rtc-ds1307: SMBus compatibility
[linux-2.6.git] / 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 enum ds_type {
28         ds_1307,
29         ds_1337,
30         ds_1338,
31         ds_1339,
32         ds_1340,
33         m41t00,
34         // rs5c372 too?  different address...
35 };
36
37
38 /* RTC registers don't differ much, except for the century flag */
39 #define DS1307_REG_SECS         0x00    /* 00-59 */
40 #       define DS1307_BIT_CH            0x80
41 #       define DS1340_BIT_nEOSC         0x80
42 #define DS1307_REG_MIN          0x01    /* 00-59 */
43 #define DS1307_REG_HOUR         0x02    /* 00-23, or 1-12{am,pm} */
44 #       define DS1307_BIT_12HR          0x40    /* in REG_HOUR */
45 #       define DS1307_BIT_PM            0x20    /* in REG_HOUR */
46 #       define DS1340_BIT_CENTURY_EN    0x80    /* in REG_HOUR */
47 #       define DS1340_BIT_CENTURY       0x40    /* in REG_HOUR */
48 #define DS1307_REG_WDAY         0x03    /* 01-07 */
49 #define DS1307_REG_MDAY         0x04    /* 01-31 */
50 #define DS1307_REG_MONTH        0x05    /* 01-12 */
51 #       define DS1337_BIT_CENTURY       0x80    /* in REG_MONTH */
52 #define DS1307_REG_YEAR         0x06    /* 00-99 */
53
54 /* Other registers (control, status, alarms, trickle charge, NVRAM, etc)
55  * start at 7, and they differ a LOT. Only control and status matter for
56  * basic RTC date and time functionality; be careful using them.
57  */
58 #define DS1307_REG_CONTROL      0x07            /* or ds1338 */
59 #       define DS1307_BIT_OUT           0x80
60 #       define DS1338_BIT_OSF           0x20
61 #       define DS1307_BIT_SQWE          0x10
62 #       define DS1307_BIT_RS1           0x02
63 #       define DS1307_BIT_RS0           0x01
64 #define DS1337_REG_CONTROL      0x0e
65 #       define DS1337_BIT_nEOSC         0x80
66 #       define DS1339_BIT_BBSQI         0x20
67 #       define DS1337_BIT_RS2           0x10
68 #       define DS1337_BIT_RS1           0x08
69 #       define DS1337_BIT_INTCN         0x04
70 #       define DS1337_BIT_A2IE          0x02
71 #       define DS1337_BIT_A1IE          0x01
72 #define DS1340_REG_CONTROL      0x07
73 #       define DS1340_BIT_OUT           0x80
74 #       define DS1340_BIT_FT            0x40
75 #       define DS1340_BIT_CALIB_SIGN    0x20
76 #       define DS1340_M_CALIBRATION     0x1f
77 #define DS1340_REG_FLAG         0x09
78 #       define DS1340_BIT_OSF           0x80
79 #define DS1337_REG_STATUS       0x0f
80 #       define DS1337_BIT_OSF           0x80
81 #       define DS1337_BIT_A2I           0x02
82 #       define DS1337_BIT_A1I           0x01
83 #define DS1339_REG_ALARM1_SECS  0x07
84 #define DS1339_REG_TRICKLE      0x10
85
86
87
88 struct ds1307 {
89         u8                      regs[11];
90         enum ds_type            type;
91         unsigned long           flags;
92 #define HAS_NVRAM       0               /* bit 0 == sysfs file active */
93 #define HAS_ALARM       1               /* bit 1 == irq claimed */
94         struct i2c_client       *client;
95         struct rtc_device       *rtc;
96         struct work_struct      work;
97 };
98
99 struct chip_desc {
100         unsigned                nvram56:1;
101         unsigned                alarm:1;
102 };
103
104 static const struct chip_desc chips[] = {
105 [ds_1307] = {
106         .nvram56        = 1,
107 },
108 [ds_1337] = {
109         .alarm          = 1,
110 },
111 [ds_1338] = {
112         .nvram56        = 1,
113 },
114 [ds_1339] = {
115         .alarm          = 1,
116 },
117 [ds_1340] = {
118 },
119 [m41t00] = {
120 }, };
121
122 static const struct i2c_device_id ds1307_id[] = {
123         { "ds1307", ds_1307 },
124         { "ds1337", ds_1337 },
125         { "ds1338", ds_1338 },
126         { "ds1339", ds_1339 },
127         { "ds1340", ds_1340 },
128         { "m41t00", m41t00 },
129         { }
130 };
131 MODULE_DEVICE_TABLE(i2c, ds1307_id);
132
133 /*----------------------------------------------------------------------*/
134
135 /*
136  * The IRQ logic includes a "real" handler running in IRQ context just
137  * long enough to schedule this workqueue entry.   We need a task context
138  * to talk to the RTC, since I2C I/O calls require that; and disable the
139  * IRQ until we clear its status on the chip, so that this handler can
140  * work with any type of triggering (not just falling edge).
