drivers/rtc/rtc-rs5c372.c

   1 /*
   2  * An I2C driver for Ricoh RS5C372, R2025S/D and RV5C38[67] RTCs
   3  *
   4  * Copyright (C) 2005 Pavel Mironchik <pmironchik@optifacio.net>
   5  * Copyright (C) 2006 Tower Technologies
   6  * Copyright (C) 2008 Paul Mundt
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/i2c.h>
  14 #include <linux/rtc.h>
  15 #include <linux/bcd.h>
  16 #include <linux/slab.h>
  17 #include <linux/module.h>
  18 #include <linux/of_device.h>
  19
  20 /*
  21  * Ricoh has a family of I2C based RTCs, which differ only slightly from
  22  * each other.  Differences center on pinout (e.g. how many interrupts,
  23  * output clock, etc) and how the control registers are used.  The '372
  24  * is significant only because that's the one this driver first supported.
  25  */
  26 #define RS5C372_REG_SECS        0
  27 #define RS5C372_REG_MINS        1
  28 #define RS5C372_REG_HOURS       2
  29 #define RS5C372_REG_WDAY        3
  30 #define RS5C372_REG_DAY         4
  31 #define RS5C372_REG_MONTH       5
  32 #define RS5C372_REG_YEAR        6
  33 #define RS5C372_REG_TRIM        7
  34 #       define RS5C372_TRIM_XSL         0x80
  35 #       define RS5C372_TRIM_MASK        0x7F
  36
  37 #define RS5C_REG_ALARM_A_MIN    8                       /* or ALARM_W */
  38 #define RS5C_REG_ALARM_A_HOURS  9
  39 #define RS5C_REG_ALARM_A_WDAY   10
  40
  41 #define RS5C_REG_ALARM_B_MIN    11                      /* or ALARM_D */
  42 #define RS5C_REG_ALARM_B_HOURS  12
  43 #define RS5C_REG_ALARM_B_WDAY   13                      /* (ALARM_B only) */
  44
  45 #define RS5C_REG_CTRL1          14
  46 #       define RS5C_CTRL1_AALE          (1 << 7)        /* or WALE */
  47 #       define RS5C_CTRL1_BALE          (1 << 6)        /* or DALE */
  48 #       define RV5C387_CTRL1_24         (1 << 5)
  49 #       define RS5C372A_CTRL1_SL1       (1 << 5)
  50 #       define RS5C_CTRL1_CT_MASK       (7 << 0)
  51 #       define RS5C_CTRL1_CT0           (0 << 0)        /* no periodic irq */
  52 #       define RS5C_CTRL1_CT4           (4 << 0)        /* 1 Hz level irq */
  53 #define RS5C_REG_CTRL2          15
  54 #       define RS5C372_CTRL2_24         (1 << 5)
  55 #       define R2025_CTRL2_XST          (1 << 5)
  56 #       define RS5C_CTRL2_XSTP          (1 << 4)        /* only if !R2025S/D */
  57 #       define RS5C_CTRL2_CTFG          (1 << 2)
  58 #       define RS5C_CTRL2_AAFG          (1 << 1)        /* or WAFG */
  59 #       define RS5C_CTRL2_BAFG          (1 << 0)        /* or DAFG */
  60
  61
  62 /* to read (style 1) or write registers starting at R */
  63 #define RS5C_ADDR(R)            (((R) << 4) | 0)
  64
  65
  66 enum rtc_type {
  67         rtc_undef = 0,
  68         rtc_r2025sd,
  69         rtc_r2221tl,
  70         rtc_rs5c372a,
  71         rtc_rs5c372b,
  72         rtc_rv5c386,
  73         rtc_rv5c387a,
  74 };
  75
  76 static const struct i2c_device_id rs5c372_id[] = {
  77         { "r2025sd", rtc_r2025sd },
  78         { "r2221tl", rtc_r2221tl },
  79         { "rs5c372a", rtc_rs5c372a },
  80         { "rs5c372b", rtc_rs5c372b },
  81         { "rv5c386", rtc_rv5c386 },
  82         { "rv5c387a", rtc_rv5c387a },
  83         { }
  84 };
  85 MODULE_DEVICE_TABLE(i2c, rs5c372_id);
  86
  87 static const struct of_device_id rs5c372_of_match[] = {
  88         {
  89                 .compatible = "ricoh,r2025sd",
  90                 .data = (void *)rtc_r2025sd
  91         },
  92         {
  93                 .compatible = "ricoh,r2221tl",
  94                 .data = (void *)rtc_r2221tl
  95         },
  96         {
  97                 .compatible = "ricoh,rs5c372a",
  98                 .data = (void *)rtc_rs5c372a
  99         },
 100         {
 101                 .compatible = "ricoh,rs5c372b",
 102                 .data = (void *)rtc_rs5c372b
 103         },
