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
  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 static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
  62 {
  63         unsigned long timeout = jiffies + HZ;
  64         int retval, i;
  65         unsigned long mins, secs;
  66         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
  67         u8 value;
  68
  69         /* Request a data read */
  70         retval = abx500_set_register_interruptible(dev,
  71                 AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
  72         if (retval < 0)
  73                 return retval;
  74
  75         /* Wait for some cycles after enabling the rtc read in ab8500 */
  76         while (time_before(jiffies, timeout)) {
  77                 retval = abx500_get_register_interruptible(dev,
  78                         AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
  79                 if (retval < 0)
  80                         return retval;
  81
  82                 if (!(value & RTC_READ_REQUEST))
  83                         break;
  84
  85                 usleep_range(1000, 5000);
  86         }
  87
  88         /* Read the Watchtime registers */
  89         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
  90                 retval = abx500_get_register_interruptible(dev,
  91                         AB8500_RTC, ab8500_rtc_time_regs[i], &value);
  92                 if (retval < 0)
  93                         return retval;
  94                 buf[i] = value;
  95         }
  96
  97         mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
  98
  99         secs =  (buf[3] << 8) | buf[4];
 100         secs =  secs / COUNTS_PER_SEC;
 101         secs =  secs + (mins * 60);
 102
 103         rtc_time_to_tm(secs, tm);
 104         return 0;
 105 }
 106
 107 static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
 108 {
 109         int retval, i;
 110         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 111         unsigned long no_secs, no_mins, secs = 0;
 112
 113         rtc_tm_to_time(tm, &secs);
 114
 115         no_mins = secs / 60;
 116
 117         no_secs = secs % 60;
 118         /* Make the seconds count as per the RTC resolution */
 119         no_secs = no_secs * COUNTS_PER_SEC;
 120
 121         buf[4] = no_secs & 0xFF;
 122         buf[3] = (no_secs >> 8) & 0xFF;
 123
 124         buf[2] = no_mins & 0xFF;
 125         buf[1] = (no_mins >> 8) & 0xFF;
 126         buf[0] = (no_mins >> 16) & 0xFF;
 127
 128         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 129                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 130                         ab8500_rtc_time_regs[i], buf[i]);
 131                 if (retval < 0)
 132                         return retval;
 133         }
 134
 135         /* Request a data write */
 136         return abx500_set_register_interruptible(dev, AB8500_RTC,
 137                 AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
 138 }
 139
 140 static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 141 {
 142         int retval, i;
 143         u8 rtc_ctrl, value;
 144         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 145         unsigned long secs, mins;
 146
 147         /* Check if the alarm is enabled or not */
 148         retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 149                 AB8500_RTC_STAT_REG, &rtc_ctrl);
 150         if (retval < 0)
 151                 return retval;
 152
 153         if (rtc_ctrl & RTC_ALARM_ENA)
 154                 alarm->enabled = 1;
 155         else
 156                 alarm->enabled = 0;
 157
 158         alarm->pending = 0;
 159
 160         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 161                 retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 162                         ab8500_rtc_alarm_regs[i], &value);
 163                 if (retval < 0)
 164                         return retval;
 165                 buf[i] = value;
 166         }
 167
 168         mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
 169         secs = mins * 60;
 170
 171         rtc_time_to_tm(secs, &alarm->time);
 172
 173         return 0;
 174 }
 175
 176 static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
 177 {
 178         return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
 179                 AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
 180                 enabled ? RTC_ALARM_ENA : 0);
 181 }
 182
 183 static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 184 {
 185         int retval, i;
 186         unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 187         unsigned long mins, secs = 0, cursec = 0;
 188         struct rtc_time curtm;
 189
 190         /* Get the number of seconds since 1970 */
 191         rtc_tm_to_time(&alarm->time, &secs);
 192
 193         /*
 194          * Check whether alarm is set less than 1min.
