linux/drivers/rtc/rtc-ab8500.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C) ST-Ericsson SA 2010
   4 *
   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
  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
  61static 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_time64_to_tm(secs, tm);
 104        return 0;
 105}
 106
 107static 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        secs = rtc_tm_to_time64(tm);
 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
 140static 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_time64_to_tm(secs, &alarm->time);
 172
 173        return 0;
 174}
 175
 176static 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
 183static 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        secs = rtc_tm_to_time64(&alarm->time);
 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        cursec = rtc_tm_to_time64(&curtm);
 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
 222static 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
 255static 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
 277static 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
 294static 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
 310static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
 311                   ab8500_sysfs_show_rtc_calibration,
 312                   ab8500_sysfs_store_rtc_calibration);
 313
 314static struct attribute *ab8500_rtc_attrs[] = {
 315        &dev_attr_rtc_calibration.attr,
 316        NULL
 317};
 318
 319static const struct attribute_group ab8500_rtc_sysfs_files = {
 320        .attrs  = ab8500_rtc_attrs,
 321};
 322
 323static 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
 334static 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
 342static const struct platform_device_id ab85xx_rtc_ids[] = {
 343        { "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
 344        { /* sentinel */ }
 345};
 346MODULE_DEVICE_TABLE(platform, ab85xx_rtc_ids);
 347
 348static 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 devm_rtc_register_device(rtc);
 408}
 409
 410static 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
 418static 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
 427module_platform_driver(ab8500_rtc_driver);
 428
 429MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
 430MODULE_DESCRIPTION("AB8500 RTC Driver");
 431MODULE_LICENSE("GPL v2");
 432