linux/drivers/rtc/rtc-s35390a.c
<<
>>
Prefs
   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Seiko Instruments S-35390A RTC Driver
   4 *
   5 * Copyright (c) 2007 Byron Bradley
   6 */
   7
   8#include <linux/module.h>
   9#include <linux/rtc.h>
  10#include <linux/i2c.h>
  11#include <linux/bitrev.h>
  12#include <linux/bcd.h>
  13#include <linux/slab.h>
  14#include <linux/delay.h>
  15
  16#define S35390A_CMD_STATUS1     0
  17#define S35390A_CMD_STATUS2     1
  18#define S35390A_CMD_TIME1       2
  19#define S35390A_CMD_TIME2       3
  20#define S35390A_CMD_INT2_REG1   5
  21
  22#define S35390A_BYTE_YEAR       0
  23#define S35390A_BYTE_MONTH      1
  24#define S35390A_BYTE_DAY        2
  25#define S35390A_BYTE_WDAY       3
  26#define S35390A_BYTE_HOURS      4
  27#define S35390A_BYTE_MINS       5
  28#define S35390A_BYTE_SECS       6
  29
  30#define S35390A_ALRM_BYTE_WDAY  0
  31#define S35390A_ALRM_BYTE_HOURS 1
  32#define S35390A_ALRM_BYTE_MINS  2
  33
  34/* flags for STATUS1 */
  35#define S35390A_FLAG_POC        BIT(0)
  36#define S35390A_FLAG_BLD        BIT(1)
  37#define S35390A_FLAG_INT2       BIT(2)
  38#define S35390A_FLAG_24H        BIT(6)
  39#define S35390A_FLAG_RESET      BIT(7)
  40
  41/* flag for STATUS2 */
  42#define S35390A_FLAG_TEST       BIT(0)
  43
  44/* INT2 pin output mode */
  45#define S35390A_INT2_MODE_MASK          0x0E
  46#define S35390A_INT2_MODE_NOINTR        0x00
  47#define S35390A_INT2_MODE_ALARM         BIT(1) /* INT2AE */
  48#define S35390A_INT2_MODE_PMIN_EDG      BIT(2) /* INT2ME */
  49#define S35390A_INT2_MODE_FREQ          BIT(3) /* INT2FE */
  50#define S35390A_INT2_MODE_PMIN          (BIT(3) | BIT(2)) /* INT2FE | INT2ME */
  51
  52static const struct i2c_device_id s35390a_id[] = {
  53        { "s35390a", 0 },
  54        { }
  55};
  56MODULE_DEVICE_TABLE(i2c, s35390a_id);
  57
  58static const __maybe_unused struct of_device_id s35390a_of_match[] = {
  59        { .compatible = "s35390a" },
  60        { .compatible = "sii,s35390a" },
  61        { }
  62};
  63MODULE_DEVICE_TABLE(of, s35390a_of_match);
  64
  65struct s35390a {
  66        struct i2c_client *client[8];
  67        struct rtc_device *rtc;
  68        int twentyfourhour;
  69};
  70
  71static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *buf, int len)
  72{
  73        struct i2c_client *client = s35390a->client[reg];
  74        struct i2c_msg msg[] = {
  75                {
  76                        .addr = client->addr,
  77                        .len = len,
  78                        .buf = buf
  79                },
  80        };
  81
  82        if ((i2c_transfer(client->adapter, msg, 1)) != 1)
  83                return -EIO;
  84
  85        return 0;
  86}
  87
  88static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
  89{
  90        struct i2c_client *client = s35390a->client[reg];
  91        struct i2c_msg msg[] = {
  92                {
  93                        .addr = client->addr,
  94                        .flags = I2C_M_RD,
  95                        .len = len,
  96                        .buf = buf
  97                },
  98        };
  99
 100        if ((i2c_transfer(client->adapter, msg, 1)) != 1)
 101                return -EIO;
 102
 103        return 0;
 104}
 105
 106static int s35390a_init(struct s35390a *s35390a)
 107{
 108        u8 buf;
 109        int ret;
 110        unsigned initcount = 0;
 111
 112        /*
 113         * At least one of POC and BLD are set, so reinitialise chip. Keeping
 114         * this information in the hardware to know later that the time isn't
 115         * valid is unfortunately not possible because POC and BLD are cleared
 116         * on read. So the reset is best done now.
 117         *
 118         * The 24H bit is kept over reset, so set it already here.