141  *
142  * The ds1337 and ds1339 both have two alarms, but we only use the first
143  * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
144  * signal; ds1339 chips have only one alarm signal.
145  */
146 static void ds1307_work(struct work_struct *work)
147 {
148         struct ds1307           *ds1307;
149         struct i2c_client       *client;
150         struct mutex            *lock;
151         int                     stat, control;
152
153         ds1307 = container_of(work, struct ds1307, work);
154         client = ds1307->client;
155         lock = &ds1307->rtc->ops_lock;
156
157         mutex_lock(lock);
158         stat = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
159         if (stat < 0)
160                 goto out;
161
162         if (stat & DS1337_BIT_A1I) {
163                 stat &= ~DS1337_BIT_A1I;
164                 i2c_smbus_write_byte_data(client, DS1337_REG_STATUS, stat);
165
166                 control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
167                 if (control < 0)
168                         goto out;
169
170                 control &= ~DS1337_BIT_A1IE;
171                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, control);
172
173                 /* rtc_update_irq() assumes that it is called
174                  * from IRQ-disabled context.
175                  */
176                 local_irq_disable();
177                 rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
178                 local_irq_enable();
179         }
180
181 out:
182         if (test_bit(HAS_ALARM, &ds1307->flags))
183                 enable_irq(client->irq);
184         mutex_unlock(lock);
185 }
186
187 static irqreturn_t ds1307_irq(int irq, void *dev_id)
188 {
189         struct i2c_client       *client = dev_id;
190         struct ds1307           *ds1307 = i2c_get_clientdata(client);
191
192         disable_irq_nosync(irq);
193         schedule_work(&ds1307->work);
194         return IRQ_HANDLED;
195 }
196
197 /*----------------------------------------------------------------------*/
198
199 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
200 {
201         struct ds1307   *ds1307 = dev_get_drvdata(dev);
202         int             tmp;
203
204         /* read the RTC date and time registers all at once */
205         tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
206                 DS1307_REG_SECS, 7, ds1307->regs);
207         if (tmp != 7) {
208                 dev_err(dev, "%s error %d\n", "read", tmp);
209                 return -EIO;
210         }
211
212         dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
213                         "read",
214                         ds1307->regs[0], ds1307->regs[1],
215                         ds1307->regs[2], ds1307->regs[3],
216                         ds1307->regs[4], ds1307->regs[5],
217                         ds1307->regs[6]);
218
219         t->tm_sec = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f);
220         t->tm_min = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f);
221         tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
222         t->tm_hour = bcd2bin(tmp);
223         t->tm_wday = bcd2bin(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
224         t->tm_mday = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
225         tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
226         t->tm_mon = bcd2bin(tmp) - 1;
227
228         /* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
229         t->tm_year = bcd2bin(ds1307->regs[DS1307_REG_YEAR]) + 100;
230
231         dev_dbg(dev, "%s secs=%d, mins=%d, "
232                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
233                 "read", t->tm_sec, t->tm_min,
234                 t->tm_hour, t->tm_mday,
235                 t->tm_mon, t->tm_year, t->tm_wday);
236
237         /* initial clock setting can be undefined */
238         return rtc_valid_tm(t);
239 }
240
241 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
242 {
243         struct ds1307   *ds1307 = dev_get_drvdata(dev);
244         int             result;
245         int             tmp;
246         u8              *buf = ds1307->regs;
