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Linux/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  *  Copyright (C) 2009 Matthias Fuchs (rx8025 support)
  7  *  Copyright (C) 2012 Bertrand Achard (nvram access fixes)
  8  *
  9  * This program is free software; you can redistribute it and/or modify
 10  * it under the terms of the GNU General Public License version 2 as
 11  * published by the Free Software Foundation.
 12  */
 13 
 14 #include <linux/bcd.h>
 15 #include <linux/i2c.h>
 16 #include <linux/init.h>
 17 #include <linux/module.h>
 18 #include <linux/rtc/ds1307.h>
 19 #include <linux/rtc.h>
 20 #include <linux/slab.h>
 21 #include <linux/string.h>
 22 
 23 /*
 24  * We can't determine type by probing, but if we expect pre-Linux code
 25  * to have set the chip up as a clock (turning on the oscillator and
 26  * setting the date and time), Linux can ignore the non-clock features.
 27  * That's a natural job for a factory or repair bench.
 28  */
 29 enum ds_type {
 30         ds_1307,
 31         ds_1337,
 32         ds_1338,
 33         ds_1339,
 34         ds_1340,
 35         ds_1388,
 36         ds_3231,
 37         m41t00,
 38         mcp794xx,
 39         rx_8025,
 40         last_ds_type /* always last */
 41         /* rs5c372 too?  different address... */
 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 DS1340_BIT_nEOSC         0x80
 49 #       define MCP794XX_BIT_ST          0x80
 50 #define DS1307_REG_MIN          0x01    /* 00-59 */
 51 #define DS1307_REG_HOUR         0x02    /* 00-23, or 1-12{am,pm} */
 52 #       define DS1307_BIT_12HR          0x40    /* in REG_HOUR */
 53 #       define DS1307_BIT_PM            0x20    /* in REG_HOUR */
 54 #       define DS1340_BIT_CENTURY_EN    0x80    /* in REG_HOUR */
 55 #       define DS1340_BIT_CENTURY       0x40    /* in REG_HOUR */
 56 #define DS1307_REG_WDAY         0x03    /* 01-07 */
 57 #       define MCP794XX_BIT_VBATEN      0x08
 58 #define DS1307_REG_MDAY         0x04    /* 01-31 */
 59 #define DS1307_REG_MONTH        0x05    /* 01-12 */
 60 #       define DS1337_BIT_CENTURY       0x80    /* in REG_MONTH */
 61 #define DS1307_REG_YEAR         0x06    /* 00-99 */
 62 
 63 /*
 64  * Other registers (control, status, alarms, trickle charge, NVRAM, etc)
 65  * start at 7, and they differ a LOT. Only control and status matter for
 66  * basic RTC date and time functionality; be careful using them.
 67  */
 68 #define DS1307_REG_CONTROL      0x07            /* or ds1338 */
 69 #       define DS1307_BIT_OUT           0x80
 70 #       define DS1338_BIT_OSF           0x20
 71 #       define DS1307_BIT_SQWE          0x10
 72 #       define DS1307_BIT_RS1           0x02
 73 #       define DS1307_BIT_RS0           0x01
 74 #define DS1337_REG_CONTROL      0x0e
 75 #       define DS1337_BIT_nEOSC         0x80
 76 #       define DS1339_BIT_BBSQI         0x20
 77 #       define DS3231_BIT_BBSQW         0x40 /* same as BBSQI */
 78 #       define DS1337_BIT_RS2           0x10
 79 #       define DS1337_BIT_RS1           0x08
 80 #       define DS1337_BIT_INTCN         0x04
 81 #       define DS1337_BIT_A2IE          0x02
 82 #       define DS1337_BIT_A1IE          0x01
 83 #define DS1340_REG_CONTROL      0x07
 84 #       define DS1340_BIT_OUT           0x80
 85 #       define DS1340_BIT_FT            0x40
 86 #       define DS1340_BIT_CALIB_SIGN    0x20
 87 #       define DS1340_M_CALIBRATION     0x1f
 88 #define DS1340_REG_FLAG         0x09
 89 #       define DS1340_BIT_OSF           0x80
 90 #define DS1337_REG_STATUS       0x0f
 91 #       define DS1337_BIT_OSF           0x80
 92 #       define DS1337_BIT_A2I           0x02
 93 #       define DS1337_BIT_A1I           0x01
 94 #define DS1339_REG_ALARM1_SECS  0x07
 95 
 96 #define DS13XX_TRICKLE_CHARGER_MAGIC    0xa0
 97 
 98 #define RX8025_REG_CTRL1        0x0e
 99 #       define RX8025_BIT_2412          0x20
100 #define RX8025_REG_CTRL2        0x0f
101 #       define RX8025_BIT_PON           0x10
102 #       define RX8025_BIT_VDET          0x40
103 #       define RX8025_BIT_XST           0x20
104 
105 
106 struct ds1307 {
107         u8                      offset; /* register's offset */
108         u8                      regs[11];
109         u16                     nvram_offset;
110         struct bin_attribute    *nvram;
111         enum ds_type            type;
112         unsigned long           flags;
113 #define HAS_NVRAM       0               /* bit 0 == sysfs file active */
114 #define HAS_ALARM       1               /* bit 1 == irq claimed */
115         struct i2c_client       *client;
116         struct rtc_device       *rtc;
117         s32 (*read_block_data)(const struct i2c_client *client, u8 command,
118                                u8 length, u8 *values);
119         s32 (*write_block_data)(const struct i2c_client *client, u8 command,
120                                 u8 length, const u8 *values);
121 };
122 
123 struct chip_desc {
124         unsigned                alarm:1;
125         u16                     nvram_offset;
126         u16                     nvram_size;
127         u16                     trickle_charger_reg;
128         u8                      trickle_charger_setup;
129         u8                      (*do_trickle_setup)(struct i2c_client *, uint32_t, bool);
130 };
131 
132 static u8 do_trickle_setup_ds1339(struct i2c_client *,
133                                   uint32_t ohms, bool diode);
134 
135 static struct chip_desc chips[last_ds_type] = {
136         [ds_1307] = {
137                 .nvram_offset   = 8,
138                 .nvram_size     = 56,
139         },
140         [ds_1337] = {
141                 .alarm          = 1,
142         },
143         [ds_1338] = {
144                 .nvram_offset   = 8,
145                 .nvram_size     = 56,
146         },
147         [ds_1339] = {
148                 .alarm          = 1,
149                 .trickle_charger_reg = 0x10,
150                 .do_trickle_setup = &do_trickle_setup_ds1339,
151         },
152         [ds_1340] = {
153                 .trickle_charger_reg = 0x08,
154         },
155         [ds_1388] = {
156                 .trickle_charger_reg = 0x0a,
