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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * rtc-ds1305.c -- driver for DS1305 and DS1306 SPI RTC chips
4 *
5 * Copyright (C) 2008 David Brownell
6 */
7#include <linux/kernel.h>
8#include <linux/init.h>
9#include <linux/bcd.h>
10#include <linux/slab.h>
11#include <linux/rtc.h>
12#include <linux/workqueue.h>
13
14#include <linux/spi/spi.h>
15#include <linux/spi/ds1305.h>
16#include <linux/module.h>
17
18
19/*
20 * Registers ... mask DS1305_WRITE into register address to write,
21 * otherwise you're reading it. All non-bitmask values are BCD.
22 */
23#define DS1305_WRITE 0x80
24
25
26/* RTC date/time ... the main special cases are that we:
27 * - Need fancy "hours" encoding in 12hour mode
28 * - Don't rely on the "day-of-week" field (or tm_wday)
29 * - Are a 21st-century clock (2000 <= year < 2100)
30 */
31#define DS1305_RTC_LEN 7 /* bytes for RTC regs */
32
33#define DS1305_SEC 0x00 /* register addresses */
34#define DS1305_MIN 0x01
35#define DS1305_HOUR 0x02
36# define DS1305_HR_12 0x40 /* set == 12 hr mode */
37# define DS1305_HR_PM 0x20 /* set == PM (12hr mode) */
38#define DS1305_WDAY 0x03
39#define DS1305_MDAY 0x04
40#define DS1305_MON 0x05
41#define DS1305_YEAR 0x06
42
43
44/* The two alarms have only sec/min/hour/wday fields (ALM_LEN).
45 * DS1305_ALM_DISABLE disables a match field (some combos are bad).
46 *
47 * NOTE that since we don't use WDAY, we limit ourselves to alarms
48 * only one day into the future (vs potentially up to a week).
49 *
50 * NOTE ALSO that while we could generate once-a-second IRQs (UIE), we
51 * don't currently support them. We'd either need to do it only when
52 * no alarm is pending (not the standard model), or to use the second
53 * alarm (implying that this is a DS1305 not DS1306, *and* that either
54 * it's wired up a second IRQ we know, or that INTCN is set)
55 */
56#define DS1305_ALM_LEN 4 /* bytes for ALM regs */
57#define DS1305_ALM_DISABLE 0x80
58
59#define DS1305_ALM0(r) (0x07 + (r)) /* register addresses */
60#define DS1305_ALM1(r) (0x0b + (r))
61
62
63/* three control registers */
64#define DS1305_CONTROL_LEN 3 /* bytes of control regs */
65
66#define DS1305_CONTROL 0x0f /* register addresses */
67# define DS1305_nEOSC 0x80 /* low enables oscillator */
68# define DS1305_WP 0x40 /* write protect */
69# define DS1305_INTCN 0x04 /* clear == only int0 used */
70# define DS1306_1HZ 0x04 /* enable 1Hz output */
71# define DS1305_AEI1 0x02 /* enable ALM1 IRQ */
72# define DS1305_AEI0 0x01 /* enable ALM0 IRQ */
73#define DS1305_STATUS 0x10
74/* status has just AEIx bits, mirrored as IRQFx */
75#define DS1305_TRICKLE 0x11
76/* trickle bits are defined in <linux/spi/ds1305.h> */
77
78/* a bunch of NVRAM */
79#define DS1305_NVRAM_LEN 96 /* bytes of NVRAM */
80
81#define DS1305_NVRAM 0x20 /* register addresses */
82
83
84struct ds1305 {
85 struct spi_device *spi;
86 struct rtc_device *rtc;
87
88 struct work_struct work;
89
90 unsigned long flags;
91#define FLAG_EXITING 0
92
93 bool hr12;
94 u8 ctrl[DS1305_CONTROL_LEN];
95};
96
97
98/*----------------------------------------------------------------------*/
99
100/*
101 * Utilities ... tolerate 12-hour AM/PM notation in case of non-Linux
102 * software (like a bootloader) which may require it.
