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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: %4ph, %3ph, %2ph\n", "alarm read",
464                 &ds1307->regs[0], &ds1307->regs[4], &ds1307->regs[7]);
465 
466         /*
467          * report alarm time (ALARM1); assume 24 hour and day-of-month modes,
468          * and that all four fields are checked matches
469          */
470         t->time.tm_sec = bcd2bin(ds1307->regs[0] & 0x7f);
471         t->time.tm_min = bcd2bin(ds1307->regs[1] & 0x7f);
472         t->time.tm_hour = bcd2bin(ds1307->regs[2] & 0x3f);
473         t->time.tm_mday = bcd2bin(ds1307->regs[3] & 0x3f);
474         t->time.tm_mon = -1;
475         t->time.tm_year = -1;
476         t->time.tm_wday = -1;
477         t->time.tm_yday = -1;
478         t->time.tm_isdst = -1;
479 
480         /* ... and status */
481         t->enabled = !!(ds1307->regs[7] & DS1337_BIT_A1IE);
482         t->pending = !!(ds1307->regs[8] & DS1337_BIT_A1I);
483 
484         dev_dbg(dev, "%s secs=%d, mins=%d, "
485                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
486                 "alarm read", t->time.tm_sec, t->time.tm_min,
487                 t->time.tm_hour, t->time.tm_mday,
488                 t->enabled, t->pending);
489 
490         return 0;
491 }
492 
493 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
494 {
495         struct i2c_client       *client = to_i2c_client(dev);
496         struct ds1307           *ds1307 = i2c_get_clientdata(client);
497         unsigned char           *buf = ds1307->regs;
498         u8                      control, status;
499         int                     ret;
500 
501         if (!test_bit(HAS_ALARM, &ds1307->flags))
502                 return -EINVAL;
503 
504         dev_dbg(dev, "%s secs=%d, mins=%d, "
505                 "hours=%d, mday=%d, enabled=%d, pending=%d\n",
506                 "alarm set", t->time.tm_sec, t->time.tm_min,
507                 t->time.tm_hour, t->time.tm_mday,
508                 t->enabled, t->pending);
509 
510         /* read current status of both alarms and the chip */
511         ret = ds1307->read_block_data(client,
512                         DS1339_REG_ALARM1_SECS, 9, buf);
513         if (ret != 9) {
514                 dev_err(dev, "%s error %d\n", "alarm write", ret);
515                 return -EIO;
516         }
517         control = ds1307->regs[7];
518         status = ds1307->regs[8];
519 
520         dev_dbg(dev, "%s: %4ph, %3ph, %02x %02x\n", "alarm set (old status)",
521                 &ds1307->regs[0], &ds1307->regs[4], control, status);
522 
523         /* set ALARM1, using 24 hour and day-of-month modes */
524         buf[0] = bin2bcd(t->time.tm_sec);
525         buf[1] = bin2bcd(t->time.tm_min);
526         buf[2] = bin2bcd(t->time.tm_hour);
527         buf[3] = bin2bcd(t->time.tm_mday);
528 
529         /* set ALARM2 to non-garbage */
530         buf[4] = 0;
531         buf[5] = 0;
532         buf[6] = 0;
533 
534         /* optionally enable ALARM1 */
535         buf[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
536         if (t->enabled) {
537                 dev_dbg(dev, "alarm IRQ armed\n");
538                 buf[7] |= DS1337_BIT_A1IE;      /* only ALARM1 is used */
539         }
540         buf[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
541 
542         ret = ds1307->write_block_data(client,
543                         DS1339_REG_ALARM1_SECS, 9, buf);
544         if (ret < 0) {
545                 dev_err(dev, "can't set alarm time\n");
546                 return ret;
547         }
548 
549         return 0;
550 }
551 
552 static int ds1307_alarm_irq_enable(struct device *dev, unsigned int enabled)
553 {
554         struct i2c_client       *client = to_i2c_client(dev);
555         struct ds1307           *ds1307 = i2c_get_clientdata(client);
556         int                     ret;
557 
558         if (!test_bit(HAS_ALARM, &ds1307->flags))
559                 return -ENOTTY;
560 
561         ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
562         if (ret < 0)
563                 return ret;
564 
565         if (enabled)
566                 ret |= DS1337_BIT_A1IE;
567         else
568                 ret &= ~DS1337_BIT_A1IE;
569 
570         ret = i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, ret);
571         if (ret < 0)
572                 return ret;
573 
574         return 0;
575 }
576 
577 static const struct rtc_class_ops ds13xx_rtc_ops = {
578         .read_time      = ds1307_get_time,
579         .set_time       = ds1307_set_time,
580         .read_alarm     = ds1337_read_alarm,
581         .set_alarm      = ds1337_set_alarm,
582         .alarm_irq_enable = ds1307_alarm_irq_enable,
583 };
584 
585 /*----------------------------------------------------------------------*/
586 
587 /*
588  * Alarm support for mcp794xx devices.