157         },
158         [ds_3231] = {
159                 .alarm          = 1,
160         },
161         [mcp794xx] = {
162                 .alarm          = 1,
163                 /* this is battery backed SRAM */
164                 .nvram_offset   = 0x20,
165                 .nvram_size     = 0x40,
166         },
167 };
168 
169 static const struct i2c_device_id ds1307_id[] = {
170         { "ds1307", ds_1307 },
171         { "ds1337", ds_1337 },
172         { "ds1338", ds_1338 },
173         { "ds1339", ds_1339 },
174         { "ds1388", ds_1388 },
175         { "ds1340", ds_1340 },
176         { "ds3231", ds_3231 },
177         { "m41t00", m41t00 },
178         { "mcp7940x", mcp794xx },
179         { "mcp7941x", mcp794xx },
180         { "pt7c4338", ds_1307 },
181         { "rx8025", rx_8025 },
182         { }
183 };
184 MODULE_DEVICE_TABLE(i2c, ds1307_id);
185 
186 /*----------------------------------------------------------------------*/
187 
188 #define BLOCK_DATA_MAX_TRIES 10
189 
190 static s32 ds1307_read_block_data_once(const struct i2c_client *client,
191                                        u8 command, u8 length, u8 *values)
192 {
193         s32 i, data;
194 
195         for (i = 0; i < length; i++) {
196                 data = i2c_smbus_read_byte_data(client, command + i);
197                 if (data < 0)
198                         return data;
199                 values[i] = data;
200         }
201         return i;
202 }
203 
204 static s32 ds1307_read_block_data(const struct i2c_client *client, u8 command,
205                                   u8 length, u8 *values)
206 {
207         u8 oldvalues[255];
208         s32 ret;
209         int tries = 0;
210 
211         dev_dbg(&client->dev, "ds1307_read_block_data (length=%d)\n", length);
212         ret = ds1307_read_block_data_once(client, command, length, values);
213         if (ret < 0)
214                 return ret;
215         do {
216                 if (++tries > BLOCK_DATA_MAX_TRIES) {
217                         dev_err(&client->dev,
218                                 "ds1307_read_block_data failed\n");
219                         return -EIO;
220                 }
221                 memcpy(oldvalues, values, length);
222                 ret = ds1307_read_block_data_once(client, command, length,
223                                                   values);
224                 if (ret < 0)
225                         return ret;
226         } while (memcmp(oldvalues, values, length));
227         return length;
228 }
229 
230 static s32 ds1307_write_block_data(const struct i2c_client *client, u8 command,
231                                    u8 length, const u8 *values)
232 {
233         u8 currvalues[255];
234         int tries = 0;
235 
236         dev_dbg(&client->dev, "ds1307_write_block_data (length=%d)\n", length);
237         do {
238                 s32 i, ret;
239 
240                 if (++tries > BLOCK_DATA_MAX_TRIES) {
241                         dev_err(&client->dev,
242                                 "ds1307_write_block_data failed\n");
243                         return -EIO;
244                 }
245                 for (i = 0; i < length; i++) {
246                         ret = i2c_smbus_write_byte_data(client, command + i,
247                                                         values[i]);
248                         if (ret < 0)
249                                 return ret;
250                 }
251                 ret = ds1307_read_block_data_once(client, command, length,
252                                                   currvalues);
253                 if (ret < 0)
254                         return ret;
255         } while (memcmp(currvalues, values, length));
256         return length;
257 }
258 
259 /*----------------------------------------------------------------------*/
260 
261 /* These RTC devices are not designed to be connected to a SMbus adapter.
262    SMbus limits block operations length to 32 bytes, whereas it's not
263    limited on I2C buses. As a result, accesses may exceed 32 bytes;
264    in that case, split them into smaller blocks */
265 
266 static s32 ds1307_native_smbus_write_block_data(const struct i2c_client *client,
267                                 u8 command, u8 length, const u8 *values)
268 {
269         u8 suboffset = 0;
270 
271         if (length <= I2C_SMBUS_BLOCK_MAX)
272                 return i2c_smbus_write_i2c_block_data(client,
273                                         command, length, values);
274 
275         while (suboffset < length) {
276                 s32 retval = i2c_smbus_write_i2c_block_data(client,
277                                 command + suboffset,
278                                 min(I2C_SMBUS_BLOCK_MAX, length - suboffset),
279                                 values + suboffset);
280                 if (retval < 0)
281                         return retval;
282 
283                 suboffset += I2C_SMBUS_BLOCK_MAX;
284         }
285         return length;
286 }
287 
288 static s32 ds1307_native_smbus_read_block_data(const struct i2c_client *client,
289                                 u8 command, u8 length, u8 *values)
290 {
291         u8 suboffset = 0;
292 
293         if (length <= I2C_SMBUS_BLOCK_MAX)
294                 return i2c_smbus_read_i2c_block_data(client,
295                                         command, length, values);
296 
297         while (suboffset < length) {
298                 s32 retval = i2c_smbus_read_i2c_block_data(client,
299                                 command + suboffset,
300                                 min(I2C_SMBUS_BLOCK_MAX, length - suboffset),
301                                 values + suboffset);
302                 if (retval < 0)
303                         return retval;
304 
305                 suboffset += I2C_SMBUS_BLOCK_MAX;
306         }
307         return length;
308 }
309 
310 /*----------------------------------------------------------------------*/
311 
312 /*
313  * The ds1337 and ds1339 both have two alarms, but we only use the first
314  * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
315  * signal; ds1339 chips have only one alarm signal.
