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
  40 /* RtcReadRequest bits */
  41 #define RTC_READ_REQUEST                0x01
  42 #define RTC_WRITE_REQUEST               0x02
  43
  44 /* RtcCtrl bits */
  45 #define RTC_ALARM_ENA                   0x04
  46 #define RTC_STATUS_DATA                 0x01
  47
  48 #define COUNTS_PER_SEC                  (0xF000 / 60)
  49 #define AB8500_RTC_EPOCH                2000
  50
  51 static const u8 ab8500_rtc_time_regs[] = {
  52         AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
  53         AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
  54         AB8500_RTC_WATCH_TSECMID_REG
  55 };
  56
  57 static const u8 ab8500_rtc_alarm_regs[] = {
  58         AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
  59         AB8500_RTC_ALRM_MIN_LOW_REG
  60 };
  61
  62 /* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
  63 static unsigned long get_elapsed_seconds(int year)
  64 {
  65         unsigned long secs;
  66         struct rtc_time tm = {
  67                 .tm_year = year - 1900,
  68                 .tm_mday = 1,
  69         };
  70
  71         /*
  72          * This function calculates secs from 1970 and not from
  73          * 1900, even if we supply the offset from year 1900.
  74          */
  75         rtc_tm_to_time(&tm, &secs);
  76         return secs;
  77 }
  78
  79 static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
  80 {
  81         unsigned long timeout = jiffies + HZ;
  82         int retval, i;
  83         unsigned long mins, secs;
  84         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
  85         u8 value;
  86
  87         /* Request a data read */
  88         retval = abx500_set_register_interruptible(dev,
  89                 AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
  90         if (retval < 0)
  91                 return retval;
  92
  93         /* Wait for some cycles after enabling the rtc read in ab8500 */
  94         while (time_before(jiffies, timeout)) {
  95                 retval = abx500_get_register_interruptible(dev,
  96                         AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
  97                 if (retval < 0)
  98                         return retval;
  99
 100                 if (!(value & RTC_READ_REQUEST))
 101                         break;
 102
 103                 usleep_range(1000, 5000);
 104         }
 105
 106         /* Read the Watchtime registers */
 107         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 108                 retval = abx500_get_register_interruptible(dev,
 109                         AB8500_RTC, ab8500_rtc_time_regs[i], &value);
 110                 if (retval < 0)
 111                         return retval;
 112                 buf[i] = value;
 113         }
 114
 115         mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
 116
 117         secs =  (buf[3] << 8) | buf[4];
 118         secs =  secs / COUNTS_PER_SEC;
 119         secs =  secs + (mins * 60);
 120
 121         /* Add back the initially subtracted number of seconds */
 122         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 123
 124         rtc_time_to_tm(secs, tm);
 125         return 0;
 126 }
 127
 128 static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
 129 {
 130         int retval, i;
 131         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 132         unsigned long no_secs, no_mins, secs = 0;
 133
 134         if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
 135                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 136                                 AB8500_RTC_EPOCH);
 137                 return -EINVAL;
 138         }
 139
 140         /* Get the number of seconds since 1970 */
 141         rtc_tm_to_time(tm, &secs);
 142
 143         /*
 144          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 145          * we only have a small counter in the RTC.
 146          */
 147         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 148
 149         no_mins = secs / 60;
 150
 151         no_secs = secs % 60;
 152         /* Make the seconds count as per the RTC resolution */
 153         no_secs = no_secs * COUNTS_PER_SEC;
 154
 155         buf[4] = no_secs & 0xFF;
 156         buf[3] = (no_secs >> 8) & 0xFF;
 157
 158         buf[2] = no_mins & 0xFF;
 159         buf[1] = (no_mins >> 8) & 0xFF;
 160         buf[0] = (no_mins >> 16) & 0xFF;
 161
 162         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 163                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 164                         ab8500_rtc_time_regs[i], buf[i]);
 165                 if (retval < 0)
 166                         return retval;
 167         }
 168
 169         /* Request a data write */
 170         return abx500_set_register_interruptible(dev, AB8500_RTC,
 171                 AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
 172 }
 173
 174 static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 175 {
 176         int retval, i;
 177         u8 rtc_ctrl, value;
 178         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 179         unsigned long secs, mins;
 180
 181         /* Check if the alarm is enabled or not */
 182         retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 183                 AB8500_RTC_STAT_REG, &rtc_ctrl);
 184         if (retval < 0)
 185                 return retval;
 186
 187         if (rtc_ctrl & RTC_ALARM_ENA)
 188                 alarm->enabled = 1;
 189         else
 190                 alarm->enabled = 0;
 191
 192         alarm->pending = 0;
 193
 194         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 195                 retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 196                         ab8500_rtc_alarm_regs[i], &value);
 197                 if (retval < 0)
 198                         return retval;
 199                 buf[i] = value;
 200         }
 201
 202         mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
 203         secs = mins * 60;
 204
 205         /* Add back the initially subtracted number of seconds */
 206         secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 207
 208         rtc_time_to_tm(secs, &alarm->time);
 209
 210         return rtc_valid_tm(&alarm->time);
 211 }
 212
 213 static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
 214 {
 215         return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
 216                 AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
 217                 enabled ? RTC_ALARM_ENA : 0);
 218 }
 219
 220 static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 221 {
 222         int retval, i;
 223         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 224         unsigned long mins, secs = 0, cursec = 0;
 225         struct rtc_time curtm;
 226
 227         if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 228                 dev_dbg(dev, "year should be equal to or greater than %d\n",
 229                                 AB8500_RTC_EPOCH);
 230                 return -EINVAL;
 231         }
 232
 233         /* Get the number of seconds since 1970 */
 234         rtc_tm_to_time(&alarm->time, &secs);
 235
 236         /*
 237          * Check whether alarm is set less than 1min.
