linux/drivers/rtc/rtc-ds1511.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * An rtc driver for the Dallas DS1511
   4 *
   5 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
   6 * Copyright (C) 2007 Andrew Sharp <andy.sharp@lsi.com>
   7 *
   8 * Real time clock driver for the Dallas 1511 chip, which also
   9 * contains a watchdog timer.  There is a tiny amount of code that
  10 * platform code could use to mess with the watchdog device a little
  11 * bit, but not a full watchdog driver.
  12 */
  13
  14#include <linux/bcd.h>
  15#include <linux/init.h>
  16#include <linux/kernel.h>
  17#include <linux/gfp.h>
  18#include <linux/delay.h>
  19#include <linux/interrupt.h>
  20#include <linux/rtc.h>
  21#include <linux/platform_device.h>
  22#include <linux/io.h>
  23#include <linux/module.h>
  24
  25enum ds1511reg {
  26        DS1511_SEC = 0x0,
  27        DS1511_MIN = 0x1,
  28        DS1511_HOUR = 0x2,
  29        DS1511_DOW = 0x3,
  30        DS1511_DOM = 0x4,
  31        DS1511_MONTH = 0x5,
  32        DS1511_YEAR = 0x6,
  33        DS1511_CENTURY = 0x7,
  34        DS1511_AM1_SEC = 0x8,
  35        DS1511_AM2_MIN = 0x9,
  36        DS1511_AM3_HOUR = 0xa,
  37        DS1511_AM4_DATE = 0xb,
  38        DS1511_WD_MSEC = 0xc,
  39        DS1511_WD_SEC = 0xd,
  40        DS1511_CONTROL_A = 0xe,
  41        DS1511_CONTROL_B = 0xf,
  42        DS1511_RAMADDR_LSB = 0x10,
  43        DS1511_RAMDATA = 0x13
  44};
  45
  46#define DS1511_BLF1     0x80
  47#define DS1511_BLF2     0x40
  48#define DS1511_PRS      0x20
  49#define DS1511_PAB      0x10
  50#define DS1511_TDF      0x08
  51#define DS1511_KSF      0x04
  52#define DS1511_WDF      0x02
  53#define DS1511_IRQF     0x01
  54#define DS1511_TE       0x80
  55#define DS1511_CS       0x40
  56#define DS1511_BME      0x20
  57#define DS1511_TPE      0x10
  58#define DS1511_TIE      0x08
  59#define DS1511_KIE      0x04
  60#define DS1511_WDE      0x02
  61#define DS1511_WDS      0x01
  62#define DS1511_RAM_MAX  0x100
  63
  64#define RTC_CMD         DS1511_CONTROL_B
  65#define RTC_CMD1        DS1511_CONTROL_A
  66
  67#define RTC_ALARM_SEC   DS1511_AM1_SEC
  68#define RTC_ALARM_MIN   DS1511_AM2_MIN
  69#define RTC_ALARM_HOUR  DS1511_AM3_HOUR
  70#define RTC_ALARM_DATE  DS1511_AM4_DATE
  71
  72#define RTC_SEC         DS1511_SEC
  73#define RTC_MIN         DS1511_MIN
  74#define RTC_HOUR        DS1511_HOUR
  75#define RTC_DOW         DS1511_DOW
  76#define RTC_DOM         DS1511_DOM
  77#define RTC_MON         DS1511_MONTH
  78#define RTC_YEAR        DS1511_YEAR
  79#define RTC_CENTURY     DS1511_CENTURY
  80
  81#define RTC_TIE DS1511_TIE
  82#define RTC_TE  DS1511_TE
  83
  84struct rtc_plat_data {
  85        struct rtc_device *rtc;
  86        void __iomem *ioaddr;           /* virtual base address */
  87        int irq;
  88        unsigned int irqen;
  89        int alrm_sec;
  90        int alrm_min;
  91        int alrm_hour;
  92        int alrm_mday;
  93        spinlock_t lock;
  94};
  95
  96static DEFINE_SPINLOCK(ds1511_lock);
  97
  98static __iomem char *ds1511_base;
  99static u32 reg_spacing = 1;
 100
 101static noinline void
 102rtc_write(uint8_t val, uint32_t reg)
 103{
 104        writeb(val, ds1511_base + (reg * reg_spacing));
 105}
 106
 107static noinline uint8_t
 108rtc_read(enum ds1511reg reg)
 109{
 110        return readb(ds1511_base + (reg * reg_spacing));
 111}
 112
 113static inline void
 114rtc_disable_update(void)
 115{
 116        rtc_write((rtc_read(RTC_CMD) & ~RTC_TE), RTC_CMD);
 117}
 118
 119static void
 120rtc_enable_update(void)
 121{
 122        rtc_write((rtc_read(RTC_CMD) | RTC_TE), RTC_CMD);
 123}
 124
 125/*
 126 * #define DS1511_WDOG_RESET_SUPPORT
 127 *
 128 * Uncomment this if you want to use these routines in
 129 * some platform code.