103 */
104
105static unsigned bcd2hour(u8 bcd)
106{
107 if (bcd & DS1305_HR_12) {
108 unsigned hour = 0;
109
110 bcd &= ~DS1305_HR_12;
111 if (bcd & DS1305_HR_PM) {
112 hour = 12;
113 bcd &= ~DS1305_HR_PM;
114 }
115 hour += bcd2bin(bcd);
116 return hour - 1;
117 }
118 return bcd2bin(bcd);
119}
120
121static u8 hour2bcd(bool hr12, int hour)
122{
123 if (hr12) {
124 hour++;
125 if (hour <= 12)
126 return DS1305_HR_12 | bin2bcd(hour);
127 hour -= 12;
128 return DS1305_HR_12 | DS1305_HR_PM | bin2bcd(hour);
129 }
130 return bin2bcd(hour);
131}
132
133/*----------------------------------------------------------------------*/
134
135/*
136 * Interface to RTC framework
137 */
138
139static int ds1305_alarm_irq_enable(struct device *dev, unsigned int enabled)
140{
141 struct ds1305 *ds1305 = dev_get_drvdata(dev);
142 u8 buf[2];
143 long err = -EINVAL;
144
145 buf[0] = DS1305_WRITE | DS1305_CONTROL;
146 buf[1] = ds1305->ctrl[0];
147
148 if (enabled) {
149 if (ds1305->ctrl[0] & DS1305_AEI0)
150 goto done;
151 buf[1] |= DS1305_AEI0;
152 } else {
153 if (!(buf[1] & DS1305_AEI0))
154 goto done;
155 buf[1] &= ~DS1305_AEI0;
156 }
157 err = spi_write_then_read(ds1305->spi, buf, sizeof(buf), NULL, 0);
158 if (err >= 0)
159 ds1305->ctrl[0] = buf[1];
160done:
161 return err;
162
163}
164
165
166/*
167 * Get/set of date and time is pretty normal.
168 */
169
170static int ds1305_get_time(struct device *dev, struct rtc_time *time)
171{
172 struct ds1305 *ds1305 = dev_get_drvdata(dev);
173 u8 addr = DS1305_SEC;
174 u8 buf[DS1305_RTC_LEN];
175 int status;
176
177 /* Use write-then-read to get all the date/time registers
178 * since dma from stack is nonportable
179 */
180 status = spi_write_then_read(ds1305->spi, &addr, sizeof(addr),
181 buf, sizeof(buf));
182 if (status < 0)
183 return status;
184
185 dev_vdbg(dev, "%s: %3ph, %4ph\n", "read", &buf[0], &buf[3]);
186
187 /* Decode the registers */
188 time->tm_sec = bcd2bin(buf[DS1305_SEC]);
189 time->tm_min = bcd2bin(buf[DS1305_MIN]);
190 time->tm_hour = bcd2hour(buf[DS1305_HOUR]);
191 time->tm_wday = buf[DS1305_WDAY] - 1;
192 time->tm_mday = bcd2bin(buf[DS1305_MDAY]);
193 time->tm_mon = bcd2bin(buf[DS1305_MON]) - 1;
194 time->tm_year = bcd2bin(buf[DS1305_YEAR]) + 100;
195
196 dev_vdbg(dev, "%s secs=%d, mins=%d, "
197 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
198 "read", time->tm_sec, time->tm_min,
199 time->tm_hour, time->tm_mday,
200 time->tm_mon, time->tm_year, time->tm_wday);
201
202 return 0;
203}
204
205static int ds1305_set_time(struct device *dev, struct rtc_time *time)
206{
207 struct ds1305 *ds1305 = dev_get_drvdata(dev);
208 u8 buf[1 + DS1305_RTC_LEN];
209 u8 *bp = buf;
210
211 dev_vdbg(dev, "%s secs=%d, mins=%d, "
212 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
213 "write", time->tm_sec, time->tm_min,
214 time->tm_hour, time->tm_mday,
215 time->tm_mon, time->tm_year, time->tm_wday);
216
217 /* Write registers starting at the first time/date address. */
218 *bp++ = DS1305_WRITE | DS1305_SEC;
219
220 *bp++ = bin2bcd(time->tm_sec);
221 *bp++ = bin2bcd(time->tm_min);
222 *bp++ = hour2bcd(ds1305->hr12, time->tm_hour);
223 *bp++ = (time->tm_wday < 7) ? (time->tm_wday + 1) : 1;
224 *bp++ = bin2bcd(time->tm_mday);
225 *bp++ = bin2bcd(time->tm_mon + 1);
226 *bp++ = bin2bcd(time->tm_year - 100);
227
228 dev_dbg(dev, "%s: %3ph, %4ph\n", "write", &buf[1], &buf[4]);
229
230 /* use write-then-read since dma from stack is nonportable */
231 return spi_write_then_read(ds1305->spi, buf, sizeof(buf),
232 NULL, 0);
233}
234
235/*
236 * Get/set of alarm is a bit funky:
237 *
238 * - First there's the inherent raciness of getting the (partitioned)
239 * status of an alarm that could trigger while we're reading parts
240 * of that status.
