linux/drivers/rtc/rtc-ab8500.c
<<
>>
Prefs
   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
  39/* RtcReadRequest bits */
  40#define RTC_READ_REQUEST                0x01
  41#define RTC_WRITE_REQUEST               0x02
  42
  43/* RtcCtrl bits */
  44#define RTC_ALARM_ENA                   0x04
  45#define RTC_STATUS_DATA                 0x01
  46
  47#define COUNTS_PER_SEC                  (0xF000 / 60)
  48#define AB8500_RTC_EPOCH                2000
  49
  50static 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
  56static 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/* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
  62static unsigned long get_elapsed_seconds(int year)
  63{
  64        unsigned long secs;
  65        struct rtc_time tm = {
  66                .tm_year = year - 1900,
  67                .tm_mday = 1,
  68        };
  69
  70        /*
  71         * This function calculates secs from 1970 and not from
  72         * 1900, even if we supply the offset from year 1900.
  73         */
  74        rtc_tm_to_time(&tm, &secs);
  75        return secs;
  76}
  77
  78static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
  79{
  80        unsigned long timeout = jiffies + HZ;
  81        int retval, i;
  82        unsigned long mins, secs;
  83        unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
  84        u8 value;
  85
  86        /* Request a data read */
  87        retval = abx500_set_register_interruptible(dev,
  88                AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
  89        if (retval < 0)
  90                return retval;
  91
  92        /* Wait for some cycles after enabling the rtc read in ab8500 */
  93        while (time_before(jiffies, timeout)) {
  94                retval = abx500_get_register_interruptible(dev,
  95                        AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
  96                if (retval < 0)
  97                        return retval;
  98
  99                if (!(value & RTC_READ_REQUEST))
 100                        break;
 101
 102                usleep_range(1000, 5000);
 103        }
 104
 105        /* Read the Watchtime registers */
 106        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 107                retval = abx500_get_register_interruptible(dev,
 108                        AB8500_RTC, ab8500_rtc_time_regs[i], &value);
 109                if (retval < 0)
 110                        return retval;
 111                buf[i] = value;
 112        }
 113
 114        mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
 115
 116        secs =  (buf[3] << 8) | buf[4];
 117        secs =  secs / COUNTS_PER_SEC;
 118        secs =  secs + (mins * 60);
 119
 120        /* Add back the initially subtracted number of seconds */
 121        secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 122
 123        rtc_time_to_tm(secs, tm);
 124        return rtc_valid_tm(tm);
 125}
 126
 127static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
 128{
 129        int retval, i;
 130        unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 131        unsigned long no_secs, no_mins, secs = 0;
 132
 133        if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
 134                dev_dbg(dev, "year should be equal to or greater than %d\n",
 135                                AB8500_RTC_EPOCH);
 136                return -EINVAL;
 137        }
 138
 139        /* Get the number of seconds since 1970 */
 140        rtc_tm_to_time(tm, &secs);
 141
 142        /*
 143         * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 144         * we only have a small counter in the RTC.
 145         */
 146        secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 147
 148        no_mins = secs / 60;
 149
 150        no_secs = secs % 60;
 151        /* Make the seconds count as per the RTC resolution */
 152        no_secs = no_secs * COUNTS_PER_SEC;
 153
 154        buf[4] = no_secs & 0xFF;
 155        buf[3] = (no_secs >> 8) & 0xFF;
 156
 157        buf[2] = no_mins & 0xFF;
 158        buf[1] = (no_mins >> 8) & 0xFF;
 159        buf[0] = (no_mins >> 16) & 0xFF;
 160
 161        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 162                retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 163                        ab8500_rtc_time_regs[i], buf[i]);
 164                if (retval < 0)
 165                        return retval;
 166        }
 167
 168        /* Request a data write */
 169        return abx500_set_register_interruptible(dev, AB8500_RTC,
 170                AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
 171}
 172
 173static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 174{
 175        int retval, i;
 176        u8 rtc_ctrl, value;
 177        unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 178        unsigned long secs, mins;
 179
 180        /* Check if the alarm is enabled or not */
 181        retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 182                AB8500_RTC_STAT_REG, &rtc_ctrl);
 183        if (retval < 0)
 184                return retval;
 185
 186        if (rtc_ctrl & RTC_ALARM_ENA)
 187                alarm->enabled = 1;
 188        else
 189                alarm->enabled = 0;
 190
 191        alarm->pending = 0;
 192
 193        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 194                retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 195                        ab8500_rtc_alarm_regs[i], &value);
 196                if (retval < 0)
 197                        return retval;
 198                buf[i] = value;
 199        }
 200
 201        mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
 202        secs = mins * 60;
 203
 204        /* Add back the initially subtracted number of seconds */
 205        secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 206
 207        rtc_time_to_tm(secs, &alarm->time);
 208
 209        return rtc_valid_tm(&alarm->time);
 210}
 211
 212static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
 213{
 214        return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
 215                AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
 216                enabled ? RTC_ALARM_ENA : 0);
 217}
 218
 219static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 220{
 221        int retval, i;
 222        unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 223        unsigned long mins, secs = 0, cursec = 0;
 224        struct rtc_time curtm;
 225
 226        if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 227                dev_dbg(dev, "year should be equal to or greater than %d\n",
 228                                AB8500_RTC_EPOCH);
 229                return -EINVAL;
 230        }
 231
 232        /* Get the number of seconds since 1970 */
 233        rtc_tm_to_time(&alarm->time, &secs);
 234
 235        /*
 236         * Check whether alarm is set less than 1min.
