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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/module.h>
 15 #include <linux/init.h>
 16 #include <linux/slab.h>
 17 #include <linux/i2c.h>
 18 #include <linux/string.h>
 19 #include <linux/rtc.h>
 20 #include <linux/bcd.h>
 21 #include <linux/rtc/ds1307.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         mcp7941x,
 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 MCP7941X_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 MCP7941X_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         struct work_struct      work;
118         s32 (*read_block_data)(const struct i2c_client *client, u8 command,
119                                u8 length, u8 *values);
120         s32 (*write_block_data)(const struct i2c_client *client, u8 command,
121                                 u8 length, const u8 *values);
122 };
123 
124 struct chip_desc {
125         unsigned                alarm:1;
126         u16                     nvram_offset;
127         u16                     nvram_size;
128         u16                     trickle_charger_reg;
129         u8                      trickle_charger_setup;
130         u8                      (*do_trickle_setup)(struct i2c_client *, uint32_t, bool);
131 };
132 
133 static u8 do_trickle_setup_ds1339(struct i2c_client *,
134                                   uint32_t ohms, bool diode);
135 
136 static struct chip_desc chips[last_ds_type] = {
137         [ds_1307] = {
138                 .nvram_offset   = 8,
139                 .nvram_size     = 56,
140         },
141         [ds_1337] = {
142                 .alarm          = 1,
143         },
144         [ds_1338] = {
145                 .nvram_offset   = 8,
146                 .nvram_size     = 56,
147         },
148         [ds_1339] = {
149                 .alarm          = 1,
150                 .trickle_charger_reg = 0x10,
151                 .do_trickle_setup = &do_trickle_setup_ds1339,
152         },
153         [ds_1340] = {
154                 .trickle_charger_reg = 0x08,
155         },
156         [ds_1388] = {
157                 .trickle_charger_reg = 0x0a,
158         },
159         [ds_3231] = {
160                 .alarm          = 1,
161         },
162         [mcp7941x] = {
163                 .alarm          = 1,
164                 /* this is battery backed SRAM */
165                 .nvram_offset   = 0x20,
166                 .nvram_size     = 0x40,
167         },
168 };
169 
170 static const struct i2c_device_id ds1307_id[] = {
171         { "ds1307", ds_1307 },
172         { "ds1337", ds_1337 },
173         { "ds1338", ds_1338 },
174         { "ds1339", ds_1339 },
175         { "ds1388", ds_1388 },
176         { "ds1340", ds_1340 },
177         { "ds3231", ds_3231 },
178         { "m41t00", m41t00 },
179         { "mcp7941x", mcp7941x },
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 IRQ logic includes a "real" handler running in IRQ context just
314  * long enough to schedule this workqueue entry.   We need a task context
315  * to talk to the RTC, since I2C I/O calls require that; and disable the
316  * IRQ until we clear its status on the chip, so that this handler can
317  * work with any type of triggering (not just falling edge).
318  *
319  * The ds1337 and ds1339 both have two alarms, but we only use the first
320  * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
321  * signal; ds1339 chips have only one alarm signal.
322  */
323 static void ds1307_work(struct work_struct *work)
324 {
325         struct ds1307           *ds1307;
326         struct i2c_client       *client;
327         struct mutex            *lock;
328         int                     stat, control;
329 
330         ds1307 = container_of(work, struct ds1307, work);
331         client = ds1307->client;
332         lock = &ds1307->rtc->ops_lock;
333 
334         mutex_lock(lock);
335         stat = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
336         if (stat < 0)
337                 goto out;
338 
339         if (stat & DS1337_BIT_A1I) {
340                 stat &= ~DS1337_BIT_A1I;
341                 i2c_smbus_write_byte_data(client, DS1337_REG_STATUS, stat);
342 
343                 control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
344                 if (control < 0)
345                         goto out;
346 
347                 control &= ~DS1337_BIT_A1IE;
348                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, control);
349 
350                 rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
351         }
352 
353 out:
354         if (test_bit(HAS_ALARM, &ds1307->flags))
355                 enable_irq(client->irq);
356         mutex_unlock(lock);
357 }
358 
359 static irqreturn_t ds1307_irq(int irq, void *dev_id)
360 {
361         struct i2c_client       *client = dev_id;
362         struct ds1307           *ds1307 = i2c_get_clientdata(client);
363 
364         disable_irq_nosync(irq);
365         schedule_work(&ds1307->work);
