xref: /openbmc/linux/drivers/rtc/rtc-ds1685.c (revision da2ef666)
1 /*
2  * An rtc driver for the Dallas/Maxim DS1685/DS1687 and related real-time
3  * chips.
4  *
5  * Copyright (C) 2011-2014 Joshua Kinard <kumba@gentoo.org>.
6  * Copyright (C) 2009 Matthias Fuchs <matthias.fuchs@esd-electronics.com>.
7  *
8  * References:
9  *    DS1685/DS1687 3V/5V Real-Time Clocks, 19-5215, Rev 4/10.
10  *    DS17x85/DS17x87 3V/5V Real-Time Clocks, 19-5222, Rev 4/10.
11  *    DS1689/DS1693 3V/5V Serialized Real-Time Clocks, Rev 112105.
12  *    Application Note 90, Using the Multiplex Bus RTC Extended Features.
13  *
14  * This program is free software; you can redistribute it and/or modify
15  * it under the terms of the GNU General Public License version 2 as
16  * published by the Free Software Foundation.
17  */
18 
19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20 
21 #include <linux/bcd.h>
22 #include <linux/delay.h>
23 #include <linux/io.h>
24 #include <linux/module.h>
25 #include <linux/platform_device.h>
26 #include <linux/rtc.h>
27 #include <linux/workqueue.h>
28 
29 #include <linux/rtc/ds1685.h>
30 
31 #ifdef CONFIG_PROC_FS
32 #include <linux/proc_fs.h>
33 #endif
34 
35 
36 /* ----------------------------------------------------------------------- */
37 /* Standard read/write functions if platform does not provide overrides */
38 
39 /**
40  * ds1685_read - read a value from an rtc register.
41  * @rtc: pointer to the ds1685 rtc structure.
42  * @reg: the register address to read.
43  */
44 static u8
45 ds1685_read(struct ds1685_priv *rtc, int reg)
46 {
47 	return readb((u8 __iomem *)rtc->regs +
48 		     (reg * rtc->regstep));
49 }
50 
51 /**
52  * ds1685_write - write a value to an rtc register.
53  * @rtc: pointer to the ds1685 rtc structure.
54  * @reg: the register address to write.
55  * @value: value to write to the register.
56  */
57 static void
58 ds1685_write(struct ds1685_priv *rtc, int reg, u8 value)
59 {
60 	writeb(value, ((u8 __iomem *)rtc->regs +
61 		       (reg * rtc->regstep)));
62 }
63 /* ----------------------------------------------------------------------- */
64 
65 
66 /* ----------------------------------------------------------------------- */
67 /* Inlined functions */
68 
69 /**
70  * ds1685_rtc_bcd2bin - bcd2bin wrapper in case platform doesn't support BCD.
71  * @rtc: pointer to the ds1685 rtc structure.
72  * @val: u8 time value to consider converting.
73  * @bcd_mask: u8 mask value if BCD mode is used.
74  * @bin_mask: u8 mask value if BIN mode is used.
75  *
76  * Returns the value, converted to BIN if originally in BCD and bcd_mode TRUE.
77  */
78 static inline u8
79 ds1685_rtc_bcd2bin(struct ds1685_priv *rtc, u8 val, u8 bcd_mask, u8 bin_mask)
80 {
81 	if (rtc->bcd_mode)
82 		return (bcd2bin(val) & bcd_mask);
83 
84 	return (val & bin_mask);
85 }
86 
87 /**
88  * ds1685_rtc_bin2bcd - bin2bcd wrapper in case platform doesn't support BCD.
89  * @rtc: pointer to the ds1685 rtc structure.
90  * @val: u8 time value to consider converting.
91  * @bin_mask: u8 mask value if BIN mode is used.
92  * @bcd_mask: u8 mask value if BCD mode is used.
93  *
94  * Returns the value, converted to BCD if originally in BIN and bcd_mode TRUE.
95  */
96 static inline u8
97 ds1685_rtc_bin2bcd(struct ds1685_priv *rtc, u8 val, u8 bin_mask, u8 bcd_mask)
98 {
99 	if (rtc->bcd_mode)
100 		return (bin2bcd(val) & bcd_mask);
101 
102 	return (val & bin_mask);
103 }
104 
105 /**
106  * s1685_rtc_check_mday - check validity of the day of month.
107  * @rtc: pointer to the ds1685 rtc structure.
108  * @mday: day of month.
109  *
110  * Returns -EDOM if the day of month is not within 1..31 range.
111  */
112 static inline int
113 ds1685_rtc_check_mday(struct ds1685_priv *rtc, u8 mday)
114 {
115 	if (rtc->bcd_mode) {
116 		if (mday < 0x01 || mday > 0x31 || (mday & 0x0f) > 0x09)
117 			return -EDOM;
118 	} else {
119 		if (mday < 1 || mday > 31)
120 			return -EDOM;
121 	}
122 	return 0;
123 }
124 
125 /**
126  * ds1685_rtc_switch_to_bank0 - switch the rtc to bank 0.
127  * @rtc: pointer to the ds1685 rtc structure.
128  */
129 static inline void
130 ds1685_rtc_switch_to_bank0(struct ds1685_priv *rtc)
131 {
132 	rtc->write(rtc, RTC_CTRL_A,
133 		   (rtc->read(rtc, RTC_CTRL_A) & ~(RTC_CTRL_A_DV0)));
134 }
135 
136 /**
137  * ds1685_rtc_switch_to_bank1 - switch the rtc to bank 1.
138  * @rtc: pointer to the ds1685 rtc structure.
139  */
140 static inline void
141 ds1685_rtc_switch_to_bank1(struct ds1685_priv *rtc)
142 {
143 	rtc->write(rtc, RTC_CTRL_A,
144 		   (rtc->read(rtc, RTC_CTRL_A) | RTC_CTRL_A_DV0));
145 }
146 
147 /**
148  * ds1685_rtc_begin_data_access - prepare the rtc for data access.
149  * @rtc: pointer to the ds1685 rtc structure.
150  *
151  * This takes several steps to prepare the rtc for access to get/set time
152  * and alarm values from the rtc registers:
153  *  - Sets the SET bit in Control Register B.
154  *  - Reads Ext Control Register 4A and checks the INCR bit.
155  *  - If INCR is active, a short delay is added before Ext Control Register 4A
156  *    is read again in a loop until INCR is inactive.
157  *  - Switches the rtc to bank 1.  This allows access to all relevant
158  *    data for normal rtc operation, as bank 0 contains only the nvram.
159  */
160 static inline void
161 ds1685_rtc_begin_data_access(struct ds1685_priv *rtc)
162 {
163 	/* Set the SET bit in Ctrl B */
164 	rtc->write(rtc, RTC_CTRL_B,
165 		   (rtc->read(rtc, RTC_CTRL_B) | RTC_CTRL_B_SET));
166 
167 	/* Read Ext Ctrl 4A and check the INCR bit to avoid a lockout. */
168 	while (rtc->read(rtc, RTC_EXT_CTRL_4A) & RTC_CTRL_4A_INCR)
169 		cpu_relax();
170 
171 	/* Switch to Bank 1 */
172 	ds1685_rtc_switch_to_bank1(rtc);
173 }
174 
175 /**
176  * ds1685_rtc_end_data_access - end data access on the rtc.
177  * @rtc: pointer to the ds1685 rtc structure.
178  *
179  * This ends what was started by ds1685_rtc_begin_data_access:
180  *  - Switches the rtc back to bank 0.
181  *  - Clears the SET bit in Control Register B.
182  */
183 static inline void
184 ds1685_rtc_end_data_access(struct ds1685_priv *rtc)
185 {
186 	/* Switch back to Bank 0 */
187 	ds1685_rtc_switch_to_bank1(rtc);
188 
189 	/* Clear the SET bit in Ctrl B */
190 	rtc->write(rtc, RTC_CTRL_B,
191 		   (rtc->read(rtc, RTC_CTRL_B) & ~(RTC_CTRL_B_SET)));
192 }
193 
194 /**
195  * ds1685_rtc_begin_ctrl_access - prepare the rtc for ctrl access.
196  * @rtc: pointer to the ds1685 rtc structure.
197  * @flags: irq flags variable for spin_lock_irqsave.
198  *
199  * This takes several steps to prepare the rtc for access to read just the
200  * control registers:
201  *  - Sets a spinlock on the rtc IRQ.
202  *  - Switches the rtc to bank 1.  This allows access to the two extended
203  *    control registers.
204  *
205  * Only use this where you are certain another lock will not be held.
206  */
207 static inline void
208 ds1685_rtc_begin_ctrl_access(struct ds1685_priv *rtc, unsigned long *flags)
209 {
210 	spin_lock_irqsave(&rtc->lock, *flags);
211 	ds1685_rtc_switch_to_bank1(rtc);
212 }
213 
214 /**
215  * ds1685_rtc_end_ctrl_access - end ctrl access on the rtc.
216  * @rtc: pointer to the ds1685 rtc structure.
217  * @flags: irq flags variable for spin_unlock_irqrestore.
218  *
219  * This ends what was started by ds1685_rtc_begin_ctrl_access:
220  *  - Switches the rtc back to bank 0.
221  *  - Unsets the spinlock on the rtc IRQ.
222  */
223 static inline void
224 ds1685_rtc_end_ctrl_access(struct ds1685_priv *rtc, unsigned long flags)
225 {
226 	ds1685_rtc_switch_to_bank0(rtc);
227 	spin_unlock_irqrestore(&rtc->lock, flags);
228 }
229 
230 /**
231  * ds1685_rtc_get_ssn - retrieve the silicon serial number.
