drivers/rtc/rtc-ds1307.c

   1 /*
   2  * rtc-ds1307.c - RTC driver for some mostly-compatible I2C chips.
   3  *
   4  *  Copyright (C) 2005 James Chapman (ds1337 core)
   5  *  Copyright (C) 2006 David Brownell
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/slab.h>
  15 #include <linux/i2c.h>
  16 #include <linux/string.h>
  17 #include <linux/rtc.h>
  18 #include <linux/bcd.h>
  19
  20
  21
  22 /* We can't determine type by probing, but if we expect pre-Linux code
  23  * to have set the chip up as a clock (turning on the oscillator and
  24  * setting the date and time), Linux can ignore the non-clock features.
  25  * That's a natural job for a factory or repair bench.
  26  *
  27  * If the I2C "force" mechanism is used, we assume the chip is a ds1337.
  28  * (Much better would be board-specific tables of I2C devices, along with
  29  * the platform_data drivers would use to sort such issues out.)
  30  */
  31 enum ds_type {
  32         unknown = 0,
  33         ds_1307,                /* or ds1338, ... */
  34         ds_1337,                /* or ds1339, ... */
  35         ds_1340,                /* or st m41t00, ... */
  36         // rs5c372 too?  different address...
  37 };
  38
  39 static unsigned short normal_i2c[] = { 0x68, I2C_CLIENT_END };
  40
  41 I2C_CLIENT_INSMOD;
  42
  43
  44
  45 /* RTC registers don't differ much, except for the century flag */
  46 #define DS1307_REG_SECS         0x00    /* 00-59 */
  47 #       define DS1307_BIT_CH            0x80
  48 #define DS1307_REG_MIN          0x01    /* 00-59 */
  49 #define DS1307_REG_HOUR         0x02    /* 00-23, or 1-12{am,pm} */
  50 #       define DS1340_BIT_CENTURY_EN    0x80    /* in REG_HOUR */
  51 #       define DS1340_BIT_CENTURY       0x40    /* in REG_HOUR */
  52 #define DS1307_REG_WDAY         0x03    /* 01-07 */
  53 #define DS1307_REG_MDAY         0x04    /* 01-31 */
  54 #define DS1307_REG_MONTH        0x05    /* 01-12 */
  55 #       define DS1337_BIT_CENTURY       0x80    /* in REG_MONTH */
  56 #define DS1307_REG_YEAR         0x06    /* 00-99 */
  57
  58 /* Other registers (control, status, alarms, trickle charge, NVRAM, etc)
  59  * start at 7, and they differ a lot. Only control and status matter for RTC;
  60  * be careful using them.
  61  */
  62 #define DS1307_REG_CONTROL      0x07
  63 #       define DS1307_BIT_OUT           0x80
  64 #       define DS1307_BIT_SQWE          0x10
  65 #       define DS1307_BIT_RS1           0x02
  66 #       define DS1307_BIT_RS0           0x01
  67 #define DS1337_REG_CONTROL      0x0e
  68 #       define DS1337_BIT_nEOSC         0x80
  69 #       define DS1337_BIT_RS2           0x10
  70 #       define DS1337_BIT_RS1           0x08
  71 #       define DS1337_BIT_INTCN         0x04
  72 #       define DS1337_BIT_A2IE          0x02
  73 #       define DS1337_BIT_A1IE          0x01
  74 #define DS1337_REG_STATUS       0x0f
  75 #       define DS1337_BIT_OSF           0x80
  76 #       define DS1337_BIT_A2I           0x02
  77 #       define DS1337_BIT_A1I           0x01
  78 #define DS1339_REG_TRICKLE      0x10
  79
  80
  81
  82 struct ds1307 {
  83         u8                      reg_addr;
  84         u8                      regs[8];
  85         enum ds_type            type;
  86         struct i2c_msg          msg[2];
  87         struct i2c_client       client;
  88         struct rtc_device       *rtc;
  89 };
  90
  91
  92 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
  93 {
  94         struct ds1307   *ds1307 = dev_get_drvdata(dev);
