drivers/rtc/rtc-rs5c372.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * An I2C driver for Ricoh RS5C372, R2025S/D and RV5C38[67] RTCs
   4  *
   5  * Copyright (C) 2005 Pavel Mironchik <pmironchik@optifacio.net>
   6  * Copyright (C) 2006 Tower Technologies
   7  * Copyright (C) 2008 Paul Mundt
   8  */
   9
  10 #include <linux/i2c.h>
  11 #include <linux/rtc.h>
  12 #include <linux/bcd.h>
  13 #include <linux/slab.h>
  14 #include <linux/module.h>
  15 #include <linux/of_device.h>
  16
  17 /*
  18  * Ricoh has a family of I2C based RTCs, which differ only slightly from
  19  * each other.  Differences center on pinout (e.g. how many interrupts,
  20  * output clock, etc) and how the control registers are used.  The '372
  21  * is significant only because that's the one this driver first supported.
  22  */
  23 #define RS5C372_REG_SECS        0
  24 #define RS5C372_REG_MINS        1
  25 #define RS5C372_REG_HOURS       2
  26 #define RS5C372_REG_WDAY        3
  27 #define RS5C372_REG_DAY         4
  28 #define RS5C372_REG_MONTH       5
  29 #define RS5C372_REG_YEAR        6
  30 #define RS5C372_REG_TRIM        7
  31 #       define RS5C372_TRIM_XSL         0x80
  32 #       define RS5C372_TRIM_MASK        0x7F
  33
  34 #define RS5C_REG_ALARM_A_MIN    8                       /* or ALARM_W */
  35 #define RS5C_REG_ALARM_A_HOURS  9
  36 #define RS5C_REG_ALARM_A_WDAY   10
  37
  38 #define RS5C_REG_ALARM_B_MIN    11                      /* or ALARM_D */
  39 #define RS5C_REG_ALARM_B_HOURS  12
  40 #define RS5C_REG_ALARM_B_WDAY   13                      /* (ALARM_B only) */
  41
  42 #define RS5C_REG_CTRL1          14
  43 #       define RS5C_CTRL1_AALE          (1 << 7)        /* or WALE */
  44 #       define RS5C_CTRL1_BALE          (1 << 6)        /* or DALE */
  45 #       define RV5C387_CTRL1_24         (1 << 5)
  46 #       define RS5C372A_CTRL1_SL1       (1 << 5)
  47 #       define RS5C_CTRL1_CT_MASK       (7 << 0)
  48 #       define RS5C_CTRL1_CT0           (0 << 0)        /* no periodic irq */
  49 #       define RS5C_CTRL1_CT4           (4 << 0)        /* 1 Hz level irq */
  50 #define RS5C_REG_CTRL2          15
  51 #       define RS5C372_CTRL2_24         (1 << 5)
  52 #       define RS5C_CTRL2_XSTP          (1 << 4)        /* only if !R2x2x */
  53 #       define R2x2x_CTRL2_VDET         (1 << 6)        /* only if  R2x2x */
  54 #       define R2x2x_CTRL2_XSTP         (1 << 5)        /* only if  R2x2x */
  55 #       define R2x2x_CTRL2_PON          (1 << 4)        /* only if  R2x2x */
  56 #       define RS5C_CTRL2_CTFG          (1 << 2)
  57 #       define RS5C_CTRL2_AAFG          (1 << 1)        /* or WAFG */
  58 #       define RS5C_CTRL2_BAFG          (1 << 0)        /* or DAFG */
  59
  60
  61 /* to read (style 1) or write registers starting at R */
  62 #define RS5C_ADDR(R)            (((R) << 4) | 0)
  63
  64
  65 enum rtc_type {
  66         rtc_undef = 0,
  67         rtc_r2025sd,
  68         rtc_r2221tl,
  69         rtc_rs5c372a,
  70         rtc_rs5c372b,
  71         rtc_rv5c386,