232  * @rtc: pointer to the ds1685 rtc structure.
233  * @ssn: u8 array to hold the bits of the silicon serial number.
234  *
235  * This number starts at 0x40, and is 8-bytes long, ending at 0x47. The
236  * first byte is the model number, the next six bytes are the serial number
237  * digits, and the final byte is a CRC check byte.  Together, they form the
238  * silicon serial number.
239  *
240  * These values are stored in bank1, so ds1685_rtc_switch_to_bank1 must be
241  * called first before calling this function, else data will be read out of
242  * the bank0 NVRAM.  Be sure to call ds1685_rtc_switch_to_bank0 when done.
243  */
244 static inline void
245 ds1685_rtc_get_ssn(struct ds1685_priv *rtc, u8 *ssn)
246 {
247 	ssn[0] = rtc->read(rtc, RTC_BANK1_SSN_MODEL);
248 	ssn[1] = rtc->read(rtc, RTC_BANK1_SSN_BYTE_1);
249 	ssn[2] = rtc->read(rtc, RTC_BANK1_SSN_BYTE_2);
250 	ssn[3] = rtc->read(rtc, RTC_BANK1_SSN_BYTE_3);
251 	ssn[4] = rtc->read(rtc, RTC_BANK1_SSN_BYTE_4);
252 	ssn[5] = rtc->read(rtc, RTC_BANK1_SSN_BYTE_5);
253 	ssn[6] = rtc->read(rtc, RTC_BANK1_SSN_BYTE_6);
254 	ssn[7] = rtc->read(rtc, RTC_BANK1_SSN_CRC);
255 }
256 /* ----------------------------------------------------------------------- */
257 
258 
259 /* ----------------------------------------------------------------------- */
260 /* Read/Set Time & Alarm functions */
261 
262 /**
263  * ds1685_rtc_read_time - reads the time registers.
264  * @dev: pointer to device structure.
265  * @tm: pointer to rtc_time structure.
266  */
267 static int
268 ds1685_rtc_read_time(struct device *dev, struct rtc_time *tm)
269 {
270 	struct ds1685_priv *rtc = dev_get_drvdata(dev);
271 	u8 ctrlb, century;
272 	u8 seconds, minutes, hours, wday, mday, month, years;
273 
274 	/* Fetch the time info from the RTC registers. */
275 	ds1685_rtc_begin_data_access(rtc);
276 	seconds = rtc->read(rtc, RTC_SECS);
277 	minutes = rtc->read(rtc, RTC_MINS);
278 	hours   = rtc->read(rtc, RTC_HRS);
279 	wday    = rtc->read(rtc, RTC_WDAY);
280 	mday    = rtc->read(rtc, RTC_MDAY);
281 	month   = rtc->read(rtc, RTC_MONTH);
282 	years   = rtc->read(rtc, RTC_YEAR);
283 	century = rtc->read(rtc, RTC_CENTURY);
284 	ctrlb   = rtc->read(rtc, RTC_CTRL_B);
285 	ds1685_rtc_end_data_access(rtc);
286 
287 	/* bcd2bin if needed, perform fixups, and store to rtc_time. */
288 	years        = ds1685_rtc_bcd2bin(rtc, years, RTC_YEAR_BCD_MASK,
289 					  RTC_YEAR_BIN_MASK);
290 	century      = ds1685_rtc_bcd2bin(rtc, century, RTC_CENTURY_MASK,
291 					  RTC_CENTURY_MASK);
292 	tm->tm_sec   = ds1685_rtc_bcd2bin(rtc, seconds, RTC_SECS_BCD_MASK,
293 					  RTC_SECS_BIN_MASK);
294 	tm->tm_min   = ds1685_rtc_bcd2bin(rtc, minutes, RTC_MINS_BCD_MASK,
295 					  RTC_MINS_BIN_MASK);
296 	tm->tm_hour  = ds1685_rtc_bcd2bin(rtc, hours, RTC_HRS_24_BCD_MASK,
297 					  RTC_HRS_24_BIN_MASK);
298 	tm->tm_wday  = (ds1685_rtc_bcd2bin(rtc, wday, RTC_WDAY_MASK,
299 					   RTC_WDAY_MASK) - 1);
300 	tm->tm_mday  = ds1685_rtc_bcd2bin(rtc, mday, RTC_MDAY_BCD_MASK,
301 					  RTC_MDAY_BIN_MASK);
302 	tm->tm_mon   = (ds1685_rtc_bcd2bin(rtc, month, RTC_MONTH_BCD_MASK,
303 					   RTC_MONTH_BIN_MASK) - 1);
304 	tm->tm_year  = ((years + (century * 100)) - 1900);
305 	tm->tm_yday  = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
306 	tm->tm_isdst = 0; /* RTC has hardcoded timezone, so don't use. */
307 
308 	return 0;
309 }
310 
311 /**
312  * ds1685_rtc_set_time - sets the time registers.
313  * @dev: pointer to device structure.
314  * @tm: pointer to rtc_time structure.
315  */
316 static int
317 ds1685_rtc_set_time(struct device *dev, struct rtc_time *tm)
318 {
319 	struct ds1685_priv *rtc = dev_get_drvdata(dev);
320 	u8 ctrlb, seconds, minutes, hours, wday, mday, month, years, century;
321 
322 	/* Fetch the time info from rtc_time. */
323 	seconds = ds1685_rtc_bin2bcd(rtc, tm->tm_sec, RTC_SECS_BIN_MASK,
324 				     RTC_SECS_BCD_MASK);
325 	minutes = ds1685_rtc_bin2bcd(rtc, tm->tm_min, RTC_MINS_BIN_MASK,
326 				     RTC_MINS_BCD_MASK);
327 	hours   = ds1685_rtc_bin2bcd(rtc, tm->tm_hour, RTC_HRS_24_BIN_MASK,
328 				     RTC_HRS_24_BCD_MASK);
329 	wday    = ds1685_rtc_bin2bcd(rtc, (tm->tm_wday + 1), RTC_WDAY_MASK,
330 				     RTC_WDAY_MASK);
331 	mday    = ds1685_rtc_bin2bcd(rtc, tm->tm_mday, RTC_MDAY_BIN_MASK,
332 				     RTC_MDAY_BCD_MASK);
333 	month   = ds1685_rtc_bin2bcd(rtc, (tm->tm_mon + 1), RTC_MONTH_BIN_MASK,
334 				     RTC_MONTH_BCD_MASK);
335 	years   = ds1685_rtc_bin2bcd(rtc, (tm->tm_year % 100),
336 				     RTC_YEAR_BIN_MASK, RTC_YEAR_BCD_MASK);
337 	century = ds1685_rtc_bin2bcd(rtc, ((tm->tm_year + 1900) / 100),
338 				     RTC_CENTURY_MASK, RTC_CENTURY_MASK);
339 
340 	/*
341 	 * Perform Sanity Checks:
342 	 *   - Months: !> 12, Month Day != 0.
343 	 *   - Month Day !> Max days in current month.
344 	 *   - Hours !>= 24, Mins !>= 60, Secs !>= 60, & Weekday !> 7.
345 	 */
346 	if ((tm->tm_mon > 11) || (mday == 0))
347 		return -EDOM;
348 
349 	if (tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year))
350 		return -EDOM;
351 
352 	if ((tm->tm_hour >= 24) || (tm->tm_min >= 60) ||
353 	    (tm->tm_sec >= 60)  || (wday > 7))
354 		return -EDOM;
355 
356 	/*
357 	 * Set the data mode to use and store the time values in the
358 	 * RTC registers.
359 	 */
360 	ds1685_rtc_begin_data_access(rtc);
361 	ctrlb = rtc->read(rtc, RTC_CTRL_B);
362 	if (rtc->bcd_mode)
363 		ctrlb &= ~(RTC_CTRL_B_DM);
364 	else
365 		ctrlb |= RTC_CTRL_B_DM;
366 	rtc->write(rtc, RTC_CTRL_B, ctrlb);
367 	rtc->write(rtc, RTC_SECS, seconds);
368 	rtc->write(rtc, RTC_MINS, minutes);
369 	rtc->write(rtc, RTC_HRS, hours);
370 	rtc->write(rtc, RTC_WDAY, wday);
371 	rtc->write(rtc, RTC_MDAY, mday);
372 	rtc->write(rtc, RTC_MONTH, month);
373 	rtc->write(rtc, RTC_YEAR, years);
374 	rtc->write(rtc, RTC_CENTURY, century);
375 	ds1685_rtc_end_data_access(rtc);
376 
377 	return 0;
378 }
379 
380 /**
381  * ds1685_rtc_read_alarm - reads the alarm registers.
382  * @dev: pointer to device structure.
383  * @alrm: pointer to rtc_wkalrm structure.
384  *
385  * There are three primary alarm registers: seconds, minutes, and hours.
386  * A fourth alarm register for the month date is also available in bank1 for
387  * kickstart/wakeup features.  The DS1685/DS1687 manual states that a
388  * "don't care" value ranging from 0xc0 to 0xff may be written into one or
389  * more of the three alarm bytes to act as a wildcard value.  The fourth
390  * byte doesn't support a "don't care" value.