241 *
242 * - Second there's its limited range (we could increase it a bit by
243 * relying on WDAY), which means it will easily roll over.
244 *
245 * - Third there's the choice of two alarms and alarm signals.
246 * Here we use ALM0 and expect that nINT0 (open drain) is used;
247 * that's the only real option for DS1306 runtime alarms, and is
248 * natural on DS1305.
249 *
250 * - Fourth, there's also ALM1, and a second interrupt signal:
251 * + On DS1305 ALM1 uses nINT1 (when INTCN=1) else nINT0;
252 * + On DS1306 ALM1 only uses INT1 (an active high pulse)
253 * and it won't work when VCC1 is active.
254 *
255 * So to be most general, we should probably set both alarms to the
256 * same value, letting ALM1 be the wakeup event source on DS1306
257 * and handling several wiring options on DS1305.
258 *
259 * - Fifth, we support the polled mode (as well as possible; why not?)
260 * even when no interrupt line is wired to an IRQ.
261 */
262
263/*
264 * Context: caller holds rtc->ops_lock (to protect ds1305->ctrl)
265 */
266static int ds1305_get_alarm(struct device *dev, struct rtc_wkalrm *alm)
267{
268 struct ds1305 *ds1305 = dev_get_drvdata(dev);
269 struct spi_device *spi = ds1305->spi;
270 u8 addr;
271 int status;
272 u8 buf[DS1305_ALM_LEN];
273
274 /* Refresh control register cache BEFORE reading ALM0 registers,
275 * since reading alarm registers acks any pending IRQ. That
276 * makes returning "pending" status a bit of a lie, but that bit
277 * of EFI status is at best fragile anyway (given IRQ handlers).
278 */
279 addr = DS1305_CONTROL;
280 status = spi_write_then_read(spi, &addr, sizeof(addr),
281 ds1305->ctrl, sizeof(ds1305->ctrl));
282 if (status < 0)
283 return status;
284
285 alm->enabled = !!(ds1305->ctrl[0] & DS1305_AEI0);
286 alm->pending = !!(ds1305->ctrl[1] & DS1305_AEI0);
287
288 /* get and check ALM0 registers */
289 addr = DS1305_ALM0(DS1305_SEC);
290 status = spi_write_then_read(spi, &addr, sizeof(addr),
291 buf, sizeof(buf));
292 if (status < 0)
293 return status;
294
295 dev_vdbg(dev, "%s: %02x %02x %02x %02x\n",
296 "alm0 read", buf[DS1305_SEC], buf[DS1305_MIN],
297 buf[DS1305_HOUR], buf[DS1305_WDAY]);
298
299 if ((DS1305_ALM_DISABLE & buf[DS1305_SEC])
300 || (DS1305_ALM_DISABLE & buf[DS1305_MIN])
301 || (DS1305_ALM_DISABLE & buf[DS1305_HOUR]))
302 return -EIO;
303
304 /* Stuff these values into alm->time and let RTC framework code
305 * fill in the rest ... and also handle rollover to tomorrow when
306 * that's needed.