589  */
590 
591 #define MCP794XX_REG_CONTROL            0x07
592 #       define MCP794XX_BIT_ALM0_EN     0x10
593 #       define MCP794XX_BIT_ALM1_EN     0x20
594 #define MCP794XX_REG_ALARM0_BASE        0x0a
595 #define MCP794XX_REG_ALARM0_CTRL        0x0d
596 #define MCP794XX_REG_ALARM1_BASE        0x11
597 #define MCP794XX_REG_ALARM1_CTRL        0x14
598 #       define MCP794XX_BIT_ALMX_IF     (1 << 3)
599 #       define MCP794XX_BIT_ALMX_C0     (1 << 4)
600 #       define MCP794XX_BIT_ALMX_C1     (1 << 5)
601 #       define MCP794XX_BIT_ALMX_C2     (1 << 6)
602 #       define MCP794XX_BIT_ALMX_POL    (1 << 7)
603 #       define MCP794XX_MSK_ALMX_MATCH  (MCP794XX_BIT_ALMX_C0 | \
604                                          MCP794XX_BIT_ALMX_C1 | \
605                                          MCP794XX_BIT_ALMX_C2)
606 
607 static irqreturn_t mcp794xx_irq(int irq, void *dev_id)
608 {
609         struct i2c_client       *client = dev_id;
610         struct ds1307           *ds1307 = i2c_get_clientdata(client);
611         struct mutex            *lock = &ds1307->rtc->ops_lock;
612         int reg, ret;
613 
614         mutex_lock(lock);
615 
616         /* Check and clear alarm 0 interrupt flag. */
617         reg = i2c_smbus_read_byte_data(client, MCP794XX_REG_ALARM0_CTRL);
618         if (reg < 0)
619                 goto out;
620         if (!(reg & MCP794XX_BIT_ALMX_IF))
621                 goto out;
622         reg &= ~MCP794XX_BIT_ALMX_IF;
623         ret = i2c_smbus_write_byte_data(client, MCP794XX_REG_ALARM0_CTRL, reg);
624         if (ret < 0)
625                 goto out;
626 
627         /* Disable alarm 0. */
628         reg = i2c_smbus_read_byte_data(client, MCP794XX_REG_CONTROL);
629         if (reg < 0)
630                 goto out;
631         reg &= ~MCP794XX_BIT_ALM0_EN;
632         ret = i2c_smbus_write_byte_data(client, MCP794XX_REG_CONTROL, reg);
633         if (ret < 0)
634                 goto out;
635 
636         rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
637 
638 out:
639         mutex_unlock(lock);
640 
641         return IRQ_HANDLED;
642 }
643 
644 static int mcp794xx_read_alarm(struct device *dev, struct rtc_wkalrm *t)
645 {
646         struct i2c_client *client = to_i2c_client(dev);
647         struct ds1307 *ds1307 = i2c_get_clientdata(client);
648         u8 *regs = ds1307->regs;
649         int ret;
650 
651         if (!test_bit(HAS_ALARM, &ds1307->flags))
652                 return -EINVAL;
653 
654         /* Read control and alarm 0 registers. */
655         ret = ds1307->read_block_data(client, MCP794XX_REG_CONTROL, 10, regs);
656         if (ret < 0)
657                 return ret;
658 
659         t->enabled = !!(regs[0] & MCP794XX_BIT_ALM0_EN);
660 
661         /* Report alarm 0 time assuming 24-hour and day-of-month modes. */
662         t->time.tm_sec = bcd2bin(ds1307->regs[3] & 0x7f);
663         t->time.tm_min = bcd2bin(ds1307->regs[4] & 0x7f);
664         t->time.tm_hour = bcd2bin(ds1307->regs[5] & 0x3f);
665         t->time.tm_wday = bcd2bin(ds1307->regs[6] & 0x7) - 1;
666         t->time.tm_mday = bcd2bin(ds1307->regs[7] & 0x3f);
667         t->time.tm_mon = bcd2bin(ds1307->regs[8] & 0x1f) - 1;
668         t->time.tm_year = -1;
669         t->time.tm_yday = -1;
670         t->time.tm_isdst = -1;
671 
672         dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
673                 "enabled=%d polarity=%d irq=%d match=%d\n", __func__,
674                 t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
675                 t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled,
676                 !!(ds1307->regs[6] & MCP794XX_BIT_ALMX_POL),
677                 !!(ds1307->regs[6] & MCP794XX_BIT_ALMX_IF),
678                 (ds1307->regs[6] & MCP794XX_MSK_ALMX_MATCH) >> 4);
679 
680         return 0;
681 }
682 
683 static int mcp794xx_set_alarm(struct device *dev, struct rtc_wkalrm *t)
684 {
685         struct i2c_client *client = to_i2c_client(dev);
686         struct ds1307 *ds1307 = i2c_get_clientdata(client);
687         unsigned char *regs = ds1307->regs;
688         int ret;
689 
690         if (!test_bit(HAS_ALARM, &ds1307->flags))
691                 return -EINVAL;
692 
693         dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
694                 "enabled=%d pending=%d\n", __func__,
695                 t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
696                 t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