247
248         dev_dbg(dev, "%s secs=%d, mins=%d, "
249                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
250                 "write", t->tm_sec, t->tm_min,
251                 t->tm_hour, t->tm_mday,
252                 t->tm_mon, t->tm_year, t->tm_wday);
253
254         buf[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
255         buf[DS1307_REG_MIN] = bin2bcd(t->tm_min);
256         buf[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
257         buf[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
258         buf[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
259         buf[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
260
261         /* assume 20YY not 19YY */
262         tmp = t->tm_year - 100;
263         buf[DS1307_REG_YEAR] = bin2bcd(tmp);
264
265         switch (ds1307->type) {
266         case ds_1337:
267         case ds_1339:
268                 buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
269                 break;
270         case ds_1340:
271                 buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
272                                 | DS1340_BIT_CENTURY;
273                 break;
274         default:
275                 break;
276         }
277
278         dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
279                 "write", buf[0], buf[1], buf[2], buf[3],
280                 buf[4], buf[5], buf[6]);
281
282         result = i2c_smbus_write_i2c_block_data(ds1307->client, 0, 7, buf);
283         if (result < 0) {
284                 dev_err(dev, "%s error %d\n", "write", result);
285                 return result;
286         }
287         return 0;
288 }
289
290 static int ds1307_read_alarm(struct device *dev, struct rtc_wkalrm *t)
291 {
292         struct i2c_client       *client = to_i2c_client(dev);
293         struct ds1307           *ds1307 = i2c_get_clientdata(client);
294         int                     ret;
295
296         if (!test_bit(HAS_ALARM, &ds1307->flags))
297                 return -EINVAL;
298
299         /* read all ALARM1, ALARM2, and status registers at once */
300         ret = i2c_smbus_read_i2c_block_data(client,
301                         DS1339_REG_ALARM1_SECS, 9, ds1307->regs);
302         if (ret != 9) {
303                 dev_err(dev, "%s error %d\n", "alarm read", ret);
304                 return -EIO;
305         }
306
307         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
308                         "alarm read",
309                         ds1307->regs[0], ds1307->regs[1],
310                         ds1307->regs[2], ds1307->regs[3],
311                         ds1307->regs[4], ds1307->regs[5],
312                         ds1307->regs[6], ds1307->regs[7],
313                         ds1307->regs[8]);
314
315         /* report alarm time (ALARM1); assume 24 hour and day-of-month modes,
316          * and that all four fields are checked matches
317          */
318         t->time.tm_sec = bcd2bin(ds1307->regs[0] & 0x7f);
319         t->time.tm_min = bcd2bin(ds1307->regs[1] & 0x7f);
320         t->time.tm_hour = bcd2bin(ds1307->regs[2] & 0x3f);
321         t->time.tm_mday = bcd2bin(ds1307->regs[3] & 0x3f);
322         t->time.tm_mon = -1;
323         t->time.tm_year = -1;
324         t->time.tm_wday = -1;
325         t->time.tm_yday = -1;
326         t->time.tm_isdst = -1;
327
328         /* ... and status */
329         t->enabled = !!(ds1307->regs[7] & DS1337_BIT_A1IE);
330         t->pending = !!(ds1307->regs[8] & DS1337_BIT_A1I);
331
332         dev_dbg(dev, "%s secs=%d, mins=%d, "
333                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
334                 "alarm read", t->time.tm_sec, t->time.tm_min,
335                 t->time.tm_hour, t->time.tm_mday,
336                 t->enabled, t->pending);
337
338         return 0;
339 }
340
341 static int ds1307_set_alarm(struct device *dev, struct rtc_wkalrm *t)
342 {
343         struct i2c_client       *client = to_i2c_client(dev);
344         struct ds1307           *ds1307 = i2c_get_clientdata(client);
345         unsigned char           *buf = ds1307->regs;
346         u8                      control, status;