316  */
317 static irqreturn_t ds1307_irq(int irq, void *dev_id)
318 {
319         struct i2c_client       *client = dev_id;
320         struct ds1307           *ds1307 = i2c_get_clientdata(client);
321         struct mutex            *lock = &ds1307->rtc->ops_lock;
322         int                     stat, control;
323 
324         mutex_lock(lock);
325         stat = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
326         if (stat < 0)
327                 goto out;
328 
329         if (stat & DS1337_BIT_A1I) {
330                 stat &= ~DS1337_BIT_A1I;
331                 i2c_smbus_write_byte_data(client, DS1337_REG_STATUS, stat);
332 
333                 control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
334                 if (control < 0)
335                         goto out;
336 
337                 control &= ~DS1337_BIT_A1IE;
338                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, control);
339 
340                 rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
341         }
342 
343 out:
344         mutex_unlock(lock);
345 
346         return IRQ_HANDLED;
347 }
348 
349 /*----------------------------------------------------------------------*/
350 
351 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
352 {
353         struct ds1307   *ds1307 = dev_get_drvdata(dev);
354         int             tmp;
355 
356         /* read the RTC date and time registers all at once */
357         tmp = ds1307->read_block_data(ds1307->client,
358                 ds1307->offset, 7, ds1307->regs);
359         if (tmp != 7) {
360                 dev_err(dev, "%s error %d\n", "read", tmp);
361                 return -EIO;
362         }
363 
364         dev_dbg(dev, "%s: %7ph\n", "read", ds1307->regs);
365 
366         t->tm_sec = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f);
367         t->tm_min = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f);
368         tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
369         t->tm_hour = bcd2bin(tmp);
370         t->tm_wday = bcd2bin(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
371         t->tm_mday = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
372         tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
373         t->tm_mon = bcd2bin(tmp) - 1;
374 
375         /* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
376         t->tm_year = bcd2bin(ds1307->regs[DS1307_REG_YEAR]) + 100;
377 
378         dev_dbg(dev, "%s secs=%d, mins=%d, "
379                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
380                 "read", t->tm_sec, t->tm_min,
381                 t->tm_hour, t->tm_mday,
382                 t->tm_mon, t->tm_year, t->tm_wday);
383 
384         /* initial clock setting can be undefined */
385         return rtc_valid_tm(t);
386 }
387 
388 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
389 {
390         struct ds1307   *ds1307 = dev_get_drvdata(dev);
391         int             result;
392         int             tmp;
393         u8              *buf = ds1307->regs;
394 
395         dev_dbg(dev, "%s secs=%d, mins=%d, "
396                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
397                 "write", t->tm_sec, t->tm_min,
398                 t->tm_hour, t->tm_mday,
399                 t->tm_mon, t->tm_year, t->tm_wday);
400 
401         buf[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
402         buf[DS1307_REG_MIN] = bin2bcd(t->tm_min);
403         buf[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
404         buf[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
405         buf[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
406         buf[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
407 
408         /* assume 20YY not 19YY */
409         tmp = t->tm_year - 100;
410         buf[DS1307_REG_YEAR] = bin2bcd(tmp);
411 
412         switch (ds1307->type) {
413         case ds_1337:
414         case ds_1339:
415         case ds_3231:
416                 buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
417                 break;
418         case ds_1340:
419                 buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
420                                 | DS1340_BIT_CENTURY;
421                 break;
422         case mcp794xx:
423                 /*
424                  * these bits were cleared when preparing the date/time
425                  * values and need to be set again before writing the
426                  * buffer out to the device.
427                  */
428                 buf[DS1307_REG_SECS] |= MCP794XX_BIT_ST;
429                 buf[DS1307_REG_WDAY] |= MCP794XX_BIT_VBATEN;
430                 break;
431         default:
432                 break;
433         }
434 
435         dev_dbg(dev, "%s: %7ph\n", "write", buf);
436 
437         result = ds1307->write_block_data(ds1307->client,
438                 ds1307->offset, 7, buf);
439         if (result < 0) {
440                 dev_err(dev, "%s error %d\n", "write", result);
441                 return result;
442         }
443         return 0;
444 }
445 
446 static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
447 {
448         struct i2c_client       *client = to_i2c_client(dev);
449         struct ds1307           *ds1307 = i2c_get_clientdata(client);
450         int                     ret;
451 
452         if (!test_bit(HAS_ALARM, &ds1307->flags))
453                 return -EINVAL;
454 
455         /* read all ALARM1, ALARM2, and status registers at once */