366         return IRQ_HANDLED;
367 }
368 
369 /*----------------------------------------------------------------------*/
370 
371 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
372 {
373         struct ds1307   *ds1307 = dev_get_drvdata(dev);
374         int             tmp;
375 
376         /* read the RTC date and time registers all at once */
377         tmp = ds1307->read_block_data(ds1307->client,
378                 ds1307->offset, 7, ds1307->regs);
379         if (tmp != 7) {
380                 dev_err(dev, "%s error %d\n", "read", tmp);
381                 return -EIO;
382         }
383 
384         dev_dbg(dev, "%s: %7ph\n", "read", ds1307->regs);
385 
386         t->tm_sec = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f);
387         t->tm_min = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f);
388         tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
389         t->tm_hour = bcd2bin(tmp);
390         t->tm_wday = bcd2bin(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
391         t->tm_mday = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
392         tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
393         t->tm_mon = bcd2bin(tmp) - 1;
394 
395         /* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
396         t->tm_year = bcd2bin(ds1307->regs[DS1307_REG_YEAR]) + 100;
397 
398         dev_dbg(dev, "%s secs=%d, mins=%d, "
399                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
400                 "read", t->tm_sec, t->tm_min,
401                 t->tm_hour, t->tm_mday,
402                 t->tm_mon, t->tm_year, t->tm_wday);
403 
404         /* initial clock setting can be undefined */
405         return rtc_valid_tm(t);
406 }
407 
408 static int ds1307_set_time(struct device *dev, struct rtc_time *t)
409 {
410         struct ds1307   *ds1307 = dev_get_drvdata(dev);
411         int             result;
412         int             tmp;
413         u8              *buf = ds1307->regs;
414 
415         dev_dbg(dev, "%s secs=%d, mins=%d, "
416                 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
417                 "write", t->tm_sec, t->tm_min,
418                 t->tm_hour, t->tm_mday,
419                 t->tm_mon, t->tm_year, t->tm_wday);
420 
421         buf[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
422         buf[DS1307_REG_MIN] = bin2bcd(t->tm_min);
423         buf[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
424         buf[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
425         buf[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
426         buf[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
427 
428         /* assume 20YY not 19YY */
429         tmp = t->tm_year - 100;
430         buf[DS1307_REG_YEAR] = bin2bcd(tmp);
431 
432         switch (ds1307->type) {
433         case ds_1337:
434         case ds_1339:
435         case ds_3231:
436                 buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
437                 break;
438         case ds_1340:
439                 buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
440                                 | DS1340_BIT_CENTURY;
441                 break;
442         case mcp7941x:
443                 /*
444                  * these bits were cleared when preparing the date/time
445                  * values and need to be set again before writing the
446                  * buffer out to the device.
447                  */
448                 buf[DS1307_REG_SECS] |= MCP7941X_BIT_ST;
449                 buf[DS1307_REG_WDAY] |= MCP7941X_BIT_VBATEN;
450                 break;
451         default:
452                 break;
453         }
454 
455         dev_dbg(dev, "%s: %7ph\n", "write", buf);
456 
457         result = ds1307->write_block_data(ds1307->client,
458                 ds1307->offset, 7, buf);
459         if (result < 0) {
460                 dev_err(dev, "%s error %d\n", "write", result);
461                 return result;
462         }
463         return 0;
464 }
465 
466 static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
467 {
468         struct i2c_client       *client = to_i2c_client(dev);
469         struct ds1307           *ds1307 = i2c_get_clientdata(client);
470         int                     ret;
471 
472         if (!test_bit(HAS_ALARM, &ds1307->flags))
473                 return -EINVAL;
474 
475         /* read all ALARM1, ALARM2, and status registers at once */
476         ret = ds1307->read_block_data(client,
477                         DS1339_REG_ALARM1_SECS, 9, ds1307->regs);
478         if (ret != 9) {
479                 dev_err(dev, "%s error %d\n", "alarm read", ret);
480                 return -EIO;
481         }
482 
483         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
484                         "alarm read",
485                         ds1307->regs[0], ds1307->regs[1],
486                         ds1307->regs[2], ds1307->regs[3],
487                         ds1307->regs[4], ds1307->regs[5],