307 */
308 alm->time.tm_sec = bcd2bin(buf[DS1305_SEC]);
309 alm->time.tm_min = bcd2bin(buf[DS1305_MIN]);
310 alm->time.tm_hour = bcd2hour(buf[DS1305_HOUR]);
311
312 return 0;
313}
314
315/*
316 * Context: caller holds rtc->ops_lock (to protect ds1305->ctrl)
317 */
318static int ds1305_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
319{
320 struct ds1305 *ds1305 = dev_get_drvdata(dev);
321 struct spi_device *spi = ds1305->spi;
322 unsigned long now, later;
323 struct rtc_time tm;
324 int status;
325 u8 buf[1 + DS1305_ALM_LEN];
326
327 /* convert desired alarm to time_t */
328 later = rtc_tm_to_time64(&alm->time);
329
330 /* Read current time as time_t */
331 status = ds1305_get_time(dev, &tm);
332 if (status < 0)
333 return status;
334 now = rtc_tm_to_time64(&tm);
335
336 /* make sure alarm fires within the next 24 hours */
337 if (later <= now)
338 return -EINVAL;
339 if ((later - now) > 24 * 60 * 60)
340 return -EDOM;
341
342 /* disable alarm if needed */
343 if (ds1305->ctrl[0] & DS1305_AEI0) {
344 ds1305->ctrl[0] &= ~DS1305_AEI0;
345
346 buf[0] = DS1305_WRITE | DS1305_CONTROL;
347 buf[1] = ds1305->ctrl[0];
348 status = spi_write_then_read(ds1305->spi, buf, 2, NULL, 0);
349 if (status < 0)
350 return status;
351 }
352
353 /* write alarm */
354 buf[0] = DS1305_WRITE | DS1305_ALM0(DS1305_SEC);
355 buf[1 + DS1305_SEC] = bin2bcd(alm->time.tm_sec);
356 buf[1 + DS1305_MIN] = bin2bcd(alm->time.tm_min);
357 buf[1 + DS1305_HOUR] = hour2bcd(ds1305->hr12, alm->time.tm_hour);
358 buf[1 + DS1305_WDAY] = DS1305_ALM_DISABLE;
359
360 dev_dbg(dev, "%s: %02x %02x %02x %02x\n",
361 "alm0 write", buf[1 + DS1305_SEC], buf[1 + DS1305_MIN],
362 buf[1 + DS1305_HOUR], buf[1 + DS1305_WDAY]);
363
364 status = spi_write_then_read(spi, buf, sizeof(buf), NULL, 0);
365 if (status < 0)
366 return status;
367
368 /* enable alarm if requested */
369 if (alm->enabled) {
370 ds1305->ctrl[0] |= DS1305_AEI0;
371
372 buf[0] = DS1305_WRITE | DS1305_CONTROL;
373 buf[1] = ds1305->ctrl[0];
374 status = spi_write_then_read(ds1305->spi, buf, 2, NULL, 0);
375 }
376
377 return status;
378}
379
380#ifdef CONFIG_PROC_FS
381
382static int ds1305_proc(struct device *dev, struct seq_file *seq)
383{
384 struct ds1305 *ds1305 = dev_get_drvdata(dev);
385 char *diodes = "no";
386 char *resistors = "";
387
388 /* ctrl[2] is treated as read-only; no locking needed */
389 if ((ds1305->ctrl[2] & 0xf0) == DS1305_TRICKLE_MAGIC) {
390 switch (ds1305->ctrl[2] & 0x0c) {
391 case DS1305_TRICKLE_DS2:
392 diodes = "2 diodes, ";
393 break;
394 case DS1305_TRICKLE_DS1:
395 diodes = "1 diode, ";
396 break;
397 default:
398 goto done;
399 }
400 switch (ds1305->ctrl[2] & 0x03) {
401 case DS1305_TRICKLE_2K:
402 resistors = "2k Ohm";
403 break;
404 case DS1305_TRICKLE_4K:
405 resistors = "4k Ohm";
406 break;
407 case DS1305_TRICKLE_8K:
408 resistors = "8k Ohm";
409 break;
410 default:
411 diodes = "no";
412 break;
413 }
414 }
415
416done:
417 seq_printf(seq, "trickle_charge\t: %s%s\n", diodes, resistors);
418
419 return 0;
420}
421
422#else
423#define ds1305_proc NULL
424#endif
425
426static const struct rtc_class_ops ds1305_ops = {
427 .read_time = ds1305_get_time,
428 .set_time = ds1305_set_time,
429 .read_alarm = ds1305_get_alarm,
430 .set_alarm = ds1305_set_alarm,
431 .proc = ds1305_proc,
432 .alarm_irq_enable = ds1305_alarm_irq_enable,
433};
434
435static void ds1305_work(struct work_struct *work)
436{
437 struct ds1305 *ds1305 = container_of(work, struct ds1305, work);
438 struct spi_device *spi = ds1305->spi;
439 u8 buf[3];
440 int status;
441
442 /* lock to protect ds1305->ctrl */
443 rtc_lock(ds1305->rtc);
444
445 /* Disable the IRQ, and clear its status ... for now, we "know"
446 * that if more than one alarm is active, they're in sync.
447 * Note that reading ALM data registers also clears IRQ status.