456         ret = ds1307->read_block_data(client,
457                         DS1339_REG_ALARM1_SECS, 9, ds1307->regs);
458         if (ret != 9) {
459                 dev_err(dev, "%s error %d\n", "alarm read", ret);
460                 return -EIO;
461         }
462 
463         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
464                         "alarm read",
465                         ds1307->regs[0], ds1307->regs[1],
466                         ds1307->regs[2], ds1307->regs[3],
467                         ds1307->regs[4], ds1307->regs[5],
468                         ds1307->regs[6], ds1307->regs[7],
469                         ds1307->regs[8]);
470 
471         /*
472          * report alarm time (ALARM1); assume 24 hour and day-of-month modes,
473          * and that all four fields are checked matches
474          */
475         t->time.tm_sec = bcd2bin(ds1307->regs[0] & 0x7f);
476         t->time.tm_min = bcd2bin(ds1307->regs[1] & 0x7f);
477         t->time.tm_hour = bcd2bin(ds1307->regs[2] & 0x3f);
478         t->time.tm_mday = bcd2bin(ds1307->regs[3] & 0x3f);
479         t->time.tm_mon = -1;
480         t->time.tm_year = -1;
481         t->time.tm_wday = -1;
482         t->time.tm_yday = -1;
483         t->time.tm_isdst = -1;
484 
485         /* ... and status */
486         t->enabled = !!(ds1307->regs[7] & DS1337_BIT_A1IE);
487         t->pending = !!(ds1307->regs[8] & DS1337_BIT_A1I);
488 
489         dev_dbg(dev, "%s secs=%d, mins=%d, "
490                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
491                 "alarm read", t->time.tm_sec, t->time.tm_min,
492                 t->time.tm_hour, t->time.tm_mday,
493                 t->enabled, t->pending);
494 
495         return 0;
496 }
497 
498 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
499 {
500         struct i2c_client       *client = to_i2c_client(dev);
501         struct ds1307           *ds1307 = i2c_get_clientdata(client);
502         unsigned char           *buf = ds1307->regs;
503         u8                      control, status;
504         int                     ret;
505 
506         if (!test_bit(HAS_ALARM, &ds1307->flags))
507                 return -EINVAL;
508 
509         dev_dbg(dev, "%s secs=%d, mins=%d, "
510                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
511                 "alarm set", t->time.tm_sec, t->time.tm_min,
512                 t->time.tm_hour, t->time.tm_mday,
513                 t->enabled, t->pending);
514 
515         /* read current status of both alarms and the chip */
516         ret = ds1307->read_block_data(client,
517                         DS1339_REG_ALARM1_SECS, 9, buf);
518         if (ret != 9) {
519                 dev_err(dev, "%s error %d\n", "alarm write", ret);
520                 return -EIO;
521         }
522         control = ds1307->regs[7];
523         status = ds1307->regs[8];
524 
525         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
526                         "alarm set (old status)",
527                         ds1307->regs[0], ds1307->regs[1],
528                         ds1307->regs[2], ds1307->regs[3],
529                         ds1307->regs[4], ds1307->regs[5],
530                         ds1307->regs[6], control, status);
531 
532         /* set ALARM1, using 24 hour and day-of-month modes */
533         buf[0] = bin2bcd(t->time.tm_sec);
534         buf[1] = bin2bcd(t->time.tm_min);
535         buf[2] = bin2bcd(t->time.tm_hour);
536         buf[3] = bin2bcd(t->time.tm_mday);
537 
538         /* set ALARM2 to non-garbage */
539         buf[4] = 0;
540         buf[5] = 0;
541         buf[6] = 0;
542 
543         /* optionally enable ALARM1 */
544         buf[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
545         if (t->enabled) {
546                 dev_dbg(dev, "alarm IRQ armed\n");
547                 buf[7] |= DS1337_BIT_A1IE;      /* only ALARM1 is used */
548         }
549         buf[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
550 
551         ret = ds1307->write_block_data(client,
552                         DS1339_REG_ALARM1_SECS, 9, buf);
553         if (ret < 0) {
554                 dev_err(dev, "can't set alarm time\n");
555                 return ret;
556         }
557 
558         return 0;
559 }
560 
561 static int ds1307_alarm_irq_enable(struct device *dev, unsigned int enabled)
562 {
563         struct i2c_client       *client = to_i2c_client(dev);
564         struct ds1307           *ds1307 = i2c_get_clientdata(client);
565         int                     ret;
566 
567         if (!test_bit(HAS_ALARM, &ds1307->flags))
568                 return -ENOTTY;
569 
570         ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
571         if (ret < 0)
572                 return ret;
573 
574         if (enabled)
575                 ret |= DS1337_BIT_A1IE;
576         else
577                 ret &= ~DS1337_BIT_A1IE;
578 
579         ret = i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, ret);
580         if (ret < 0)
581                 return ret;
582 
583         return 0;
584 }
585 
586 static const struct rtc_class_ops ds13xx_rtc_ops = {
587         .read_time      = ds1307_get_time,
588         .set_time       = ds1307_set_time,
589         .read_alarm     = ds1337_read_alarm,
590         .set_alarm      = ds1337_set_alarm,
591         .alarm_irq_enable = ds1307_alarm_irq_enable,
592 };
593 
594 /*----------------------------------------------------------------------*/
595 
596 /*
597  * Alarm support for mcp794xx devices.