697                 t->enabled, t->pending);
698 
699         /* Read control and alarm 0 registers. */
700         ret = ds1307->read_block_data(client, MCP794XX_REG_CONTROL, 10, regs);
701         if (ret < 0)
702                 return ret;
703 
704         /* Set alarm 0, using 24-hour and day-of-month modes. */
705         regs[3] = bin2bcd(t->time.tm_sec);
706         regs[4] = bin2bcd(t->time.tm_min);
707         regs[5] = bin2bcd(t->time.tm_hour);
708         regs[6] = bin2bcd(t->time.tm_wday + 1);
709         regs[7] = bin2bcd(t->time.tm_mday);
710         regs[8] = bin2bcd(t->time.tm_mon + 1);
711 
712         /* Clear the alarm 0 interrupt flag. */
713         regs[6] &= ~MCP794XX_BIT_ALMX_IF;
714         /* Set alarm match: second, minute, hour, day, date, month. */
715         regs[6] |= MCP794XX_MSK_ALMX_MATCH;
716         /* Disable interrupt. We will not enable until completely programmed */
717         regs[0] &= ~MCP794XX_BIT_ALM0_EN;
718 
719         ret = ds1307->write_block_data(client, MCP794XX_REG_CONTROL, 10, regs);
720         if (ret < 0)
721                 return ret;
722 
723         if (!t->enabled)
724                 return 0;
725         regs[0] |= MCP794XX_BIT_ALM0_EN;
726         return i2c_smbus_write_byte_data(client, MCP794XX_REG_CONTROL, regs[0]);
727 }
728 
729 static int mcp794xx_alarm_irq_enable(struct device *dev, unsigned int enabled)
730 {
731         struct i2c_client *client = to_i2c_client(dev);
732         struct ds1307 *ds1307 = i2c_get_clientdata(client);
733         int reg;
734 
735         if (!test_bit(HAS_ALARM, &ds1307->flags))
736                 return -EINVAL;
737 
738         reg = i2c_smbus_read_byte_data(client, MCP794XX_REG_CONTROL);
739         if (reg < 0)
740                 return reg;
741 
742         if (enabled)
743                 reg |= MCP794XX_BIT_ALM0_EN;
744         else
745                 reg &= ~MCP794XX_BIT_ALM0_EN;
746 
747         return i2c_smbus_write_byte_data(client, MCP794XX_REG_CONTROL, reg);
748 }
749 
750 static const struct rtc_class_ops mcp794xx_rtc_ops = {
751         .read_time      = ds1307_get_time,
752         .set_time       = ds1307_set_time,
753         .read_alarm     = mcp794xx_read_alarm,
754         .set_alarm      = mcp794xx_set_alarm,
755         .alarm_irq_enable = mcp794xx_alarm_irq_enable,
756 };
757 
758 /*----------------------------------------------------------------------*/
759 
760 static ssize_t
761 ds1307_nvram_read(struct file *filp, struct kobject *kobj,
762                 struct bin_attribute *attr,
763                 char *buf, loff_t off, size_t count)
764 {
765         struct i2c_client       *client;
766         struct ds1307           *ds1307;
767         int                     result;
768 
769         client = kobj_to_i2c_client(kobj);
770         ds1307 = i2c_get_clientdata(client);
771 
772         result = ds1307->read_block_data(client, ds1307->nvram_offset + off,
773                                                                 count, buf);
774         if (result < 0)
775                 dev_err(&client->dev, "%s error %d\n", "nvram read", result);
776         return result;
777 }
778 
779 static ssize_t
780 ds1307_nvram_write(struct file *filp, struct kobject *kobj,
781                 struct bin_attribute *attr,
782                 char *buf, loff_t off, size_t count)
783 {
784         struct i2c_client       *client;
785         struct ds1307           *ds1307;
786         int                     result;
787 
788         client = kobj_to_i2c_client(kobj);
789         ds1307 = i2c_get_clientdata(client);
790 
791         result = ds1307->write_block_data(client, ds1307->nvram_offset + off,
792                                                                 count, buf);
793         if (result < 0) {
794                 dev_err(&client->dev, "%s error %d\n", "nvram write", result);
795                 return result;
796         }
797         return count;
798 }
799 
800 
801 /*----------------------------------------------------------------------*/
802 
803 static u8 do_trickle_setup_ds1339(struct i2c_client *client,
804                                   uint32_t ohms, bool diode)
805 {
806         u8 setup = (diode) ? DS1307_TRICKLE_CHARGER_DIODE :
807                 DS1307_TRICKLE_CHARGER_NO_DIODE;
808 
809         switch (ohms) {
810         case 250:
811                 setup |= DS1307_TRICKLE_CHARGER_250_OHM;
812                 break;
813         case 2000:
814                 setup |= DS1307_TRICKLE_CHARGER_2K_OHM;
815                 break;
816         case 4000:
817                 setup |= DS1307_TRICKLE_CHARGER_4K_OHM;
818                 break;
819         default:
820                 dev_warn(&client->dev,
821                          "Unsupported ohm value %u in dt\n", ohms);
822                 return 0;
823         }
824         return setup;
825 }
826 
827 static void ds1307_trickle_of_init(struct i2c_client *client,
828                                    struct chip_desc *chip)
829 {
830         uint32_t ohms = 0;
831         bool diode = true;
832 
833         if (!chip->do_trickle_setup)
834                 goto out;
835         if (of_property_read_u32(client->dev.of_node, "trickle-resistor-ohms" , &ohms))
836                 goto out;
837         if (of_property_read_bool(client->dev.of_node, "trickle-diode-disable"))
838                 diode = false;
839         chip->trickle_charger_setup = chip->do_trickle_setup(client,
840                                                              ohms, diode);
841 out:
842         return;
843 }
844 
845 static int ds1307_probe(struct i2c_client *client,
846                         const struct i2c_device_id *id)
847 {
848         struct ds1307           *ds1307;
849         int                     err = -ENODEV;
850         int                     tmp;
851         struct chip_desc        *chip = &chips[id->driver_data];
852         struct i2c_adapter      *adapter = to_i2c_adapter(client->dev.parent);
853         bool                    want_irq = false;
854         unsigned char           *buf;
855         struct ds1307_platform_data *pdata = dev_get_platdata(&client->dev);
856         irq_handler_t   irq_handler = ds1307_irq;
857 
858         static const int        bbsqi_bitpos[] = {
859                 [ds_1337] = 0,
860                 [ds_1339] = DS1339_BIT_BBSQI,
861                 [ds_3231] = DS3231_BIT_BBSQW,
862         };
863         const struct rtc_class_ops *rtc_ops = &ds13xx_rtc_ops;
864 
865         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)
866             && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
867                 return -EIO;
868 
869         ds1307 = devm_kzalloc(&client->dev, sizeof(struct ds1307), GFP_KERNEL);
870         if (!ds1307)
871                 return -ENOMEM;
872 
873         i2c_set_clientdata(client, ds1307);
874 
875         ds1307->client  = client;
876         ds1307->type    = id->driver_data;
877 
878         if (!pdata && client->dev.of_node)
879                 ds1307_trickle_of_init(client, chip);
880         else if (pdata && pdata->trickle_charger_setup)
881                 chip->trickle_charger_setup = pdata->trickle_charger_setup;
882 
883         if (chip->trickle_charger_setup && chip->trickle_charger_reg) {
884                 dev_dbg(&client->dev, "writing trickle charger info 0x%x to 0x%x\n",
885                     DS13XX_TRICKLE_CHARGER_MAGIC | chip->trickle_charger_setup,
886                     chip->trickle_charger_reg);
887                 i2c_smbus_write_byte_data(client, chip->trickle_charger_reg,
888                     DS13XX_TRICKLE_CHARGER_MAGIC |
889                     chip->trickle_charger_setup);
890         }
891 
892         buf = ds1307->regs;
893         if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
894                 ds1307->read_block_data = ds1307_native_smbus_read_block_data;
895                 ds1307->write_block_data = ds1307_native_smbus_write_block_data;
896         } else {
897                 ds1307->read_block_data = ds1307_read_block_data;
898                 ds1307->write_block_data = ds1307_write_block_data;
899         }
900 
901         switch (ds1307->type) {
902         case ds_1337:
903         case ds_1339:
904         case ds_3231:
905                 /* get registers that the "rtc" read below won't read... */
906                 tmp = ds1307->read_block_data(ds1307->client,
907                                 DS1337_REG_CONTROL, 2, buf);
908                 if (tmp != 2) {
909                         dev_dbg(&client->dev, "read error %d\n", tmp);
910                         err = -EIO;
911                         goto exit;
912                 }
913 
914                 /* oscillator off?  turn it on, so clock can tick. */
915                 if (ds1307->regs[0] & DS1337_BIT_nEOSC)
916                         ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
917 
918                 /*