 130 */
 131#ifdef DS1511_WDOG_RESET_SUPPORT
 132/*
 133 * just enough code to set the watchdog timer so that it
 134 * will reboot the system
 135 */
 136void
 137ds1511_wdog_set(unsigned long deciseconds)
 138{
 139        /*
 140         * the wdog timer can take 99.99 seconds
 141         */
 142        deciseconds %= 10000;
 143        /*
 144         * set the wdog values in the wdog registers
 145         */
 146        rtc_write(bin2bcd(deciseconds % 100), DS1511_WD_MSEC);
 147        rtc_write(bin2bcd(deciseconds / 100), DS1511_WD_SEC);
 148        /*
 149         * set wdog enable and wdog 'steering' bit to issue a reset
 150         */
 151        rtc_write(rtc_read(RTC_CMD) | DS1511_WDE | DS1511_WDS, RTC_CMD);
 152}
 153
 154void
 155ds1511_wdog_disable(void)
 156{
 157        /*
 158         * clear wdog enable and wdog 'steering' bits
 159         */
 160        rtc_write(rtc_read(RTC_CMD) & ~(DS1511_WDE | DS1511_WDS), RTC_CMD);
 161        /*
 162         * clear the wdog counter
 163         */
 164        rtc_write(0, DS1511_WD_MSEC);
 165        rtc_write(0, DS1511_WD_SEC);
 166}
 167#endif
 168
 169/*
 170 * set the rtc chip's idea of the time.
 171 * stupidly, some callers call with year unmolested;
 172 * and some call with  year = year - 1900.  thanks.
 173 */
 174static int ds1511_rtc_set_time(struct device *dev, struct rtc_time *rtc_tm)
 175{
 176        u8 mon, day, dow, hrs, min, sec, yrs, cen;
 177        unsigned long flags;
 178
 179        /*
 180         * won't have to change this for a while
 181         */
 182        if (rtc_tm->tm_year < 1900)
 183                rtc_tm->tm_year += 1900;
 184
 185        if (rtc_tm->tm_year < 1970)
 186                return -EINVAL;
 187
 188        yrs = rtc_tm->tm_year % 100;
 189        cen = rtc_tm->tm_year / 100;
 190        mon = rtc_tm->tm_mon + 1;   /* tm_mon starts at zero */
 191        day = rtc_tm->tm_mday;
 192        dow = rtc_tm->tm_wday & 0x7; /* automatic BCD */
 193        hrs = rtc_tm->tm_hour;
 194        min = rtc_tm->tm_min;
 195        sec = rtc_tm->tm_sec;
 196
 197        if ((mon > 12) || (day == 0))
 198                return -EINVAL;
 199
 200        if (day > rtc_month_days(rtc_tm->tm_mon, rtc_tm->tm_year))
 201                return -EINVAL;
 202
 203        if ((hrs >= 24) || (min >= 60) || (sec >= 60))
 204                return -EINVAL;
 205
 206        /*
 207         * each register is a different number of valid bits
 208         */
 209        sec = bin2bcd(sec) & 0x7f;
 210        min = bin2bcd(min) & 0x7f;
 211        hrs = bin2bcd(hrs) & 0x3f;
 212        day = bin2bcd(day) & 0x3f;
 213        mon = bin2bcd(mon) & 0x1f;
 214        yrs = bin2bcd(yrs) & 0xff;
 215        cen = bin2bcd(cen) & 0xff;
 216
 217        spin_lock_irqsave(&ds1511_lock, flags);
 218        rtc_disable_update();
 219        rtc_write(cen, RTC_CENTURY);
 220        rtc_write(yrs, RTC_YEAR);
 221        rtc_write((rtc_read(RTC_MON) & 0xe0) | mon, RTC_MON);
 222        rtc_write(day, RTC_DOM);
 223        rtc_write(hrs, RTC_HOUR);
 224        rtc_write(min, RTC_MIN);
 225        rtc_write(sec, RTC_SEC);
 226        rtc_write(dow, RTC_DOW);
 227        rtc_enable_update();
 228        spin_unlock_irqrestore(&ds1511_lock, flags);
 229
 230        return 0;
 231}
 232
 233static int ds1511_rtc_read_time(struct device *dev, struct rtc_time *rtc_tm)
 234{
 235        unsigned int century;
 236        unsigned long flags;
 237
 238        spin_lock_irqsave(&ds1511_lock, flags);
 239        rtc_disable_update();
 240
 241        rtc_tm->tm_sec = rtc_read(RTC_SEC) & 0x7f;
 242        rtc_tm->tm_min = rtc_read(RTC_MIN) & 0x7f;
 243        rtc_tm->tm_hour = rtc_read(RTC_HOUR) & 0x3f;
 244        rtc_tm->tm_mday = rtc_read(RTC_DOM) & 0x3f;
 245        rtc_tm->tm_wday = rtc_read(RTC_DOW) & 0x7;
 246        rtc_tm->tm_mon = rtc_read(RTC_MON) & 0x1f;
 247        rtc_tm->tm_year = rtc_read(RTC_YEAR) & 0x7f;
 248        century = rtc_read(RTC_CENTURY);
 249
 250        rtc_enable_update();
 251        spin_unlock_irqrestore(&ds1511_lock, flags);
 252
 253        rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
 254        rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
 255        rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
