8500_rtc_read_alarm,
 442         .set_alarm              = ab8540_rtc_set_alarm,
 443         .alarm_irq_enable       = ab8500_rtc_irq_enable,
 444 };
 445
 446 static const struct platform_device_id ab85xx_rtc_ids[] = {
 447         { "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
 448         { "ab8540-rtc", (kernel_ulong_t)&ab8540_rtc_ops, },
 449         { /* sentinel */ }
 450 };
 451 MODULE_DEVICE_TABLE(platform, ab85xx_rtc_ids);
 452
 453 static int ab8500_rtc_probe(struct platform_device *pdev)
 454 {
 455         const struct platform_device_id *platid = platform_get_device_id(pdev);
 456         int err;
 457         struct rtc_device *rtc;
 458         u8 rtc_ctrl;
 459         int irq;
 460
 461         irq = platform_get_irq_byname(pdev, "ALARM");
 462         if (irq < 0)
 463                 return irq;
 464
 465         /* For RTC supply test */
 466         err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
 467                 AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
 468         if (err < 0)
 469                 return err;
 470
 471         /* Wait for reset by the PorRtc */
 472         usleep_range(1000, 5000);
 473
 474         err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
 475                 AB8500_RTC_STAT_REG, &rtc_ctrl);
 476         if (err < 0)
 477                 return err;
 478
 479         /* Check if the RTC Supply fails */
 480         if (!(rtc_ctrl & RTC_STATUS_DATA)) {
 481                 dev_err(&pdev->dev, "RTC supply failure\n");
 482                 return -ENODEV;
 483         }
 484
 485         device_init_wakeup(&pdev->dev, true);
 486
 487         rtc = devm_rtc_device_register(&pdev->dev, "ab8500-rtc",
 488                                 (struct rtc_class_ops *)platid->driver_data,
 489                                 THIS_MODULE);
 490         if (IS_ERR(rtc)) {
 491                 dev_err(&pdev->dev, "Registration failed\n");
 492                 err = PTR_ERR(rtc);
 493                 return err;
 494         }
 495
 496         err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
 497                         rtc_alarm_handler, IRQF_ONESHOT,
 498                         "ab8500-rtc", rtc);
 499         if (err < 0)
 500                 return err;
 501
 502         dev_pm_set_wake_irq(&pdev->dev, irq);
 503         platform_set_drvdata(pdev, rtc);
 504
 505         err = ab8500_sysfs_rtc_register(&pdev->dev);
 506         if (err) {
 507                 dev_err(&pdev->dev, "sysfs RTC failed to register\n");
 508                 return err;
 509         }
 510
 511         rtc->uie_unsupported = 1;
 512
 513         return 0;
 514 }
 515
 516 static int ab8500_rtc_remove(struct platform_device *pdev)
 517 {
 518         dev_pm_clear_wake_irq(&pdev->dev);
 519         device_init_wakeup(&pdev->dev, false);
 520         ab8500_sysfs_rtc_unregister(&pdev->dev);
 521
 522         return 0;
 523 }
 524
 525 static struct platform_driver ab8500_rtc_driver = {
 526         .driver = {
 527                 .name = "ab8500-rtc",
 528         },
 529         .probe  = ab8500_rtc_probe,
 530         .remove = ab8500_rtc_remove,
 531         .id_table = ab85xx_rtc_ids,
 532 };
 533
 534 module_platform_driver(ab8500_rtc_driver);
 535
 536 MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
 537 MODULE_DESCRIPTION("AB8500 RTC Driver");
 538 MODULE_LICENSE("GPL v2");