598  */
599 
600 #define MCP794XX_REG_CONTROL            0x07
601 #       define MCP794XX_BIT_ALM0_EN     0x10
602 #       define MCP794XX_BIT_ALM1_EN     0x20
603 #define MCP794XX_REG_ALARM0_BASE        0x0a
604 #define MCP794XX_REG_ALARM0_CTRL        0x0d
605 #define MCP794XX_REG_ALARM1_BASE        0x11
606 #define MCP794XX_REG_ALARM1_CTRL        0x14
607 #       define MCP794XX_BIT_ALMX_IF     (1 << 3)
608 #       define MCP794XX_BIT_ALMX_C0     (1 << 4)
609 #       define MCP794XX_BIT_ALMX_C1     (1 << 5)
610 #       define MCP794XX_BIT_ALMX_C2     (1 << 6)
611 #       define MCP794XX_BIT_ALMX_POL    (1 << 7)
612 #       define MCP794XX_MSK_ALMX_MATCH  (MCP794XX_BIT_ALMX_C0 | \
613                                          MCP794XX_BIT_ALMX_C1 | \
614                                          MCP794XX_BIT_ALMX_C2)
615 
616 static irqreturn_t mcp794xx_irq(int irq, void *dev_id)
617 {
618         struct i2c_client       *client = dev_id;
619         struct ds1307           *ds1307 = i2c_get_clientdata(client);
620         struct mutex            *lock = &ds1307->rtc->ops_lock;
621         int reg, ret;
622 
623         mutex_lock(lock);
624 
625         /* Check and clear alarm 0 interrupt flag. */
626         reg = i2c_smbus_read_byte_data(client, MCP794XX_REG_ALARM0_CTRL);
627         if (reg < 0)
628                 goto out;
629         if (!(reg & MCP794XX_BIT_ALMX_IF))
630                 goto out;
631         reg &= ~MCP794XX_BIT_ALMX_IF;
632         ret = i2c_smbus_write_byte_data(client, MCP794XX_REG_ALARM0_CTRL, reg);
633         if (ret < 0)
634                 goto out;
635 
636         /* Disable alarm 0. */
637         reg = i2c_smbus_read_byte_data(client, MCP794XX_REG_CONTROL);
638         if (reg < 0)
639                 goto out;
640         reg &= ~MCP794XX_BIT_ALM0_EN;
641         ret = i2c_smbus_write_byte_data(client, MCP794XX_REG_CONTROL, reg);
642         if (ret < 0)
643                 goto out;
644 
645         rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
646 
647 out:
648         mutex_unlock(lock);
649 
650         return IRQ_HANDLED;
651 }
652 
653 static int mcp794xx_read_alarm(struct device *dev, struct rtc_wkalrm *t)
654 {
655         struct i2c_client *client = to_i2c_client(dev);
656         struct ds1307 *ds1307 = i2c_get_clientdata(client);
657         u8 *regs = ds1307->regs;
658         int ret;
659 
660         if (!test_bit(HAS_ALARM, &ds1307->flags))
661                 return -EINVAL;
662 
663         /* Read control and alarm 0 registers. */
664         ret = ds1307->read_block_data(client, MCP794XX_REG_CONTROL, 10, regs);
665         if (ret < 0)
666                 return ret;
667 
668         t->enabled = !!(regs[0] & MCP794XX_BIT_ALM0_EN);
669 
670         /* Report alarm 0 time assuming 24-hour and day-of-month modes. */
671         t->time.tm_sec = bcd2bin(ds1307->regs[3] & 0x7f);
672         t->time.tm_min = bcd2bin(ds1307->regs[4] & 0x7f);
673         t->time.tm_hour = bcd2bin(ds1307->regs[5] & 0x3f);
674         t->time.tm_wday = bcd2bin(ds1307->regs[6] & 0x7) - 1;
675         t->time.tm_mday = bcd2bin(ds1307->regs[7] & 0x3f);
676         t->time.tm_mon = bcd2bin(ds1307->regs[8] & 0x1f) - 1;
677         t->time.tm_year = -1;
678         t->time.tm_yday = -1;
679         t->time.tm_isdst = -1;
680 
681         dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
682                 "enabled=%d polarity=%d irq=%d match=%d\n", __func__,
683                 t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
684                 t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled,
685                 !!(ds1307->regs[6] & MCP794XX_BIT_ALMX_POL),
686                 !!(ds1307->regs[6] & MCP794XX_BIT_ALMX_IF),
687                 (ds1307->regs[6] & MCP794XX_MSK_ALMX_MATCH) >> 4);
688 
689         return 0;
690 }
691 
692 static int mcp794xx_set_alarm(struct device *dev, struct rtc_wkalrm *t)
693 {
694         struct i2c_client *client = to_i2c_client(dev);
695         struct ds1307 *ds1307 = i2c_get_clientdata(client);
696         unsigned char *regs = ds1307->regs;
697         int ret;
698 
699         if (!test_bit(HAS_ALARM, &ds1307->flags))
700                 return -EINVAL;
701 
702         dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
703                 "enabled=%d pending=%d\n", __func__,
704                 t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
705                 t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
706                 t->enabled, t->pending);
707 
708         /* Read control and alarm 0 registers. */
709         ret = ds1307->read_block_data(client, MCP794XX_REG_CONTROL, 10, regs);
710         if (ret < 0)
711                 return ret;
712 
713         /* Set alarm 0, using 24-hour and day-of-month modes. */
714         regs[3] = bin2bcd(t->time.tm_sec);
715         regs[4] = bin2bcd(t->time.tm_min);
716         regs[5] = bin2bcd(t->time.tm_hour);
717         regs[6] = bin2bcd(t->time.tm_wday + 1);
718         regs[7] = bin2bcd(t->time.tm_mday);
719         regs[8] = bin2bcd(t->time.tm_mon + 1);
720 
721         /* Clear the alarm 0 interrupt flag. */
722         regs[6] &= ~MCP794XX_BIT_ALMX_IF;
723         /* Set alarm match: second, minute, hour, day, date, month. */
724         regs[6] |= MCP794XX_MSK_ALMX_MATCH;
725         /* Disable interrupt. We will not enable until completely programmed */
726         regs[0] &= ~MCP794XX_BIT_ALM0_EN;
727 
728         ret = ds1307->write_block_data(client, MCP794XX_REG_CONTROL, 10, regs);
729         if (ret < 0)
730                 return ret;
731 
732         if (!t->enabled)
733                 return 0;
734         regs[0] |= MCP794XX_BIT_ALM0_EN;
735         return i2c_smbus_write_byte_data(client, MCP794XX_REG_CONTROL, regs[0]);
736 }
737 
738 static int mcp794xx_alarm_irq_enable(struct device *dev, unsigned int enabled)
739 {
740         struct i2c_client *client = to_i2c_client(dev);
741         struct ds1307 *ds1307 = i2c_get_clientdata(client);
742         int reg;
743 
744         if (!test_bit(HAS_ALARM, &ds1307->flags))
745                 return -EINVAL;
746 
747         reg = i2c_smbus_read_byte_data(client, MCP794XX_REG_CONTROL);
748         if (reg < 0)
749                 return reg;
750 
751         if (enabled)
752                 reg |= MCP794XX_BIT_ALM0_EN;
753         else
754                 reg &= ~MCP794XX_BIT_ALM0_EN;
755 
756         return i2c_smbus_write_byte_data(client, MCP794XX_REG_CONTROL, reg);
757 }
758 
759 static const struct rtc_class_ops mcp794xx_rtc_ops = {
760         .read_time      = ds1307_get_time,
761         .set_time       = ds1307_set_time,
762         .read_alarm     = mcp794xx_read_alarm,
763         .set_alarm      = mcp794xx_set_alarm,