 119         */
 120initialize:
 121        buf = S35390A_FLAG_RESET | S35390A_FLAG_24H;
 122        ret = s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
 123
 124        if (ret < 0)
 125                return ret;
 126
 127        ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
 128        if (ret < 0)
 129                return ret;
 130
 131        if (buf & (S35390A_FLAG_POC | S35390A_FLAG_BLD)) {
 132                /* Try up to five times to reset the chip */
 133                if (initcount < 5) {
 134                        ++initcount;
 135                        goto initialize;
 136                } else
 137                        return -EIO;
 138        }
 139
 140        return 1;
 141}
 142
 143/*
 144 * Returns <0 on error, 0 if rtc is setup fine and 1 if the chip was reset.
 145 * To keep the information if an irq is pending, pass the value read from
 146 * STATUS1 to the caller.
 147 */
 148static int s35390a_read_status(struct s35390a *s35390a, char *status1)
 149{
 150        int ret;
 151
 152        ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, status1, 1);
 153        if (ret < 0)
 154                return ret;
 155
 156        if (*status1 & S35390A_FLAG_POC) {
 157                /*
 158                 * Do not communicate for 0.5 seconds since the power-on
 159                 * detection circuit is in operation.
 160                 */
 161                msleep(500);
 162                return 1;
 163        } else if (*status1 & S35390A_FLAG_BLD)
 164                return 1;
 165        /*
 166         * If both POC and BLD are unset everything is fine.
 167         */
 168        return 0;
 169}
 170
 171static int s35390a_disable_test_mode(struct s35390a *s35390a)
 172{
 173        char buf[1];
 174
 175        if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf)) < 0)
 176                return -EIO;
 177
 178        if (!(buf[0] & S35390A_FLAG_TEST))
 179                return 0;
 180
 181        buf[0] &= ~S35390A_FLAG_TEST;
 182        return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
 183}
 184
 185static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
 186{
 187        if (s35390a->twentyfourhour)
 188                return bin2bcd(hour);
 189
 190        if (hour < 12)
 191                return bin2bcd(hour);
 192
 193        return 0x40 | bin2bcd(hour - 12);
 194}
 195
 196static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
 197{
 198        unsigned hour;
 199
 200        if (s35390a->twentyfourhour)
 201                return bcd2bin(reg & 0x3f);
 202
 203        hour = bcd2bin(reg & 0x3f);
 204        if (reg & 0x40)
 205                hour += 12;
 206
 207        return hour;
 208}
 209
 210static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
 211{
 212        struct i2c_client *client = to_i2c_client(dev);
 213        struct s35390a  *s35390a = i2c_get_clientdata(client);
 214        int i, err;
 215        char buf[7], status;
 216
 217        dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d mday=%d, "
 218                "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
 219                tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
 220                tm->tm_wday);
 221
 222        if (s35390a_read_status(s35390a, &status) == 1)
 223                s35390a_init(s35390a);
 224
 225        buf[S35390A_BYTE_YEAR] = bin2bcd(tm->tm_year - 100);
 226        buf[S35390A_BYTE_MONTH] = bin2bcd(tm->tm_mon + 1);
 227        buf[S35390A_BYTE_DAY] = bin2bcd(tm->tm_mday);
 228        buf[S35390A_BYTE_WDAY] = bin2bcd(tm->tm_wday);
 229        buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
 230        buf[S35390A_BYTE_MINS] = bin2bcd(tm->tm_min);
 231        buf[S35390A_BYTE_SECS] = bin2bcd(tm->tm_sec);
 232
 233        /* This chip expects the bits of each byte to be in reverse order */
 234        for (i = 0; i < 7; ++i)
 235                buf[i] = bitrev8(buf[i]);
 236
 237        err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
 238
 239        return err;
 240}
 241
 242static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
 243{
 244        struct i2c_client *client = to_i2c_client(dev);
 245        struct s35390a *s35390a = i2c_get_clientdata(client);
 246        char buf[7], status;
 247        int i, err;
 248
 249        if (s35390a_read_status(s35390a, &status) == 1)
 250                return -EINVAL;
 251
 252        err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