347         int                     ret;
348
349         if (!test_bit(HAS_ALARM, &ds1307->flags))
350                 return -EINVAL;
351
352         dev_dbg(dev, "%s secs=%d, mins=%d, "
353                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
354                 "alarm set", t->time.tm_sec, t->time.tm_min,
355                 t->time.tm_hour, t->time.tm_mday,
356                 t->enabled, t->pending);
357
358         /* read current status of both alarms and the chip */
359         ret = i2c_smbus_read_i2c_block_data(client,
360                         DS1339_REG_ALARM1_SECS, 9, buf);
361         if (ret != 9) {
362                 dev_err(dev, "%s error %d\n", "alarm write", ret);
363                 return -EIO;
364         }
365         control = ds1307->regs[7];
366         status = ds1307->regs[8];
367
368         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
369                         "alarm set (old status)",
370                         ds1307->regs[0], ds1307->regs[1],
371                         ds1307->regs[2], ds1307->regs[3],
372                         ds1307->regs[4], ds1307->regs[5],
373                         ds1307->regs[6], control, status);
374
375         /* set ALARM1, using 24 hour and day-of-month modes */
376         buf[0] = bin2bcd(t->time.tm_sec);
377         buf[1] = bin2bcd(t->time.tm_min);
378         buf[2] = bin2bcd(t->time.tm_hour);
379         buf[3] = bin2bcd(t->time.tm_mday);
380
381         /* set ALARM2 to non-garbage */
382         buf[4] = 0;
383         buf[5] = 0;
384         buf[6] = 0;
385
386         /* optionally enable ALARM1 */
387         buf[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
388         if (t->enabled) {
389                 dev_dbg(dev, "alarm IRQ armed\n");
390                 buf[7] |= DS1337_BIT_A1IE;      /* only ALARM1 is used */
391         }
392         buf[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
393
394         ret = i2c_smbus_write_i2c_block_data(client,
395                         DS1339_REG_ALARM1_SECS, 9, buf);
396         if (ret < 0) {
397                 dev_err(dev, "can't set alarm time\n");
398                 return ret;
399         }
400
401         return 0;
402 }
403
404 static int ds1307_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
405 {
406         struct i2c_client       *client = to_i2c_client(dev);
407         struct ds1307           *ds1307 = i2c_get_clientdata(client);
408         int                     ret;
409
410         switch (cmd) {
411         case RTC_AIE_OFF:
412                 if (!test_bit(HAS_ALARM, &ds1307->flags))
413                         return -ENOTTY;
414
415                 ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
416                 if (ret < 0)
417                         return ret;
418
419                 ret &= ~DS1337_BIT_A1IE;
420
421                 ret = i2c_smbus_write_byte_data(client,
422                                                 DS1337_REG_CONTROL, ret);
423                 if (ret < 0)
424                         return ret;
425
426                 break;
427
428         case RTC_AIE_ON:
429                 if (!test_bit(HAS_ALARM, &ds1307->flags))
430                         return -ENOTTY;
431
432                 ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
433                 if (ret < 0)
434                         return ret;
435
436                 ret |= DS1337_BIT_A1IE;
437
438                 ret = i2c_smbus_write_byte_data(client,
439                                                 DS1337_REG_CONTROL, ret);
440                 if (ret < 0)
441                         return ret;
442
443                 break;
444
445         default:
446                 return -ENOIOCTLCMD;
447         }
448
449         return 0;
450 }
451
452 static const struct rtc_class_ops ds13xx_rtc_ops = {
453         .read_time      = ds1307_get_time,
454         .set_time       = ds1307_set_time,
455         .read_alarm     = ds1307_read_alarm,
456         .set_alarm      = ds1307_set_alarm,
457         .ioctl          = ds1307_ioctl,
458 };
459
460 /*----------------------------------------------------------------------*/
461