391  */
392 static int
393 ds1685_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
394 {
395 	struct ds1685_priv *rtc = dev_get_drvdata(dev);
396 	u8 seconds, minutes, hours, mday, ctrlb, ctrlc;
397 	int ret;
398 
399 	/* Fetch the alarm info from the RTC alarm registers. */
400 	ds1685_rtc_begin_data_access(rtc);
401 	seconds	= rtc->read(rtc, RTC_SECS_ALARM);
402 	minutes	= rtc->read(rtc, RTC_MINS_ALARM);
403 	hours	= rtc->read(rtc, RTC_HRS_ALARM);
404 	mday	= rtc->read(rtc, RTC_MDAY_ALARM);
405 	ctrlb	= rtc->read(rtc, RTC_CTRL_B);
406 	ctrlc	= rtc->read(rtc, RTC_CTRL_C);
407 	ds1685_rtc_end_data_access(rtc);
408 
409 	/* Check the month date for validity. */
410 	ret = ds1685_rtc_check_mday(rtc, mday);
411 	if (ret)
412 		return ret;
413 
414 	/*
415 	 * Check the three alarm bytes.
416 	 *
417 	 * The Linux RTC system doesn't support the "don't care" capability
418 	 * of this RTC chip.  We check for it anyways in case support is
419 	 * added in the future and only assign when we care.
420 	 */
421 	if (likely(seconds < 0xc0))
422 		alrm->time.tm_sec = ds1685_rtc_bcd2bin(rtc, seconds,
423 						       RTC_SECS_BCD_MASK,
424 						       RTC_SECS_BIN_MASK);
425 
426 	if (likely(minutes < 0xc0))
427 		alrm->time.tm_min = ds1685_rtc_bcd2bin(rtc, minutes,
428 						       RTC_MINS_BCD_MASK,
429 						       RTC_MINS_BIN_MASK);
430 
431 	if (likely(hours < 0xc0))
432 		alrm->time.tm_hour = ds1685_rtc_bcd2bin(rtc, hours,
433 							RTC_HRS_24_BCD_MASK,
434 							RTC_HRS_24_BIN_MASK);
435 
436 	/* Write the data to rtc_wkalrm. */
437 	alrm->time.tm_mday = ds1685_rtc_bcd2bin(rtc, mday, RTC_MDAY_BCD_MASK,
438 						RTC_MDAY_BIN_MASK);
439 	alrm->enabled = !!(ctrlb & RTC_CTRL_B_AIE);
440 	alrm->pending = !!(ctrlc & RTC_CTRL_C_AF);
441 
442 	return 0;
443 }
444 
445 /**
446  * ds1685_rtc_set_alarm - sets the alarm in registers.
447  * @dev: pointer to device structure.
448  * @alrm: pointer to rtc_wkalrm structure.
449  */
450 static int
451 ds1685_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
452 {
453 	struct ds1685_priv *rtc = dev_get_drvdata(dev);
454 	u8 ctrlb, seconds, minutes, hours, mday;
455 	int ret;
456 
457 	/* Fetch the alarm info and convert to BCD. */
458 	seconds	= ds1685_rtc_bin2bcd(rtc, alrm->time.tm_sec,
459 				     RTC_SECS_BIN_MASK,
460 				     RTC_SECS_BCD_MASK);
461 	minutes	= ds1685_rtc_bin2bcd(rtc, alrm->time.tm_min,
462 				     RTC_MINS_BIN_MASK,
463 				     RTC_MINS_BCD_MASK);
464 	hours	= ds1685_rtc_bin2bcd(rtc, alrm->time.tm_hour,
465 				     RTC_HRS_24_BIN_MASK,
466 				     RTC_HRS_24_BCD_MASK);
467 	mday	= ds1685_rtc_bin2bcd(rtc, alrm->time.tm_mday,
468 				     RTC_MDAY_BIN_MASK,
469 				     RTC_MDAY_BCD_MASK);
470 
471 	/* Check the month date for validity. */
472 	ret = ds1685_rtc_check_mday(rtc, mday);
473 	if (ret)
474 		return ret;
475 
476 	/*
477 	 * Check the three alarm bytes.
478 	 *
479 	 * The Linux RTC system doesn't support the "don't care" capability
480 	 * of this RTC chip because rtc_valid_tm tries to validate every
481 	 * field, and we only support four fields.  We put the support
482 	 * here anyways for the future.
483 	 */
484 	if (unlikely(seconds >= 0xc0))
485 		seconds = 0xff;
486 
487 	if (unlikely(minutes >= 0xc0))
488 		minutes = 0xff;
489 
490 	if (unlikely(hours >= 0xc0))
491 		hours = 0xff;
492 
493 	alrm->time.tm_mon	= -1;
494 	alrm->time.tm_year	= -1;
495 	alrm->time.tm_wday	= -1;
496 	alrm->time.tm_yday	= -1;
497 	alrm->time.tm_isdst	= -1;
498 
499 	/* Disable the alarm interrupt first. */
500 	ds1685_rtc_begin_data_access(rtc);
501 	ctrlb = rtc->read(rtc, RTC_CTRL_B);
502 	rtc->write(rtc, RTC_CTRL_B, (ctrlb & ~(RTC_CTRL_B_AIE)));
503 
504 	/* Read ctrlc to clear RTC_CTRL_C_AF. */
505 	rtc->read(rtc, RTC_CTRL_C);
506 
507 	/*
508 	 * Set the data mode to use and store the time values in the
509 	 * RTC registers.
510 	 */
511 	ctrlb = rtc->read(rtc, RTC_CTRL_B);
512 	if (rtc->bcd_mode)
513 		ctrlb &= ~(RTC_CTRL_B_DM);
514 	else
515 		ctrlb |= RTC_CTRL_B_DM;
516 	rtc->write(rtc, RTC_CTRL_B, ctrlb);
517 	rtc->write(rtc, RTC_SECS_ALARM, seconds);
518 	rtc->write(rtc, RTC_MINS_ALARM, minutes);
519 	rtc->write(rtc, RTC_HRS_ALARM, hours);
520 	rtc->write(rtc, RTC_MDAY_ALARM, mday);
521 
522 	/* Re-enable the alarm if needed. */
523 	if (alrm->enabled) {
524 		ctrlb = rtc->read(rtc, RTC_CTRL_B);
525 		ctrlb |= RTC_CTRL_B_AIE;
526 		rtc->write(rtc, RTC_CTRL_B, ctrlb);
527 	}
528 
529 	/* Done! */
530 	ds1685_rtc_end_data_access(rtc);
531 
532 	return 0;
533 }
534 /* ----------------------------------------------------------------------- */
535 
536 
537 /* ----------------------------------------------------------------------- */
538 /* /dev/rtcX Interface functions */
539 
540 /**
541  * ds1685_rtc_alarm_irq_enable - replaces ioctl() RTC_AIE on/off.
542  * @dev: pointer to device structure.
543  * @enabled: flag indicating whether to enable or disable.
544  */
545 static int
546 ds1685_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
547 {
548 	struct ds1685_priv *rtc = dev_get_drvdata(dev);
549 	unsigned long flags = 0;
550 
551 	/* Enable/disable the Alarm IRQ-Enable flag. */
552 	spin_lock_irqsave(&rtc->lock, flags);
553 
554 	/* Flip the requisite interrupt-enable bit. */
555 	if (enabled)
556 		rtc->write(rtc, RTC_CTRL_B, (rtc->read(rtc, RTC_CTRL_B) |
557 					     RTC_CTRL_B_AIE));
558 	else
559 		rtc->write(rtc, RTC_CTRL_B, (rtc->read(rtc, RTC_CTRL_B) &
560 					     ~(RTC_CTRL_B_AIE)));
561 
562 	/* Read Control C to clear all the flag bits. */
563 	rtc->read(rtc, RTC_CTRL_C);
564 	spin_unlock_irqrestore(&rtc->lock, flags);
565 
566 	return 0;
567 }
568 /* ----------------------------------------------------------------------- */
569 
570 
571 /* ----------------------------------------------------------------------- */
572 /* IRQ handler & workqueue. */
573 
574 /**
575  * ds1685_rtc_irq_handler - IRQ handler.
576  * @irq: IRQ number.
577  * @dev_id: platform device pointer.
578  */
579 static irqreturn_t
580 ds1685_rtc_irq_handler(int irq, void *dev_id)
581 {
582 	struct platform_device *pdev = dev_id;
583 	struct ds1685_priv *rtc = platform_get_drvdata(pdev);
584 	u8 ctrlb, ctrlc;
585 	unsigned long events = 0;
586 	u8 num_irqs = 0;
587 
588 	/* Abort early if the device isn't ready yet (i.e., DEBUG_SHIRQ). */
589 	if (unlikely(!rtc))
590 		return IRQ_HANDLED;
591 
592 	/* Ctrlb holds the interrupt-enable bits and ctrlc the flag bits. */
593 	spin_lock(&rtc->lock);
594 	ctrlb = rtc->read(rtc, RTC_CTRL_B);
595 	ctrlc = rtc->read(rtc, RTC_CTRL_C);
596 
597 	/* Is the IRQF bit set? */
598 	if (likely(ctrlc & RTC_CTRL_C_IRQF)) {
599 		/*
600 		 * We need to determine if it was one of the standard
601 		 * events: PF, AF, or UF.  If so, we handle them and
602 		 * update the RTC core.
603 		 */
604 		if (likely(ctrlc & RTC_CTRL_B_PAU_MASK)) {
605 			events = RTC_IRQF;
606 
607 			/* Check for a periodic interrupt. */
608 			if ((ctrlb & RTC_CTRL_B_PIE) &&
609 			    (ctrlc & RTC_CTRL_C_PF)) {
610 				events |= RTC_PF;
611 				num_irqs++;
612 			}
613 
614 			/* Check for an alarm interrupt. */
615 			if ((ctrlb & RTC_CTRL_B_AIE) &&
616 			    (ctrlc & RTC_CTRL_C_AF)) {
617 				events |= RTC_AF;
618 				num_irqs++;
619 			}
620 
621 			/* Check for an update interrupt. */
622 			if ((ctrlb & RTC_CTRL_B_UIE) &&
623 			    (ctrlc & RTC_CTRL_C_UF)) {
624 				events |= RTC_UF;
625 				num_irqs++;
626 			}
627 
628 			rtc_update_irq(rtc->dev, num_irqs, events);
629 		} else {
630 			/*
631 			 * One of the "extended" interrupts was received that
632 			 * is not recognized by the RTC core.  These need to
633 			 * be handled in task context as they can call other
634 			 * functions and the time spent in irq context needs
635 			 * to be minimized.  Schedule them into a workqueue
636 			 * and inform the RTC core that the IRQs were handled.