 104         {
 105                 .compatible = "ricoh,rv5c386",
 106                 .data = (void *)rtc_rv5c386
 107         },
 108         {
 109                 .compatible = "ricoh,rv5c387a",
 110                 .data = (void *)rtc_rv5c387a
 111         },
 112         { }
 113 };
 114 MODULE_DEVICE_TABLE(of, rs5c372_of_match);
 115
 116 /* REVISIT:  this assumes that:
 117  *  - we're in the 21st century, so it's safe to ignore the century
 118  *    bit for rv5c38[67] (REG_MONTH bit 7);
 119  *  - we should use ALARM_A not ALARM_B (may be wrong on some boards)
 120  */
 121 struct rs5c372 {
 122         struct i2c_client       *client;
 123         struct rtc_device       *rtc;
 124         enum rtc_type           type;
 125         unsigned                time24:1;
 126         unsigned                has_irq:1;
 127         unsigned                smbus:1;
 128         char                    buf[17];
 129         char                    *regs;
 130 };
 131
 132 static int rs5c_get_regs(struct rs5c372 *rs5c)
 133 {
 134         struct i2c_client       *client = rs5c->client;
 135         struct i2c_msg          msgs[] = {
 136                 {
 137                         .addr = client->addr,
 138                         .flags = I2C_M_RD,
 139                         .len = sizeof(rs5c->buf),
 140                         .buf = rs5c->buf
 141                 },
 142         };
 143
 144         /* This implements the third reading method from the datasheet, using
 145          * an internal address that's reset after each transaction (by STOP)
 146          * to 0x0f ... so we read extra registers, and skip the first one.
 147          *
 148          * The first method doesn't work with the iop3xx adapter driver, on at
 149          * least 80219 chips; this works around that bug.
 150          *
 151          * The third method on the other hand doesn't work for the SMBus-only
 152          * configurations, so we use the the first method there, stripping off
 153          * the extra register in the process.
 154          */
 155         if (rs5c->smbus) {
 156                 int addr = RS5C_ADDR(RS5C372_REG_SECS);
 157                 int size = sizeof(rs5c->buf) - 1;
 158
 159                 if (i2c_smbus_read_i2c_block_data(client, addr, size,
 160                                                   rs5c->buf + 1) != size) {
 161                         dev_warn(&client->dev, "can't read registers\n");
 162                         return -EIO;
 163                 }
 164         } else {
 165                 if ((i2c_transfer(client->adapter, msgs, 1)) != 1) {
 166                         dev_warn(&client->dev, "can't read registers\n");
 167                         return -EIO;
 168                 }
 169         }
 170
 171         dev_dbg(&client->dev,
 172                 "%3ph (%02x) %3ph (%02x), %3ph, %3ph; %02x %02x\n",
 173                 rs5c->regs + 0, rs5c->regs[3],
 174                 rs5c->regs + 4, rs5c->regs[7],
 175                 rs5c->regs + 8, rs5c->regs + 11,
 176                 rs5c->regs[14], rs5c->regs[15]);
 177
 178         return 0;
 179 }
 180
 181 static unsigned rs5c_reg2hr(struct rs5c372 *rs5c, unsigned reg)
 182 {
 183         unsigned        hour;
 184
 185         if (rs5c->time24)
 186                 return bcd2bin(reg & 0x3f);
 187
 188         hour = bcd2bin(reg & 0x1f);
 189         if (hour == 12)
 190                 hour = 0;
 191         if (reg & 0x20)
 192                 hour += 12;
 193         return hour;
 194 }
 195
 196 static unsigned rs5c_hr2reg(struct rs5c372 *rs5c, unsigned hour)
 197 {
 198         if (rs5c->time24)
 199                 return bin2bcd(hour);
 200
 201         if (hour > 12)
 202                 return 0x20 | bin2bcd(hour - 12);
 203         if (hour == 12)
 204                 return 0x20 | bin2bcd(12);
 205         if (hour == 0)