 256        rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
 257        rtc_tm->tm_wday = bcd2bin(rtc_tm->tm_wday);
 258        rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
 259        rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
 260        century = bcd2bin(century) * 100;
 261
 262        /*
 263         * Account for differences between how the RTC uses the values
 264         * and how they are defined in a struct rtc_time;
 265         */
 266        century += rtc_tm->tm_year;
 267        rtc_tm->tm_year = century - 1900;
 268
 269        rtc_tm->tm_mon--;
 270
 271        return 0;
 272}
 273
 274/*
 275 * write the alarm register settings
 276 *
 277 * we only have the use to interrupt every second, otherwise
 278 * known as the update interrupt, or the interrupt if the whole
 279 * date/hours/mins/secs matches.  the ds1511 has many more
 280 * permutations, but the kernel doesn't.
 281 */
 282static void
 283ds1511_rtc_update_alarm(struct rtc_plat_data *pdata)
 284{
 285        unsigned long flags;
 286
 287        spin_lock_irqsave(&pdata->lock, flags);
 288        rtc_write(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
 289               0x80 : bin2bcd(pdata->alrm_mday) & 0x3f,
 290               RTC_ALARM_DATE);
 291        rtc_write(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
 292               0x80 : bin2bcd(pdata->alrm_hour) & 0x3f,
 293               RTC_ALARM_HOUR);
 294        rtc_write(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
 295               0x80 : bin2bcd(pdata->alrm_min) & 0x7f,
 296               RTC_ALARM_MIN);
 297        rtc_write(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
 298               0x80 : bin2bcd(pdata->alrm_sec) & 0x7f,
 299               RTC_ALARM_SEC);
 300        rtc_write(rtc_read(RTC_CMD) | (pdata->irqen ? RTC_TIE : 0), RTC_CMD);
 301        rtc_read(RTC_CMD1);     /* clear interrupts */
 302        spin_unlock_irqrestore(&pdata->lock, flags);
 303}
 304
 305static int
 306ds1511_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 307{
 308        struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 309
 310        if (pdata->irq <= 0)
 311                return -EINVAL;
 312
 313        pdata->alrm_mday = alrm->time.tm_mday;
 314        pdata->alrm_hour = alrm->time.tm_hour;
 315        pdata->alrm_min = alrm->time.tm_min;
 316        pdata->alrm_sec = alrm->time.tm_sec;
 317        if (alrm->enabled)
 318                pdata->irqen |= RTC_AF;
 319
 320        ds1511_rtc_update_alarm(pdata);
 321        return 0;
 322}
 323
 324static int
 325ds1511_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 326{
 327        struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 328
 329        if (pdata->irq <= 0)
 330                return -EINVAL;
 331
 332        alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
 333        alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
 334        alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
 335        alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
 336        alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
 337        return 0;
 338}
 339
 340static irqreturn_t
 341ds1511_interrupt(int irq, void *dev_id)
 342{
 343        struct platform_device *pdev = dev_id;
 344        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 345        unsigned long events = 0;
 346
 347        spin_lock(&pdata->lock);
 348        /*
 349         * read and clear interrupt
 350         */
 351        if (rtc_read(RTC_CMD1) & DS1511_IRQF) {
 352                events = RTC_IRQF;
 353                if (rtc_read(RTC_ALARM_SEC) & 0x80)
 354                        events |= RTC_UF;
 355                else
 356                        events |= RTC_AF;
 357                rtc_update_irq(pdata->rtc, 1, events);
 358        }
 359        spin_unlock(&pdata->lock);
 360        return events ? IRQ_HANDLED : IRQ_NONE;
 361}
 362
 363static int ds1511_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 364{
 365        struct rtc_plat_data *pdata = dev_get_drvdata(dev);
 366
 367        if (pdata->irq <= 0)
 368                return -EINVAL;
 369        if (enabled)