462 #define NVRAM_SIZE      56
463
464 static ssize_t
465 ds1307_nvram_read(struct kobject *kobj, struct bin_attribute *attr,
466                 char *buf, loff_t off, size_t count)
467 {
468         struct i2c_client       *client;
469         struct ds1307           *ds1307;
470         int                     result;
471
472         client = kobj_to_i2c_client(kobj);
473         ds1307 = i2c_get_clientdata(client);
474
475         if (unlikely(off >= NVRAM_SIZE))
476                 return 0;
477         if ((off + count) > NVRAM_SIZE)
478                 count = NVRAM_SIZE - off;
479         if (unlikely(!count))
480                 return count;
481
482         result = i2c_smbus_read_i2c_block_data(client, 8 + off, count, buf);
483         if (result < 0)
484                 dev_err(&client->dev, "%s error %d\n", "nvram read", result);
485         return result;
486 }
487
488 static ssize_t
489 ds1307_nvram_write(struct kobject *kobj, struct bin_attribute *attr,
490                 char *buf, loff_t off, size_t count)
491 {
492         struct i2c_client       *client;
493         int                     result;
494
495         client = kobj_to_i2c_client(kobj);
496
497         if (unlikely(off >= NVRAM_SIZE))
498                 return -EFBIG;
499         if ((off + count) > NVRAM_SIZE)
500                 count = NVRAM_SIZE - off;
501         if (unlikely(!count))
502                 return count;
503
504         result = i2c_smbus_write_i2c_block_data(client, 8 + off, count, buf);
505         if (result < 0) {
506                 dev_err(&client->dev, "%s error %d\n", "nvram write", result);
507                 return result;
508         }
509         return count;
510 }
511
512 static struct bin_attribute nvram = {
513         .attr = {
514                 .name   = "nvram",
515                 .mode   = S_IRUGO | S_IWUSR,
516         },
517
518         .read   = ds1307_nvram_read,
519         .write  = ds1307_nvram_write,
520         .size   = NVRAM_SIZE,
521 };
522
523 /*----------------------------------------------------------------------*/
524
525 static struct i2c_driver ds1307_driver;
526
527 static int __devinit ds1307_probe(struct i2c_client *client,
528                                   const struct i2c_device_id *id)
529 {
530         struct ds1307           *ds1307;
531         int                     err = -ENODEV;
532         int                     tmp;
533         const struct chip_desc  *chip = &chips[id->driver_data];
534         struct i2c_adapter      *adapter = to_i2c_adapter(client->dev.parent);
535         int                     want_irq = false;
536         unsigned char           *buf;
537
538         if (!i2c_check_functionality(adapter,
539                         I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
540                         I2C_FUNC_SMBUS_I2C_BLOCK))
541                 return -EIO;
542
543         if (!(ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL)))
544                 return -ENOMEM;
545
546         ds1307->client = client;
547         i2c_set_clientdata(client, ds1307);
548         ds1307->type = id->driver_data;
549         buf = ds1307->regs;
550
551         switch (ds1307->type) {
552         case ds_1337:
553         case ds_1339:
554                 /* has IRQ? */
555                 if (ds1307->client->irq > 0 && chip->alarm) {
556                         INIT_WORK(&ds1307->work, ds1307_work);
557                         want_irq = true;
558                 }
559                 /* get registers that the "rtc" read below won't read... */
560                 tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
561                                 DS1337_REG_CONTROL, 2, buf);
562                 if (tmp != 2) {
563                         pr_debug("read error %d\n", tmp);
564                         err = -EIO;
565                         goto exit_free;
566                 }
567
568                 /* oscillator off?  turn it on, so clock can tick. */
569                 if (ds1307->regs[0] & DS1337_BIT_nEOSC)
570                         ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
571
572                 /* Using IRQ?  Disable the square wave and both alarms.