 206                 return bin2bcd(12);
 207         return bin2bcd(hour);
 208 }
 209
 210 static int rs5c372_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 211 {
 212         struct rs5c372  *rs5c = i2c_get_clientdata(client);
 213         int             status = rs5c_get_regs(rs5c);
 214
 215         if (status < 0)
 216                 return status;
 217
 218         tm->tm_sec = bcd2bin(rs5c->regs[RS5C372_REG_SECS] & 0x7f);
 219         tm->tm_min = bcd2bin(rs5c->regs[RS5C372_REG_MINS] & 0x7f);
 220         tm->tm_hour = rs5c_reg2hr(rs5c, rs5c->regs[RS5C372_REG_HOURS]);
 221
 222         tm->tm_wday = bcd2bin(rs5c->regs[RS5C372_REG_WDAY] & 0x07);
 223         tm->tm_mday = bcd2bin(rs5c->regs[RS5C372_REG_DAY] & 0x3f);
 224
 225         /* tm->tm_mon is zero-based */
 226         tm->tm_mon = bcd2bin(rs5c->regs[RS5C372_REG_MONTH] & 0x1f) - 1;
 227
 228         /* year is 1900 + tm->tm_year */
 229         tm->tm_year = bcd2bin(rs5c->regs[RS5C372_REG_YEAR]) + 100;
 230
 231         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 232                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 233                 __func__,
 234                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 235                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 236
 237         /* rtc might need initialization */
 238         return rtc_valid_tm(tm);
 239 }
 240
 241 static int rs5c372_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 242 {
 243         struct rs5c372  *rs5c = i2c_get_clientdata(client);
 244         unsigned char   buf[7];
 245         int             addr;
 246
 247         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d "
 248                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 249                 __func__,
 250                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 251                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 252
 253         addr   = RS5C_ADDR(RS5C372_REG_SECS);
 254         buf[0] = bin2bcd(tm->tm_sec);
 255         buf[1] = bin2bcd(tm->tm_min);
 256         buf[2] = rs5c_hr2reg(rs5c, tm->tm_hour);
 257         buf[3] = bin2bcd(tm->tm_wday);
 258         buf[4] = bin2bcd(tm->tm_mday);
 259         buf[5] = bin2bcd(tm->tm_mon + 1);
 260         buf[6] = bin2bcd(tm->tm_year - 100);
 261
 262         if (i2c_smbus_write_i2c_block_data(client, addr, sizeof(buf), buf) < 0) {
 263                 dev_err(&client->dev, "%s: write error\n", __func__);
 264                 return -EIO;
 265         }
 266
 267         return 0;
 268 }
 269
 270 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
 271 #define NEED_TRIM
 272 #endif
 273
 274 #if IS_ENABLED(CONFIG_RTC_INTF_SYSFS)
 275 #define NEED_TRIM
 276 #endif
 277
 278 #ifdef  NEED_TRIM
 279 static int rs5c372_get_trim(struct i2c_client *client, int *osc, int *trim)
 280 {
 281         struct rs5c372 *rs5c372 = i2c_get_clientdata(client);
 282         u8 tmp = rs5c372->regs[RS5C372_REG_TRIM];
 283
 284         if (osc)
 285                 *osc = (tmp & RS5C372_TRIM_XSL) ? 32000 : 32768;
 286
 287         if (trim) {
 288                 dev_dbg(&client->dev, "%s: raw trim=%x\n", __func__, tmp);
 289                 tmp &= RS5C372_TRIM_MASK;
 290                 if (tmp & 0x3e) {
 291                         int t = tmp & 0x3f;
 292
 293                         if (tmp & 0x40)
 294                                 t = (~t | (s8)0xc0) + 1;
 295                         else
 296                                 t = t - 1;
 297
 298                         tmp = t * 2;
 299                 } else
 300                         tmp = 0;
 301                 *trim = tmp;
 302         }
 303
 304         return 0;
 305 }
 306 #endif
 307
 308 static int rs5c372_rtc_read_time(struct device *dev, struct rtc_time *tm)
 309 {