637 			 */
638 			spin_unlock(&rtc->lock);
639 			schedule_work(&rtc->work);
640 			rtc_update_irq(rtc->dev, 0, 0);
641 			return IRQ_HANDLED;
642 		}
643 	}
644 	spin_unlock(&rtc->lock);
645 
646 	return events ? IRQ_HANDLED : IRQ_NONE;
647 }
648 
649 /**
650  * ds1685_rtc_work_queue - work queue handler.
651  * @work: work_struct containing data to work on in task context.
652  */
653 static void
654 ds1685_rtc_work_queue(struct work_struct *work)
655 {
656 	struct ds1685_priv *rtc = container_of(work,
657 					       struct ds1685_priv, work);
658 	struct platform_device *pdev = to_platform_device(&rtc->dev->dev);
659 	struct mutex *rtc_mutex = &rtc->dev->ops_lock;
660 	u8 ctrl4a, ctrl4b;
661 
662 	mutex_lock(rtc_mutex);
663 
664 	ds1685_rtc_switch_to_bank1(rtc);
665 	ctrl4a = rtc->read(rtc, RTC_EXT_CTRL_4A);
666 	ctrl4b = rtc->read(rtc, RTC_EXT_CTRL_4B);
667 
668 	/*
669 	 * Check for a kickstart interrupt. With Vcc applied, this
670 	 * typically means that the power button was pressed, so we
671 	 * begin the shutdown sequence.
672 	 */
673 	if ((ctrl4b & RTC_CTRL_4B_KSE) && (ctrl4a & RTC_CTRL_4A_KF)) {
674 		/* Briefly disable kickstarts to debounce button presses. */
675 		rtc->write(rtc, RTC_EXT_CTRL_4B,
676 			   (rtc->read(rtc, RTC_EXT_CTRL_4B) &
677 			    ~(RTC_CTRL_4B_KSE)));
678 
679 		/* Clear the kickstart flag. */
680 		rtc->write(rtc, RTC_EXT_CTRL_4A,
681 			   (ctrl4a & ~(RTC_CTRL_4A_KF)));
682 
683 
684 		/*
685 		 * Sleep 500ms before re-enabling kickstarts.  This allows
686 		 * adequate time to avoid reading signal jitter as additional
687 		 * button presses.
688 		 */
689 		msleep(500);
690 		rtc->write(rtc, RTC_EXT_CTRL_4B,
691 			   (rtc->read(rtc, RTC_EXT_CTRL_4B) |
692 			    RTC_CTRL_4B_KSE));
693 
694 		/* Call the platform pre-poweroff function. Else, shutdown. */
695 		if (rtc->prepare_poweroff != NULL)
696 			rtc->prepare_poweroff();
697 		else
698 			ds1685_rtc_poweroff(pdev);
699 	}
700 
701 	/*
702 	 * Check for a wake-up interrupt.  With Vcc applied, this is
703 	 * essentially a second alarm interrupt, except it takes into
704 	 * account the 'date' register in bank1 in addition to the
705 	 * standard three alarm registers.
706 	 */
707 	if ((ctrl4b & RTC_CTRL_4B_WIE) && (ctrl4a & RTC_CTRL_4A_WF)) {
708 		rtc->write(rtc, RTC_EXT_CTRL_4A,
709 			   (ctrl4a & ~(RTC_CTRL_4A_WF)));
710 
711 		/* Call the platform wake_alarm function if defined. */
712 		if (rtc->wake_alarm != NULL)
713 			rtc->wake_alarm();
714 		else
715 			dev_warn(&pdev->dev,
716 				 "Wake Alarm IRQ just occurred!\n");
717 	}
718 
719 	/*
720 	 * Check for a ram-clear interrupt.  This happens if RIE=1 and RF=0
721 	 * when RCE=1 in 4B.  This clears all NVRAM bytes in bank0 by setting
722 	 * each byte to a logic 1.  This has no effect on any extended
723 	 * NV-SRAM that might be present, nor on the time/calendar/alarm
724 	 * registers.  After a ram-clear is completed, there is a minimum
725 	 * recovery time of ~150ms in which all reads/writes are locked out.
726 	 * NOTE: A ram-clear can still occur if RCE=1 and RIE=0.  We cannot
727 	 * catch this scenario.
728 	 */
729 	if ((ctrl4b & RTC_CTRL_4B_RIE) && (ctrl4a & RTC_CTRL_4A_RF)) {
730 		rtc->write(rtc, RTC_EXT_CTRL_4A,
731 			   (ctrl4a & ~(RTC_CTRL_4A_RF)));
732 		msleep(150);
733 
734 		/* Call the platform post_ram_clear function if defined. */
735 		if (rtc->post_ram_clear != NULL)
736 			rtc->post_ram_clear();
737 		else
738 			dev_warn(&pdev->dev,
739 				 "RAM-Clear IRQ just occurred!\n");
740 	}
741 	ds1685_rtc_switch_to_bank0(rtc);
742 
743 	mutex_unlock(rtc_mutex);
744 }
745 /* ----------------------------------------------------------------------- */
746 
747 
748 /* ----------------------------------------------------------------------- */
749 /* ProcFS interface */
750 
751 #ifdef CONFIG_PROC_FS
752 #define NUM_REGS	6	/* Num of control registers. */
753 #define NUM_BITS	8	/* Num bits per register. */
754 #define NUM_SPACES	4	/* Num spaces between each bit. */
755 
756 /*
757  * Periodic Interrupt Rates.
758  */
759 static const char *ds1685_rtc_pirq_rate[16] = {
760 	"none", "3.90625ms", "7.8125ms", "0.122070ms", "0.244141ms",
761 	"0.488281ms", "0.9765625ms", "1.953125ms", "3.90625ms", "7.8125ms",
762 	"15.625ms", "31.25ms", "62.5ms", "125ms", "250ms", "500ms"
763 };
764 
765 /*
766  * Square-Wave Output Frequencies.
767  */
768 static const char *ds1685_rtc_sqw_freq[16] = {
769 	"none", "256Hz", "128Hz", "8192Hz", "4096Hz", "2048Hz", "1024Hz",
770 	"512Hz", "256Hz", "128Hz", "64Hz", "32Hz", "16Hz", "8Hz", "4Hz", "2Hz"
771 };
772 
773 #ifdef CONFIG_RTC_DS1685_PROC_REGS
774 /**
775  * ds1685_rtc_print_regs - helper function to print register values.
776  * @hex: hex byte to convert into binary bits.
777  * @dest: destination char array.
778  *
779  * This is basically a hex->binary function, just with extra spacing between
780  * the digits.  It only works on 1-byte values (8 bits).
781  */
782 static char*
783 ds1685_rtc_print_regs(u8 hex, char *dest)
784 {
785 	u32 i, j;
786 	char *tmp = dest;
787 
788 	for (i = 0; i < NUM_BITS; i++) {
789 		*tmp++ = ((hex & 0x80) != 0 ? '1' : '0');
790 		for (j = 0; j < NUM_SPACES; j++)
791 			*tmp++ = ' ';
792 		hex <<= 1;
793 	}
794 	*tmp++ = '\0';
795 
796 	return dest;
797 }
798 #endif
799 
800 /**
801  * ds1685_rtc_proc - procfs access function.
802  * @dev: pointer to device structure.
803  * @seq: pointer to seq_file structure.