488                         ds1307->regs[6], ds1307->regs[7],
489                         ds1307->regs[8]);
490 
491         /*
492          * report alarm time (ALARM1); assume 24 hour and day-of-month modes,
493          * and that all four fields are checked matches
494          */
495         t->time.tm_sec = bcd2bin(ds1307->regs[0] & 0x7f);
496         t->time.tm_min = bcd2bin(ds1307->regs[1] & 0x7f);
497         t->time.tm_hour = bcd2bin(ds1307->regs[2] & 0x3f);
498         t->time.tm_mday = bcd2bin(ds1307->regs[3] & 0x3f);
499         t->time.tm_mon = -1;
500         t->time.tm_year = -1;
501         t->time.tm_wday = -1;
502         t->time.tm_yday = -1;
503         t->time.tm_isdst = -1;
504 
505         /* ... and status */
506         t->enabled = !!(ds1307->regs[7] & DS1337_BIT_A1IE);
507         t->pending = !!(ds1307->regs[8] & DS1337_BIT_A1I);
508 
509         dev_dbg(dev, "%s secs=%d, mins=%d, "
510                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
511                 "alarm read", t->time.tm_sec, t->time.tm_min,
512                 t->time.tm_hour, t->time.tm_mday,
513                 t->enabled, t->pending);
514 
515         return 0;
516 }
517 
518 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
519 {
520         struct i2c_client       *client = to_i2c_client(dev);
521         struct ds1307           *ds1307 = i2c_get_clientdata(client);
522         unsigned char           *buf = ds1307->regs;
523         u8                      control, status;
524         int                     ret;
525 
526         if (!test_bit(HAS_ALARM, &ds1307->flags))
527                 return -EINVAL;
528 
529         dev_dbg(dev, "%s secs=%d, mins=%d, "
530                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
531                 "alarm set", t->time.tm_sec, t->time.tm_min,
532                 t->time.tm_hour, t->time.tm_mday,
533                 t->enabled, t->pending);
534 
535         /* read current status of both alarms and the chip */
536         ret = ds1307->read_block_data(client,
537                         DS1339_REG_ALARM1_SECS, 9, buf);
538         if (ret != 9) {
539                 dev_err(dev, "%s error %d\n", "alarm write", ret);
540                 return -EIO;
541         }
542         control = ds1307->regs[7];
543         status = ds1307->regs[8];
544 
545         dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
546                         "alarm set (old status)",
547                         ds1307->regs[0], ds1307->regs[1],
548                         ds1307->regs[2], ds1307->regs[3],
549                         ds1307->regs[4], ds1307->regs[5],
550                         ds1307->regs[6], control, status);
551 
552         /* set ALARM1, using 24 hour and day-of-month modes */
553         buf[0] = bin2bcd(t->time.tm_sec);
554         buf[1] = bin2bcd(t->time.tm_min);
555         buf[2] = bin2bcd(t->time.tm_hour);
556         buf[3] = bin2bcd(t->time.tm_mday);
557 
558         /* set ALARM2 to non-garbage */
559         buf[4] = 0;
560         buf[5] = 0;
561         buf[6] = 0;
562 
563         /* optionally enable ALARM1 */
564         buf[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
565         if (t->enabled) {
566                 dev_dbg(dev, "alarm IRQ armed\n");
567                 buf[7] |= DS1337_BIT_A1IE;      /* only ALARM1 is used */
568         }
569         buf[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
570 
571         ret = ds1307->write_block_data(client,
572                         DS1339_REG_ALARM1_SECS, 9, buf);
573         if (ret < 0) {
574                 dev_err(dev, "can't set alarm time\n");
575                 return ret;
576         }
577 
578         return 0;
579 }
580 
581 static int ds1307_alarm_irq_enable(struct device *dev, unsigned int enabled)
582 {
583         struct i2c_client       *client = to_i2c_client(dev);
584         struct ds1307           *ds1307 = i2c_get_clientdata(client);
585         int                     ret;
586 
587         if (!test_bit(HAS_ALARM, &ds1307->flags))
588                 return -ENOTTY;
589 
590         ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
591         if (ret < 0)
592                 return ret;
593 
594         if (enabled)
595                 ret |= DS1337_BIT_A1IE;
596         else
597                 ret &= ~DS1337_BIT_A1IE;
598 
599         ret = i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, ret);
600         if (ret < 0)
601                 return ret;
602 
603         return 0;
604 }
605 
606 static const struct rtc_class_ops ds13xx_rtc_ops = {
607         .read_time      = ds1307_get_time,
608         .set_time       = ds1307_set_time,
609         .read_alarm     = ds1337_read_alarm,
610         .set_alarm      = ds1337_set_alarm,
611         .alarm_irq_enable = ds1307_alarm_irq_enable,
612 };
613 
614 /*----------------------------------------------------------------------*/
615 
616 /*
617  * Alarm support for mcp7941x devices.