919                  * Using IRQ?  Disable the square wave and both alarms.
920                  * For some variants, be sure alarms can trigger when we're
921                  * running on Vbackup (BBSQI/BBSQW)
922                  */
923                 if (ds1307->client->irq > 0 && chip->alarm) {
924                         ds1307->regs[0] |= DS1337_BIT_INTCN
925                                         | bbsqi_bitpos[ds1307->type];
926                         ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
927 
928                         want_irq = true;
929                 }
930 
931                 i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
932                                                         ds1307->regs[0]);
933 
934                 /* oscillator fault?  clear flag, and warn */
935                 if (ds1307->regs[1] & DS1337_BIT_OSF) {
936                         i2c_smbus_write_byte_data(client, DS1337_REG_STATUS,
937                                 ds1307->regs[1] & ~DS1337_BIT_OSF);
938                         dev_warn(&client->dev, "SET TIME!\n");
939                 }
940                 break;
941 
942         case rx_8025:
943                 tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
944                                 RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
945                 if (tmp != 2) {
946                         dev_dbg(&client->dev, "read error %d\n", tmp);
947                         err = -EIO;
948                         goto exit;
949                 }
950 
951                 /* oscillator off?  turn it on, so clock can tick. */
952                 if (!(ds1307->regs[1] & RX8025_BIT_XST)) {
953                         ds1307->regs[1] |= RX8025_BIT_XST;
954                         i2c_smbus_write_byte_data(client,
955                                                   RX8025_REG_CTRL2 << 4 | 0x08,
956                                                   ds1307->regs[1]);
957                         dev_warn(&client->dev,
958                                  "oscillator stop detected - SET TIME!\n");
959                 }
960 
961                 if (ds1307->regs[1] & RX8025_BIT_PON) {
962                         ds1307->regs[1] &= ~RX8025_BIT_PON;
963                         i2c_smbus_write_byte_data(client,
964                                                   RX8025_REG_CTRL2 << 4 | 0x08,
965                                                   ds1307->regs[1]);
966                         dev_warn(&client->dev, "power-on detected\n");
967                 }
968 
969                 if (ds1307->regs[1] & RX8025_BIT_VDET) {
970                         ds1307->regs[1] &= ~RX8025_BIT_VDET;
971                         i2c_smbus_write_byte_data(client,
972                                                   RX8025_REG_CTRL2 << 4 | 0x08,
973                                                   ds1307->regs[1]);
974                         dev_warn(&client->dev, "voltage drop detected\n");
975                 }
976 
977                 /* make sure we are running in 24hour mode */
978                 if (!(ds1307->regs[0] & RX8025_BIT_2412)) {
979                         u8 hour;
980 
981                         /* switch to 24 hour mode */
982                         i2c_smbus_write_byte_data(client,
983                                                   RX8025_REG_CTRL1 << 4 | 0x08,
984                                                   ds1307->regs[0] |
985                                                   RX8025_BIT_2412);
986 
987                         tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
988                                         RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
989                         if (tmp != 2) {
990                                 dev_dbg(&client->dev, "read error %d\n", tmp);
991                                 err = -EIO;
992                                 goto exit;
993                         }
994 
995                         /* correct hour */
996                         hour = bcd2bin(ds1307->regs[DS1307_REG_HOUR]);
997                         if (hour == 12)
998                                 hour = 0;
999                         if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1000                                 hour += 12;
1001 
1002                         i2c_smbus_write_byte_data(client,
1003                                                   DS1307_REG_HOUR << 4 | 0x08,