573                  * For ds1339, be sure alarms can trigger when we're
574                  * running on Vbackup (BBSQI); we assume ds1337 will
575                  * ignore that bit
576                  */
577                 if (want_irq) {
578                         ds1307->regs[0] |= DS1337_BIT_INTCN | DS1339_BIT_BBSQI;
579                         ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
580                 }
581
582                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
583                                                         ds1307->regs[0]);
584
585                 /* oscillator fault?  clear flag, and warn */
586                 if (ds1307->regs[1] & DS1337_BIT_OSF) {
587                         i2c_smbus_write_byte_data(client, DS1337_REG_STATUS,
588                                 ds1307->regs[1] & ~DS1337_BIT_OSF);
589                         dev_warn(&client->dev, "SET TIME!\n");
590                 }
591                 break;
592         default:
593                 break;
594         }
595
596 read_rtc:
597         /* read RTC registers */
598         tmp = i2c_smbus_read_i2c_block_data(ds1307->client, 0, 8, buf);
599         if (tmp != 8) {
600                 pr_debug("read error %d\n", tmp);
601                 err = -EIO;
602                 goto exit_free;
603         }
604
605         /* minimal sanity checking; some chips (like DS1340) don't
606          * specify the extra bits as must-be-zero, but there are
607          * still a few values that are clearly out-of-range.
608          */
609         tmp = ds1307->regs[DS1307_REG_SECS];
610         switch (ds1307->type) {
611         case ds_1307:
612         case m41t00:
613                 /* clock halted?  turn it on, so clock can tick. */
614                 if (tmp & DS1307_BIT_CH) {
615                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
616                         dev_warn(&client->dev, "SET TIME!\n");
617                         goto read_rtc;
618                 }
619                 break;
620         case ds_1338:
621                 /* clock halted?  turn it on, so clock can tick. */
622                 if (tmp & DS1307_BIT_CH)
623                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
624
625                 /* oscillator fault?  clear flag, and warn */
626                 if (ds1307->regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
627                         i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL,
628                                         ds1307->regs[DS1307_REG_CONTROL]
629                                         & ~DS1338_BIT_OSF);
630                         dev_warn(&client->dev, "SET TIME!\n");
631                         goto read_rtc;
632                 }
633                 break;
634         case ds_1340:
635                 /* clock halted?  turn it on, so clock can tick. */
636                 if (tmp & DS1340_BIT_nEOSC)
637                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
638
639                 tmp = i2c_smbus_read_byte_data(client, DS1340_REG_FLAG);
640                 if (tmp < 0) {
641                         pr_debug("read error %d\n", tmp);
642                         err = -EIO;
643                         goto exit_free;
644                 }
645
646                 /* oscillator fault?  clear flag, and warn */
647                 if (tmp & DS1340_BIT_OSF) {
648                         i2c_smbus_write_byte_data(client, DS1340_REG_FLAG, 0);
649                         dev_warn(&client->dev, "SET TIME!\n");
650                 }
651                 break;
652         case ds_1337:
653         case ds_1339:
654                 break;
655         }
656
657         tmp = ds1307->regs[DS1307_REG_SECS];
658         tmp = bcd2bin(tmp & 0x7f);
659         if (tmp > 60)
660                 goto exit_bad;
661         tmp = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f);
662         if (tmp > 60)
663                 goto exit_bad;
664
665         tmp = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
666         if (tmp == 0 || tmp > 31)
667                 goto exit_bad;
668
669         tmp = bcd2bin(ds1307->regs[DS1307_REG_MONTH] & 0x1f);
670         if (tmp == 0 || tmp > 12)
671                 goto exit_bad;
672
673         tmp = ds1307->regs[DS1307_REG_HOUR];
674         switch (ds1307->type) {
675         case ds_1340:
676         case m41t00:
677                 /* NOTE: ignores century bits; fix before deploying
678                  * systems that will run through year 2100.