  95         int             tmp;
  96
  97         /* read the RTC registers all at once */
  98         ds1307->msg[1].flags = I2C_M_RD;
  99         ds1307->msg[1].len = 7;
 100
 101         tmp = i2c_transfer(ds1307->client.adapter, ds1307->msg, 2);
 102         if (tmp != 2) {
 103                 dev_err(dev, "%s error %d\n", "read", tmp);
 104                 return -EIO;
 105         }
 106
 107         dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
 108                         "read",
 109                         ds1307->regs[0], ds1307->regs[1],
 110                         ds1307->regs[2], ds1307->regs[3],
 111                         ds1307->regs[4], ds1307->regs[5],
 112                         ds1307->regs[6]);
 113
 114         t->tm_sec = BCD2BIN(ds1307->regs[DS1307_REG_SECS] & 0x7f);
 115         t->tm_min = BCD2BIN(ds1307->regs[DS1307_REG_MIN] & 0x7f);
 116         tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
 117         t->tm_hour = BCD2BIN(tmp);
 118         t->tm_wday = BCD2BIN(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
 119         t->tm_mday = BCD2BIN(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
 120         tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
 121         t->tm_mon = BCD2BIN(tmp) - 1;
 122
 123         /* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
 124         t->tm_year = BCD2BIN(ds1307->regs[DS1307_REG_YEAR]) + 100;
 125
 126         dev_dbg(dev, "%s secs=%d, mins=%d, "
 127                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
 128                 "read", t->tm_sec, t->tm_min,
 129                 t->tm_hour, t->tm_mday,
 130                 t->tm_mon, t->tm_year, t->tm_wday);
 131
 132         return 0;
 133 }
 134
 135 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
 136 {
 137         struct ds1307   *ds1307 = dev_get_drvdata(dev);
 138         int             result;
 139         int             tmp;
 140         u8              *buf = ds1307->regs;
 141
 142         dev_dbg(dev, "%s secs=%d, mins=%d, "
 143                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
 144                 "write", dt->tm_sec, dt->tm_min,
 145                 dt->tm_hour, dt->tm_mday,
 146                 dt->tm_mon, dt->tm_year, dt->tm_wday);
 147
 148         *buf++ = 0;             /* first register addr */
 149         buf[DS1307_REG_SECS] = BIN2BCD(t->tm_sec);
 150         buf[DS1307_REG_MIN] = BIN2BCD(t->tm_min);
 151         buf[DS1307_REG_HOUR] = BIN2BCD(t->tm_hour);
 152         buf[DS1307_REG_WDAY] = BIN2BCD(t->tm_wday + 1);
 153         buf[DS1307_REG_MDAY] = BIN2BCD(t->tm_mday);
 154         buf[DS1307_REG_MONTH] = BIN2BCD(t->tm_mon + 1);
 155
 156         /* assume 20YY not 19YY */
 157         tmp = t->tm_year - 100;
 158         buf[DS1307_REG_YEAR] = BIN2BCD(tmp);
 159
 160         if (ds1307->type == ds_1337)
 161                 buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
 162         else if (ds1307->type == ds_1340)
 163                 buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
 164                                 | DS1340_BIT_CENTURY;
 165
 166         ds1307->msg[1].flags = 0;
 167         ds1307->msg[1].len = 8;
 168
 169         dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
 170                 "write", buf[0], buf[1], buf[2], buf[3],
 171                 buf[4], buf[5], buf[6]);
 172
 173         result = i2c_transfer(ds1307->client.adapter, &ds1307->msg[1], 1);
 174         if (result != 1) {