1004                                                   hour);
1005                 }
1006                 break;
1007         case ds_1388:
1008                 ds1307->offset = 1; /* Seconds starts at 1 */
1009                 break;
1010         case mcp794xx:
1011                 rtc_ops = &mcp794xx_rtc_ops;
1012                 if (ds1307->client->irq > 0 && chip->alarm) {
1013                         irq_handler = mcp794xx_irq;
1014                         want_irq = true;
1015                 }
1016                 break;
1017         default:
1018                 break;
1019         }
1020 
1021 read_rtc:
1022         /* read RTC registers */
1023         tmp = ds1307->read_block_data(ds1307->client, ds1307->offset, 8, buf);
1024         if (tmp != 8) {
1025                 dev_dbg(&client->dev, "read error %d\n", tmp);
1026                 err = -EIO;
1027                 goto exit;
1028         }
1029 
1030         /*
1031          * minimal sanity checking; some chips (like DS1340) don't
1032          * specify the extra bits as must-be-zero, but there are
1033          * still a few values that are clearly out-of-range.
1034          */
1035         tmp = ds1307->regs[DS1307_REG_SECS];
1036         switch (ds1307->type) {
1037         case ds_1307:
1038         case m41t00:
1039                 /* clock halted?  turn it on, so clock can tick. */
1040                 if (tmp & DS1307_BIT_CH) {
1041                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
1042                         dev_warn(&client->dev, "SET TIME!\n");
1043                         goto read_rtc;
1044                 }
1045                 break;
1046         case ds_1338:
1047                 /* clock halted?  turn it on, so clock can tick. */
1048                 if (tmp & DS1307_BIT_CH)
1049                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
1050 
1051                 /* oscillator fault?  clear flag, and warn */
1052                 if (ds1307->regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
1053                         i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL,
1054                                         ds1307->regs[DS1307_REG_CONTROL]
1055                                         & ~DS1338_BIT_OSF);
1056                         dev_warn(&client->dev, "SET TIME!\n");
1057                         goto read_rtc;
1058                 }
1059                 break;
1060         case ds_1340:
1061                 /* clock halted?  turn it on, so clock can tick. */
1062                 if (tmp & DS1340_BIT_nEOSC)
1063                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
1064 
1065                 tmp = i2c_smbus_read_byte_data(client, DS1340_REG_FLAG);
1066                 if (tmp < 0) {
1067                         dev_dbg(&client->dev, "read error %d\n", tmp);
1068                         err = -EIO;
1069                         goto exit;
1070                 }
1071 
1072                 /* oscillator fault?  clear flag, and warn */
1073                 if (tmp & DS1340_BIT_OSF) {
1074                         i2c_smbus_write_byte_data(client, DS1340_REG_FLAG, 0);
1075                         dev_warn(&client->dev, "SET TIME!\n");
1076                 }
1077                 break;
1078         case mcp794xx:
1079                 /* make sure that the backup battery is enabled */
1080                 if (!(ds1307->regs[DS1307_REG_WDAY] & MCP794XX_BIT_VBATEN)) {
1081                         i2c_smbus_write_byte_data(client, DS1307_REG_WDAY,
1082                                         ds1307->regs[DS1307_REG_WDAY]
1083                                         | MCP794XX_BIT_VBATEN);
1084                 }
1085 
1086                 /* clock halted?  turn it on, so clock can tick. */
1087                 if (!(tmp & MCP794XX_BIT_ST)) {
1088                         i2c_smbus_write_byte_data(client, DS1307_REG_SECS,
1089                                         MCP794XX_BIT_ST);
1090                         dev_warn(&client->dev, "SET TIME!\n");
1091                         goto read_rtc;
1092                 }
1093 
1094                 break;
1095         default:
1096                 break;
1097         }
1098 
1099         tmp = ds1307->regs[DS1307_REG_HOUR];
1100         switch (ds1307->type) {
1101         case ds_1340:
1102         case m41t00:
1103                 /*
1104                  * NOTE: ignores century bits; fix before deploying
1105                  * systems that will run through year 2100.