 238          * Since our RTC doesn't support alarm resolution less than 1min,
 239          * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
 240          */
 241         ab8500_rtc_read_time(dev, &curtm); /* Read current time */
 242         rtc_tm_to_time(&curtm, &cursec);
 243         if ((secs - cursec) < 59) {
 244                 dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
 245                 return -EINVAL;
 246         }
 247
 248         /*
 249          * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 250          * we only have a small counter in the RTC.
 251          */
 252         secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 253
 254         mins = secs / 60;
 255
 256         buf[2] = mins & 0xFF;
 257         buf[1] = (mins >> 8) & 0xFF;
 258         buf[0] = (mins >> 16) & 0xFF;
 259
 260         /* Set the alarm time */
 261         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 262                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 263                         ab8500_rtc_alarm_regs[i], buf[i]);
 264                 if (retval < 0)
 265                         return retval;
 266         }
 267
 268         return ab8500_rtc_irq_enable(dev, alarm->enabled);
 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 const struct platform_device_id ab85xx_rtc_ids[] = {
 393         { "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
 394         { /* sentinel */ }
 395 };
 396 MODULE_DEVICE_TABLE(platform, ab85xx_rtc_ids);
 397
 398 static int ab8500_rtc_probe(struct platform_device *pdev)
 399 {
 400         const struct platform_device_id *platid = platform_get_device_id(pdev);
 401         int err;
 402         struct rtc_device *rtc;
 403         u8 rtc_ctrl;
 404         int irq;
 405
 406         irq = platform_get_irq_byname(pdev, "ALARM");
 407         if (irq < 0)
 408                 return irq;
 409
 410         /* For RTC supply test */
 411         err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
 412                 AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
 413         if (err < 0)
 414                 return err;
 415
 416         /* Wait for reset by the PorRtc */
 417         usleep_range(1000, 5000);
 418
 419         err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
 420                 AB8500_RTC_STAT_REG, &rtc_ctrl);
 421         if (err < 0)
 422                 return err;
 423
 424         /* Check if the RTC Supply fails */
 425         if (!(rtc_ctrl & RTC_STATUS_DATA)) {
 426                 dev_err(&pdev->dev, "RTC supply failure\n");
 427                 return -ENODEV;
 428         }
 429
 430         device_init_wakeup(&pdev->dev, true);
 431
 432         rtc = devm_rtc_device_register(&pdev->dev, "ab8500-rtc",
 433                                 (struct rtc_class_ops *)platid->driver_data,
 434                                 THIS_MODULE);
 435         if (IS_ERR(rtc)) {
 436                 dev_err(&pdev->dev, "Registration failed\n");
 437                 err = PTR_ERR(rtc);
 438                 return err;
 439         }
 440
 441         err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
 442                         rtc_alarm_handler, IRQF_ONESHOT,
 443                         "ab8500-rtc", rtc);
 444         if (err < 0)
 445                 return err;
 446
 447         dev_pm_set_wake_irq(&pdev->dev, irq);
 448         platform_set_drvdata(pdev, rtc);
 449
 450         err = ab8500_sysfs_rtc_register(&pdev->dev);
 451         if (err) {
 452                 dev_err(&pdev->dev, "sysfs RTC failed to register\n");
 453                 return err;
 454         }
 455
 456         rtc->uie_unsupported = 1;
 457
 458         return 0;
 459 }
 460
 461 static int ab8500_rtc_remove(struct platform_device *pdev)
 462 {
 463         dev_pm_clear_wake_irq(&pdev->dev);
 464         device_init_wakeup(&pdev->dev, false);
 465         ab8500_sysfs_rtc_unregister(&pdev->dev);
 466
 467         return 0;
 468 }
 469
 470 static struct platform_driver ab8500_rtc_driver = {
 471         .driver = {
 472                 .name = "ab8500-rtc",
 473         },
 474         .probe  = ab8500_rtc_probe,
 475         .remove = ab8500_rtc_remove,
 476         .id_table = ab85xx_rtc_ids,
 477 };
 478
 479 module_platform_driver(ab8500_rtc_driver);
 480
 481 MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
 482 MODULE_DESCRIPTION("AB8500 RTC Driver");
 483 MODULE_LICENSE("GPL v2");