  72         rtc_rv5c387a,
  73 };
  74
  75 static const struct i2c_device_id rs5c372_id[] = {
  76         { "r2025sd", rtc_r2025sd },
  77         { "r2221tl", rtc_r2221tl },
  78         { "rs5c372a", rtc_rs5c372a },
  79         { "rs5c372b", rtc_rs5c372b },
  80         { "rv5c386", rtc_rv5c386 },
  81         { "rv5c387a", rtc_rv5c387a },
  82         { }
  83 };
  84 MODULE_DEVICE_TABLE(i2c, rs5c372_id);
  85
  86 static const __maybe_unused struct of_device_id rs5c372_of_match[] = {
  87         {
  88                 .compatible = "ricoh,r2025sd",
  89                 .data = (void *)rtc_r2025sd
  90         },
  91         {
  92                 .compatible = "ricoh,r2221tl",
  93                 .data = (void *)rtc_r2221tl
  94         },
  95         {
  96                 .compatible = "ricoh,rs5c372a",
  97                 .data = (void *)rtc_rs5c372a
  98         },
  99         {
 100                 .compatible = "ricoh,rs5c372b",
 101                 .data = (void *)rtc_rs5c372b
 102         },
 103         {
 104                 .compatible = "ricoh,rv5c386",
 105                 .data = (void *)rtc_rv5c386
 106         },
 107         {
 108                 .compatible = "ricoh,rv5c387a",
 109                 .data = (void *)rtc_rv5c387a
 110         },
 111         { }
 112 };
 113 MODULE_DEVICE_TABLE(of, rs5c372_of_match);
 114
 115 /* REVISIT:  this assumes that:
 116  *  - we're in the 21st century, so it's safe to ignore the century
 117  *    bit for rv5c38[67] (REG_MONTH bit 7);
 118  *  - we should use ALARM_A not ALARM_B (may be wrong on some boards)
 119  */
 120 struct rs5c372 {
 121         struct i2c_client       *client;
 122         struct rtc_device       *rtc;
 123         enum rtc_type           type;
 124         unsigned                time24:1;
 125         unsigned                has_irq:1;
 126         unsigned                smbus:1;
 127         char                    buf[17];
 128         char                    *regs;
 129 };
 130
 131 static int rs5c_get_regs(struct rs5c372 *rs5c)
 132 {
 133         struct i2c_client       *client = rs5c->client;
 134         struct i2c_msg          msgs[] = {
 135                 {
 136                         .addr = client->addr,
 137                         .flags = I2C_M_RD,
 138                         .len = sizeof(rs5c->buf),
 139                         .buf = rs5c->buf
 140                 },
 141         };
 142
 143         /* This implements the third reading method from the datasheet, using
 144          * an internal address that's reset after each transaction (by STOP)
 145          * to 0x0f ... so we read extra registers, and skip the first one.
 146          *
 147          * The first method doesn't work with the iop3xx adapter driver, on at
 148          * least 80219 chips; this works around that bug.
 149          *
 150          * The third method on the other hand doesn't work for the SMBus-only
 151          * configurations, so we use the the first method there, stripping off
 152          * the extra register in the process.