 310         return rs5c372_get_datetime(to_i2c_client(dev), tm);
 311 }
 312
 313 static int rs5c372_rtc_set_time(struct device *dev, struct rtc_time *tm)
 314 {
 315         return rs5c372_set_datetime(to_i2c_client(dev), tm);
 316 }
 317
 318
 319 static int rs5c_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 320 {
 321         struct i2c_client       *client = to_i2c_client(dev);
 322         struct rs5c372          *rs5c = i2c_get_clientdata(client);
 323         unsigned char           buf;
 324         int                     status, addr;
 325
 326         buf = rs5c->regs[RS5C_REG_CTRL1];
 327
 328         if (!rs5c->has_irq)
 329                 return -EINVAL;
 330
 331         status = rs5c_get_regs(rs5c);
 332         if (status < 0)
 333                 return status;
 334
 335         addr = RS5C_ADDR(RS5C_REG_CTRL1);
 336         if (enabled)
 337                 buf |= RS5C_CTRL1_AALE;
 338         else
 339                 buf &= ~RS5C_CTRL1_AALE;
 340
 341         if (i2c_smbus_write_byte_data(client, addr, buf) < 0) {
 342                 dev_warn(dev, "can't update alarm\n");
 343                 status = -EIO;
 344         } else
 345                 rs5c->regs[RS5C_REG_CTRL1] = buf;
 346
 347         return status;
 348 }
 349
 350
 351 /* NOTE:  Since RTC_WKALM_{RD,SET} were originally defined for EFI,
 352  * which only exposes a polled programming interface; and since
 353  * these calls map directly to those EFI requests; we don't demand
 354  * we have an IRQ for this chip when we go through this API.
 355  *
 356  * The older x86_pc derived RTC_ALM_{READ,SET} calls require irqs
 357  * though, managed through RTC_AIE_{ON,OFF} requests.
 358  */
 359
 360 static int rs5c_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 361 {
 362         struct i2c_client       *client = to_i2c_client(dev);
 363         struct rs5c372          *rs5c = i2c_get_clientdata(client);
 364         int                     status;
 365
 366         status = rs5c_get_regs(rs5c);
 367         if (status < 0)
 368                 return status;
 369
 370         /* report alarm time */
 371         t->time.tm_sec = 0;
 372         t->time.tm_min = bcd2bin(rs5c->regs[RS5C_REG_ALARM_A_MIN] & 0x7f);
 373         t->time.tm_hour = rs5c_reg2hr(rs5c, rs5c->regs[RS5C_REG_ALARM_A_HOURS]);
 374
 375         /* ... and status */
 376         t->enabled = !!(rs5c->regs[RS5C_REG_CTRL1] & RS5C_CTRL1_AALE);
 377         t->pending = !!(rs5c->regs[RS5C_REG_CTRL2] & RS5C_CTRL2_AAFG);
 378
 379         return 0;
 380 }
 381
 382 static int rs5c_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 383 {
 384         struct i2c_client       *client = to_i2c_client(dev);
 385         struct rs5c372          *rs5c = i2c_get_clientdata(client);
 386         int                     status, addr, i;
 387         unsigned char           buf[3];
 388
 389         /* only handle up to 24 hours in the future, like RTC_ALM_SET */
 390         if (t->time.tm_mday != -1
 391                         || t->time.tm_mon != -1
 392                         || t->time.tm_year != -1)
 393                 return -EINVAL;
 394
 395         /* REVISIT: round up tm_sec */
 396
 397         /* if needed, disable irq (clears pending status) */
 398         status = rs5c_get_regs(rs5c);
 399         if (status < 0)
 400                 return status;
 401         if (rs5c->regs[RS5C_REG_CTRL1] & RS5C_CTRL1_AALE) {
 402                 addr = RS5C_ADDR(RS5C_REG_CTRL1);
 403                 buf[0] = rs5c->regs[RS5C_REG_CTRL1] & ~RS5C_CTRL1_AALE;
 404                 if (i2c_smbus_write_byte_data(client, addr, buf[0]) < 0) {
 405                         dev_dbg(dev, "can't disable alarm\n");
 406                         return -EIO;
 407                 }
 408                 rs5c->regs[RS5C_REG_CTRL1] = buf[0];
 409         }
 410
 411         /* set alarm */