764         .alarm_irq_enable = mcp794xx_alarm_irq_enable,
765 };
766 
767 /*----------------------------------------------------------------------*/
768 
769 static ssize_t
770 ds1307_nvram_read(struct file *filp, struct kobject *kobj,
771                 struct bin_attribute *attr,
772                 char *buf, loff_t off, size_t count)
773 {
774         struct i2c_client       *client;
775         struct ds1307           *ds1307;
776         int                     result;
777 
778         client = kobj_to_i2c_client(kobj);
779         ds1307 = i2c_get_clientdata(client);
780 
781         result = ds1307->read_block_data(client, ds1307->nvram_offset + off,
782                                                                 count, buf);
783         if (result < 0)
784                 dev_err(&client->dev, "%s error %d\n", "nvram read", result);
785         return result;
786 }
787 
788 static ssize_t
789 ds1307_nvram_write(struct file *filp, struct kobject *kobj,
790                 struct bin_attribute *attr,
791                 char *buf, loff_t off, size_t count)
792 {
793         struct i2c_client       *client;
794         struct ds1307           *ds1307;
795         int                     result;
796 
797         client = kobj_to_i2c_client(kobj);
798         ds1307 = i2c_get_clientdata(client);
799 
800         result = ds1307->write_block_data(client, ds1307->nvram_offset + off,
801                                                                 count, buf);
802         if (result < 0) {
803                 dev_err(&client->dev, "%s error %d\n", "nvram write", result);
804                 return result;
805         }
806         return count;
807 }
808 
809 
810 /*----------------------------------------------------------------------*/
811 
812 static u8 do_trickle_setup_ds1339(struct i2c_client *client,
813                                   uint32_t ohms, bool diode)
814 {
815         u8 setup = (diode) ? DS1307_TRICKLE_CHARGER_DIODE :
816                 DS1307_TRICKLE_CHARGER_NO_DIODE;
817 
818         switch (ohms) {
819         case 250:
820                 setup |= DS1307_TRICKLE_CHARGER_250_OHM;
821                 break;
822         case 2000:
823                 setup |= DS1307_TRICKLE_CHARGER_2K_OHM;
824                 break;
825         case 4000:
826                 setup |= DS1307_TRICKLE_CHARGER_4K_OHM;
827                 break;
828         default:
829                 dev_warn(&client->dev,
830                          "Unsupported ohm value %u in dt\n", ohms);
831                 return 0;
832         }
833         return setup;
834 }
835 
836 static void ds1307_trickle_of_init(struct i2c_client *client,
837                                    struct chip_desc *chip)
838 {
839         uint32_t ohms = 0;
840         bool diode = true;
841 
842         if (!chip->do_trickle_setup)
843                 goto out;
844         if (of_property_read_u32(client->dev.of_node, "trickle-resistor-ohms" , &ohms))
845                 goto out;
846         if (of_property_read_bool(client->dev.of_node, "trickle-diode-disable"))
847                 diode = false;
848         chip->trickle_charger_setup = chip->do_trickle_setup(client,
849                                                              ohms, diode);
850 out:
851         return;
852 }
853 
854 static int ds1307_probe(struct i2c_client *client,
855                         const struct i2c_device_id *id)
856 {
857         struct ds1307           *ds1307;
858         int                     err = -ENODEV;
859         int                     tmp;
860         struct chip_desc        *chip = &chips[id->driver_data];
861         struct i2c_adapter      *adapter = to_i2c_adapter(client->dev.parent);
862         bool                    want_irq = false;
863         unsigned char           *buf;
864         struct ds1307_platform_data *pdata = dev_get_platdata(&client->dev);
865         irq_handler_t   irq_handler = ds1307_irq;
866 
867         static const int        bbsqi_bitpos[] = {
868                 [ds_1337] = 0,
869                 [ds_1339] = DS1339_BIT_BBSQI,
870                 [ds_3231] = DS3231_BIT_BBSQW,
871         };
872         const struct rtc_class_ops *rtc_ops = &ds13xx_rtc_ops;
873 
874         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)
875             && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
876                 return -EIO;
877 
878         ds1307 = devm_kzalloc(&client->dev, sizeof(struct ds1307), GFP_KERNEL);
879         if (!ds1307)
880                 return -ENOMEM;
881 
882         i2c_set_clientdata(client, ds1307);
883 
884         ds1307->client  = client;
885         ds1307->type    = id->driver_data;
886 
887         if (!pdata && client->dev.of_node)
888                 ds1307_trickle_of_init(client, chip);
889         else if (pdata && pdata->trickle_charger_setup)
890                 chip->trickle_charger_setup = pdata->trickle_charger_setup;
891 
892         if (chip->trickle_charger_setup && chip->trickle_charger_reg) {
893                 dev_dbg(&client->dev, "writing trickle charger info 0x%x to 0x%x\n",
894                     DS13XX_TRICKLE_CHARGER_MAGIC | chip->trickle_charger_setup,
895                     chip->trickle_charger_reg);
896                 i2c_smbus_write_byte_data(client, chip->trickle_charger_reg,
897                     DS13XX_TRICKLE_CHARGER_MAGIC |
898                     chip->trickle_charger_setup);
899         }
900 
901         buf = ds1307->regs;
902         if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
903                 ds1307->read_block_data = ds1307_native_smbus_read_block_data;
904                 ds1307->write_block_data = ds1307_native_smbus_write_block_data;
905         } else {
906                 ds1307->read_block_data = ds1307_read_block_data;
907                 ds1307->write_block_data = ds1307_write_block_data;
908         }
909 
910         switch (ds1307->type) {
911         case ds_1337:
912         case ds_1339:
913         case ds_3231:
914                 /* get registers that the "rtc" read below won't read... */
915                 tmp = ds1307->read_block_data(ds1307->client,
916                                 DS1337_REG_CONTROL, 2, buf);
917                 if (tmp != 2) {
918                         dev_dbg(&client->dev, "read error %d\n", tmp);
919                         err = -EIO;
920                         goto exit;
921                 }
922 
923                 /* oscillator off?  turn it on, so clock can tick. */
924                 if (ds1307->regs[0] & DS1337_BIT_nEOSC)
925                         ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
926 
927                 /*
928                  * Using IRQ?  Disable the square wave and both alarms.