618  */
619 
620 #define MCP7941X_REG_CONTROL            0x07
621 #       define MCP7941X_BIT_ALM0_EN     0x10
622 #       define MCP7941X_BIT_ALM1_EN     0x20
623 #define MCP7941X_REG_ALARM0_BASE        0x0a
624 #define MCP7941X_REG_ALARM0_CTRL        0x0d
625 #define MCP7941X_REG_ALARM1_BASE        0x11
626 #define MCP7941X_REG_ALARM1_CTRL        0x14
627 #       define MCP7941X_BIT_ALMX_IF     (1 << 3)
628 #       define MCP7941X_BIT_ALMX_C0     (1 << 4)
629 #       define MCP7941X_BIT_ALMX_C1     (1 << 5)
630 #       define MCP7941X_BIT_ALMX_C2     (1 << 6)
631 #       define MCP7941X_BIT_ALMX_POL    (1 << 7)
632 #       define MCP7941X_MSK_ALMX_MATCH  (MCP7941X_BIT_ALMX_C0 | \
633                                          MCP7941X_BIT_ALMX_C1 | \
634                                          MCP7941X_BIT_ALMX_C2)
635 
636 static void mcp7941x_work(struct work_struct *work)
637 {
638         struct ds1307 *ds1307 = container_of(work, struct ds1307, work);
639         struct i2c_client *client = ds1307->client;
640         int reg, ret;
641 
642         mutex_lock(&ds1307->rtc->ops_lock);
643 
644         /* Check and clear alarm 0 interrupt flag. */
645         reg = i2c_smbus_read_byte_data(client, MCP7941X_REG_ALARM0_CTRL);
646         if (reg < 0)
647                 goto out;
648         if (!(reg & MCP7941X_BIT_ALMX_IF))
649                 goto out;
650         reg &= ~MCP7941X_BIT_ALMX_IF;
651         ret = i2c_smbus_write_byte_data(client, MCP7941X_REG_ALARM0_CTRL, reg);
652         if (ret < 0)
653                 goto out;
654 
655         /* Disable alarm 0. */
656         reg = i2c_smbus_read_byte_data(client, MCP7941X_REG_CONTROL);
657         if (reg < 0)
658                 goto out;
659         reg &= ~MCP7941X_BIT_ALM0_EN;
660         ret = i2c_smbus_write_byte_data(client, MCP7941X_REG_CONTROL, reg);
661         if (ret < 0)
662                 goto out;
663 
664         rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
665 
666 out:
667         if (test_bit(HAS_ALARM, &ds1307->flags))
668                 enable_irq(client->irq);
669         mutex_unlock(&ds1307->rtc->ops_lock);
670 }
671 
672 static int mcp7941x_read_alarm(struct device *dev, struct rtc_wkalrm *t)
673 {
674         struct i2c_client *client = to_i2c_client(dev);
675         struct ds1307 *ds1307 = i2c_get_clientdata(client);
676         u8 *regs = ds1307->regs;
677         int ret;
678 
679         if (!test_bit(HAS_ALARM, &ds1307->flags))
680                 return -EINVAL;
681 
682         /* Read control and alarm 0 registers. */
683         ret = ds1307->read_block_data(client, MCP7941X_REG_CONTROL, 10, regs);
684         if (ret < 0)
685                 return ret;
686 
687         t->enabled = !!(regs[0] & MCP7941X_BIT_ALM0_EN);
688 
689         /* Report alarm 0 time assuming 24-hour and day-of-month modes. */
690         t->time.tm_sec = bcd2bin(ds1307->regs[3] & 0x7f);
691         t->time.tm_min = bcd2bin(ds1307->regs[4] & 0x7f);
692         t->time.tm_hour = bcd2bin(ds1307->regs[5] & 0x3f);
693         t->time.tm_wday = bcd2bin(ds1307->regs[6] & 0x7) - 1;
694         t->time.tm_mday = bcd2bin(ds1307->regs[7] & 0x3f);
695         t->time.tm_mon = bcd2bin(ds1307->regs[8] & 0x1f) - 1;
696         t->time.tm_year = -1;
697         t->time.tm_yday = -1;
698         t->time.tm_isdst = -1;
699 
700         dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
701                 "enabled=%d polarity=%d irq=%d match=%d\n", __func__,
702                 t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
703                 t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled,
704                 !!(ds1307->regs[6] & MCP7941X_BIT_ALMX_POL),
705                 !!(ds1307->regs[6] & MCP7941X_BIT_ALMX_IF),
706                 (ds1307->regs[6] & MCP7941X_MSK_ALMX_MATCH) >> 4);
707 
708         return 0;
709 }
710 
711 static int mcp7941x_set_alarm(struct device *dev, struct rtc_wkalrm *t)
712 {
713         struct i2c_client *client = to_i2c_client(dev);
714         struct ds1307 *ds1307 = i2c_get_clientdata(client);
715         unsigned char *regs = ds1307->regs;
716         int ret;
717 
718         if (!test_bit(HAS_ALARM, &ds1307->flags))
719                 return -EINVAL;
720 
721         dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
722                 "enabled=%d pending=%d\n", __func__,
723                 t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
724                 t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
725                 t->enabled, t->pending);
726 
727         /* Read control and alarm 0 registers. */
728         ret = ds1307->read_block_data(client, MCP7941X_REG_CONTROL, 10, regs);
729         if (ret < 0)
730                 return ret;
731 
732         /* Set alarm 0, using 24-hour and day-of-month modes. */
733         regs[3] = bin2bcd(t->time.tm_sec);
734         regs[4] = bin2bcd(t->time.tm_min);
735         regs[5] = bin2bcd(t->time.tm_hour);
736         regs[6] = bin2bcd(t->time.tm_wday) + 1;
737         regs[7] = bin2bcd(t->time.tm_mday);
738         regs[8] = bin2bcd(t->time.tm_mon) + 1;
739 
740         /* Clear the alarm 0 interrupt flag. */
741         regs[6] &= ~MCP7941X_BIT_ALMX_IF;
742         /* Set alarm match: second, minute, hour, day, date, month. */
743         regs[6] |= MCP7941X_MSK_ALMX_MATCH;
744 
745         if (t->enabled)
746                 regs[0] |= MCP7941X_BIT_ALM0_EN;
747         else
748                 regs[0] &= ~MCP7941X_BIT_ALM0_EN;
749 
750         ret = ds1307->write_block_data(client, MCP7941X_REG_CONTROL, 10, regs);
751         if (ret < 0)
752                 return ret;