 175                 dev_err(dev, "%s error %d\n", "write", tmp);
 176                 return -EIO;
 177         }
 178         return 0;
 179 }
 180
 181 static struct rtc_class_ops ds13xx_rtc_ops = {
 182         .read_time      = ds1307_get_time,
 183         .set_time       = ds1307_set_time,
 184 };
 185
 186 static struct i2c_driver ds1307_driver;
 187
 188 static int __devinit
 189 ds1307_detect(struct i2c_adapter *adapter, int address, int kind)
 190 {
 191         struct ds1307           *ds1307;
 192         int                     err = -ENODEV;
 193         struct i2c_client       *client;
 194         int                     tmp;
 195
 196         if (!(ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL))) {
 197                 err = -ENOMEM;
 198                 goto exit;
 199         }
 200
 201         client = &ds1307->client;
 202         client->addr = address;
 203         client->adapter = adapter;
 204         client->driver = &ds1307_driver;
 205         client->flags = 0;
 206
 207         i2c_set_clientdata(client, ds1307);
 208
 209         ds1307->msg[0].addr = client->addr;
 210         ds1307->msg[0].flags = 0;
 211         ds1307->msg[0].len = 1;
 212         ds1307->msg[0].buf = &ds1307->reg_addr;
 213
 214         ds1307->msg[1].addr = client->addr;
 215         ds1307->msg[1].flags = I2C_M_RD;
 216         ds1307->msg[1].len = sizeof(ds1307->regs);
 217         ds1307->msg[1].buf = ds1307->regs;
 218
 219         /* HACK: "force" implies "needs ds1337-style-oscillator setup" */
 220         if (kind >= 0) {
 221                 ds1307->type = ds_1337;
 222
 223                 ds1307->reg_addr = DS1337_REG_CONTROL;
 224                 ds1307->msg[1].len = 2;
 225
 226                 tmp = i2c_transfer(client->adapter, ds1307->msg, 2);
 227                 if (tmp != 2) {
 228                         pr_debug("read error %d\n", tmp);
 229                         err = -EIO;
 230                         goto exit_free;
 231                 }
 232
 233                 ds1307->reg_addr = 0;
 234                 ds1307->msg[1].len = sizeof(ds1307->regs);
 235
 236                 /* oscillator is off; need to turn it on */
 237                 if ((ds1307->regs[0] & DS1337_BIT_nEOSC)
 238                                 || (ds1307->regs[1] & DS1337_BIT_OSF)) {
 239                         printk(KERN_ERR "no ds1337 oscillator code\n");
 240                         goto exit_free;
 241                 }
 242         } else
 243                 ds1307->type = ds_1307;
 244
 245 read_rtc:
 246         /* read RTC registers */
 247
 248         tmp = i2c_transfer(client->adapter, ds1307->msg, 2);
 249         if (tmp != 2) {
 250                 pr_debug("read error %d\n", tmp);
 251                 err = -EIO;
 252                 goto exit_free;
 253         }
 254
 255         /* minimal sanity checking; some chips (like DS1340) don't
 256          * specify the extra bits as must-be-zero, but there are
 257          * still a few values that are clearly out-of-range.
 258          */
 259         tmp = ds1307->regs[DS1307_REG_SECS];
 260         if (tmp & DS1307_BIT_CH) {
 261                 if (ds1307->type && ds1307->type != ds_1307) {
 262                         pr_debug("not a ds1307?\n");
 263                         goto exit_free;
 264                 }
 265                 ds1307->type = ds_1307;
 266
 267                 /* this partial initialization should work for ds1307,
 268                  * ds1338, ds1340, st m41t00, and more.