 153          */
 154         if (rs5c->smbus) {
 155                 int addr = RS5C_ADDR(RS5C372_REG_SECS);
 156                 int size = sizeof(rs5c->buf) - 1;
 157
 158                 if (i2c_smbus_read_i2c_block_data(client, addr, size,
 159                                                   rs5c->buf + 1) != size) {
 160                         dev_warn(&client->dev, "can't read registers\n");
 161                         return -EIO;
 162                 }
 163         } else {
 164                 if ((i2c_transfer(client->adapter, msgs, 1)) != 1) {
 165                         dev_warn(&client->dev, "can't read registers\n");
 166                         return -EIO;
 167                 }
 168         }
 169
 170         dev_dbg(&client->dev,
 171                 "%3ph (%02x) %3ph (%02x), %3ph, %3ph; %02x %02x\n",
 172                 rs5c->regs + 0, rs5c->regs[3],
 173                 rs5c->regs + 4, rs5c->regs[7],
 174                 rs5c->regs + 8, rs5c->regs + 11,
 175                 rs5c->regs[14], rs5c->regs[15]);
 176
 177         return 0;
 178 }
 179
 180 static unsigned rs5c_reg2hr(struct rs5c372 *rs5c, unsigned reg)
 181 {
 182         unsigned        hour;
 183
 184         if (rs5c->time24)
 185                 return bcd2bin(reg & 0x3f);
 186
 187         hour = bcd2bin(reg & 0x1f);
 188         if (hour == 12)
 189                 hour = 0;
 190         if (reg & 0x20)
 191                 hour += 12;
 192         return hour;
 193 }
 194
 195 static unsigned rs5c_hr2reg(struct rs5c372 *rs5c, unsigned hour)
 196 {
 197         if (rs5c->time24)
 198                 return bin2bcd(hour);
 199
 200         if (hour > 12)
 201                 return 0x20 | bin2bcd(hour - 12);
 202         if (hour == 12)
 203                 return 0x20 | bin2bcd(12);
 204         if (hour == 0)
 205                 return bin2bcd(12);
 206         return bin2bcd(hour);
 207 }
 208
 209 static int rs5c372_rtc_read_time(struct device *dev, struct rtc_time *tm)
 210 {
 211         struct i2c_client *client = to_i2c_client(dev);
 212         struct rs5c372  *rs5c = i2c_get_clientdata(client);
 213         int             status = rs5c_get_regs(rs5c);
 214         unsigned char ctrl2 = rs5c->regs[RS5C_REG_CTRL2];
 215
 216         if (status < 0)
 217                 return status;
 218
 219         switch (rs5c->type) {
 220         case rtc_r2025sd:
 221         case rtc_r2221tl:
 222                 if ((rs5c->type == rtc_r2025sd && !(ctrl2 & R2x2x_CTRL2_XSTP)) ||
 223                     (rs5c->type == rtc_r2221tl &&  (ctrl2 & R2x2x_CTRL2_XSTP))) {
 224                         dev_warn(&client->dev, "rtc oscillator interruption detected. Please reset the rtc clock.\n");
 225                         return -EINVAL;
 226                 }
 227                 break;
 228         default:
 229                 if (ctrl2 & RS5C_CTRL2_XSTP) {
 230                         dev_warn(&client->dev, "rtc oscillator interruption detected. Please reset the rtc clock.\n");
 231                         return -EINVAL;
 232                 }
 233         }
 234
 235         tm->tm_sec = bcd2bin(rs5c->regs[RS5C372_REG_SECS] & 0x7f);
 236         tm->tm_min = bcd2bin(rs5c->regs[RS5C372_REG_MINS] & 0x7f);
 237         tm->tm_hour = rs5c_reg2hr(rs5c, rs5c->regs[RS5C372_REG_HOURS]);
 238
 239         tm->tm_wday = bcd2bin(rs5c->regs[RS5C372_REG_WDAY] & 0x07);
 240         tm->tm_mday = bcd2bin(rs5c->regs[RS5C372_REG_DAY] & 0x3f);
 241
 242         /* tm->tm_mon is zero-based */
 243         tm->tm_mon = bcd2bin(rs5c->regs[RS5C372_REG_MONTH] & 0x1f) - 1;
 244
 245         /* year is 1900 + tm->tm_year */
 246         tm->tm_year = bcd2bin(rs5c->regs[RS5C372_REG_YEAR]) + 100;
 247
 248         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 249                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 250                 __func__,
 251                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 252                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 253
 254         return 0;
 255 }
 256
 257 static int rs5c372_rtc_set_time(struct device *dev, struct rtc_time *tm)
 258 {
 259         struct i2c_client *client = to_i2c_client(dev);
 260         struct rs5c372  *rs5c = i2c_get_clientdata(client);
 261         unsigned char   buf[7];
 262         unsigned char   ctrl2;
 263         int             addr;