804  */
805 static int
806 ds1685_rtc_proc(struct device *dev, struct seq_file *seq)
807 {
808 	struct platform_device *pdev = to_platform_device(dev);
809 	struct ds1685_priv *rtc = platform_get_drvdata(pdev);
810 	u8 ctrla, ctrlb, ctrlc, ctrld, ctrl4a, ctrl4b, ssn[8];
811 	char *model;
812 #ifdef CONFIG_RTC_DS1685_PROC_REGS
813 	char bits[NUM_REGS][(NUM_BITS * NUM_SPACES) + NUM_BITS + 1];
814 #endif
815 
816 	/* Read all the relevant data from the control registers. */
817 	ds1685_rtc_switch_to_bank1(rtc);
818 	ds1685_rtc_get_ssn(rtc, ssn);
819 	ctrla = rtc->read(rtc, RTC_CTRL_A);
820 	ctrlb = rtc->read(rtc, RTC_CTRL_B);
821 	ctrlc = rtc->read(rtc, RTC_CTRL_C);
822 	ctrld = rtc->read(rtc, RTC_CTRL_D);
823 	ctrl4a = rtc->read(rtc, RTC_EXT_CTRL_4A);
824 	ctrl4b = rtc->read(rtc, RTC_EXT_CTRL_4B);
825 	ds1685_rtc_switch_to_bank0(rtc);
826 
827 	/* Determine the RTC model. */
828 	switch (ssn[0]) {
829 	case RTC_MODEL_DS1685:
830 		model = "DS1685/DS1687\0";
831 		break;
832 	case RTC_MODEL_DS1689:
833 		model = "DS1689/DS1693\0";
834 		break;
835 	case RTC_MODEL_DS17285:
836 		model = "DS17285/DS17287\0";
837 		break;
838 	case RTC_MODEL_DS17485:
839 		model = "DS17485/DS17487\0";
840 		break;
841 	case RTC_MODEL_DS17885:
842 		model = "DS17885/DS17887\0";
843 		break;
844 	default:
845 		model = "Unknown\0";
846 		break;
847 	}
848 
849 	/* Print out the information. */
850 	seq_printf(seq,
851 	   "Model\t\t: %s\n"
852 	   "Oscillator\t: %s\n"
853 	   "12/24hr\t\t: %s\n"
854 	   "DST\t\t: %s\n"
855 	   "Data mode\t: %s\n"
856 	   "Battery\t\t: %s\n"
857 	   "Aux batt\t: %s\n"
858 	   "Update IRQ\t: %s\n"
859 	   "Periodic IRQ\t: %s\n"
860 	   "Periodic Rate\t: %s\n"
861 	   "SQW Freq\t: %s\n"
862 #ifdef CONFIG_RTC_DS1685_PROC_REGS
863 	   "Serial #\t: %8phC\n"
864 	   "Register Status\t:\n"
865 	   "   Ctrl A\t: UIP  DV2  DV1  DV0  RS3  RS2  RS1  RS0\n"
866 	   "\t\t:  %s\n"
867 	   "   Ctrl B\t: SET  PIE  AIE  UIE  SQWE  DM  2412 DSE\n"
868 	   "\t\t:  %s\n"
869 	   "   Ctrl C\t: IRQF  PF   AF   UF  ---  ---  ---  ---\n"
870 	   "\t\t:  %s\n"
871 	   "   Ctrl D\t: VRT  ---  ---  ---  ---  ---  ---  ---\n"
872 	   "\t\t:  %s\n"
873 #if !defined(CONFIG_RTC_DRV_DS1685) && !defined(CONFIG_RTC_DRV_DS1689)
874 	   "   Ctrl 4A\t: VRT2 INCR BME  ---  PAB   RF   WF   KF\n"
875 #else
876 	   "   Ctrl 4A\t: VRT2 INCR ---  ---  PAB   RF   WF   KF\n"
877 #endif
878 	   "\t\t:  %s\n"
879 	   "   Ctrl 4B\t: ABE  E32k  CS  RCE  PRS  RIE  WIE  KSE\n"
880 	   "\t\t:  %s\n",
881 #else
882 	   "Serial #\t: %8phC\n",
883 #endif
884 	   model,
885 	   ((ctrla & RTC_CTRL_A_DV1) ? "enabled" : "disabled"),
886 	   ((ctrlb & RTC_CTRL_B_2412) ? "24-hour" : "12-hour"),
887 	   ((ctrlb & RTC_CTRL_B_DSE) ? "enabled" : "disabled"),
888 	   ((ctrlb & RTC_CTRL_B_DM) ? "binary" : "BCD"),
889 	   ((ctrld & RTC_CTRL_D_VRT) ? "ok" : "exhausted or n/a"),
890 	   ((ctrl4a & RTC_CTRL_4A_VRT2) ? "ok" : "exhausted or n/a"),
891 	   ((ctrlb & RTC_CTRL_B_UIE) ? "yes" : "no"),
892 	   ((ctrlb & RTC_CTRL_B_PIE) ? "yes" : "no"),
893 	   (!(ctrl4b & RTC_CTRL_4B_E32K) ?
894 	    ds1685_rtc_pirq_rate[(ctrla & RTC_CTRL_A_RS_MASK)] : "none"),
895 	   (!((ctrl4b & RTC_CTRL_4B_E32K)) ?
896 	    ds1685_rtc_sqw_freq[(ctrla & RTC_CTRL_A_RS_MASK)] : "32768Hz"),
897 #ifdef CONFIG_RTC_DS1685_PROC_REGS
898 	   ssn,
899 	   ds1685_rtc_print_regs(ctrla, bits[0]),
900 	   ds1685_rtc_print_regs(ctrlb, bits[1]),
901 	   ds1685_rtc_print_regs(ctrlc, bits[2]),
902 	   ds1685_rtc_print_regs(ctrld, bits[3]),
903 	   ds1685_rtc_print_regs(ctrl4a, bits[4]),
904 	   ds1685_rtc_print_regs(ctrl4b, bits[5]));
905 #else
906 	   ssn);
907 #endif
908 	return 0;
909 }
910 #else
911 #define ds1685_rtc_proc NULL
912 #endif /* CONFIG_PROC_FS */
913 /* ----------------------------------------------------------------------- */
914 
915 
916 /* ----------------------------------------------------------------------- */
917 /* RTC Class operations */
918 
919 static const struct rtc_class_ops
920 ds1685_rtc_ops = {
921 	.proc = ds1685_rtc_proc,
922 	.read_time = ds1685_rtc_read_time,
923 	.set_time = ds1685_rtc_set_time,
924 	.read_alarm = ds1685_rtc_read_alarm,
925 	.set_alarm = ds1685_rtc_set_alarm,
926 	.alarm_irq_enable = ds1685_rtc_alarm_irq_enable,
927 };
928 /* ----------------------------------------------------------------------- */
929 
930 
931 /* ----------------------------------------------------------------------- */
932 /* SysFS interface */
933 
934 #ifdef CONFIG_SYSFS
935 /**
936  * ds1685_rtc_sysfs_nvram_read - reads rtc nvram via sysfs.
937  * @file: pointer to file structure.
938  * @kobj: pointer to kobject structure.
939  * @bin_attr: pointer to bin_attribute structure.
940  * @buf: pointer to char array to hold the output.
941  * @pos: current file position pointer.
942  * @size: size of the data to read.
943  */
944 static ssize_t
945 ds1685_rtc_sysfs_nvram_read(struct file *filp, struct kobject *kobj,
946 			    struct bin_attribute *bin_attr, char *buf,
947 			    loff_t pos, size_t size)
948 {
949 	struct platform_device *pdev =
950 		to_platform_device(container_of(kobj, struct device, kobj));
951 	struct ds1685_priv *rtc = platform_get_drvdata(pdev);
952 	ssize_t count;
953 	unsigned long flags = 0;
954 
955 	spin_lock_irqsave(&rtc->lock, flags);
956 	ds1685_rtc_switch_to_bank0(rtc);
957 
958 	/* Read NVRAM in time and bank0 registers. */
959 	for (count = 0; size > 0 && pos < NVRAM_TOTAL_SZ_BANK0;
960 	     count++, size--) {
961 		if (count < NVRAM_SZ_TIME)
962 			*buf++ = rtc->read(rtc, (NVRAM_TIME_BASE + pos++));
963 		else
964 			*buf++ = rtc->read(rtc, (NVRAM_BANK0_BASE + pos++));
965 	}
966 
967 #ifndef CONFIG_RTC_DRV_DS1689
968 	if (size > 0) {
969 		ds1685_rtc_switch_to_bank1(rtc);
970 
971 #ifndef CONFIG_RTC_DRV_DS1685
972 		/* Enable burst-mode on DS17x85/DS17x87 */
973 		rtc->write(rtc, RTC_EXT_CTRL_4A,
974 			   (rtc->read(rtc, RTC_EXT_CTRL_4A) |
975 			    RTC_CTRL_4A_BME));
976 
977 		/* We need one write to RTC_BANK1_RAM_ADDR_LSB to start
978 		 * reading with burst-mode */
979 		rtc->write(rtc, RTC_BANK1_RAM_ADDR_LSB,
980 			   (pos - NVRAM_TOTAL_SZ_BANK0));
981 #endif
982 
983 		/* Read NVRAM in bank1 registers. */
984 		for (count = 0; size > 0 && pos < NVRAM_TOTAL_SZ;
985 		     count++, size--) {
986 #ifdef CONFIG_RTC_DRV_DS1685
987 			/* DS1685/DS1687 has to write to RTC_BANK1_RAM_ADDR
988 			 * before each read. */
989 			rtc->write(rtc, RTC_BANK1_RAM_ADDR,
990 				   (pos - NVRAM_TOTAL_SZ_BANK0));
991 #endif
992 			*buf++ = rtc->read(rtc, RTC_BANK1_RAM_DATA_PORT);
993 			pos++;
994 		}
995 
996 #ifndef CONFIG_RTC_DRV_DS1685
997 		/* Disable burst-mode on DS17x85/DS17x87 */
998 		rtc->write(rtc, RTC_EXT_CTRL_4A,
999 			   (rtc->read(rtc, RTC_EXT_CTRL_4A) &
1000 			    ~(RTC_CTRL_4A_BME)));
1001 #endif
1002 		ds1685_rtc_switch_to_bank0(rtc);
1003 	}
1004 #endif /* !CONFIG_RTC_DRV_DS1689 */
1005 	spin_unlock_irqrestore(&rtc->lock, flags);
1006 
1007 	/*
1008 	 * XXX: Bug? this appears to cause the function to get executed
1009 	 * several times in succession.  But it's the only way to actually get
1010 	 * data written out to a file.
1011 	 */
1012 	return count;
1013 }
1014 
1015 /**
1016  * ds1685_rtc_sysfs_nvram_write - writes rtc nvram via sysfs.
1017  * @file: pointer to file structure.
1018  * @kobj: pointer to kobject structure.
1019  * @bin_attr: pointer to bin_attribute structure.
1020  * @buf: pointer to char array to hold the input.
1021  * @pos: current file position pointer.
1022  * @size: size of the data to write.