1106                  */
1107                 break;
1108         case rx_8025:
1109                 break;
1110         default:
1111                 if (!(tmp & DS1307_BIT_12HR))
1112                         break;
1113 
1114                 /*
1115                  * Be sure we're in 24 hour mode.  Multi-master systems
1116                  * take note...
1117                  */
1118                 tmp = bcd2bin(tmp & 0x1f);
1119                 if (tmp == 12)
1120                         tmp = 0;
1121                 if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
1122                         tmp += 12;
1123                 i2c_smbus_write_byte_data(client,
1124                                 ds1307->offset + DS1307_REG_HOUR,
1125                                 bin2bcd(tmp));
1126         }
1127 
1128         if (want_irq) {
1129                 device_set_wakeup_capable(&client->dev, true);
1130                 set_bit(HAS_ALARM, &ds1307->flags);
1131         }
1132         ds1307->rtc = devm_rtc_device_register(&client->dev, client->name,
1133                                 rtc_ops, THIS_MODULE);
1134         if (IS_ERR(ds1307->rtc)) {
1135                 return PTR_ERR(ds1307->rtc);
1136         }
1137 
1138         if (want_irq) {
1139                 err = devm_request_threaded_irq(&client->dev,
1140                                                 client->irq, NULL, irq_handler,
1141                                                 IRQF_SHARED | IRQF_ONESHOT,
1142                                                 ds1307->rtc->name, client);
1143                 if (err) {
1144                         client->irq = 0;
1145                         device_set_wakeup_capable(&client->dev, false);
1146                         clear_bit(HAS_ALARM, &ds1307->flags);
1147                         dev_err(&client->dev, "unable to request IRQ!\n");
1148                 } else
1149                         dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
1150         }
1151 
1152         if (chip->nvram_size) {
1153 
1154                 ds1307->nvram = devm_kzalloc(&client->dev,
1155                                         sizeof(struct bin_attribute),
1156                                         GFP_KERNEL);
1157                 if (!ds1307->nvram) {
1158                         dev_err(&client->dev, "cannot allocate memory for nvram sysfs\n");
1159                 } else {
1160 
1161                         ds1307->nvram->attr.name = "nvram";
1162                         ds1307->nvram->attr.mode = S_IRUGO | S_IWUSR;
1163 
1164                         sysfs_bin_attr_init(ds1307->nvram);
1165 
1166                         ds1307->nvram->read = ds1307_nvram_read;
1167                         ds1307->nvram->write = ds1307_nvram_write;
1168                         ds1307->nvram->size = chip->nvram_size;
1169                         ds1307->nvram_offset = chip->nvram_offset;
1170 
1171                         err = sysfs_create_bin_file(&client->dev.kobj,
1172                                                     ds1307->nvram);
1173                         if (err) {
1174                                 dev_err(&client->dev,
1175                                         "unable to create sysfs file: %s\n",
1176                                         ds1307->nvram->attr.name);
1177                         } else {
1178                                 set_bit(HAS_NVRAM, &ds1307->flags);
1179                                 dev_info(&client->dev, "%zu bytes nvram\n",
1180                                          ds1307->nvram->size);
1181                         }
1182                 }
1183         }
1184 
1185         return 0;
1186 
1187 exit:
1188         return err;
1189 }
1190 
1191 static int ds1307_remove(struct i2c_client *client)
1192 {
1193         struct ds1307 *ds1307 = i2c_get_clientdata(client);
1194 
1195         if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
1196                 sysfs_remove_bin_file(&client->dev.kobj, ds1307->nvram);
1197 
1198         return 0;
1199 }
1200 
1201 static struct i2c_driver ds1307_driver = {
1202         .driver = {
1203                 .name   = "rtc-ds1307",
1204         },
1205         .probe          = ds1307_probe,
1206         .remove         = ds1307_remove,
1207         .id_table       = ds1307_id,
1208 };
1209 
1210 module_i2c_driver(ds1307_driver);
1211 
1212 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
1213 MODULE_LICENSE("GPL");
1214 

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