 269                  */
 270                 dev_warn(&client->dev, "oscillator started; SET TIME!\n");
 271                 i2c_smbus_write_byte_data(client, 0, 0);
 272                 goto read_rtc;
 273         }
 274         tmp = BCD2BIN(tmp & 0x7f);
 275         if (tmp > 60)
 276                 goto exit_free;
 277         tmp = BCD2BIN(ds1307->regs[DS1307_REG_MIN] & 0x7f);
 278         if (tmp > 60)
 279                 goto exit_free;
 280
 281         tmp = BCD2BIN(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
 282         if (tmp == 0 || tmp > 31)
 283                 goto exit_free;
 284
 285         tmp = BCD2BIN(ds1307->regs[DS1307_REG_MONTH] & 0x1f);
 286         if (tmp == 0 || tmp > 12)
 287                 goto exit_free;
 288
 289         /* force into in 24 hour mode (most chips) or
 290          * disable century bit (ds1340)
 291          */
 292         tmp = ds1307->regs[DS1307_REG_HOUR];
 293         if (tmp & (1 << 6)) {
 294                 if (tmp & (1 << 5))
 295                         tmp = BCD2BIN(tmp & 0x1f) + 12;
 296                 else
 297                         tmp = BCD2BIN(tmp);
 298                 i2c_smbus_write_byte_data(client,
 299                                 DS1307_REG_HOUR,
 300                                 BIN2BCD(tmp));
 301         }
 302
 303         /* FIXME chips like 1337 can generate alarm irqs too; those are
 304          * worth exposing through the API (especially when the irq is
 305          * wakeup-capable).
 306          */
 307
 308         switch (ds1307->type) {
 309         case unknown:
 310                 strlcpy(client->name, "unknown", I2C_NAME_SIZE);
 311                 break;
 312         case ds_1307:
 313                 strlcpy(client->name, "ds1307", I2C_NAME_SIZE);
 314                 break;
 315         case ds_1337:
 316                 strlcpy(client->name, "ds1337", I2C_NAME_SIZE);
 317                 break;
 318         case ds_1340:
 319                 strlcpy(client->name, "ds1340", I2C_NAME_SIZE);
 320                 break;
 321         }
 322
 323         /* Tell the I2C layer a new client has arrived */
 324         if ((err = i2c_attach_client(client)))
 325                 goto exit_free;
 326
 327         ds1307->rtc = rtc_device_register(client->name, &client->dev,
 328                                 &ds13xx_rtc_ops, THIS_MODULE);
 329         if (IS_ERR(ds1307->rtc)) {
 330                 err = PTR_ERR(ds1307->rtc);
 331                 dev_err(&client->dev,
 332                         "unable to register the class device\n");
 333                 goto exit_detach;
 334         }
 335
 336         return 0;
 337
 338 exit_detach:
 339         i2c_detach_client(client);
 340 exit_free:
 341         kfree(ds1307);
 342 exit:
 343         return err;
 344 }
 345
 346 static int __devinit
 347 ds1307_attach_adapter(struct i2c_adapter *adapter)
 348 {
 349         if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
 350                 return 0;
 351         return i2c_probe(adapter, &addr_data, ds1307_detect);
 352 }
 353
 354 static int __devexit ds1307_detach_client(struct i2c_client *client)
 355 {
 356         int             err;
 357         struct ds1307   *ds1307 = i2c_get_clientdata(client);
 358
 359         rtc_device_unregister(ds1307->rtc);
 360         if ((err = i2c_detach_client(client)))
 361                 return err;
 362         kfree(ds1307);
 363         return 0;
 364 }
 365
 366 static struct i2c_driver ds1307_driver = {
 367         .driver = {
 368                 .name   = "ds1307",
 369                 .owner  = THIS_MODULE,
 370         },
 371         .attach_adapter = ds1307_attach_adapter,
 372         .detach_client  = __devexit_p(ds1307_detach_client),
 373 };
 374
 375 static int __init ds1307_init(void)
 376 {
 377         return i2c_add_driver(&ds1307_driver);
 378 }
 379 module_init(ds1307_init);
 380
 381 static void __exit ds1307_exit(void)
 382 {
 383         i2c_del_driver(&ds1307_driver);
 384 }
 385 module_exit(ds1307_exit);
 386
 387 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
 388 MODULE_LICENSE("GPL");