1023  */
1024 static ssize_t
1025 ds1685_rtc_sysfs_nvram_write(struct file *filp, struct kobject *kobj,
1026 			     struct bin_attribute *bin_attr, char *buf,
1027 			     loff_t pos, size_t size)
1028 {
1029 	struct platform_device *pdev =
1030 		to_platform_device(container_of(kobj, struct device, kobj));
1031 	struct ds1685_priv *rtc = platform_get_drvdata(pdev);
1032 	ssize_t count;
1033 	unsigned long flags = 0;
1034 
1035 	spin_lock_irqsave(&rtc->lock, flags);
1036 	ds1685_rtc_switch_to_bank0(rtc);
1037 
1038 	/* Write NVRAM in time and bank0 registers. */
1039 	for (count = 0; size > 0 && pos < NVRAM_TOTAL_SZ_BANK0;
1040 	     count++, size--)
1041 		if (count < NVRAM_SZ_TIME)
1042 			rtc->write(rtc, (NVRAM_TIME_BASE + pos++),
1043 				   *buf++);
1044 		else
1045 			rtc->write(rtc, (NVRAM_BANK0_BASE), *buf++);
1046 
1047 #ifndef CONFIG_RTC_DRV_DS1689
1048 	if (size > 0) {
1049 		ds1685_rtc_switch_to_bank1(rtc);
1050 
1051 #ifndef CONFIG_RTC_DRV_DS1685
1052 		/* Enable burst-mode on DS17x85/DS17x87 */
1053 		rtc->write(rtc, RTC_EXT_CTRL_4A,
1054 			   (rtc->read(rtc, RTC_EXT_CTRL_4A) |
1055 			    RTC_CTRL_4A_BME));
1056 
1057 		/* We need one write to RTC_BANK1_RAM_ADDR_LSB to start
1058 		 * writing with burst-mode */
1059 		rtc->write(rtc, RTC_BANK1_RAM_ADDR_LSB,
1060 			   (pos - NVRAM_TOTAL_SZ_BANK0));
1061 #endif
1062 
1063 		/* Write NVRAM in bank1 registers. */
1064 		for (count = 0; size > 0 && pos < NVRAM_TOTAL_SZ;
1065 		     count++, size--) {
1066 #ifdef CONFIG_RTC_DRV_DS1685
1067 			/* DS1685/DS1687 has to write to RTC_BANK1_RAM_ADDR
1068 			 * before each read. */
1069 			rtc->write(rtc, RTC_BANK1_RAM_ADDR,
1070 				   (pos - NVRAM_TOTAL_SZ_BANK0));
1071 #endif
1072 			rtc->write(rtc, RTC_BANK1_RAM_DATA_PORT, *buf++);
1073 			pos++;
1074 		}
1075 
1076 #ifndef CONFIG_RTC_DRV_DS1685
1077 		/* Disable burst-mode on DS17x85/DS17x87 */
1078 		rtc->write(rtc, RTC_EXT_CTRL_4A,
1079 			   (rtc->read(rtc, RTC_EXT_CTRL_4A) &
1080 			    ~(RTC_CTRL_4A_BME)));
1081 #endif
1082 		ds1685_rtc_switch_to_bank0(rtc);
1083 	}
1084 #endif /* !CONFIG_RTC_DRV_DS1689 */
1085 	spin_unlock_irqrestore(&rtc->lock, flags);
1086 
1087 	return count;
1088 }
1089 
1090 /**
1091  * struct ds1685_rtc_sysfs_nvram_attr - sysfs attributes for rtc nvram.
1092  * @attr: nvram attributes.
1093  * @read: nvram read function.
1094  * @write: nvram write function.
1095  * @size: nvram total size (bank0 + extended).
1096  */
1097 static struct bin_attribute
1098 ds1685_rtc_sysfs_nvram_attr = {
1099 	.attr = {
1100 		.name = "nvram",
1101 		.mode = S_IRUGO | S_IWUSR,
1102 	},
1103 	.read = ds1685_rtc_sysfs_nvram_read,
1104 	.write = ds1685_rtc_sysfs_nvram_write,
1105 	.size = NVRAM_TOTAL_SZ
1106 };
1107 
1108 /**
1109  * ds1685_rtc_sysfs_battery_show - sysfs file for main battery status.
1110  * @dev: pointer to device structure.
1111  * @attr: pointer to device_attribute structure.
1112  * @buf: pointer to char array to hold the output.
1113  */
1114 static ssize_t
1115 ds1685_rtc_sysfs_battery_show(struct device *dev,
1116 			      struct device_attribute *attr, char *buf)
1117 {
1118 	struct ds1685_priv *rtc = dev_get_drvdata(dev);
1119 	u8 ctrld;
1120 
1121 	ctrld = rtc->read(rtc, RTC_CTRL_D);
1122 
1123 	return sprintf(buf, "%s\n",
1124 			(ctrld & RTC_CTRL_D_VRT) ? "ok" : "not ok or N/A");
1125 }
1126 static DEVICE_ATTR(battery, S_IRUGO, ds1685_rtc_sysfs_battery_show, NULL);
1127 
1128 /**
1129  * ds1685_rtc_sysfs_auxbatt_show - sysfs file for aux battery status.
1130  * @dev: pointer to device structure.
1131  * @attr: pointer to device_attribute structure.
1132  * @buf: pointer to char array to hold the output.
1133  */
1134 static ssize_t
1135 ds1685_rtc_sysfs_auxbatt_show(struct device *dev,
1136 			      struct device_attribute *attr, char *buf)
1137 {
1138 	struct ds1685_priv *rtc = dev_get_drvdata(dev);
1139 	u8 ctrl4a;
1140 
1141 	ds1685_rtc_switch_to_bank1(rtc);
1142 	ctrl4a = rtc->read(rtc, RTC_EXT_CTRL_4A);
1143 	ds1685_rtc_switch_to_bank0(rtc);
1144 
1145 	return sprintf(buf, "%s\n",
1146 			(ctrl4a & RTC_CTRL_4A_VRT2) ? "ok" : "not ok or N/A");
1147 }
1148 static DEVICE_ATTR(auxbatt, S_IRUGO, ds1685_rtc_sysfs_auxbatt_show, NULL);
1149 
1150 /**
1151  * ds1685_rtc_sysfs_serial_show - sysfs file for silicon serial number.
1152  * @dev: pointer to device structure.
1153  * @attr: pointer to device_attribute structure.
1154  * @buf: pointer to char array to hold the output.
1155  */
1156 static ssize_t
1157 ds1685_rtc_sysfs_serial_show(struct device *dev,
1158 			     struct device_attribute *attr, char *buf)
1159 {
1160 	struct ds1685_priv *rtc = dev_get_drvdata(dev);
1161 	u8 ssn[8];
1162 
1163 	ds1685_rtc_switch_to_bank1(rtc);
1164 	ds1685_rtc_get_ssn(rtc, ssn);
1165 	ds1685_rtc_switch_to_bank0(rtc);
1166 
1167 	return sprintf(buf, "%8phC\n", ssn);
1168 }
1169 static DEVICE_ATTR(serial, S_IRUGO, ds1685_rtc_sysfs_serial_show, NULL);
1170 
1171 /**
1172  * struct ds1685_rtc_sysfs_misc_attrs - list for misc RTC features.
1173  */
1174 static struct attribute*
1175 ds1685_rtc_sysfs_misc_attrs[] = {
1176 	&dev_attr_battery.attr,
1177 	&dev_attr_auxbatt.attr,
1178 	&dev_attr_serial.attr,
1179 	NULL,
1180 };
1181 
1182 /**
1183  * struct ds1685_rtc_sysfs_misc_grp - attr group for misc RTC features.
1184  */
1185 static const struct attribute_group
1186 ds1685_rtc_sysfs_misc_grp = {
1187 	.name = "misc",
1188 	.attrs = ds1685_rtc_sysfs_misc_attrs,
1189 };
1190 
1191 /**
1192  * ds1685_rtc_sysfs_register - register sysfs files.
1193  * @dev: pointer to device structure.
1194  */
1195 static int
1196 ds1685_rtc_sysfs_register(struct device *dev)
1197 {
1198 	int ret = 0;
1199 
1200 	sysfs_bin_attr_init(&ds1685_rtc_sysfs_nvram_attr);
1201 	ret = sysfs_create_bin_file(&dev->kobj, &ds1685_rtc_sysfs_nvram_attr);
1202 	if (ret)
1203 		return ret;
1204 
1205 	ret = sysfs_create_group(&dev->kobj, &ds1685_rtc_sysfs_misc_grp);
1206 	if (ret)
1207 		return ret;
1208 
1209 	return 0;
1210 }
1211 
1212 /**
1213  * ds1685_rtc_sysfs_unregister - unregister sysfs files.
1214  * @dev: pointer to device structure.
1215  */
1216 static int
1217 ds1685_rtc_sysfs_unregister(struct device *dev)
1218 {
1219 	sysfs_remove_bin_file(&dev->kobj, &ds1685_rtc_sysfs_nvram_attr);
1220 	sysfs_remove_group(&dev->kobj, &ds1685_rtc_sysfs_misc_grp);
1221 
1222 	return 0;
1223 }
1224 #endif /* CONFIG_SYSFS */
1225 
1226 
1227 
1228 /* ----------------------------------------------------------------------- */
1229 /* Driver Probe/Removal */
1230 
1231 /**
1232  * ds1685_rtc_probe - initializes rtc driver.
1233  * @pdev: pointer to platform_device structure.