753 
754         return 0;
755 }
756 
757 static int mcp7941x_alarm_irq_enable(struct device *dev, unsigned int enabled)
758 {
759         struct i2c_client *client = to_i2c_client(dev);
760         struct ds1307 *ds1307 = i2c_get_clientdata(client);
761         int reg;
762 
763         if (!test_bit(HAS_ALARM, &ds1307->flags))
764                 return -EINVAL;
765 
766         reg = i2c_smbus_read_byte_data(client, MCP7941X_REG_CONTROL);
767         if (reg < 0)
768                 return reg;
769 
770         if (enabled)
771                 reg |= MCP7941X_BIT_ALM0_EN;
772         else
773                 reg &= ~MCP7941X_BIT_ALM0_EN;
774 
775         return i2c_smbus_write_byte_data(client, MCP7941X_REG_CONTROL, reg);
776 }
777 
778 static const struct rtc_class_ops mcp7941x_rtc_ops = {
779         .read_time      = ds1307_get_time,
780         .set_time       = ds1307_set_time,
781         .read_alarm     = mcp7941x_read_alarm,
782         .set_alarm      = mcp7941x_set_alarm,
783         .alarm_irq_enable = mcp7941x_alarm_irq_enable,
784 };
785 
786 /*----------------------------------------------------------------------*/
787 
788 static ssize_t
789 ds1307_nvram_read(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         if (unlikely(off >= ds1307->nvram->size))
801                 return 0;
802         if ((off + count) > ds1307->nvram->size)
803                 count = ds1307->nvram->size - off;
804         if (unlikely(!count))
805                 return count;
806 
807         result = ds1307->read_block_data(client, ds1307->nvram_offset + off,
808                                                                 count, buf);
809         if (result < 0)
810                 dev_err(&client->dev, "%s error %d\n", "nvram read", result);
811         return result;
812 }
813 
814 static ssize_t
815 ds1307_nvram_write(struct file *filp, struct kobject *kobj,
816                 struct bin_attribute *attr,
817                 char *buf, loff_t off, size_t count)
818 {
819         struct i2c_client       *client;
820         struct ds1307           *ds1307;
821         int                     result;
822 
823         client = kobj_to_i2c_client(kobj);
824         ds1307 = i2c_get_clientdata(client);
825 
826         if (unlikely(off >= ds1307->nvram->size))
827                 return -EFBIG;
828         if ((off + count) > ds1307->nvram->size)
829                 count = ds1307->nvram->size - off;
830         if (unlikely(!count))
831                 return count;
832 
833         result = ds1307->write_block_data(client, ds1307->nvram_offset + off,
834                                                                 count, buf);
835         if (result < 0) {
836                 dev_err(&client->dev, "%s error %d\n", "nvram write", result);
837                 return result;
838         }
839         return count;
840 }
841 
842 
843 /*----------------------------------------------------------------------*/
844 
845 static u8 do_trickle_setup_ds1339(struct i2c_client *client,
846                                   uint32_t ohms, bool diode)
847 {
848         u8 setup = (diode) ? DS1307_TRICKLE_CHARGER_DIODE :
849                 DS1307_TRICKLE_CHARGER_NO_DIODE;
850 
851         switch (ohms) {
852         case 250:
853                 setup |= DS1307_TRICKLE_CHARGER_250_OHM;
854                 break;
855         case 2000:
856                 setup |= DS1307_TRICKLE_CHARGER_2K_OHM;
857                 break;
858         case 4000:
859                 setup |= DS1307_TRICKLE_CHARGER_4K_OHM;
860                 break;
861         default:
862                 dev_warn(&client->dev,
863                          "Unsupported ohm value %u in dt\n", ohms);
864                 return 0;
865         }
866         return setup;
867 }
868 
869 static void ds1307_trickle_of_init(struct i2c_client *client,
870                                    struct chip_desc *chip)
871 {
872         uint32_t ohms = 0;
873         bool diode = true;
874 
875         if (!chip->do_trickle_setup)
876                 goto out;
877         if (of_property_read_u32(client->dev.of_node, "trickle-resistor-ohms" , &ohms))
878                 goto out;
879         if (of_property_read_bool(client->dev.of_node, "trickle-diode-disable"))
880                 diode = false;
881         chip->trickle_charger_setup = chip->do_trickle_setup(client,
882                                                              ohms, diode);
883 out:
884         return;
885 }
886 
887 static int ds1307_probe(struct i2c_client *client,
888                         const struct i2c_device_id *id)
889 {
890         struct ds1307           *ds1307;
891         int                     err = -ENODEV;
892         int                     tmp;
893         struct chip_desc        *chip = &chips[id->driver_data];
894         struct i2c_adapter      *adapter = to_i2c_adapter(client->dev.parent);
895         bool                    want_irq = false;
896         unsigned char           *buf;
897         struct ds1307_platform_data *pdata = dev_get_platdata(&client->dev);
898         static const int        bbsqi_bitpos[] = {
899                 [ds_1337] = 0,
900                 [ds_1339] = DS1339_BIT_BBSQI,
901                 [ds_3231] = DS3231_BIT_BBSQW,
902         };
903         const struct rtc_class_ops *rtc_ops = &ds13xx_rtc_ops;
904 
905         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)
906             && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
907                 return -EIO;
908 
909         ds1307 = devm_kzalloc(&client->dev, sizeof(struct ds1307), GFP_KERNEL);
910         if (!ds1307)