448 */
449 ds1305->ctrl[0] &= ~(DS1305_AEI1 | DS1305_AEI0);
450 ds1305->ctrl[1] = 0;
451
452 buf[0] = DS1305_WRITE | DS1305_CONTROL;
453 buf[1] = ds1305->ctrl[0];
454 buf[2] = 0;
455
456 status = spi_write_then_read(spi, buf, sizeof(buf),
457 NULL, 0);
458 if (status < 0)
459 dev_dbg(&spi->dev, "clear irq --> %d\n", status);
460
461 rtc_unlock(ds1305->rtc);
462
463 if (!test_bit(FLAG_EXITING, &ds1305->flags))
464 enable_irq(spi->irq);
465
466 rtc_update_irq(ds1305->rtc, 1, RTC_AF | RTC_IRQF);
467}
468
469/*
470 * This "real" IRQ handler hands off to a workqueue mostly to allow
471 * mutex locking for ds1305->ctrl ... unlike I2C, we could issue async
472 * I/O requests in IRQ context (to clear the IRQ status).
473 */
474static irqreturn_t ds1305_irq(int irq, void *p)
475{
476 struct ds1305 *ds1305 = p;
477
478 disable_irq(irq);
479 schedule_work(&ds1305->work);
480 return IRQ_HANDLED;
481}
482
483/*----------------------------------------------------------------------*/
484
485/*
486 * Interface for NVRAM
487 */
488
489static void msg_init(struct spi_message *m, struct spi_transfer *x,
490 u8 *addr, size_t count, char *tx, char *rx)
491{
492 spi_message_init(m);
493 memset(x, 0, 2 * sizeof(*x));
494
495 x->tx_buf = addr;
496 x->len = 1;
497 spi_message_add_tail(x, m);
498
499 x++;
500
501 x->tx_buf = tx;
502 x->rx_buf = rx;
503 x->len = count;
504 spi_message_add_tail(x, m);
505}
506
507static int ds1305_nvram_read(void *priv, unsigned int off, void *buf,
508 size_t count)
509{
510 struct ds1305 *ds1305 = priv;
511 struct spi_device *spi = ds1305->spi;
512 u8 addr;
513 struct spi_message m;
514 struct spi_transfer x[2];
515
516 addr = DS1305_NVRAM + off;
517 msg_init(&m, x, &addr, count, NULL, buf);
518
519 return spi_sync(spi, &m);
520}
521
522static int ds1305_nvram_write(void *priv, unsigned int off, void *buf,
523 size_t count)
524{
525 struct ds1305 *ds1305 = priv;
526 struct spi_device *spi = ds1305->spi;
527 u8 addr;
528 struct spi_message m;
529 struct spi_transfer x[2];
530
531 addr = (DS1305_WRITE | DS1305_NVRAM) + off;
532 msg_init(&m, x, &addr, count, buf, NULL);
533
534 return spi_sync(spi, &m);
535}
536
537/*----------------------------------------------------------------------*/
538
539/*
540 * Interface to SPI stack
541 */
542
543static int ds1305_probe(struct spi_device *spi)
544{
545 struct ds1305 *ds1305;
546 int status;
547 u8 addr, value;
548 struct ds1305_platform_data *pdata = dev_get_platdata(&spi->dev);
549 bool write_ctrl = false;
550 struct nvmem_config ds1305_nvmem_cfg = {
551 .name = "ds1305_nvram",
552 .word_size = 1,
553 .stride = 1,
554 .size = DS1305_NVRAM_LEN,
555 .reg_read = ds1305_nvram_read,
556 .reg_write = ds1305_nvram_write,
557 };
558
559 /* Sanity check board setup data. This may be hooked up
560 * in 3wire mode, but we don't care. Note that unless
561 * there's an inverter in place, this needs SPI_CS_HIGH!
562 */
563 if ((spi->bits_per_word && spi->bits_per_word != 8)
564 || (spi->max_speed_hz > 2000000)
565 || !(spi->mode & SPI_CPHA))
566 return -EINVAL;
567
568 /* set up driver data */
569 ds1305 = devm_kzalloc(&spi->dev, sizeof(*ds1305), GFP_KERNEL);
570 if (!ds1305)
571 return -ENOMEM;
572 ds1305->spi = spi;
573 spi_set_drvdata(spi, ds1305);
574
575 /* read and cache control registers */
576 addr = DS1305_CONTROL;
577 status = spi_write_then_read(spi, &addr, sizeof(addr),
578 ds1305->ctrl, sizeof(ds1305->ctrl));
579 if (status < 0) {
580 dev_dbg(&spi->dev, "can't %s, %d\n",
581 "read", status);
582 return status;
583 }
584
585 dev_dbg(&spi->dev, "ctrl %s: %3ph\n", "read", ds1305->ctrl);
586
587 /* Sanity check register values ... partially compensating for the
588 * fact that SPI has no device handshake. A pullup on MISO would
589 * make these tests fail; but not all systems will have one. If
590 * some register is neither 0x00 nor 0xff, a chip is likely there.