 195          * Since our RTC doesn't support alarm resolution less than 1min,
 196          * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
 197          */
 198         ab8500_rtc_read_time(dev, &curtm); /* Read current time */
 199         rtc_tm_to_time(&curtm, &cursec);
 200         if ((secs - cursec) < 59) {
 201                 dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
 202                 return -EINVAL;
 203         }
 204
 205         mins = secs / 60;
 206
 207         buf[2] = mins & 0xFF;
 208         buf[1] = (mins >> 8) & 0xFF;
 209         buf[0] = (mins >> 16) & 0xFF;
 210
 211         /* Set the alarm time */
 212         for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 213                 retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 214                         ab8500_rtc_alarm_regs[i], buf[i]);
 215                 if (retval < 0)
 216                         return retval;
 217         }
 218
 219         return ab8500_rtc_irq_enable(dev, alarm->enabled);
 220 }
 221
 222 static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
 223 {
 224         int retval;
 225         u8  rtccal = 0;
 226
 227         /*
 228          * Check that the calibration value (which is in units of 0.5
 229          * parts-per-million) is in the AB8500's range for RtcCalibration
 230          * register. -128 (0x80) is not permitted because the AB8500 uses
 231          * a sign-bit rather than two's complement, so 0x80 is just another
 232          * representation of zero.
 233          */
 234         if ((calibration < -127) || (calibration > 127)) {
 235                 dev_err(dev, "RtcCalibration value outside permitted range\n");
 236                 return -EINVAL;
 237         }
 238
 239         /*
 240          * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 241          * so need to convert to this sort of representation before writing
 242          * into RtcCalibration register...
 243          */
 244         if (calibration >= 0)
 245                 rtccal = 0x7F & calibration;
 246         else
 247                 rtccal = ~(calibration - 1) | 0x80;
 248
 249         retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 250                         AB8500_RTC_CALIB_REG, rtccal);
 251
 252         return retval;
 253 }
 254
 255 static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
 256 {
 257         int retval;
 258         u8  rtccal = 0;
 259
 260         retval =  abx500_get_register_interruptible(dev, AB8500_RTC,
 261                         AB8500_RTC_CALIB_REG, &rtccal);
 262         if (retval >= 0) {
 263                 /*
 264                  * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 265                  * so need to convert value from RtcCalibration register into
 266                  * a two's complement signed value...
 267                  */
 268                 if (rtccal & 0x80)
 269                         *calibration = 0 - (rtccal & 0x7F);
 270                 else
 271                         *calibration = 0x7F & rtccal;
 272         }
 273
 274         return retval;
 275 }
 276
 277 static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
 278                                 struct device_attribute *attr,
 279                                 const char *buf, size_t count)
 280 {
 281         int retval;
 282         int calibration = 0;
 283
 284         if (sscanf(buf, " %i ", &calibration) != 1) {
 285                 dev_err(dev, "Failed to store RTC calibration attribute\n");
 286                 return -EINVAL;
 287         }
 288
 289         retval = ab8500_rtc_set_calibration(dev, calibration);
 290
 291         return retval ? retval : count;
 292 }
 293
 294 static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
 295                                 struct device_attribute *attr, char *buf)
 296 {
 297         int  retval = 0;
 298         int  calibration = 0;
 299
 300         retval = ab8500_rtc_get_calibration(dev, &calibration);
 301         if (retval < 0) {
 302                 dev_err(dev, "Failed to read RTC calibration attribute\n");
 303                 sprintf(buf, "0\n");
 304                 return retval;
 305         }
 306