 264
 265         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d "
 266                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 267                 __func__,
 268                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 269                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 270
 271         addr   = RS5C_ADDR(RS5C372_REG_SECS);
 272         buf[0] = bin2bcd(tm->tm_sec);
 273         buf[1] = bin2bcd(tm->tm_min);
 274         buf[2] = rs5c_hr2reg(rs5c, tm->tm_hour);
 275         buf[3] = bin2bcd(tm->tm_wday);
 276         buf[4] = bin2bcd(tm->tm_mday);
 277         buf[5] = bin2bcd(tm->tm_mon + 1);
 278         buf[6] = bin2bcd(tm->tm_year - 100);
 279
 280         if (i2c_smbus_write_i2c_block_data(client, addr, sizeof(buf), buf) < 0) {
 281                 dev_dbg(&client->dev, "%s: write error in line %i\n",
 282                         __func__, __LINE__);
 283                 return -EIO;
 284         }
 285
 286         addr = RS5C_ADDR(RS5C_REG_CTRL2);
 287         ctrl2 = i2c_smbus_read_byte_data(client, addr);
 288
 289         /* clear rtc warning bits */
 290         switch (rs5c->type) {
 291         case rtc_r2025sd:
 292         case rtc_r2221tl:
 293                 ctrl2 &= ~(R2x2x_CTRL2_VDET | R2x2x_CTRL2_PON);
 294                 if (rs5c->type == rtc_r2025sd)
 295                         ctrl2 |= R2x2x_CTRL2_XSTP;
 296                 else
 297                         ctrl2 &= ~R2x2x_CTRL2_XSTP;
 298                 break;
 299         default:
 300                 ctrl2 &= ~RS5C_CTRL2_XSTP;
 301                 break;
 302         }
 303
 304         if (i2c_smbus_write_byte_data(client, addr, ctrl2) < 0) {
 305                 dev_dbg(&client->dev, "%s: write error in line %i\n",
 306                         __func__, __LINE__);
 307                 return -EIO;
 308         }
 309
 310         return 0;
 311 }
 312
 313 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
 314 #define NEED_TRIM
 315 #endif
 316
 317 #if IS_ENABLED(CONFIG_RTC_INTF_SYSFS)
 318 #define NEED_TRIM
 319 #endif
 320
 321 #ifdef  NEED_TRIM
 322 static int rs5c372_get_trim(struct i2c_client *client, int *osc, int *trim)
 323 {
 324         struct rs5c372 *rs5c372 = i2c_get_clientdata(client);
 325         u8 tmp = rs5c372->regs[RS5C372_REG_TRIM];
 326
 327         if (osc)
 328                 *osc = (tmp & RS5C372_TRIM_XSL) ? 32000 : 32768;
 329
 330         if (trim) {
 331                 dev_dbg(&client->dev, "%s: raw trim=%x\n", __func__, tmp);
 332                 tmp &= RS5C372_TRIM_MASK;
 333                 if (tmp & 0x3e) {
 334                         int t = tmp & 0x3f;
 335
 336                         if (tmp & 0x40)
 337                                 t = (~t | (s8)0xc0) + 1;
 338                         else
 339                                 t = t - 1;
 340
 341                         tmp = t * 2;
 342                 } else
 343                         tmp = 0;
 344                 *trim = tmp;
 345         }
 346
 347         return 0;
 348 }
 349 #endif
 350
 351 static int rs5c_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 352 {
 353         struct i2c_client       *client = to_i2c_client(dev);
 354         struct rs5c372          *rs5c = i2c_get_clientdata(client);
 355         unsigned char           buf;
 356         int                     status, addr;
 357
 358         buf = rs5c->regs[RS5C_REG_CTRL1];
 359
 360         if (!rs5c->has_irq)
 361                 return -EINVAL;
 362
 363         status = rs5c_get_regs(rs5c);
 364         if (status < 0)
 365                 return status;
 366
 367         addr = RS5C_ADDR(RS5C_REG_CTRL1);
 368         if (enabled)
 369                 buf |= RS5C_CTRL1_AALE;
 370         else
 371                 buf &= ~RS5C_CTRL1_AALE;
 372
 373         if (i2c_smbus_write_byte_data(client, addr, buf) < 0) {
 374                 dev_warn(dev, "can't update alarm\n");
 375                 status = -EIO;
 376         } else
 377                 rs5c->regs[RS5C_REG_CTRL1] = buf;
 378
 379         return status;
 380 }
 381
 382
 383 /* NOTE:  Since RTC_WKALM_{RD,SET} were originally defined for EFI,
 384  * which only exposes a polled programming interface; and since
 385  * these calls map directly to those EFI requests; we don't demand
 386  * we have an IRQ for this chip when we go through this API.