679                  */
680                 break;
681         default:
682                 if (!(tmp & DS1307_BIT_12HR))
683                         break;
684
685                 /* Be sure we're in 24 hour mode.  Multi-master systems
686                  * take note...
687                  */
688                 tmp = bcd2bin(tmp & 0x1f);
689                 if (tmp == 12)
690                         tmp = 0;
691                 if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
692                         tmp += 12;
693                 i2c_smbus_write_byte_data(client,
694                                 DS1307_REG_HOUR,
695                                 bin2bcd(tmp));
696         }
697
698         ds1307->rtc = rtc_device_register(client->name, &client->dev,
699                                 &ds13xx_rtc_ops, THIS_MODULE);
700         if (IS_ERR(ds1307->rtc)) {
701                 err = PTR_ERR(ds1307->rtc);
702                 dev_err(&client->dev,
703                         "unable to register the class device\n");
704                 goto exit_free;
705         }
706
707         if (want_irq) {
708                 err = request_irq(client->irq, ds1307_irq, 0,
709                           ds1307->rtc->name, client);
710                 if (err) {
711                         dev_err(&client->dev,
712                                 "unable to request IRQ!\n");
713                         goto exit_irq;
714                 }
715                 set_bit(HAS_ALARM, &ds1307->flags);
716                 dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
717         }
718
719         if (chip->nvram56) {
720                 err = sysfs_create_bin_file(&client->dev.kobj, &nvram);
721                 if (err == 0) {
722                         set_bit(HAS_NVRAM, &ds1307->flags);
723                         dev_info(&client->dev, "56 bytes nvram\n");
724                 }
725         }
726
727         return 0;
728
729 exit_bad:
730         dev_dbg(&client->dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
731                         "bogus register",
732                         ds1307->regs[0], ds1307->regs[1],
733                         ds1307->regs[2], ds1307->regs[3],
734                         ds1307->regs[4], ds1307->regs[5],
735                         ds1307->regs[6]);
736 exit_irq:
737         if (ds1307->rtc)
738                 rtc_device_unregister(ds1307->rtc);
739 exit_free:
740         kfree(ds1307);
741         return err;
742 }
743
744 static int __devexit ds1307_remove(struct i2c_client *client)
745 {
746         struct ds1307           *ds1307 = i2c_get_clientdata(client);
747
748         if (test_and_clear_bit(HAS_ALARM, &ds1307->flags)) {
749                 free_irq(client->irq, client);
750                 cancel_work_sync(&ds1307->work);
751         }
752
753         if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
754                 sysfs_remove_bin_file(&client->dev.kobj, &nvram);
755
756         rtc_device_unregister(ds1307->rtc);
757         kfree(ds1307);
758         return 0;
759 }
760
761 static struct i2c_driver ds1307_driver = {
762         .driver = {
763                 .name   = "rtc-ds1307",
764                 .owner  = THIS_MODULE,
765         },
766         .probe          = ds1307_probe,
767         .remove         = __devexit_p(ds1307_remove),
768         .id_table       = ds1307_id,
769 };
770
771 static int __init ds1307_init(void)
772 {
773         return i2c_add_driver(&ds1307_driver);
774 }
775 module_init(ds1307_init);
776
777 static void __exit ds1307_exit(void)
778 {
779         i2c_del_driver(&ds1307_driver);
780 }
781 module_exit(ds1307_exit);
782
783 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
784 MODULE_LICENSE("GPL");