1234  */
1235 static int
1236 ds1685_rtc_probe(struct platform_device *pdev)
1237 {
1238 	struct rtc_device *rtc_dev;
1239 	struct resource *res;
1240 	struct ds1685_priv *rtc;
1241 	struct ds1685_rtc_platform_data *pdata;
1242 	u8 ctrla, ctrlb, hours;
1243 	unsigned char am_pm;
1244 	int ret = 0;
1245 
1246 	/* Get the platform data. */
1247 	pdata = (struct ds1685_rtc_platform_data *) pdev->dev.platform_data;
1248 	if (!pdata)
1249 		return -ENODEV;
1250 
1251 	/* Allocate memory for the rtc device. */
1252 	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
1253 	if (!rtc)
1254 		return -ENOMEM;
1255 
1256 	/*
1257 	 * Allocate/setup any IORESOURCE_MEM resources, if required.  Not all
1258 	 * platforms put the RTC in an easy-access place.  Like the SGI Octane,
1259 	 * which attaches the RTC to a "ByteBus", hooked to a SuperIO chip
1260 	 * that sits behind the IOC3 PCI metadevice.
1261 	 */
1262 	if (pdata->alloc_io_resources) {
1263 		/* Get the platform resources. */
1264 		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
1265 		if (!res)
1266 			return -ENXIO;
1267 		rtc->size = resource_size(res);
1268 
1269 		/* Request a memory region. */
1270 		/* XXX: mmio-only for now. */
1271 		if (!devm_request_mem_region(&pdev->dev, res->start, rtc->size,
1272 					     pdev->name))
1273 			return -EBUSY;
1274 
1275 		/*
1276 		 * Set the base address for the rtc, and ioremap its
1277 		 * registers.
1278 		 */
1279 		rtc->baseaddr = res->start;
1280 		rtc->regs = devm_ioremap(&pdev->dev, res->start, rtc->size);
1281 		if (!rtc->regs)
1282 			return -ENOMEM;
1283 	}
1284 	rtc->alloc_io_resources = pdata->alloc_io_resources;
1285 
1286 	/* Get the register step size. */
1287 	if (pdata->regstep > 0)
1288 		rtc->regstep = pdata->regstep;
1289 	else
1290 		rtc->regstep = 1;
1291 
1292 	/* Platform read function, else default if mmio setup */
1293 	if (pdata->plat_read)
1294 		rtc->read = pdata->plat_read;
1295 	else
1296 		if (pdata->alloc_io_resources)
1297 			rtc->read = ds1685_read;
1298 		else
1299 			return -ENXIO;
1300 
1301 	/* Platform write function, else default if mmio setup */
1302 	if (pdata->plat_write)
1303 		rtc->write = pdata->plat_write;
1304 	else
1305 		if (pdata->alloc_io_resources)
1306 			rtc->write = ds1685_write;
1307 		else
1308 			return -ENXIO;
1309 
1310 	/* Platform pre-shutdown function, if defined. */
1311 	if (pdata->plat_prepare_poweroff)
1312 		rtc->prepare_poweroff = pdata->plat_prepare_poweroff;
1313 
1314 	/* Platform wake_alarm function, if defined. */
1315 	if (pdata->plat_wake_alarm)
1316 		rtc->wake_alarm = pdata->plat_wake_alarm;
1317 
1318 	/* Platform post_ram_clear function, if defined. */
1319 	if (pdata->plat_post_ram_clear)
1320 		rtc->post_ram_clear = pdata->plat_post_ram_clear;
1321 
1322 	/* Init the spinlock, workqueue, & set the driver data. */
1323 	spin_lock_init(&rtc->lock);
1324 	INIT_WORK(&rtc->work, ds1685_rtc_work_queue);
1325 	platform_set_drvdata(pdev, rtc);
1326 
1327 	/* Turn the oscillator on if is not already on (DV1 = 1). */
1328 	ctrla = rtc->read(rtc, RTC_CTRL_A);
1329 	if (!(ctrla & RTC_CTRL_A_DV1))
1330 		ctrla |= RTC_CTRL_A_DV1;
1331 
1332 	/* Enable the countdown chain (DV2 = 0) */
1333 	ctrla &= ~(RTC_CTRL_A_DV2);
1334 
1335 	/* Clear RS3-RS0 in Control A. */
1336 	ctrla &= ~(RTC_CTRL_A_RS_MASK);
1337 
1338 	/*
1339 	 * All done with Control A.  Switch to Bank 1 for the remainder of
1340 	 * the RTC setup so we have access to the extended functions.
1341 	 */
1342 	ctrla |= RTC_CTRL_A_DV0;
1343 	rtc->write(rtc, RTC_CTRL_A, ctrla);
1344 
1345 	/* Default to 32768kHz output. */
1346 	rtc->write(rtc, RTC_EXT_CTRL_4B,
1347 		   (rtc->read(rtc, RTC_EXT_CTRL_4B) | RTC_CTRL_4B_E32K));
1348 
1349 	/* Set the SET bit in Control B so we can do some housekeeping. */
1350 	rtc->write(rtc, RTC_CTRL_B,
1351 		   (rtc->read(rtc, RTC_CTRL_B) | RTC_CTRL_B_SET));
1352 
1353 	/* Read Ext Ctrl 4A and check the INCR bit to avoid a lockout. */
1354 	while (rtc->read(rtc, RTC_EXT_CTRL_4A) & RTC_CTRL_4A_INCR)
1355 		cpu_relax();
1356 
1357 	/*
1358 	 * If the platform supports BCD mode, then set DM=0 in Control B.
1359 	 * Otherwise, set DM=1 for BIN mode.
1360 	 */
1361 	ctrlb = rtc->read(rtc, RTC_CTRL_B);
1362 	if (pdata->bcd_mode)
1363 		ctrlb &= ~(RTC_CTRL_B_DM);
1364 	else
1365 		ctrlb |= RTC_CTRL_B_DM;
1366 	rtc->bcd_mode = pdata->bcd_mode;
1367 
1368 	/*
1369 	 * Disable Daylight Savings Time (DSE = 0).
1370 	 * The RTC has hardcoded timezone information that is rendered
1371 	 * obselete.  We'll let the OS deal with DST settings instead.
1372 	 */
1373 	if (ctrlb & RTC_CTRL_B_DSE)
1374 		ctrlb &= ~(RTC_CTRL_B_DSE);
1375 
1376 	/* Force 24-hour mode (2412 = 1). */
1377 	if (!(ctrlb & RTC_CTRL_B_2412)) {
1378 		/* Reinitialize the time hours. */
1379 		hours = rtc->read(rtc, RTC_HRS);
1380 		am_pm = hours & RTC_HRS_AMPM_MASK;
1381 		hours = ds1685_rtc_bcd2bin(rtc, hours, RTC_HRS_12_BCD_MASK,
1382 					   RTC_HRS_12_BIN_MASK);
1383 		hours = ((hours == 12) ? 0 : ((am_pm) ? hours + 12 : hours));
1384 
1385 		/* Enable 24-hour mode. */
1386 		ctrlb |= RTC_CTRL_B_2412;
1387 
1388 		/* Write back to Control B, including DM & DSE bits. */
1389 		rtc->write(rtc, RTC_CTRL_B, ctrlb);
1390 
1391 		/* Write the time hours back. */
1392 		rtc->write(rtc, RTC_HRS,
1393 			   ds1685_rtc_bin2bcd(rtc, hours,
1394 					      RTC_HRS_24_BIN_MASK,
1395 					      RTC_HRS_24_BCD_MASK));
1396 
1397 		/* Reinitialize the alarm hours. */
1398 		hours = rtc->read(rtc, RTC_HRS_ALARM);
1399 		am_pm = hours & RTC_HRS_AMPM_MASK;
1400 		hours = ds1685_rtc_bcd2bin(rtc, hours, RTC_HRS_12_BCD_MASK,
1401 					   RTC_HRS_12_BIN_MASK);
1402 		hours = ((hours == 12) ? 0 : ((am_pm) ? hours + 12 : hours));
1403 
1404 		/* Write the alarm hours back. */
1405 		rtc->write(rtc, RTC_HRS_ALARM,
1406 			   ds1685_rtc_bin2bcd(rtc, hours,
1407 					      RTC_HRS_24_BIN_MASK,
1408 					      RTC_HRS_24_BCD_MASK));
1409 	} else {
1410 		/* 24-hour mode is already set, so write Control B back. */
1411 		rtc->write(rtc, RTC_CTRL_B, ctrlb);
1412 	}
1413 
1414 	/* Unset the SET bit in Control B so the RTC can update. */
1415 	rtc->write(rtc, RTC_CTRL_B,
1416 		   (rtc->read(rtc, RTC_CTRL_B) & ~(RTC_CTRL_B_SET)));
1417 
1418 	/* Check the main battery. */
1419 	if (!(rtc->read(rtc, RTC_CTRL_D) & RTC_CTRL_D_VRT))
1420 		dev_warn(&pdev->dev,
1421 			 "Main battery is exhausted! RTC may be invalid!\n");
1422 
1423 	/* Check the auxillary battery.  It is optional. */
1424 	if (!(rtc->read(rtc, RTC_EXT_CTRL_4A) & RTC_CTRL_4A_VRT2))
1425 		dev_warn(&pdev->dev,
1426 			 "Aux battery is exhausted or not available.\n");
1427 
1428 	/* Read Ctrl B and clear PIE/AIE/UIE. */
1429 	rtc->write(rtc, RTC_CTRL_B,
1430 		   (rtc->read(rtc, RTC_CTRL_B) & ~(RTC_CTRL_B_PAU_MASK)));
1431 
1432 	/* Reading Ctrl C auto-clears PF/AF/UF. */
1433 	rtc->read(rtc, RTC_CTRL_C);
1434 
1435 	/* Read Ctrl 4B and clear RIE/WIE/KSE. */
1436 	rtc->write(rtc, RTC_EXT_CTRL_4B,
1437 		   (rtc->read(rtc, RTC_EXT_CTRL_4B) & ~(RTC_CTRL_4B_RWK_MASK)));
1438 
1439 	/* Clear RF/WF/KF in Ctrl 4A. */
1440 	rtc->write(rtc, RTC_EXT_CTRL_4A,
1441 		   (rtc->read(rtc, RTC_EXT_CTRL_4A) & ~(RTC_CTRL_4A_RWK_MASK)));
1442 
1443 	/*
1444 	 * Re-enable KSE to handle power button events.  We do not enable
1445 	 * WIE or RIE by default.