929                  * For some variants, be sure alarms can trigger when we're
930                  * running on Vbackup (BBSQI/BBSQW)
931                  */
932                 if (ds1307->client->irq > 0 && chip->alarm) {
933                         ds1307->regs[0] |= DS1337_BIT_INTCN
934                                         | bbsqi_bitpos[ds1307->type];
935                         ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
936 
937                         want_irq = true;
938                 }
939 
940                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
941                                                         ds1307->regs[0]);
942 
943                 /* oscillator fault?  clear flag, and warn */
944                 if (ds1307->regs[1] & DS1337_BIT_OSF) {
945                         i2c_smbus_write_byte_data(client, DS1337_REG_STATUS,
946                                 ds1307->regs[1] & ~DS1337_BIT_OSF);
947                         dev_warn(&client->dev, "SET TIME!\n");
948                 }
949                 break;
950 
951         case rx_8025:
952                 tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
953                                 RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
954                 if (tmp != 2) {
955                         dev_dbg(&client->dev, "read error %d\n", tmp);
956                         err = -EIO;
957                         goto exit;
958                 }
959 
960                 /* oscillator off?  turn it on, so clock can tick. */
961                 if (!(ds1307->regs[1] & RX8025_BIT_XST)) {
962                         ds1307->regs[1] |= RX8025_BIT_XST;
963                         i2c_smbus_write_byte_data(client,
964                                                   RX8025_REG_CTRL2 << 4 | 0x08,
965                                                   ds1307->regs[1]);
966                         dev_warn(&client->dev,
967                                  "oscillator stop detected - SET TIME!\n");
968                 }
969 
970                 if (ds1307->regs[1] & RX8025_BIT_PON) {
971                         ds1307->regs[1] &= ~RX8025_BIT_PON;
972                         i2c_smbus_write_byte_data(client,
973                                                   RX8025_REG_CTRL2 << 4 | 0x08,
974                                                   ds1307->regs[1]);
975                         dev_warn(&client->dev, "power-on detected\n");
976                 }
977 
978                 if (ds1307->regs[1] & RX8025_BIT_VDET) {
979                         ds1307->regs[1] &= ~RX8025_BIT_VDET;
980                         i2c_smbus_write_byte_data(client,
981                                                   RX8025_REG_CTRL2 << 4 | 0x08,
982                                                   ds1307->regs[1]);
983                         dev_warn(&client->dev, "voltage drop detected\n");
984                 }
985 
986                 /* make sure we are running in 24hour mode */
987                 if (!(ds1307->regs[0] & RX8025_BIT_2412)) {
988                         u8 hour;
989 
990                         /* switch to 24 hour mode */
991                         i2c_smbus_write_byte_data(client,
992                                                   RX8025_REG_CTRL1 << 4 | 0x08,
993                                                   ds1307->regs[0] |
994                                                   RX8025_BIT_2412);
995 
996                         tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
997                                         RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
998                         if (tmp != 2) {
999                                 dev_dbg(&client->dev, "read error %d\n", tmp);
1000                                 err = -EIO;
1001                                 goto exit;
1002                         }
1003 
1004                         /* correct hour */
1005                         hour = bcd2bin(ds1307->regs[DS1307_REG_HOUR]);
1006                         if (hour == 12)
1007                                 hour = 0;
1008                         if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1009                                 hour += 12;
1010 
1011                         i2c_smbus_write_byte_data(client,
1012                                                   DS1307_REG_HOUR << 4 | 0x08,
1013                                                   hour);
1014                 }
1015                 break;
1016         case ds_1388:
1017                 ds1307->offset = 1; /* Seconds starts at 1 */
1018                 break;
1019         case mcp794xx:
1020                 rtc_ops = &mcp794xx_rtc_ops;
1021                 if (ds1307->client->irq > 0 && chip->alarm) {
1022                         irq_handler = mcp794xx_irq;
1023                         want_irq = true;
1024                 }
1025                 break;
1026         default:
1027                 break;
1028         }
1029 
1030 read_rtc:
1031         /* read RTC registers */
1032         tmp = ds1307->read_block_data(ds1307->client, ds1307->offset, 8, buf);
1033         if (tmp != 8) {
1034                 dev_dbg(&client->dev, "read error %d\n", tmp);
1035                 err = -EIO;
1036                 goto exit;
1037         }
1038 
1039         /*
1040          * minimal sanity checking; some chips (like DS1340) don't
1041          * specify the extra bits as must-be-zero, but there are
1042          * still a few values that are clearly out-of-range.