591 */
592 if ((ds1305->ctrl[0] & 0x38) != 0 || (ds1305->ctrl[1] & 0xfc) != 0) {
593 dev_dbg(&spi->dev, "RTC chip is not present\n");
594 return -ENODEV;
595 }
596 if (ds1305->ctrl[2] == 0)
597 dev_dbg(&spi->dev, "chip may not be present\n");
598
599 /* enable writes if needed ... if we were paranoid it would
600 * make sense to enable them only when absolutely necessary.
601 */
602 if (ds1305->ctrl[0] & DS1305_WP) {
603 u8 buf[2];
604
605 ds1305->ctrl[0] &= ~DS1305_WP;
606
607 buf[0] = DS1305_WRITE | DS1305_CONTROL;
608 buf[1] = ds1305->ctrl[0];
609 status = spi_write_then_read(spi, buf, sizeof(buf), NULL, 0);
610
611 dev_dbg(&spi->dev, "clear WP --> %d\n", status);
612 if (status < 0)
613 return status;
614 }
615
616 /* on DS1305, maybe start oscillator; like most low power
617 * oscillators, it may take a second to stabilize
618 */
619 if (ds1305->ctrl[0] & DS1305_nEOSC) {
620 ds1305->ctrl[0] &= ~DS1305_nEOSC;
621 write_ctrl = true;
622 dev_warn(&spi->dev, "SET TIME!\n");
623 }
624
625 /* ack any pending IRQs */
626 if (ds1305->ctrl[1]) {
627 ds1305->ctrl[1] = 0;
628 write_ctrl = true;
629 }
630
631 /* this may need one-time (re)init */
632 if (pdata) {
633 /* maybe enable trickle charge */
634 if (((ds1305->ctrl[2] & 0xf0) != DS1305_TRICKLE_MAGIC)) {
635 ds1305->ctrl[2] = DS1305_TRICKLE_MAGIC
636 | pdata->trickle;
637 write_ctrl = true;
638 }
639
640 /* on DS1306, configure 1 Hz signal */
641 if (pdata->is_ds1306) {
642 if (pdata->en_1hz) {
643 if (!(ds1305->ctrl[0] & DS1306_1HZ)) {
644 ds1305->ctrl[0] |= DS1306_1HZ;
645 write_ctrl = true;
646 }
647 } else {
648 if (ds1305->ctrl[0] & DS1306_1HZ) {
649 ds1305->ctrl[0] &= ~DS1306_1HZ;
650 write_ctrl = true;
651 }
652 }
653 }
654 }
655
656 if (write_ctrl) {
657 u8 buf[4];
658
659 buf[0] = DS1305_WRITE | DS1305_CONTROL;
660 buf[1] = ds1305->ctrl[0];
661 buf[2] = ds1305->ctrl[1];
662 buf[3] = ds1305->ctrl[2];
663 status = spi_write_then_read(spi, buf, sizeof(buf), NULL, 0);
664 if (status < 0) {
665 dev_dbg(&spi->dev, "can't %s, %d\n",
666 "write", status);
667 return status;
668 }
669
670 dev_dbg(&spi->dev, "ctrl %s: %3ph\n", "write", ds1305->ctrl);
671 }
672
673 /* see if non-Linux software set up AM/PM mode */
674 addr = DS1305_HOUR;
675 status = spi_write_then_read(spi, &addr, sizeof(addr),
676 &value, sizeof(value));
677 if (status < 0) {
678 dev_dbg(&spi->dev, "read HOUR --> %d\n", status);
679 return status;
680 }
681
682 ds1305->hr12 = (DS1305_HR_12 & value) != 0;
683 if (ds1305->hr12)
684 dev_dbg(&spi->dev, "AM/PM\n");
685
686 /* register RTC ... from here on, ds1305->ctrl needs locking */
687 ds1305->rtc = devm_rtc_allocate_device(&spi->dev);
688 if (IS_ERR(ds1305->rtc))
689 return PTR_ERR(ds1305->rtc);
690
691 ds1305->rtc->ops = &ds1305_ops;
692 ds1305->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
693 ds1305->rtc->range_max = RTC_TIMESTAMP_END_2099;
694
695 ds1305_nvmem_cfg.priv = ds1305;
696 status = devm_rtc_register_device(ds1305->rtc);
697 if (status)
698 return status;
699
700 devm_rtc_nvmem_register(ds1305->rtc, &ds1305_nvmem_cfg);
701
702 /* Maybe set up alarm IRQ; be ready to handle it triggering right
703 * away. NOTE that we don't share this. The signal is active low,
704 * and we can't ack it before a SPI message delay. We temporarily
705 * disable the IRQ until it's acked, which lets us work with more
706 * IRQ trigger modes (not all IRQ controllers can do falling edge).