 412         buf[0] = bin2bcd(t->time.tm_min);
 413         buf[1] = rs5c_hr2reg(rs5c, t->time.tm_hour);
 414         buf[2] = 0x7f;  /* any/all days */
 415
 416         for (i = 0; i < sizeof(buf); i++) {
 417                 addr = RS5C_ADDR(RS5C_REG_ALARM_A_MIN + i);
 418                 if (i2c_smbus_write_byte_data(client, addr, buf[i]) < 0) {
 419                         dev_dbg(dev, "can't set alarm time\n");
 420                         return -EIO;
 421                 }
 422         }
 423
 424         /* ... and maybe enable its irq */
 425         if (t->enabled) {
 426                 addr = RS5C_ADDR(RS5C_REG_CTRL1);
 427                 buf[0] = rs5c->regs[RS5C_REG_CTRL1] | RS5C_CTRL1_AALE;
 428                 if (i2c_smbus_write_byte_data(client, addr, buf[0]) < 0)
 429                         dev_warn(dev, "can't enable alarm\n");
 430                 rs5c->regs[RS5C_REG_CTRL1] = buf[0];
 431         }
 432
 433         return 0;
 434 }
 435
 436 #if IS_ENABLED(CONFIG_RTC_INTF_PROC)
 437
 438 static int rs5c372_rtc_proc(struct device *dev, struct seq_file *seq)
 439 {
 440         int err, osc, trim;
 441
 442         err = rs5c372_get_trim(to_i2c_client(dev), &osc, &trim);
 443         if (err == 0) {
 444                 seq_printf(seq, "crystal\t\t: %d.%03d KHz\n",
 445                                 osc / 1000, osc % 1000);
 446                 seq_printf(seq, "trim\t\t: %d\n", trim);
 447         }
 448
 449         return 0;
 450 }
 451
 452 #else
 453 #define rs5c372_rtc_proc        NULL
 454 #endif
 455
 456 static const struct rtc_class_ops rs5c372_rtc_ops = {
 457         .proc           = rs5c372_rtc_proc,
 458         .read_time      = rs5c372_rtc_read_time,
 459         .set_time       = rs5c372_rtc_set_time,
 460         .read_alarm     = rs5c_read_alarm,
 461         .set_alarm      = rs5c_set_alarm,
 462         .alarm_irq_enable = rs5c_rtc_alarm_irq_enable,
 463 };
 464
 465 #if IS_ENABLED(CONFIG_RTC_INTF_SYSFS)
 466
 467 static ssize_t rs5c372_sysfs_show_trim(struct device *dev,
 468                                 struct device_attribute *attr, char *buf)
 469 {
 470         int err, trim;
 471
 472         err = rs5c372_get_trim(to_i2c_client(dev), NULL, &trim);
 473         if (err)
 474                 return err;
 475
 476         return sprintf(buf, "%d\n", trim);
 477 }
 478 static DEVICE_ATTR(trim, S_IRUGO, rs5c372_sysfs_show_trim, NULL);
 479
 480 static ssize_t rs5c372_sysfs_show_osc(struct device *dev,
 481                                 struct device_attribute *attr, char *buf)
 482 {
 483         int err, osc;
 484
 485         err = rs5c372_get_trim(to_i2c_client(dev), &osc, NULL);
 486         if (err)
 487                 return err;
 488
 489         return sprintf(buf, "%d.%03d KHz\n", osc / 1000, osc % 1000);
 490 }
 491 static DEVICE_ATTR(osc, S_IRUGO, rs5c372_sysfs_show_osc, NULL);
 492
 493 static int rs5c_sysfs_register(struct device *dev)
 494 {
 495         int err;
 496
 497         err = device_create_file(dev, &dev_attr_trim);
 498         if (err)
 499                 return err;
 500         err = device_create_file(dev, &dev_attr_osc);
 501         if (err)
 502                 device_remove_file(dev, &dev_attr_trim);
 503
 504         return err;
 505 }
 506
 507 static void rs5c_sysfs_unregister(struct device *dev)
 508 {
 509         device_remove_file(dev, &dev_attr_trim);
 510         device_remove_file(dev, &dev_attr_osc);
 511 }
 512
 513 #else
 514 static int rs5c_sysfs_register(struct device *dev)
 515 {
 516         return 0;
 517 }
 518
 519 static void rs5c_sysfs_unregister(struct device *dev)
 520 {
 521         /* nothing */
 522 }
 523 #endif  /* SYSFS */
 524
 525 static struct i2c_driver rs5c372_driver;
 526
 527 static int rs5c_oscillator_setup(struct rs5c372 *rs5c372)
 528 {
 529         unsigned char buf[2];
 530         int addr, i, ret = 0;