1043          */
1044         tmp = ds1307->regs[DS1307_REG_SECS];
1045         switch (ds1307->type) {
1046         case ds_1307:
1047         case m41t00:
1048                 /* clock halted?  turn it on, so clock can tick. */
1049                 if (tmp & DS1307_BIT_CH) {
1050                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
1051                         dev_warn(&client->dev, "SET TIME!\n");
1052                         goto read_rtc;
1053                 }
1054                 break;
1055         case ds_1338:
1056                 /* clock halted?  turn it on, so clock can tick. */
1057                 if (tmp & DS1307_BIT_CH)
1058                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
1059 
1060                 /* oscillator fault?  clear flag, and warn */
1061                 if (ds1307->regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
1062                         i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL,
1063                                         ds1307->regs[DS1307_REG_CONTROL]
1064                                         & ~DS1338_BIT_OSF);
1065                         dev_warn(&client->dev, "SET TIME!\n");
1066                         goto read_rtc;
1067                 }
1068                 break;
1069         case ds_1340:
1070                 /* clock halted?  turn it on, so clock can tick. */
1071                 if (tmp & DS1340_BIT_nEOSC)
1072                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
1073 
1074                 tmp = i2c_smbus_read_byte_data(client, DS1340_REG_FLAG);
1075                 if (tmp < 0) {
1076                         dev_dbg(&client->dev, "read error %d\n", tmp);
1077                         err = -EIO;
1078                         goto exit;
1079                 }
1080 
1081                 /* oscillator fault?  clear flag, and warn */
1082                 if (tmp & DS1340_BIT_OSF) {
1083                         i2c_smbus_write_byte_data(client, DS1340_REG_FLAG, 0);
1084                         dev_warn(&client->dev, "SET TIME!\n");
1085                 }
1086                 break;
1087         case mcp794xx:
1088                 /* make sure that the backup battery is enabled */
1089                 if (!(ds1307->regs[DS1307_REG_WDAY] & MCP794XX_BIT_VBATEN)) {
1090                         i2c_smbus_write_byte_data(client, DS1307_REG_WDAY,
1091                                         ds1307->regs[DS1307_REG_WDAY]
1092                                         | MCP794XX_BIT_VBATEN);
1093                 }
1094 
1095                 /* clock halted?  turn it on, so clock can tick. */
1096                 if (!(tmp & MCP794XX_BIT_ST)) {
1097                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS,
1098                                         MCP794XX_BIT_ST);
1099                         dev_warn(&client->dev, "SET TIME!\n");
1100                         goto read_rtc;
1101                 }
1102 
1103                 break;
1104         default:
1105                 break;
1106         }
1107 
1108         tmp = ds1307->regs[DS1307_REG_HOUR];
1109         switch (ds1307->type) {
1110         case ds_1340:
1111         case m41t00:
1112                 /*
1113                  * NOTE: ignores century bits; fix before deploying
1114                  * systems that will run through year 2100.
1115                  */
1116                 break;
1117         case rx_8025:
1118                 break;
1119         default:
1120                 if (!(tmp & DS1307_BIT_12HR))
1121                         break;
1122 
1123                 /*
1124                  * Be sure we're in 24 hour mode.  Multi-master systems
1125                  * take note...
1126                  */
1127                 tmp = bcd2bin(tmp & 0x1f);
1128                 if (tmp == 12)
1129                         tmp = 0;
1130                 if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1131                         tmp += 12;
1132                 i2c_smbus_write_byte_data(client,
1133                                 ds1307->offset + DS1307_REG_HOUR,
1134                                 bin2bcd(tmp));
1135         }
1136 
1137         if (want_irq) {
1138                 device_set_wakeup_capable(&client->dev, true);
1139                 set_bit(HAS_ALARM, &ds1307->flags);
1140         }
1141         ds1307->rtc = devm_rtc_device_register(&client->dev, client->name,
1142                                 rtc_ops, THIS_MODULE);
1143         if (IS_ERR(ds1307->rtc)) {
1144                 return PTR_ERR(ds1307->rtc);
1145         }
1146 
1147         if (want_irq) {
1148                 err = devm_request_threaded_irq(&client->dev,
1149                                                 client->irq, NULL, irq_handler,
1150                                                 IRQF_SHARED | IRQF_ONESHOT,
1151                                                 ds1307->rtc->name, client);
1152                 if (err) {
1153                         client->irq = 0;
1154                         device_set_wakeup_capable(&client->dev, false);
1155                         clear_bit(HAS_ALARM, &ds1307->flags);
1156                         dev_err(&client->dev, "unable to request IRQ!\n");
1157                 } else
1158                         dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
1159         }
1160 
1161         if (chip->nvram_size) {
1162 
1163                 ds1307->nvram = devm_kzalloc(&client->dev,
1164                                         sizeof(struct bin_attribute),
1165                                         GFP_KERNEL);
1166                 if (!ds1307->nvram) {
1167                         dev_err(&client->dev, "cannot allocate memory for nvram sysfs\n");
1168                 } else {
1169 
1170                         ds1307->nvram->attr.name = "nvram";
1171                         ds1307->nvram->attr.mode = S_IRUGO | S_IWUSR;
1172 
1173                         sysfs_bin_attr_init(ds1307->nvram);
1174 
1175                         ds1307->nvram->read = ds1307_nvram_read;
1176                         ds1307->nvram->write = ds1307_nvram_write;
1177                         ds1307->nvram->size = chip->nvram_size;
1178                         ds1307->nvram_offset = chip->nvram_offset;
1179 
1180                         err = sysfs_create_bin_file(&client->dev.kobj,
1181                                                     ds1307->nvram);
1182                         if (err) {
1183                                 dev_err(&client->dev,
1184                                         "unable to create sysfs file: %s\n",
1185                                         ds1307->nvram->attr.name);
1186                         } else {
1187                                 set_bit(HAS_NVRAM, &ds1307->flags);
1188                                 dev_info(&client->dev, "%zu bytes nvram\n",
1189                                          ds1307->nvram->size);
1190                         }
1191                 }
1192         }
1193 
1194         return 0;
1195 
1196 exit:
1197         return err;
1198 }
1199 
1200 static int ds1307_remove(struct i2c_client *client)
1201 {
1202         struct ds1307 *ds1307 = i2c_get_clientdata(client);
1203 
1204         if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
1205                 sysfs_remove_bin_file(&client->dev.kobj, ds1307->nvram);
1206 
1207         return 0;
1208 }
1209 
1210 static struct i2c_driver ds1307_driver = {
1211         .driver = {
1212                 .name   = "rtc-ds1307",
1213         },
1214         .probe          = ds1307_probe,
1215         .remove         = ds1307_remove,
1216         .id_table       = ds1307_id,
1217 };
1218 
1219 module_i2c_driver(ds1307_driver);
1220 
1221 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
1222 MODULE_LICENSE("GPL");
1223 

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