 253        if (err < 0)
 254                return err;
 255
 256        /* This chip returns the bits of each byte in reverse order */
 257        for (i = 0; i < 7; ++i)
 258                buf[i] = bitrev8(buf[i]);
 259
 260        tm->tm_sec = bcd2bin(buf[S35390A_BYTE_SECS]);
 261        tm->tm_min = bcd2bin(buf[S35390A_BYTE_MINS]);
 262        tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
 263        tm->tm_wday = bcd2bin(buf[S35390A_BYTE_WDAY]);
 264        tm->tm_mday = bcd2bin(buf[S35390A_BYTE_DAY]);
 265        tm->tm_mon = bcd2bin(buf[S35390A_BYTE_MONTH]) - 1;
 266        tm->tm_year = bcd2bin(buf[S35390A_BYTE_YEAR]) + 100;
 267
 268        dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
 269                "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
 270                tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
 271                tm->tm_wday);
 272
 273        return 0;
 274}
 275
 276static int s35390a_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
 277{
 278        struct i2c_client *client = to_i2c_client(dev);
 279        struct s35390a *s35390a = i2c_get_clientdata(client);
 280        char buf[3], sts = 0;
 281        int err, i;
 282
 283        dev_dbg(&client->dev, "%s: alm is secs=%d, mins=%d, hours=%d mday=%d, "\
 284                "mon=%d, year=%d, wday=%d\n", __func__, alm->time.tm_sec,
 285                alm->time.tm_min, alm->time.tm_hour, alm->time.tm_mday,
 286                alm->time.tm_mon, alm->time.tm_year, alm->time.tm_wday);
 287
 288        if (alm->time.tm_sec != 0)
 289                dev_warn(&client->dev, "Alarms are only supported on a per minute basis!\n");
 290
 291        /* disable interrupt (which deasserts the irq line) */
 292        err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
 293        if (err < 0)
 294                return err;
 295
 296        /* clear pending interrupt (in STATUS1 only), if any */
 297        err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &sts, sizeof(sts));
 298        if (err < 0)
 299                return err;
 300
 301        if (alm->enabled)
 302                sts = S35390A_INT2_MODE_ALARM;
 303        else
 304                sts = S35390A_INT2_MODE_NOINTR;
 305
 306        /* set interupt mode*/
 307        err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
 308        if (err < 0)
 309                return err;
 310
 311        if (alm->time.tm_wday != -1)
 312                buf[S35390A_ALRM_BYTE_WDAY] = bin2bcd(alm->time.tm_wday) | 0x80;
 313        else
 314                buf[S35390A_ALRM_BYTE_WDAY] = 0;
 315
 316        buf[S35390A_ALRM_BYTE_HOURS] = s35390a_hr2reg(s35390a,
 317                        alm->time.tm_hour) | 0x80;
 318        buf[S35390A_ALRM_BYTE_MINS] = bin2bcd(alm->time.tm_min) | 0x80;
 319
 320        if (alm->time.tm_hour >= 12)
 321                buf[S35390A_ALRM_BYTE_HOURS] |= 0x40;
 322
 323        for (i = 0; i < 3; ++i)
 324                buf[i] = bitrev8(buf[i]);
 325
 326        err = s35390a_set_reg(s35390a, S35390A_CMD_INT2_REG1, buf,
 327                                                                sizeof(buf));
 328
 329        return err;
 330}
 331
 332static int s35390a_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
 333{
 334        struct i2c_client *client = to_i2c_client(dev);
 335        struct s35390a *s35390a = i2c_get_clientdata(client);
 336        char buf[3], sts;
 337        int i, err;
 338
 339        err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, &sts, sizeof(sts));
 340        if (err < 0)
 341                return err;
 342
 343        if ((sts & S35390A_INT2_MODE_MASK) != S35390A_INT2_MODE_ALARM) {
 344                /*
 345                 * When the alarm isn't enabled, the register to configure
 346                 * the alarm time isn't accessible.
 347                 */
 348                alm->enabled = 0;
 349                return 0;
 350        } else {
 351                alm->enabled = 1;
 352        }
 353
 354        err = s35390a_get_reg(s35390a, S35390A_CMD_INT2_REG1, buf, sizeof(buf));
 355        if (err < 0)
 356                return err;
 357
 358        /* This chip returns the bits of each byte in reverse order */
 359        for (i = 0; i < 3; ++i)
 360                buf[i] = bitrev8(buf[i]);
 361
 362        /*
 363         * B0 of the three matching registers is an enable flag. Iff it is set
 364         * the configured value is used for matching.