707 */
708 if (spi->irq) {
709 INIT_WORK(&ds1305->work, ds1305_work);
710 status = devm_request_irq(&spi->dev, spi->irq, ds1305_irq,
711 0, dev_name(&ds1305->rtc->dev), ds1305);
712 if (status < 0) {
713 dev_err(&spi->dev, "request_irq %d --> %d\n",
714 spi->irq, status);
715 } else {
716 device_set_wakeup_capable(&spi->dev, 1);
717 }
718 }
719
720 return 0;
721}
722
723static void ds1305_remove(struct spi_device *spi)
724{
725 struct ds1305 *ds1305 = spi_get_drvdata(spi);
726
727 /* carefully shut down irq and workqueue, if present */
728 if (spi->irq) {
729 set_bit(FLAG_EXITING, &ds1305->flags);
730 devm_free_irq(&spi->dev, spi->irq, ds1305);
731 cancel_work_sync(&ds1305->work);
732 }
733}
734
735static struct spi_driver ds1305_driver = {
736 .driver.name = "rtc-ds1305",
737 .probe = ds1305_probe,
738 .remove = ds1305_remove,
739 /* REVISIT add suspend/resume */
740};
741
742module_spi_driver(ds1305_driver);
743
744MODULE_DESCRIPTION("RTC driver for DS1305 and DS1306 chips");
745MODULE_LICENSE("GPL");
746MODULE_ALIAS("spi:rtc-ds1305");
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * rtc-ds1305.c -- driver for DS1305 and DS1306 SPI RTC chips
4 *
5 * Copyright (C) 2008 David Brownell
6 */
7#include <linux/kernel.h>
8#include <linux/init.h>
9#include <linux/bcd.h>
10#include <linux/slab.h>
11#include <linux/rtc.h>
12#include <linux/workqueue.h>
13
14#include <linux/spi/spi.h>
15#include <linux/spi/ds1305.h>
16#include <linux/module.h>
17
18
19/*
20 * Registers ... mask DS1305_WRITE into register address to write,
21 * otherwise you're reading it. All non-bitmask values are BCD.
22 */
23#define DS1305_WRITE 0x80
24
25
26/* RTC date/time ... the main special cases are that we:
27 * - Need fancy "hours" encoding in 12hour mode
28 * - Don't rely on the "day-of-week" field (or tm_wday)
29 * - Are a 21st-century clock (2000 <= year < 2100)
30 */
31#define DS1305_RTC_LEN 7 /* bytes for RTC regs */
32
33#define DS1305_SEC 0x00 /* register addresses */
34#define DS1305_MIN 0x01
35#define DS1305_HOUR 0x02
36# define DS1305_HR_12 0x40 /* set == 12 hr mode */
37# define DS1305_HR_PM 0x20 /* set == PM (12hr mode) */
38#define DS1305_WDAY 0x03
39#define DS1305_MDAY 0x04
40#define DS1305_MON 0x05
41#define DS1305_YEAR 0x06
42
43
44/* The two alarms have only sec/min/hour/wday fields (ALM_LEN).
45 * DS1305_ALM_DISABLE disables a match field (some combos are bad).
46 *
47 * NOTE that since we don't use WDAY, we limit ourselves to alarms
48 * only one day into the future (vs potentially up to a week).