 387  *
 388  * The older x86_pc derived RTC_ALM_{READ,SET} calls require irqs
 389  * though, managed through RTC_AIE_{ON,OFF} requests.
 390  */
 391
 392 static int rs5c_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 393 {
 394         struct i2c_client       *client = to_i2c_client(dev);
 395         struct rs5c372          *rs5c = i2c_get_clientdata(client);
 396         int                     status;
 397
 398         status = rs5c_get_regs(rs5c);
 399         if (status < 0)
 400                 return status;
 401
 402         /* report alarm time */
 403         t->time.tm_sec = 0;
 404         t->time.tm_min = bcd2bin(rs5c->regs[RS5C_REG_ALARM_A_MIN] & 0x7f);
 405         t->time.tm_hour = rs5c_reg2hr(rs5c, rs5c->regs[RS5C_REG_ALARM_A_HOURS]);
 406
 407         /* ... and status */
 408         t->enabled = !!(rs5c->regs[RS5C_REG_CTRL1] & RS5C_CTRL1_AALE);
 409         t->pending = !!(rs5c->regs[RS5C_REG_CTRL2] & RS5C_CTRL2_AAFG);
 410
 411         return 0;
 412 }
 413
 414 static int rs5c_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 415 {
 416         struct i2c_client       *client = to_i2c_client(dev);
 417         struct rs5c372          *rs5c = i2c_get_clientdata(client);
 418         int                     status, addr, i;
 419         unsigned char           buf[3];
 420
 421         /* only handle up to 24 hours in the future, like RTC_ALM_SET */
 422         if (t->time.tm_mday != -1
 423                         || t->time.tm_mon != -1
 424                         || t->time.tm_year != -1)
 425                 return -EINVAL;
 426
 427         /* REVISIT: round up tm_sec */
 428
 429         /* if needed, disable irq (clears pending status) */
 430         status = rs5c_get_regs(rs5c);
 431         if (status < 0)
 432                 return status;
 433         if (rs5c->regs[RS5C_REG_CTRL1] & RS5C_CTRL1_AALE) {
 434                 addr = RS5C_ADDR(RS5C_REG_CTRL1);
 435                 buf[0] = rs5c->regs[RS5C_REG_CTRL1] & ~RS5C_CTRL1_AALE;
 436                 if (i2c_smbus_write_byte_data(client, addr, buf[0]) < 0) {
 437                         dev_dbg(dev, "can't disable alarm\n");
 438                         return -EIO;
 439                 }
 440                 rs5c->regs[RS5C_REG_CTRL1] = buf[0];
 441         }
 442
 443         /* set alarm */
 444         buf[0] = bin2bcd(t->time.tm_min);
 445         buf[1] = rs5c_hr2reg(rs5c, t->time.tm_hour);
 446         buf[2] = 0x7f;  /* any/all days */
 447
 448         for (i = 0; i < sizeof(buf); i++) {
 449                 addr = RS5C_ADDR(RS5C_REG_ALARM_A_MIN + i);
 450                 if (i2c_smbus_write_byte_data(client, addr, buf[i]) < 0) {
 451                         dev_dbg(dev, "can't set alarm time\n");
 452                         return -EIO;
 453                 }
 454         }
 455
 456         /* ... and maybe enable its irq */
 457         if (t->enabled) {
 458                 addr = RS5C_ADDR(RS5C_REG_CTRL1);
 459                 buf[0] = rs5c->regs[RS5C_REG_CTRL1] | RS5C_CTRL1_AALE;
 460                 if (i2c_smbus_write_byte_data(client, addr, buf[0]) < 0)
 461                         dev_warn(dev, "can't enable alarm\n");
 462                 rs5c->regs[RS5C_REG_CTRL1] = buf[0];
 463         }
 464
 465         return 0;
 466 }
 467
 468 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
 469
