linux/drivers/rtc/rtc-ab8500.c
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   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
  21#define AB8500_RTC_SOFF_STAT_REG        0x00
  22#define AB8500_RTC_CC_CONF_REG          0x01
  23#define AB8500_RTC_READ_REQ_REG         0x02
  24#define AB8500_RTC_WATCH_TSECMID_REG    0x03
  25#define AB8500_RTC_WATCH_TSECHI_REG     0x04
  26#define AB8500_RTC_WATCH_TMIN_LOW_REG   0x05
  27#define AB8500_RTC_WATCH_TMIN_MID_REG   0x06
  28#define AB8500_RTC_WATCH_TMIN_HI_REG    0x07
  29#define AB8500_RTC_ALRM_MIN_LOW_REG     0x08
  30#define AB8500_RTC_ALRM_MIN_MID_REG     0x09
  31#define AB8500_RTC_ALRM_MIN_HI_REG      0x0A
  32#define AB8500_RTC_STAT_REG             0x0B
  33#define AB8500_RTC_BKUP_CHG_REG         0x0C
  34#define AB8500_RTC_FORCE_BKUP_REG       0x0D
  35#define AB8500_RTC_CALIB_REG            0x0E
  36#define AB8500_RTC_SWITCH_STAT_REG      0x0F
  37
  38/* RtcReadRequest bits */
  39#define RTC_READ_REQUEST                0x01
  40#define RTC_WRITE_REQUEST               0x02
  41
  42/* RtcCtrl bits */
  43#define RTC_ALARM_ENA                   0x04
  44#define RTC_STATUS_DATA                 0x01
  45
  46#define COUNTS_PER_SEC                  (0xF000 / 60)
  47#define AB8500_RTC_EPOCH                2000
  48
  49static const u8 ab8500_rtc_time_regs[] = {
  50        AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
  51        AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
  52        AB8500_RTC_WATCH_TSECMID_REG
  53};
  54
  55static const u8 ab8500_rtc_alarm_regs[] = {
  56        AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
  57        AB8500_RTC_ALRM_MIN_LOW_REG
  58};
  59
  60/* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
  61static unsigned long get_elapsed_seconds(int year)
  62{
  63        unsigned long secs;
  64        struct rtc_time tm = {
  65                .tm_year = year - 1900,
  66                .tm_mday = 1,
  67        };
  68
  69        /*
  70         * This function calculates secs from 1970 and not from
  71         * 1900, even if we supply the offset from year 1900.
  72         */
  73        rtc_tm_to_time(&tm, &secs);
  74        return secs;
  75}
  76
  77static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
  78{
  79        unsigned long timeout = jiffies + HZ;
  80        int retval, i;
  81        unsigned long mins, secs;
  82        unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
  83        u8 value;
  84
  85        /* Request a data read */
  86        retval = abx500_set_register_interruptible(dev,
  87                AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
  88        if (retval < 0)
  89                return retval;
  90
  91        /* Early AB8500 chips will not clear the rtc read request bit */
  92        if (abx500_get_chip_id(dev) == 0) {
  93                usleep_range(1000, 1000);
  94        } else {
  95                /* Wait for some cycles after enabling the rtc read in ab8500 */
  96                while (time_before(jiffies, timeout)) {
  97                        retval = abx500_get_register_interruptible(dev,
  98                                AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
  99                        if (retval < 0)
 100                                return retval;
 101
 102                        if (!(value & RTC_READ_REQUEST))
 103                                break;
 104
 105                        usleep_range(1000, 5000);
 106                }
 107        }
 108
 109        /* Read the Watchtime registers */
 110        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 111                retval = abx500_get_register_interruptible(dev,
 112                        AB8500_RTC, ab8500_rtc_time_regs[i], &value);
 113                if (retval < 0)
 114                        return retval;
 115                buf[i] = value;
 116        }
 117
 118        mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
 119
 120        secs =  (buf[3] << 8) | buf[4];
 121        secs =  secs / COUNTS_PER_SEC;
 122        secs =  secs + (mins * 60);
 123
 124        /* Add back the initially subtracted number of seconds */
 125        secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 126
 127        rtc_time_to_tm(secs, tm);
 128        return rtc_valid_tm(tm);
 129}
 130
 131static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
 132{
 133        int retval, i;
 134        unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 135        unsigned long no_secs, no_mins, secs = 0;
 136
 137        if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
 138                dev_dbg(dev, "year should be equal to or greater than %d\n",
 139                                AB8500_RTC_EPOCH);
 140                return -EINVAL;
 141        }
 142
 143        /* Get the number of seconds since 1970 */
 144        rtc_tm_to_time(tm, &secs);
 145
 146        /*
 147         * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 148         * we only have a small counter in the RTC.