 237         * Since our RTC doesn't support alarm resolution less than 1min,
 238         * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
 239         */
 240        ab8500_rtc_read_time(dev, &curtm); /* Read current time */
 241        rtc_tm_to_time(&curtm, &cursec);
 242        if ((secs - cursec) < 59) {
 243                dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
 244                return -EINVAL;
 245        }
 246
 247        /*
 248         * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 249         * we only have a small counter in the RTC.
 250         */
 251        secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 252
 253        mins = secs / 60;
 254
 255        buf[2] = mins & 0xFF;
 256        buf[1] = (mins >> 8) & 0xFF;
 257        buf[0] = (mins >> 16) & 0xFF;
 258
 259        /* Set the alarm time */
 260        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 261                retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 262                        ab8500_rtc_alarm_regs[i], buf[i]);
 263                if (retval < 0)
 264                        return retval;
 265        }
 266
 267        return ab8500_rtc_irq_enable(dev, alarm->enabled);
 268}
 269
 270
 271static 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
 304static 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
 326static 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
 343static 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
 359static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
 360                   ab8500_sysfs_show_rtc_calibration,
 361                   ab8500_sysfs_store_rtc_calibration);
 362
 363static int ab8500_sysfs_rtc_register(struct device *dev)
 364{
 365        return device_create_file(dev, &dev_attr_rtc_calibration);
 366}
 367
 368static void ab8500_sysfs_rtc_unregister(struct device *dev)
 369{
 370        device_remove_file(dev, &dev_attr_rtc_calibration);
 371}
 372
 373static 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
 384static 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
 392static int ab8500_rtc_probe(struct platform_device *pdev)
 393{
 394        int err;
 395        struct rtc_device *rtc;
 396        u8 rtc_ctrl;
 397        int irq;
 398
 399        irq = platform_get_irq_byname(pdev, "ALARM");
 400        if (irq < 0)
 401                return irq;
 402
 403        /* For RTC supply test */
 404        err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
 405                AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
 406        if (err < 0)
 407                return err;
 408
 409        /* Wait for reset by the PorRtc */
 410        usleep_range(1000, 5000);
 411
 412        err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
 413                AB8500_RTC_STAT_REG, &rtc_ctrl);
 414        if (err < 0)
 415                return err;
 416
 417        /* Check if the RTC Supply fails */
 418        if (!(rtc_ctrl & RTC_STATUS_DATA)) {
 419                dev_err(&pdev->dev, "RTC supply failure\n");
 420                return -ENODEV;
 421        }
 422
 423        device_init_wakeup(&pdev->dev, true);
 424
 425        rtc = rtc_device_register("ab8500-rtc", &pdev->dev, &ab8500_rtc_ops,
 426                        THIS_MODULE);
 427        if (IS_ERR(rtc)) {
 428                dev_err(&pdev->dev, "Registration failed\n");
 429                err = PTR_ERR(rtc);
 430                return err;
 431        }
 432
 433        err = request_threaded_irq(irq, NULL, rtc_alarm_handler,
 434                IRQF_NO_SUSPEND | IRQF_ONESHOT, "ab8500-rtc", rtc);
 435        if (err < 0) {
 436                rtc_device_unregister(rtc);
 437                return err;
 438        }
 439
 440        platform_set_drvdata(pdev, rtc);
 441
 442        err = ab8500_sysfs_rtc_register(&pdev->dev);
 443        if (err) {
 444                dev_err(&pdev->dev, "sysfs RTC failed to register\n");
 445                return err;
 446        }
 447
 448        return 0;
 449}
 450
 451static int ab8500_rtc_remove(struct platform_device *pdev)
 452{
 453        struct rtc_device *rtc = platform_get_drvdata(pdev);
 454        int irq = platform_get_irq_byname(pdev, "ALARM");
 455
 456        ab8500_sysfs_rtc_unregister(&pdev->dev);
 457
 458        free_irq(irq, rtc);
 459        rtc_device_unregister(rtc);
 460        platform_set_drvdata(pdev, NULL);
 461
 462        return 0;
 463}
 464
 465static struct platform_driver ab8500_rtc_driver = {
 466        .driver = {
 467                .name = "ab8500-rtc",
 468                .owner = THIS_MODULE,
 469        },
 470        .probe  = ab8500_rtc_probe,
 471        .remove = ab8500_rtc_remove,
 472};
 473
 474module_platform_driver(ab8500_rtc_driver);
 475
 476MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
 477MODULE_DESCRIPTION("AB8500 RTC Driver");
 478MODULE_LICENSE("GPL v2");
 479
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.