1446 	 */
1447 	rtc->write(rtc, RTC_EXT_CTRL_4B,
1448 		   (rtc->read(rtc, RTC_EXT_CTRL_4B) | RTC_CTRL_4B_KSE));
1449 
1450 	rtc_dev = devm_rtc_allocate_device(&pdev->dev);
1451 	if (IS_ERR(rtc_dev))
1452 		return PTR_ERR(rtc_dev);
1453 
1454 	rtc_dev->ops = &ds1685_rtc_ops;
1455 
1456 	/* Century bit is useless because leap year fails in 1900 and 2100 */
1457 	rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_2000;
1458 	rtc_dev->range_max = RTC_TIMESTAMP_END_2099;
1459 
1460 	/* Maximum periodic rate is 8192Hz (0.122070ms). */
1461 	rtc_dev->max_user_freq = RTC_MAX_USER_FREQ;
1462 
1463 	/* See if the platform doesn't support UIE. */
1464 	if (pdata->uie_unsupported)
1465 		rtc_dev->uie_unsupported = 1;
1466 	rtc->uie_unsupported = pdata->uie_unsupported;
1467 
1468 	rtc->dev = rtc_dev;
1469 
1470 	/*
1471 	 * Fetch the IRQ and setup the interrupt handler.
1472 	 *
1473 	 * Not all platforms have the IRQF pin tied to something.  If not, the
1474 	 * RTC will still set the *IE / *F flags and raise IRQF in ctrlc, but
1475 	 * there won't be an automatic way of notifying the kernel about it,
1476 	 * unless ctrlc is explicitly polled.
1477 	 */
1478 	if (!pdata->no_irq) {
1479 		ret = platform_get_irq(pdev, 0);
1480 		if (ret > 0) {
1481 			rtc->irq_num = ret;
1482 
1483 			/* Request an IRQ. */
1484 			ret = devm_request_irq(&pdev->dev, rtc->irq_num,
1485 					       ds1685_rtc_irq_handler,
1486 					       IRQF_SHARED, pdev->name, pdev);
1487 
1488 			/* Check to see if something came back. */
1489 			if (unlikely(ret)) {
1490 				dev_warn(&pdev->dev,
1491 					 "RTC interrupt not available\n");
1492 				rtc->irq_num = 0;
1493 			}
1494 		} else
1495 			return ret;
1496 	}
1497 	rtc->no_irq = pdata->no_irq;
1498 
1499 	/* Setup complete. */
1500 	ds1685_rtc_switch_to_bank0(rtc);
1501 
1502 #ifdef CONFIG_SYSFS
1503 	ret = ds1685_rtc_sysfs_register(&pdev->dev);
1504 	if (ret)
1505 		return ret;
1506 #endif
1507 
1508 	return rtc_register_device(rtc_dev);
1509 }
1510 
1511 /**
1512  * ds1685_rtc_remove - removes rtc driver.
1513  * @pdev: pointer to platform_device structure.
1514  */
1515 static int
1516 ds1685_rtc_remove(struct platform_device *pdev)
1517 {
1518 	struct ds1685_priv *rtc = platform_get_drvdata(pdev);
1519 
1520 #ifdef CONFIG_SYSFS
1521 	ds1685_rtc_sysfs_unregister(&pdev->dev);
1522 #endif
1523 
1524 	/* Read Ctrl B and clear PIE/AIE/UIE. */
1525 	rtc->write(rtc, RTC_CTRL_B,
1526 		   (rtc->read(rtc, RTC_CTRL_B) &
1527 		    ~(RTC_CTRL_B_PAU_MASK)));
1528 
1529 	/* Reading Ctrl C auto-clears PF/AF/UF. */
1530 	rtc->read(rtc, RTC_CTRL_C);
1531 
1532 	/* Read Ctrl 4B and clear RIE/WIE/KSE. */
1533 	rtc->write(rtc, RTC_EXT_CTRL_4B,
1534 		   (rtc->read(rtc, RTC_EXT_CTRL_4B) &
1535 		    ~(RTC_CTRL_4B_RWK_MASK)));
1536 
1537 	/* Manually clear RF/WF/KF in Ctrl 4A. */
1538 	rtc->write(rtc, RTC_EXT_CTRL_4A,
1539 		   (rtc->read(rtc, RTC_EXT_CTRL_4A) &
1540 		    ~(RTC_CTRL_4A_RWK_MASK)));
1541 
1542 	cancel_work_sync(&rtc->work);
1543 
1544 	return 0;
1545 }
1546 
1547 /**
1548  * ds1685_rtc_driver - rtc driver properties.
1549  */
1550 static struct platform_driver ds1685_rtc_driver = {
1551 	.driver		= {
1552 		.name	= "rtc-ds1685",
1553 	},
1554 	.probe		= ds1685_rtc_probe,
1555 	.remove		= ds1685_rtc_remove,
1556 };
1557 module_platform_driver(ds1685_rtc_driver);
1558 /* ----------------------------------------------------------------------- */
1559 
1560 
1561 /* ----------------------------------------------------------------------- */
1562 /* Poweroff function */
1563 
1564 /**
1565  * ds1685_rtc_poweroff - uses the RTC chip to power the system off.
1566  * @pdev: pointer to platform_device structure.
1567  */
1568 void __noreturn
1569 ds1685_rtc_poweroff(struct platform_device *pdev)
1570 {
1571 	u8 ctrla, ctrl4a, ctrl4b;
1572 	struct ds1685_priv *rtc;
1573 
1574 	/* Check for valid RTC data, else, spin forever. */
1575 	if (unlikely(!pdev)) {
1576 		pr_emerg("platform device data not available, spinning forever ...\n");
1577 		while(1);
1578 		unreachable();
1579 	} else {
1580 		/* Get the rtc data. */
1581 		rtc = platform_get_drvdata(pdev);
1582 
1583 		/*
1584 		 * Disable our IRQ.  We're powering down, so we're not
1585 		 * going to worry about cleaning up.  Most of that should
1586 		 * have been taken care of by the shutdown scripts and this
1587 		 * is the final function call.
1588 		 */
1589 		if (!rtc->no_irq)
1590 			disable_irq_nosync(rtc->irq_num);
1591 
1592 		/* Oscillator must be on and the countdown chain enabled. */
1593 		ctrla = rtc->read(rtc, RTC_CTRL_A);
1594 		ctrla |= RTC_CTRL_A_DV1;
1595 		ctrla &= ~(RTC_CTRL_A_DV2);
1596 		rtc->write(rtc, RTC_CTRL_A, ctrla);
1597 
1598 		/*
1599 		 * Read Control 4A and check the status of the auxillary
1600 		 * battery.  This must be present and working (VRT2 = 1)
1601 		 * for wakeup and kickstart functionality to be useful.
1602 		 */
1603 		ds1685_rtc_switch_to_bank1(rtc);
1604 		ctrl4a = rtc->read(rtc, RTC_EXT_CTRL_4A);
1605 		if (ctrl4a & RTC_CTRL_4A_VRT2) {
1606 			/* Clear all of the interrupt flags on Control 4A. */
1607 			ctrl4a &= ~(RTC_CTRL_4A_RWK_MASK);
1608 			rtc->write(rtc, RTC_EXT_CTRL_4A, ctrl4a);
1609 
1610 			/*
1611 			 * The auxillary battery is present and working.
1612 			 * Enable extended functions (ABE=1), enable
1613 			 * wake-up (WIE=1), and enable kickstart (KSE=1)
1614 			 * in Control 4B.
1615 			 */
1616 			ctrl4b = rtc->read(rtc, RTC_EXT_CTRL_4B);
1617 			ctrl4b |= (RTC_CTRL_4B_ABE | RTC_CTRL_4B_WIE |
1618 				   RTC_CTRL_4B_KSE);
1619 			rtc->write(rtc, RTC_EXT_CTRL_4B, ctrl4b);
1620 		}
1621 
1622 		/* Set PAB to 1 in Control 4A to power the system down. */
1623 		dev_warn(&pdev->dev, "Powerdown.\n");
1624 		msleep(20);
1625 		rtc->write(rtc, RTC_EXT_CTRL_4A,
1626 			   (ctrl4a | RTC_CTRL_4A_PAB));
1627 
1628 		/* Spin ... we do not switch back to bank0. */
1629 		while(1);
1630 		unreachable();
1631 	}
1632 }
1633 EXPORT_SYMBOL(ds1685_rtc_poweroff);
1634 /* ----------------------------------------------------------------------- */
1635 
1636 
1637 MODULE_AUTHOR("Joshua Kinard <kumba@gentoo.org>");
1638 MODULE_AUTHOR("Matthias Fuchs <matthias.fuchs@esd-electronics.com>");
1639 MODULE_DESCRIPTION("Dallas/Maxim DS1685/DS1687-series RTC driver");
1640 MODULE_LICENSE("GPL");
1641 MODULE_ALIAS("platform:rtc-ds1685");
1642