 470 static int rs5c372_rtc_proc(struct device *dev, struct seq_file *seq)
 471 {
 472         int err, osc, trim;
 473
 474         err = rs5c372_get_trim(to_i2c_client(dev), &osc, &trim);
 475         if (err == 0) {
 476                 seq_printf(seq, "crystal\t\t: %d.%03d KHz\n",
 477                                 osc / 1000, osc % 1000);
 478                 seq_printf(seq, "trim\t\t: %d\n", trim);
 479         }
 480
 481         return 0;
 482 }
 483
 484 #else
 485 #define rs5c372_rtc_proc        NULL
 486 #endif
 487
 488 static const struct rtc_class_ops rs5c372_rtc_ops = {
 489         .proc           = rs5c372_rtc_proc,
 490         .read_time      = rs5c372_rtc_read_time,
 491         .set_time       = rs5c372_rtc_set_time,
 492         .read_alarm     = rs5c_read_alarm,
 493         .set_alarm      = rs5c_set_alarm,
 494         .alarm_irq_enable = rs5c_rtc_alarm_irq_enable,
 495 };
 496
 497 #if IS_ENABLED(CONFIG_RTC_INTF_SYSFS)
 498
 499 static ssize_t rs5c372_sysfs_show_trim(struct device *dev,
 500                                 struct device_attribute *attr, char *buf)
 501 {
 502         int err, trim;
 503
 504         err = rs5c372_get_trim(to_i2c_client(dev), NULL, &trim);
 505         if (err)
 506                 return err;
 507
 508         return sprintf(buf, "%d\n", trim);
 509 }
 510 static DEVICE_ATTR(trim, S_IRUGO, rs5c372_sysfs_show_trim, NULL);
 511
 512 static ssize_t rs5c372_sysfs_show_osc(struct device *dev,
 513                                 struct device_attribute *attr, char *buf)
 514 {
 515         int err, osc;
 516
 517         err = rs5c372_get_trim(to_i2c_client(dev), &osc, NULL);
 518         if (err)
 519                 return err;
 520
 521         return sprintf(buf, "%d.%03d KHz\n", osc / 1000, osc % 1000);
 522 }
 523 static DEVICE_ATTR(osc, S_IRUGO, rs5c372_sysfs_show_osc, NULL);
 524
 525 static int rs5c_sysfs_register(struct device *dev)
 526 {
 527         int err;
 528
 529         err = device_create_file(dev, &dev_attr_trim);
 530         if (err)
 531                 return err;
 532         err = device_create_file(dev, &dev_attr_osc);
 533         if (err)
 534                 device_remove_file(dev, &dev_attr_trim);
 535
 536         return err;
 537 }
 538
 539 static void rs5c_sysfs_unregister(struct device *dev)
 540 {
 541         device_remove_file(dev, &dev_attr_trim);
 542         device_remove_file(dev, &dev_attr_osc);
 543 }
 544
 545 #else
 546 static int rs5c_sysfs_register(struct device *dev)
 547 {
 548         return 0;
 549 }
 550
 551 static void rs5c_sysfs_unregister(struct device *dev)
 552 {
 553         /* nothing */
 554 }
 555 #endif  /* SYSFS */
 556
 557 static struct i2c_driver rs5c372_driver;
 558
 559 static int rs5c_oscillator_setup(struct rs5c372 *rs5c372)
 560 {
 561         unsigned char buf[2];
 562         int addr, i, ret = 0;
 563
 564         addr   = RS5C_ADDR(RS5C_REG_CTRL1);
 565         buf[0] = rs5c372->regs[RS5C_REG_CTRL1];
 566         buf[1] = rs5c372->regs[RS5C_REG_CTRL2];
 567
 568         switch (rs5c372->type) {
 569         case rtc_r2025sd:
 570                 if (buf[1] & R2x2x_CTRL2_XSTP)
 571                         return ret;
 572                 break;
 573         case rtc_r2221tl:
 574                 if (!(buf[1] & R2x2x_CTRL2_XSTP))
 575                         return ret;
 576                 break;