 370                pdata->irqen |= RTC_AF;
 371        else
 372                pdata->irqen &= ~RTC_AF;
 373        ds1511_rtc_update_alarm(pdata);
 374        return 0;
 375}
 376
 377static const struct rtc_class_ops ds1511_rtc_ops = {
 378        .read_time              = ds1511_rtc_read_time,
 379        .set_time               = ds1511_rtc_set_time,
 380        .read_alarm             = ds1511_rtc_read_alarm,
 381        .set_alarm              = ds1511_rtc_set_alarm,
 382        .alarm_irq_enable       = ds1511_rtc_alarm_irq_enable,
 383};
 384
 385static int ds1511_nvram_read(void *priv, unsigned int pos, void *buf,
 386                             size_t size)
 387{
 388        int i;
 389
 390        rtc_write(pos, DS1511_RAMADDR_LSB);
 391        for (i = 0; i < size; i++)
 392                *(char *)buf++ = rtc_read(DS1511_RAMDATA);
 393
 394        return 0;
 395}
 396
 397static int ds1511_nvram_write(void *priv, unsigned int pos, void *buf,
 398                              size_t size)
 399{
 400        int i;
 401
 402        rtc_write(pos, DS1511_RAMADDR_LSB);
 403        for (i = 0; i < size; i++)
 404                rtc_write(*(char *)buf++, DS1511_RAMDATA);
 405
 406        return 0;
 407}
 408
 409static int ds1511_rtc_probe(struct platform_device *pdev)
 410{
 411        struct rtc_plat_data *pdata;
 412        int ret = 0;
 413        struct nvmem_config ds1511_nvmem_cfg = {
 414                .name = "ds1511_nvram",
 415                .word_size = 1,
 416                .stride = 1,
 417                .size = DS1511_RAM_MAX,
 418                .reg_read = ds1511_nvram_read,
 419                .reg_write = ds1511_nvram_write,
 420                .priv = &pdev->dev,
 421        };
 422
 423        pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 424        if (!pdata)
 425                return -ENOMEM;
 426
 427        ds1511_base = devm_platform_ioremap_resource(pdev, 0);
 428        if (IS_ERR(ds1511_base))
 429                return PTR_ERR(ds1511_base);
 430        pdata->ioaddr = ds1511_base;
 431        pdata->irq = platform_get_irq(pdev, 0);
 432
 433        /*
 434         * turn on the clock and the crystal, etc.
 435         */
 436        rtc_write(DS1511_BME, RTC_CMD);
 437        rtc_write(0, RTC_CMD1);
 438        /*
 439         * clear the wdog counter
 440         */
 441        rtc_write(0, DS1511_WD_MSEC);
 442        rtc_write(0, DS1511_WD_SEC);
 443        /*
 444         * start the clock
 445         */
 446        rtc_enable_update();
 447
 448        /*
 449         * check for a dying bat-tree
 450         */
 451        if (rtc_read(RTC_CMD1) & DS1511_BLF1)
 452                dev_warn(&pdev->dev, "voltage-low detected.\n");
 453
 454        spin_lock_init(&pdata->lock);
 455        platform_set_drvdata(pdev, pdata);
 456
 457        pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
 458        if (IS_ERR(pdata->rtc))
 459                return PTR_ERR(pdata->rtc);
 460
 461        pdata->rtc->ops = &ds1511_rtc_ops;
 462
 463        ret = devm_rtc_register_device(pdata->rtc);
 464        if (ret)
 465                return ret;
 466
 467        devm_rtc_nvmem_register(pdata->rtc, &ds1511_nvmem_cfg);
 468
 469        /*
 470         * if the platform has an interrupt in mind for this device,
 471         * then by all means, set it
 472         */
 473        if (pdata->irq > 0) {
 474                rtc_read(RTC_CMD1);
 475                if (devm_request_irq(&pdev->dev, pdata->irq, ds1511_interrupt,
 476                        IRQF_SHARED, pdev->name, pdev) < 0) {
 477
 478                        dev_warn(&pdev->dev, "interrupt not available.\n");
 479                        pdata->irq = 0;
 480                }
 481        }
 482
 483        return 0;
 484}
 485
 486/* work with hotplug and coldplug */
 487MODULE_ALIAS("platform:ds1511");
 488
 489static struct platform_driver ds1511_rtc_driver = {
 490        .probe          = ds1511_rtc_probe,
 491        .driver         = {
 492                .name   = "ds1511",
 493        },
 494};
 495
 496module_platform_driver(ds1511_rtc_driver);
 497
 498MODULE_AUTHOR("Andrew Sharp <andy.sharp@lsi.com>");
 499MODULE_DESCRIPTION("Dallas DS1511 RTC driver");
 500MODULE_LICENSE("GPL");
 501