911                 return -ENOMEM;
912 
913         i2c_set_clientdata(client, ds1307);
914 
915         ds1307->client  = client;
916         ds1307->type    = id->driver_data;
917 
918         if (!pdata && client->dev.of_node)
919                 ds1307_trickle_of_init(client, chip);
920         else if (pdata && pdata->trickle_charger_setup)
921                 chip->trickle_charger_setup = pdata->trickle_charger_setup;
922 
923         if (chip->trickle_charger_setup && chip->trickle_charger_reg) {
924                 dev_dbg(&client->dev, "writing trickle charger info 0x%x to 0x%x\n",
925                     DS13XX_TRICKLE_CHARGER_MAGIC | chip->trickle_charger_setup,
926                     chip->trickle_charger_reg);
927                 i2c_smbus_write_byte_data(client, chip->trickle_charger_reg,
928                     DS13XX_TRICKLE_CHARGER_MAGIC |
929                     chip->trickle_charger_setup);
930         }
931 
932         buf = ds1307->regs;
933         if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
934                 ds1307->read_block_data = ds1307_native_smbus_read_block_data;
935                 ds1307->write_block_data = ds1307_native_smbus_write_block_data;
936         } else {
937                 ds1307->read_block_data = ds1307_read_block_data;
938                 ds1307->write_block_data = ds1307_write_block_data;
939         }
940 
941         switch (ds1307->type) {
942         case ds_1337:
943         case ds_1339:
944         case ds_3231:
945                 /* get registers that the "rtc" read below won't read... */
946                 tmp = ds1307->read_block_data(ds1307->client,
947                                 DS1337_REG_CONTROL, 2, buf);
948                 if (tmp != 2) {
949                         dev_dbg(&client->dev, "read error %d\n", tmp);
950                         err = -EIO;
951                         goto exit;
952                 }
953 
954                 /* oscillator off?  turn it on, so clock can tick. */
955                 if (ds1307->regs[0] & DS1337_BIT_nEOSC)
956                         ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
957 
958                 /*
959                  * Using IRQ?  Disable the square wave and both alarms.
960                  * For some variants, be sure alarms can trigger when we're
961                  * running on Vbackup (BBSQI/BBSQW)
962                  */
963                 if (ds1307->client->irq > 0 && chip->alarm) {
964                         INIT_WORK(&ds1307->work, ds1307_work);
965 
966                         ds1307->regs[0] |= DS1337_BIT_INTCN
967                                         | bbsqi_bitpos[ds1307->type];
968                         ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
969 
970                         want_irq = true;
971                 }
972 
973                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
974                                                         ds1307->regs[0]);
975 
976                 /* oscillator fault?  clear flag, and warn */
977                 if (ds1307->regs[1] & DS1337_BIT_OSF) {
978                         i2c_smbus_write_byte_data(client, DS1337_REG_STATUS,
979                                 ds1307->regs[1] & ~DS1337_BIT_OSF);
980                         dev_warn(&client->dev, "SET TIME!\n");
981                 }
982                 break;
983 
984         case rx_8025:
985                 tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
986                                 RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
987                 if (tmp != 2) {
988                         dev_dbg(&client->dev, "read error %d\n", tmp);
989                         err = -EIO;
990                         goto exit;
991                 }
992 
993                 /* oscillator off?  turn it on, so clock can tick. */
994                 if (!(ds1307->regs[1] & RX8025_BIT_XST)) {
995                         ds1307->regs[1] |= RX8025_BIT_XST;
996                         i2c_smbus_write_byte_data(client,
997                                                   RX8025_REG_CTRL2 << 4 | 0x08,
998                                                   ds1307->regs[1]);
999                         dev_warn(&client->dev,
1000                                  "oscillator stop detected - SET TIME!\n");
1001                 }
1002 
1003                 if (ds1307->regs[1] & RX8025_BIT_PON) {
1004                         ds1307->regs[1] &= ~RX8025_BIT_PON;
1005                         i2c_smbus_write_byte_data(client,
1006                                                   RX8025_REG_CTRL2 << 4 | 0x08,
1007                                                   ds1307->regs[1]);
1008                         dev_warn(&client->dev, "power-on detected\n");
1009                 }
1010 
1011                 if (ds1307->regs[1] & RX8025_BIT_VDET) {
1012                         ds1307->regs[1] &= ~RX8025_BIT_VDET;
1013                         i2c_smbus_write_byte_data(client,
1014                                                   RX8025_REG_CTRL2 << 4 | 0x08,
1015                                                   ds1307->regs[1]);
1016                         dev_warn(&client->dev, "voltage drop detected\n");
1017                 }
1018 
1019                 /* make sure we are running in 24hour mode */
1020                 if (!(ds1307->regs[0] & RX8025_BIT_2412)) {
1021                         u8 hour;
1022 
1023                         /* switch to 24 hour mode */
1024                         i2c_smbus_write_byte_data(client,
1025                                                   RX8025_REG_CTRL1 << 4 | 0x08,