 149         */
 150        secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 151
 152        no_mins = secs / 60;
 153
 154        no_secs = secs % 60;
 155        /* Make the seconds count as per the RTC resolution */
 156        no_secs = no_secs * COUNTS_PER_SEC;
 157
 158        buf[4] = no_secs & 0xFF;
 159        buf[3] = (no_secs >> 8) & 0xFF;
 160
 161        buf[2] = no_mins & 0xFF;
 162        buf[1] = (no_mins >> 8) & 0xFF;
 163        buf[0] = (no_mins >> 16) & 0xFF;
 164
 165        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 166                retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 167                        ab8500_rtc_time_regs[i], buf[i]);
 168                if (retval < 0)
 169                        return retval;
 170        }
 171
 172        /* Request a data write */
 173        return abx500_set_register_interruptible(dev, AB8500_RTC,
 174                AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
 175}
 176
 177static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 178{
 179        int retval, i;
 180        u8 rtc_ctrl, value;
 181        unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 182        unsigned long secs, mins;
 183
 184        /* Check if the alarm is enabled or not */
 185        retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 186                AB8500_RTC_STAT_REG, &rtc_ctrl);
 187        if (retval < 0)
 188                return retval;
 189
 190        if (rtc_ctrl & RTC_ALARM_ENA)
 191                alarm->enabled = 1;
 192        else
 193                alarm->enabled = 0;
 194
 195        alarm->pending = 0;
 196
 197        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 198                retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 199                        ab8500_rtc_alarm_regs[i], &value);
 200                if (retval < 0)
 201                        return retval;
 202                buf[i] = value;
 203        }
 204
 205        mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
 206        secs = mins * 60;
 207
 208        /* Add back the initially subtracted number of seconds */
 209        secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 210
 211        rtc_time_to_tm(secs, &alarm->time);
 212
 213        return rtc_valid_tm(&alarm->time);
 214}
 215
 216static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
 217{
 218        return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
 219                AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
 220                enabled ? RTC_ALARM_ENA : 0);
 221}
 222
 223static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 224{
 225        int retval, i;
 226        unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 227        unsigned long mins, secs = 0;
 228
 229        if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 230                dev_dbg(dev, "year should be equal to or greater than %d\n",
 231                                AB8500_RTC_EPOCH);
 232                return -EINVAL;
 233        }
 234
 235        /* Get the number of seconds since 1970 */
 236        rtc_tm_to_time(&alarm->time, &secs);
 237
 238        /*
 239         * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 240         * we only have a small counter in the RTC.
 241         */
 242        secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 243
 244        mins = secs / 60;
 245
 246        buf[2] = mins & 0xFF;
 247        buf[1] = (mins >> 8) & 0xFF;
 248        buf[0] = (mins >> 16) & 0xFF;
 249
 250        /* Set the alarm time */
 251        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 252                retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 253                        ab8500_rtc_alarm_regs[i], buf[i]);
 254                if (retval < 0)
 255                        return retval;
 256        }
 257
 258        return ab8500_rtc_irq_enable(dev, alarm->enabled);
 259}
 260
 261
 262static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
 263{
 264        int retval;
 265        u8  rtccal = 0;
 266
 267        /*
 268         * Check that the calibration value (which is in units of 0.5
 269         * parts-per-million) is in the AB8500's range for RtcCalibration
 270         * register. -128 (0x80) is not permitted because the AB8500 uses
 271         * a sign-bit rather than two's complement, so 0x80 is just another
 272         * representation of zero.
 273         */
 274        if ((calibration < -127) || (calibration > 127)) {
 275                dev_err(dev, "RtcCalibration value outside permitted range\n");
 276                return -EINVAL;
 277        }
 278
 279        /*
 280         * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 281         * so need to convert to this sort of representation before writing
 282         * into RtcCalibration register...
 283         */
 284        if (calibration >= 0)
 285                rtccal = 0x7F & calibration;
 286        else
 287                rtccal = ~(calibration - 1) | 0x80;
 288
 289        retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 290                        AB8500_RTC_CALIB_REG, rtccal);
 291
 292        return retval;
 293}
 294
 295static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
 296{
 297        int retval;
 298        u8  rtccal = 0;
 299
 300        retval =  abx500_get_register_interruptible(dev, AB8500_RTC,
 301                        AB8500_RTC_CALIB_REG, &rtccal);
 302        if (retval >= 0) {
 303                /*
 304                 * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 305                 * so need to convert value from RtcCalibration register into
 306                 * a two's complement signed value...