 577         default:
 578                 if (!(buf[1] & RS5C_CTRL2_XSTP))
 579                         return ret;
 580                 break;
 581         }
 582
 583         /* use 24hr mode */
 584         switch (rs5c372->type) {
 585         case rtc_rs5c372a:
 586         case rtc_rs5c372b:
 587                 buf[1] |= RS5C372_CTRL2_24;
 588                 rs5c372->time24 = 1;
 589                 break;
 590         case rtc_r2025sd:
 591         case rtc_r2221tl:
 592         case rtc_rv5c386:
 593         case rtc_rv5c387a:
 594                 buf[0] |= RV5C387_CTRL1_24;
 595                 rs5c372->time24 = 1;
 596                 break;
 597         default:
 598                 /* impossible */
 599                 break;
 600         }
 601
 602         for (i = 0; i < sizeof(buf); i++) {
 603                 addr = RS5C_ADDR(RS5C_REG_CTRL1 + i);
 604                 ret = i2c_smbus_write_byte_data(rs5c372->client, addr, buf[i]);
 605                 if (unlikely(ret < 0))
 606                         return ret;
 607         }
 608
 609         rs5c372->regs[RS5C_REG_CTRL1] = buf[0];
 610         rs5c372->regs[RS5C_REG_CTRL2] = buf[1];
 611
 612         return 0;
 613 }
 614
 615 static int rs5c372_probe(struct i2c_client *client,
 616                          const struct i2c_device_id *id)
 617 {
 618         int err = 0;
 619         int smbus_mode = 0;
 620         struct rs5c372 *rs5c372;
 621
 622         dev_dbg(&client->dev, "%s\n", __func__);
 623
 624         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
 625                         I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK)) {
 626                 /*
 627                  * If we don't have any master mode adapter, try breaking
 628                  * it down in to the barest of capabilities.
 629                  */
 630                 if (i2c_check_functionality(client->adapter,
 631                                 I2C_FUNC_SMBUS_BYTE_DATA |
 632                                 I2C_FUNC_SMBUS_I2C_BLOCK))
 633                         smbus_mode = 1;
 634                 else {
 635                         /* Still no good, give up */
 636                         err = -ENODEV;
 637                         goto exit;
 638                 }
 639         }
 640
 641         rs5c372 = devm_kzalloc(&client->dev, sizeof(struct rs5c372),
 642                                 GFP_KERNEL);
 643         if (!rs5c372) {
 644                 err = -ENOMEM;
 645                 goto exit;
 646         }
 647
 648         rs5c372->client = client;
 649         i2c_set_clientdata(client, rs5c372);
 650         if (client->dev.of_node)
 651                 rs5c372->type = (enum rtc_type)
 652                         of_device_get_match_data(&client->dev);
 653         else
 654                 rs5c372->type = id->driver_data;
 655
 656         /* we read registers 0x0f then 0x00-0x0f; skip the first one */
 657         rs5c372->regs = &rs5c372->buf[1];
 658         rs5c372->smbus = smbus_mode;
 659
 660         err = rs5c_get_regs(rs5c372);
 661         if (err < 0)
 662                 goto exit;
 663
 664         /* clock may be set for am/pm or 24 hr time */
 665         switch (rs5c372->type) {
 666         case rtc_rs5c372a:
 667         case rtc_rs5c372b:
 668                 /* alarm uses ALARM_A; and nINTRA on 372a, nINTR on 372b.