1026                                                   ds1307->regs[0] |
1027                                                   RX8025_BIT_2412);
1028 
1029                         tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
1030                                         RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
1031                         if (tmp != 2) {
1032                                 dev_dbg(&client->dev, "read error %d\n", tmp);
1033                                 err = -EIO;
1034                                 goto exit;
1035                         }
1036 
1037                         /* correct hour */
1038                         hour = bcd2bin(ds1307->regs[DS1307_REG_HOUR]);
1039                         if (hour == 12)
1040                                 hour = 0;
1041                         if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1042                                 hour += 12;
1043 
1044                         i2c_smbus_write_byte_data(client,
1045                                                   DS1307_REG_HOUR << 4 | 0x08,
1046                                                   hour);
1047                 }
1048                 break;
1049         case ds_1388:
1050                 ds1307->offset = 1; /* Seconds starts at 1 */
1051                 break;
1052         case mcp7941x:
1053                 rtc_ops = &mcp7941x_rtc_ops;
1054                 if (ds1307->client->irq > 0 && chip->alarm) {
1055                         INIT_WORK(&ds1307->work, mcp7941x_work);
1056                         want_irq = true;
1057                 }
1058                 break;
1059         default:
1060                 break;
1061         }
1062 
1063 read_rtc:
1064         /* read RTC registers */
1065         tmp = ds1307->read_block_data(ds1307->client, ds1307->offset, 8, buf);
1066         if (tmp != 8) {
1067                 dev_dbg(&client->dev, "read error %d\n", tmp);
1068                 err = -EIO;
1069                 goto exit;
1070         }
1071 
1072         /*
1073          * minimal sanity checking; some chips (like DS1340) don't
1074          * specify the extra bits as must-be-zero, but there are
1075          * still a few values that are clearly out-of-range.
1076          */
1077         tmp = ds1307->regs[DS1307_REG_SECS];
1078         switch (ds1307->type) {
1079         case ds_1307:
1080         case m41t00:
1081                 /* clock halted?  turn it on, so clock can tick. */
1082                 if (tmp & DS1307_BIT_CH) {
1083                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
1084                         dev_warn(&client->dev, "SET TIME!\n");
1085                         goto read_rtc;
1086                 }
1087                 break;
1088         case ds_1338:
1089                 /* clock halted?  turn it on, so clock can tick. */
1090                 if (tmp & DS1307_BIT_CH)
1091                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
1092 
1093                 /* oscillator fault?  clear flag, and warn */
1094                 if (ds1307->regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
1095                         i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL,
1096                                         ds1307->regs[DS1307_REG_CONTROL]
1097                                         & ~DS1338_BIT_OSF);
1098                         dev_warn(&client->dev, "SET TIME!\n");
1099                         goto read_rtc;
1100                 }
1101                 break;
1102         case ds_1340:
1103                 /* clock halted?  turn it on, so clock can tick. */
1104                 if (tmp & DS1340_BIT_nEOSC)
1105                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
1106 
1107                 tmp = i2c_smbus_read_byte_data(client, DS1340_REG_FLAG);
1108                 if (tmp < 0) {
1109                         dev_dbg(&client->dev, "read error %d\n", tmp);
1110                         err = -EIO;
1111                         goto exit;
1112                 }
1113 
1114                 /* oscillator fault?  clear flag, and warn */
1115                 if (tmp & DS1340_BIT_OSF) {
1116                         i2c_smbus_write_byte_data(client, DS1340_REG_FLAG, 0);
1117                         dev_warn(&client->dev, "SET TIME!\n");
1118                 }
1119                 break;
1120         case mcp7941x:
1121                 /* make sure that the backup battery is enabled */
1122                 if (!(ds1307->regs[DS1307_REG_WDAY] & MCP7941X_BIT_VBATEN)) {
1123                         i2c_smbus_write_byte_data(client, DS1307_REG_WDAY,
1124                                         ds1307->regs[DS1307_REG_WDAY]
1125                                         | MCP7941X_BIT_VBATEN);
1126                 }
1127 
1128                 /* clock halted?  turn it on, so clock can tick. */
1129                 if (!(tmp & MCP7941X_BIT_ST)) {
1130                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS,
1131                                         MCP7941X_BIT_ST);
1132                         dev_warn(&client->dev, "SET TIME!\n");
1133                         goto read_rtc;
1134                 }
1135 
1136                 break;
1137         default:
1138                 break;
1139         }
1140 
1141         tmp = ds1307->regs[DS1307_REG_HOUR];
1142         switch (ds1307->type) {
1143         case ds_1340:
1144         case m41t00:
1145                 /*
1146                  * NOTE: ignores century bits; fix before deploying
1147                  * systems that will run through year 2100.