 531
 532         if (rs5c372->type == rtc_r2025sd) {
 533                 if (rs5c372->regs[RS5C_REG_CTRL2] & R2025_CTRL2_XST)
 534                         return ret;
 535                 rs5c372->regs[RS5C_REG_CTRL2] |= R2025_CTRL2_XST;
 536         } else {
 537                 if (!(rs5c372->regs[RS5C_REG_CTRL2] & RS5C_CTRL2_XSTP))
 538                         return ret;
 539                 rs5c372->regs[RS5C_REG_CTRL2] &= ~RS5C_CTRL2_XSTP;
 540         }
 541
 542         addr   = RS5C_ADDR(RS5C_REG_CTRL1);
 543         buf[0] = rs5c372->regs[RS5C_REG_CTRL1];
 544         buf[1] = rs5c372->regs[RS5C_REG_CTRL2];
 545
 546         /* use 24hr mode */
 547         switch (rs5c372->type) {
 548         case rtc_rs5c372a:
 549         case rtc_rs5c372b:
 550                 buf[1] |= RS5C372_CTRL2_24;
 551                 rs5c372->time24 = 1;
 552                 break;
 553         case rtc_r2025sd:
 554         case rtc_r2221tl:
 555         case rtc_rv5c386:
 556         case rtc_rv5c387a:
 557                 buf[0] |= RV5C387_CTRL1_24;
 558                 rs5c372->time24 = 1;
 559                 break;
 560         default:
 561                 /* impossible */
 562                 break;
 563         }
 564
 565         for (i = 0; i < sizeof(buf); i++) {
 566                 addr = RS5C_ADDR(RS5C_REG_CTRL1 + i);
 567                 ret = i2c_smbus_write_byte_data(rs5c372->client, addr, buf[i]);
 568                 if (unlikely(ret < 0))
 569                         return ret;
 570         }
 571
 572         rs5c372->regs[RS5C_REG_CTRL1] = buf[0];
 573         rs5c372->regs[RS5C_REG_CTRL2] = buf[1];
 574
 575         return 0;
 576 }
 577
 578 static int rs5c372_probe(struct i2c_client *client,
 579                          const struct i2c_device_id *id)
 580 {
 581         int err = 0;
 582         int smbus_mode = 0;
 583         struct rs5c372 *rs5c372;
 584         struct rtc_time tm;
 585
 586         dev_dbg(&client->dev, "%s\n", __func__);
 587
 588         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
 589                         I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK)) {
 590                 /*
 591                  * If we don't have any master mode adapter, try breaking
 592                  * it down in to the barest of capabilities.
 593                  */
 594                 if (i2c_check_functionality(client->adapter,
 595                                 I2C_FUNC_SMBUS_BYTE_DATA |
 596                                 I2C_FUNC_SMBUS_I2C_BLOCK))
 597                         smbus_mode = 1;
 598                 else {
 599                         /* Still no good, give up */
 600                         err = -ENODEV;
 601                         goto exit;
 602                 }
 603         }
 604
 605         rs5c372 = devm_kzalloc(&client->dev, sizeof(struct rs5c372),
 606                                 GFP_KERNEL);
 607         if (!rs5c372) {
 608                 err = -ENOMEM;
 609                 goto exit;
 610         }
 611
 612         rs5c372->client = client;
 613         i2c_set_clientdata(client, rs5c372);
 614         if (client->dev.of_node)
 615                 rs5c372->type = (enum rtc_type)
 616                         of_device_get_match_data(&client->dev);
 617         else
 618                 rs5c372->type = id->driver_data;
 619
 620         /* we read registers 0x0f then 0x00-0x0f; skip the first one */
 621         rs5c372->regs = &rs5c372->buf[1];
 622         rs5c372->smbus = smbus_mode;
 623
 624         err = rs5c_get_regs(rs5c372);
 625         if (err < 0)
 626                 goto exit;
 627
 628         /* clock may be set for am/pm or 24 hr time */
 629         switch (rs5c372->type) {
 630         case rtc_rs5c372a:
 631         case rtc_rs5c372b:
 632                 /* alarm uses ALARM_A; and nINTRA on 372a, nINTR on 372b.