 669                  * so does periodic irq, except some 327a modes.
 670                  */
 671                 if (rs5c372->regs[RS5C_REG_CTRL2] & RS5C372_CTRL2_24)
 672                         rs5c372->time24 = 1;
 673                 break;
 674         case rtc_r2025sd:
 675         case rtc_r2221tl:
 676         case rtc_rv5c386:
 677         case rtc_rv5c387a:
 678                 if (rs5c372->regs[RS5C_REG_CTRL1] & RV5C387_CTRL1_24)
 679                         rs5c372->time24 = 1;
 680                 /* alarm uses ALARM_W; and nINTRB for alarm and periodic
 681                  * irq, on both 386 and 387
 682                  */
 683                 break;
 684         default:
 685                 dev_err(&client->dev, "unknown RTC type\n");
 686                 goto exit;
 687         }
 688
 689         /* if the oscillator lost power and no other software (like
 690          * the bootloader) set it up, do it here.
 691          *
 692          * The R2025S/D does this a little differently than the other
 693          * parts, so we special case that..
 694          */
 695         err = rs5c_oscillator_setup(rs5c372);
 696         if (unlikely(err < 0)) {
 697                 dev_err(&client->dev, "setup error\n");
 698                 goto exit;
 699         }
 700
 701         dev_info(&client->dev, "%s found, %s\n",
 702                         ({ char *s; switch (rs5c372->type) {
 703                         case rtc_r2025sd:       s = "r2025sd"; break;
 704                         case rtc_r2221tl:       s = "r2221tl"; break;
 705                         case rtc_rs5c372a:      s = "rs5c372a"; break;
 706                         case rtc_rs5c372b:      s = "rs5c372b"; break;
 707                         case rtc_rv5c386:       s = "rv5c386"; break;
 708                         case rtc_rv5c387a:      s = "rv5c387a"; break;
 709                         default:                s = "chip"; break;
 710                         }; s;}),
 711                         rs5c372->time24 ? "24hr" : "am/pm"
 712                         );
 713
 714         /* REVISIT use client->irq to register alarm irq ... */
 715         rs5c372->rtc = devm_rtc_device_register(&client->dev,
 716                                         rs5c372_driver.driver.name,
 717                                         &rs5c372_rtc_ops, THIS_MODULE);
 718
 719         if (IS_ERR(rs5c372->rtc)) {
 720                 err = PTR_ERR(rs5c372->rtc);
 721                 goto exit;
 722         }
 723
 724         err = rs5c_sysfs_register(&client->dev);
 725         if (err)
 726                 goto exit;
 727
 728         return 0;
 729
 730 exit:
 731         return err;
 732 }
 733
 734 static int rs5c372_remove(struct i2c_client *client)
 735 {
 736         rs5c_sysfs_unregister(&client->dev);
 737         return 0;
 738 }
 739
 740 static struct i2c_driver rs5c372_driver = {
 741         .driver         = {
 742                 .name   = "rtc-rs5c372",
 743                 .of_match_table = of_match_ptr(rs5c372_of_match),
 744         },
 745         .probe          = rs5c372_probe,
 746         .remove         = rs5c372_remove,
 747         .id_table       = rs5c372_id,
 748 };
 749
 750 module_i2c_driver(rs5c372_driver);
 751
 752 MODULE_AUTHOR(
 753                 "Pavel Mironchik <pmironchik@optifacio.net>, "
 754                 "Alessandro Zummo <a.zummo@towertech.it>, "
 755                 "Paul Mundt <lethal@linux-sh.org>");
 756 MODULE_DESCRIPTION("Ricoh RS5C372 RTC driver");
 757 MODULE_LICENSE("GPL");