1148                  */
1149                 break;
1150         case rx_8025:
1151                 break;
1152         default:
1153                 if (!(tmp & DS1307_BIT_12HR))
1154                         break;
1155 
1156                 /*
1157                  * Be sure we're in 24 hour mode.  Multi-master systems
1158                  * take note...
1159                  */
1160                 tmp = bcd2bin(tmp & 0x1f);
1161                 if (tmp == 12)
1162                         tmp = 0;
1163                 if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1164                         tmp += 12;
1165                 i2c_smbus_write_byte_data(client,
1166                                 ds1307->offset + DS1307_REG_HOUR,
1167                                 bin2bcd(tmp));
1168         }
1169 
1170         device_set_wakeup_capable(&client->dev, want_irq);
1171         ds1307->rtc = devm_rtc_device_register(&client->dev, client->name,
1172                                 rtc_ops, THIS_MODULE);
1173         if (IS_ERR(ds1307->rtc)) {
1174                 return PTR_ERR(ds1307->rtc);
1175         }
1176 
1177         if (want_irq) {
1178                 err = request_irq(client->irq, ds1307_irq, IRQF_SHARED,
1179                           ds1307->rtc->name, client);
1180                 if (err) {
1181                         client->irq = 0;
1182                         dev_err(&client->dev, "unable to request IRQ!\n");
1183                 } else {
1184 
1185                         set_bit(HAS_ALARM, &ds1307->flags);
1186                         dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
1187                 }
1188         }
1189 
1190         if (chip->nvram_size) {
1191 
1192                 ds1307->nvram = devm_kzalloc(&client->dev,
1193                                         sizeof(struct bin_attribute),
1194                                         GFP_KERNEL);
1195                 if (!ds1307->nvram) {
1196                         dev_err(&client->dev, "cannot allocate memory for nvram sysfs\n");
1197                 } else {
1198 
1199                         ds1307->nvram->attr.name = "nvram";
1200                         ds1307->nvram->attr.mode = S_IRUGO | S_IWUSR;
1201 
1202                         sysfs_bin_attr_init(ds1307->nvram);
1203 
1204                         ds1307->nvram->read = ds1307_nvram_read;
1205                         ds1307->nvram->write = ds1307_nvram_write;
1206                         ds1307->nvram->size = chip->nvram_size;
1207                         ds1307->nvram_offset = chip->nvram_offset;
1208 
1209                         err = sysfs_create_bin_file(&client->dev.kobj,
1210                                                     ds1307->nvram);
1211                         if (err) {
1212                                 dev_err(&client->dev,
1213                                         "unable to create sysfs file: %s\n",
1214                                         ds1307->nvram->attr.name);
1215                         } else {
1216                                 set_bit(HAS_NVRAM, &ds1307->flags);
1217                                 dev_info(&client->dev, "%zu bytes nvram\n",
1218                                          ds1307->nvram->size);
1219                         }
1220                 }
1221         }
1222 
1223         return 0;
1224 
1225 exit:
1226         return err;
1227 }
1228 
1229 static int ds1307_remove(struct i2c_client *client)
1230 {
1231         struct ds1307 *ds1307 = i2c_get_clientdata(client);
1232 
1233         if (test_and_clear_bit(HAS_ALARM, &ds1307->flags)) {
1234                 free_irq(client->irq, client);
1235                 cancel_work_sync(&ds1307->work);
1236         }
1237 
1238         if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
1239                 sysfs_remove_bin_file(&client->dev.kobj, ds1307->nvram);
1240 
1241         return 0;
1242 }
1243 
1244 static struct i2c_driver ds1307_driver = {
1245         .driver = {
1246                 .name   = "rtc-ds1307",
1247                 .owner  = THIS_MODULE,
1248         },
1249         .probe          = ds1307_probe,
1250         .remove         = ds1307_remove,
1251         .id_table       = ds1307_id,
1252 };
1253 
1254 module_i2c_driver(ds1307_driver);
1255 
1256 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
1257 MODULE_LICENSE("GPL");
1258 

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