 307         return sprintf(buf, "%d\n", calibration);
 308 }
 309
 310 static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
 311                    ab8500_sysfs_show_rtc_calibration,
 312                    ab8500_sysfs_store_rtc_calibration);
 313
 314 static struct attribute *ab8500_rtc_attrs[] = {
 315         &dev_attr_rtc_calibration.attr,
 316         NULL
 317 };
 318
 319 static const struct attribute_group ab8500_rtc_sysfs_files = {
 320         .attrs  = ab8500_rtc_attrs,
 321 };
 322
 323 static irqreturn_t rtc_alarm_handler(int irq, void *data)
 324 {
 325         struct rtc_device *rtc = data;
 326         unsigned long events = RTC_IRQF | RTC_AF;
 327
 328         dev_dbg(&rtc->dev, "%s\n", __func__);
 329         rtc_update_irq(rtc, 1, events);
 330
 331         return IRQ_HANDLED;
 332 }
 333
 334 static const struct rtc_class_ops ab8500_rtc_ops = {
 335         .read_time              = ab8500_rtc_read_time,
 336         .set_time               = ab8500_rtc_set_time,
 337         .read_alarm             = ab8500_rtc_read_alarm,
 338         .set_alarm              = ab8500_rtc_set_alarm,
 339         .alarm_irq_enable       = ab8500_rtc_irq_enable,
 340 };
 341
 342 static const struct platform_device_id ab85xx_rtc_ids[] = {
 343         { "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
 344         { /* sentinel */ }
 345 };
 346 MODULE_DEVICE_TABLE(platform, ab85xx_rtc_ids);
 347
 348 static int ab8500_rtc_probe(struct platform_device *pdev)
 349 {
 350         const struct platform_device_id *platid = platform_get_device_id(pdev);
 351         int err;
 352         struct rtc_device *rtc;
 353         u8 rtc_ctrl;
 354         int irq;
 355
 356         irq = platform_get_irq_byname(pdev, "ALARM");
 357         if (irq < 0)
 358                 return irq;
 359
 360         /* For RTC supply test */
 361         err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
 362                 AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
 363         if (err < 0)
 364                 return err;
 365
 366         /* Wait for reset by the PorRtc */
 367         usleep_range(1000, 5000);
 368
 369         err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
 370                 AB8500_RTC_STAT_REG, &rtc_ctrl);
 371         if (err < 0)
 372                 return err;
 373
 374         /* Check if the RTC Supply fails */
 375         if (!(rtc_ctrl & RTC_STATUS_DATA)) {
 376                 dev_err(&pdev->dev, "RTC supply failure\n");
 377                 return -ENODEV;
 378         }
 379
 380         device_init_wakeup(&pdev->dev, true);
 381
 382         rtc = devm_rtc_allocate_device(&pdev->dev);
 383         if (IS_ERR(rtc))
 384                 return PTR_ERR(rtc);
 385
 386         rtc->ops = (struct rtc_class_ops *)platid->driver_data;
 387
 388         err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
 389                         rtc_alarm_handler, IRQF_ONESHOT,
 390                         "ab8500-rtc", rtc);
 391         if (err < 0)
 392                 return err;
 393
 394         dev_pm_set_wake_irq(&pdev->dev, irq);
 395         platform_set_drvdata(pdev, rtc);
 396
 397         rtc->uie_unsupported = 1;
 398
 399         rtc->range_max = (1ULL << 24) * 60 - 1; // 24-bit minutes + 59 secs
 400         rtc->start_secs = RTC_TIMESTAMP_BEGIN_2000;
 401         rtc->set_start_time = true;
 402
 403         err = rtc_add_group(rtc, &ab8500_rtc_sysfs_files);
 404         if (err)
 405                 return err;
 406
 407         return rtc_register_device(rtc);
 408 }
 409
 410 static int ab8500_rtc_remove(struct platform_device *pdev)
 411 {
 412         dev_pm_clear_wake_irq(&pdev->dev);
 413         device_init_wakeup(&pdev->dev, false);
 414
 415         return 0;
 416 }
 417
 418 static struct platform_driver ab8500_rtc_driver = {
 419         .driver = {
 420                 .name = "ab8500-rtc",
 421         },
 422         .probe  = ab8500_rtc_probe,
 423         .remove = ab8500_rtc_remove,
 424         .id_table = ab85xx_rtc_ids,
 425 };
 426
 427 module_platform_driver(ab8500_rtc_driver);
 428
 429 MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
 430 MODULE_DESCRIPTION("AB8500 RTC Driver");
 431 MODULE_LICENSE("GPL v2");