 633                  * so does periodic irq, except some 327a modes.
 634                  */
 635                 if (rs5c372->regs[RS5C_REG_CTRL2] & RS5C372_CTRL2_24)
 636                         rs5c372->time24 = 1;
 637                 break;
 638         case rtc_r2025sd:
 639         case rtc_r2221tl:
 640         case rtc_rv5c386:
 641         case rtc_rv5c387a:
 642                 if (rs5c372->regs[RS5C_REG_CTRL1] & RV5C387_CTRL1_24)
 643                         rs5c372->time24 = 1;
 644                 /* alarm uses ALARM_W; and nINTRB for alarm and periodic
 645                  * irq, on both 386 and 387
 646                  */
 647                 break;
 648         default:
 649                 dev_err(&client->dev, "unknown RTC type\n");
 650                 goto exit;
 651         }
 652
 653         /* if the oscillator lost power and no other software (like
 654          * the bootloader) set it up, do it here.
 655          *
 656          * The R2025S/D does this a little differently than the other
 657          * parts, so we special case that..
 658          */
 659         err = rs5c_oscillator_setup(rs5c372);
 660         if (unlikely(err < 0)) {
 661                 dev_err(&client->dev, "setup error\n");
 662                 goto exit;
 663         }
 664
 665         if (rs5c372_get_datetime(client, &tm) < 0)
 666                 dev_warn(&client->dev, "clock needs to be set\n");
 667
 668         dev_info(&client->dev, "%s found, %s\n",
 669                         ({ char *s; switch (rs5c372->type) {
 670                         case rtc_r2025sd:       s = "r2025sd"; break;
 671                         case rtc_r2221tl:       s = "r2221tl"; break;
 672                         case rtc_rs5c372a:      s = "rs5c372a"; break;
 673                         case rtc_rs5c372b:      s = "rs5c372b"; break;
 674                         case rtc_rv5c386:       s = "rv5c386"; break;
 675                         case rtc_rv5c387a:      s = "rv5c387a"; break;
 676                         default:                s = "chip"; break;
 677                         }; s;}),
 678                         rs5c372->time24 ? "24hr" : "am/pm"
 679                         );
 680
 681         /* REVISIT use client->irq to register alarm irq ... */
 682         rs5c372->rtc = devm_rtc_device_register(&client->dev,
 683                                         rs5c372_driver.driver.name,
 684                                         &rs5c372_rtc_ops, THIS_MODULE);
 685
 686         if (IS_ERR(rs5c372->rtc)) {
 687                 err = PTR_ERR(rs5c372->rtc);
 688                 goto exit;
 689         }
 690
 691         err = rs5c_sysfs_register(&client->dev);
 692         if (err)
 693                 goto exit;
 694
 695         return 0;
 696
 697 exit:
 698         return err;
 699 }
 700
 701 static int rs5c372_remove(struct i2c_client *client)
 702 {
 703         rs5c_sysfs_unregister(&client->dev);
 704         return 0;
 705 }
 706
 707 static struct i2c_driver rs5c372_driver = {
 708         .driver         = {
 709                 .name   = "rtc-rs5c372",
 710                 .of_match_table = of_match_ptr(rs5c372_of_match),
 711         },
 712         .probe          = rs5c372_probe,
 713         .remove         = rs5c372_remove,
 714         .id_table       = rs5c372_id,
 715 };
 716
 717 module_i2c_driver(rs5c372_driver);
 718
 719 MODULE_AUTHOR(
 720                 "Pavel Mironchik <pmironchik@optifacio.net>, "
 721                 "Alessandro Zummo <a.zummo@towertech.it>, "
 722                 "Paul Mundt <lethal@linux-sh.org>");
 723 MODULE_DESCRIPTION("Ricoh RS5C372 RTC driver");
 724 MODULE_LICENSE("GPL");