 365         */
 366        if (buf[S35390A_ALRM_BYTE_WDAY] & 0x80)
 367                alm->time.tm_wday =
 368                        bcd2bin(buf[S35390A_ALRM_BYTE_WDAY] & ~0x80);
 369
 370        if (buf[S35390A_ALRM_BYTE_HOURS] & 0x80)
 371                alm->time.tm_hour =
 372                        s35390a_reg2hr(s35390a,
 373                                       buf[S35390A_ALRM_BYTE_HOURS] & ~0x80);
 374
 375        if (buf[S35390A_ALRM_BYTE_MINS] & 0x80)
 376                alm->time.tm_min = bcd2bin(buf[S35390A_ALRM_BYTE_MINS] & ~0x80);
 377
 378        /* alarm triggers always at s=0 */
 379        alm->time.tm_sec = 0;
 380
 381        dev_dbg(&client->dev, "%s: alm is mins=%d, hours=%d, wday=%d\n",
 382                        __func__, alm->time.tm_min, alm->time.tm_hour,
 383                        alm->time.tm_wday);
 384
 385        return 0;
 386}
 387
 388static int s35390a_rtc_ioctl(struct device *dev, unsigned int cmd,
 389                             unsigned long arg)
 390{
 391        struct i2c_client *client = to_i2c_client(dev);
 392        struct s35390a *s35390a = i2c_get_clientdata(client);
 393        char sts;
 394        int err;
 395
 396        switch (cmd) {
 397        case RTC_VL_READ:
 398                /* s35390a_reset set lowvoltage flag and init RTC if needed */
 399                err = s35390a_read_status(s35390a, &sts);
 400                if (err < 0)
 401                        return err;
 402                if (copy_to_user((void __user *)arg, &err, sizeof(int)))
 403                        return -EFAULT;
 404                break;
 405        case RTC_VL_CLR:
 406                /* update flag and clear register */
 407                err = s35390a_init(s35390a);
 408                if (err < 0)
 409                        return err;
 410                break;
 411        default:
 412                return -ENOIOCTLCMD;
 413        }
 414
 415        return 0;
 416}
 417
 418static const struct rtc_class_ops s35390a_rtc_ops = {
 419        .read_time      = s35390a_rtc_read_time,
 420        .set_time       = s35390a_rtc_set_time,
 421        .set_alarm      = s35390a_rtc_set_alarm,
 422        .read_alarm     = s35390a_rtc_read_alarm,
 423        .ioctl          = s35390a_rtc_ioctl,
 424};
 425
 426static int s35390a_probe(struct i2c_client *client,
 427                         const struct i2c_device_id *id)
 428{
 429        int err, err_read;
 430        unsigned int i;
 431        struct s35390a *s35390a;
 432        char buf, status1;
 433        struct device *dev = &client->dev;
 434
 435        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 436                return -ENODEV;
 437
 438        s35390a = devm_kzalloc(dev, sizeof(struct s35390a), GFP_KERNEL);
 439        if (!s35390a)
 440                return -ENOMEM;
 441
 442        s35390a->client[0] = client;
 443        i2c_set_clientdata(client, s35390a);
 444
 445        /* This chip uses multiple addresses, use dummy devices for them */
 446        for (i = 1; i < 8; ++i) {
 447                s35390a->client[i] = devm_i2c_new_dummy_device(dev,
 448                                                               client->adapter,
 449                                                               client->addr + i);
 450                if (IS_ERR(s35390a->client[i])) {
 451                        dev_err(dev, "Address %02x unavailable\n",
 452                                client->addr + i);
 453                        return PTR_ERR(s35390a->client[i]);
 454                }
 455        }
 456
 457        s35390a->rtc = devm_rtc_allocate_device(dev);
 458        if (IS_ERR(s35390a->rtc))
 459                return PTR_ERR(s35390a->rtc);
 460
 461        err_read = s35390a_read_status(s35390a, &status1);
 462        if (err_read < 0) {
 463                dev_err(dev, "error resetting chip\n");
 464                return err_read;
 465        }
 466
 467        if (status1 & S35390A_FLAG_24H)
 468                s35390a->twentyfourhour = 1;
 469        else
 470                s35390a->twentyfourhour = 0;
 471
 472        if (status1 & S35390A_FLAG_INT2) {
 473                /* disable alarm (and maybe test mode) */
 474                buf = 0;
 475                err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, &buf, 1);
 476                if (err < 0) {
 477                        dev_err(dev, "error disabling alarm");
 478                        return err;
 479                }
 480        } else {
 481                err = s35390a_disable_test_mode(s35390a);
 482                if (err < 0) {
 483                        dev_err(dev, "error disabling test mode\n");
 484                        return err;
 485                }
 486        }
 487
 488        device_set_wakeup_capable(dev, 1);
 489
 490        s35390a->rtc->ops = &s35390a_rtc_ops;
 491        s35390a->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 492        s35390a->rtc->range_max = RTC_TIMESTAMP_END_2099;
 493
 494        /* supports per-minute alarms only, therefore set uie_unsupported */
 495        s35390a->rtc->uie_unsupported = 1;
 496
 497        if (status1 & S35390A_FLAG_INT2)
 498                rtc_update_irq(s35390a->rtc, 1, RTC_AF);
 499
 500        return devm_rtc_register_device(s35390a->rtc);
 501}
 502
 503static struct i2c_driver s35390a_driver = {
 504        .driver         = {
 505                .name   = "rtc-s35390a",
 506                .of_match_table = of_match_ptr(s35390a_of_match),
 507        },
 508        .probe          = s35390a_probe,
 509        .id_table       = s35390a_id,
 510};
 511
 512module_i2c_driver(s35390a_driver);
 513
 514MODULE_AUTHOR("Byron Bradley <byron.bbradley@gmail.com>");
 515MODULE_DESCRIPTION("S35390A RTC driver");
 516MODULE_LICENSE("GPL");
 517