 307                 */
 308                if (rtccal & 0x80)
 309                        *calibration = 0 - (rtccal & 0x7F);
 310                else
 311                        *calibration = 0x7F & rtccal;
 312        }
 313
 314        return retval;
 315}
 316
 317static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
 318                                struct device_attribute *attr,
 319                                const char *buf, size_t count)
 320{
 321        int retval;
 322        int calibration = 0;
 323
 324        if (sscanf(buf, " %i ", &calibration) != 1) {
 325                dev_err(dev, "Failed to store RTC calibration attribute\n");
 326                return -EINVAL;
 327        }
 328
 329        retval = ab8500_rtc_set_calibration(dev, calibration);
 330
 331        return retval ? retval : count;
 332}
 333
 334static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
 335                                struct device_attribute *attr, char *buf)
 336{
 337        int  retval = 0;
 338        int  calibration = 0;
 339
 340        retval = ab8500_rtc_get_calibration(dev, &calibration);
 341        if (retval < 0) {
 342                dev_err(dev, "Failed to read RTC calibration attribute\n");
 343                sprintf(buf, "0\n");
 344                return retval;
 345        }
 346
 347        return sprintf(buf, "%d\n", calibration);
 348}
 349
 350static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
 351                   ab8500_sysfs_show_rtc_calibration,
 352                   ab8500_sysfs_store_rtc_calibration);
 353
 354static int ab8500_sysfs_rtc_register(struct device *dev)
 355{
 356        return device_create_file(dev, &dev_attr_rtc_calibration);
 357}
 358
 359static void ab8500_sysfs_rtc_unregister(struct device *dev)
 360{
 361        device_remove_file(dev, &dev_attr_rtc_calibration);
 362}
 363
 364static irqreturn_t rtc_alarm_handler(int irq, void *data)
 365{
 366        struct rtc_device *rtc = data;
 367        unsigned long events = RTC_IRQF | RTC_AF;
 368
 369        dev_dbg(&rtc->dev, "%s\n", __func__);
 370        rtc_update_irq(rtc, 1, events);
 371
 372        return IRQ_HANDLED;
 373}
 374
 375static const struct rtc_class_ops ab8500_rtc_ops = {
 376        .read_time              = ab8500_rtc_read_time,
 377        .set_time               = ab8500_rtc_set_time,
 378        .read_alarm             = ab8500_rtc_read_alarm,
 379        .set_alarm              = ab8500_rtc_set_alarm,
 380        .alarm_irq_enable       = ab8500_rtc_irq_enable,
 381};
 382
 383static int __devinit ab8500_rtc_probe(struct platform_device *pdev)
 384{
 385        int err;
 386        struct rtc_device *rtc;
 387        u8 rtc_ctrl;
 388        int irq;
 389
 390        irq = platform_get_irq_byname(pdev, "ALARM");
 391        if (irq < 0)
 392                return irq;
 393
 394        /* For RTC supply test */
 395        err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
 396                AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
 397        if (err < 0)
 398                return err;
 399
 400        /* Wait for reset by the PorRtc */
 401        usleep_range(1000, 5000);
 402
 403        err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
 404                AB8500_RTC_STAT_REG, &rtc_ctrl);
 405        if (err < 0)
 406                return err;
 407
 408        /* Check if the RTC Supply fails */
 409        if (!(rtc_ctrl & RTC_STATUS_DATA)) {
 410                dev_err(&pdev->dev, "RTC supply failure\n");
 411                return -ENODEV;
 412        }
 413
 414        device_init_wakeup(&pdev->dev, true);
 415
 416        rtc = rtc_device_register("ab8500-rtc", &pdev->dev, &ab8500_rtc_ops,
 417                        THIS_MODULE);
 418        if (IS_ERR(rtc)) {
 419                dev_err(&pdev->dev, "Registration failed\n");
 420                err = PTR_ERR(rtc);
 421                return err;
 422        }
 423
 424        err = request_threaded_irq(irq, NULL, rtc_alarm_handler,
 425                IRQF_NO_SUSPEND, "ab8500-rtc", rtc);
 426        if (err < 0) {
 427                rtc_device_unregister(rtc);
 428                return err;
 429        }
 430
 431        platform_set_drvdata(pdev, rtc);
 432
 433
 434        err = ab8500_sysfs_rtc_register(&pdev->dev);
 435        if (err) {
 436                dev_err(&pdev->dev, "sysfs RTC failed to register\n");
 437                return err;
 438        }
 439
 440        return 0;
 441}
 442
 443static int __devexit ab8500_rtc_remove(struct platform_device *pdev)
 444{
 445        struct rtc_device *rtc = platform_get_drvdata(pdev);
 446        int irq = platform_get_irq_byname(pdev, "ALARM");
 447
 448        ab8500_sysfs_rtc_unregister(&pdev->dev);
 449
 450        free_irq(irq, rtc);
 451        rtc_device_unregister(rtc);
 452        platform_set_drvdata(pdev, NULL);
 453
 454        return 0;
 455}
 456
 457static struct platform_driver ab8500_rtc_driver = {
 458        .driver = {
 459                .name = "ab8500-rtc",
 460                .owner = THIS_MODULE,
 461        },
 462        .probe  = ab8500_rtc_probe,
 463        .remove = __devexit_p(ab8500_rtc_remove),
 464};
 465
 466module_platform_driver(ab8500_rtc_driver);
 467
 468MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
 469MODULE_DESCRIPTION("AB8500 RTC Driver");
 470MODULE_LICENSE("GPL v2");
 471