49 *
50 * NOTE ALSO that while we could generate once-a-second IRQs (UIE), we
51 * don't currently support them. We'd either need to do it only when
52 * no alarm is pending (not the standard model), or to use the second
53 * alarm (implying that this is a DS1305 not DS1306, *and* that either
54 * it's wired up a second IRQ we know, or that INTCN is set)
55 */
56#define DS1305_ALM_LEN 4 /* bytes for ALM regs */
57#define DS1305_ALM_DISABLE 0x80
58
59#define DS1305_ALM0(r) (0x07 + (r)) /* register addresses */
60#define DS1305_ALM1(r) (0x0b + (r))
61
62
63/* three control registers */
64#define DS1305_CONTROL_LEN 3 /* bytes of control regs */
65
66#define DS1305_CONTROL 0x0f /* register addresses */
67# define DS1305_nEOSC 0x80 /* low enables oscillator */
68# define DS1305_WP 0x40 /* write protect */
69# define DS1305_INTCN 0x04 /* clear == only int0 used */
70# define DS1306_1HZ 0x04 /* enable 1Hz output */
71# define DS1305_AEI1 0x02 /* enable ALM1 IRQ */
72# define DS1305_AEI0 0x01 /* enable ALM0 IRQ */
73#define DS1305_STATUS 0x10
74/* status has just AEIx bits, mirrored as IRQFx */
75#define DS1305_TRICKLE 0x11
76/* trickle bits are defined in <linux/spi/ds1305.h> */
77
78/* a bunch of NVRAM */
79#define DS1305_NVRAM_LEN 96 /* bytes of NVRAM */
80
81#define DS1305_NVRAM 0x20 /* register addresses */
82
83
84struct ds1305 {
85 struct spi_device *spi;
86 struct rtc_device *rtc;
87
88 struct work_struct work;
89
90 unsigned long flags;
91#define FLAG_EXITING 0
92
93 bool hr12;
94 u8 ctrl[DS1305_CONTROL_LEN];
95};
96
97
98/*----------------------------------------------------------------------*/
99
100/*
101 * Utilities ... tolerate 12-hour AM/PM notation in case of non-Linux
102 * software (like a bootloader) which may require it.
103 */
104
105static unsigned bcd2hour(u8 bcd)
106{
107 if (bcd & DS1305_HR_12) {
108 unsigned hour = 0;
109
110 bcd &= ~DS1305_HR_12;
111 if (bcd & DS1305_HR_PM) {
112 hour = 12;
113 bcd &= ~DS1305_HR_PM;
114 }
115 hour += bcd2bin(bcd);
116 return hour - 1;
117 }
118 return bcd2bin(bcd);
119}
120
121static u8 hour2bcd(bool hr12, int hour)
122{
123 if (hr12) {
124 hour++;
125 if (hour <= 12)
126 return DS1305_HR_12 | bin2bcd(hour);
127 hour -= 12;
128 return DS1305_HR_12 | DS1305_HR_PM | bin2bcd(hour);
129 }
130 return bin2bcd(hour);
131}
132
133/*----------------------------------------------------------------------*/
134
135/*
136 * Interface to RTC framework
137 */
138
139static int ds1305_alarm_irq_enable(struct device *dev, unsigned int enabled)
140{
141 struct ds1305 *ds1305 = dev_get_drvdata(dev);
142 u8 buf[2];
143 long err = -EINVAL;
144
145 buf[0] = DS1305_WRITE | DS1305_CONTROL;
146 buf[1] = ds1305->ctrl[0];
147
148 if (enabled) {
149 if (ds1305->ctrl[0] & DS1305_AEI0)
150 goto done;
151 buf[1] |= DS1305_AEI0;
152 } else {
153 if (!(buf[1] & DS1305_AEI0))
154 goto done;
155 buf[1] &= ~DS1305_AEI0;
156 }
157 err = spi_write_then_read(ds1305->spi, buf, sizeof(buf), NULL, 0);
158 if (err >= 0)
159 ds1305->ctrl[0] = buf[1];
160done:
161 return err;
162
163}
164
165
166/*
167 * Get/set of date and time is pretty normal.
168 */
169
170static int ds1305_get_time(struct device *dev, struct rtc_time *time)
171{
172 struct ds1305 *ds1305 = dev_get_drvdata(dev);
173 u8 addr = DS1305_SEC;
174 u8 buf[DS1305_RTC_LEN];
175 int status;
176
177 /* Use write-then-read to get all the date/time registers
178 * since dma from stack is nonportable
179 */
180 status = spi_write_then_read(ds1305->spi, &addr, sizeof(addr),
181 buf, sizeof(buf));
182 if (status < 0)
183 return status;
184
185 dev_vdbg(dev, "%s: %3ph, %4ph\n", "read", &buf[0], &buf[3]);
186
187 /* Decode the registers */
188 time->tm_sec = bcd2bin(buf[DS1305_SEC]);
189 time->tm_min = bcd2bin(buf[DS1305_MIN]);
190 time->tm_hour = bcd2hour(buf[DS1305_HOUR]);
191 time->tm_wday = buf[DS1305_WDAY] - 1;
192 time->tm_mday = bcd2bin(buf[DS1305_MDAY]);
193 time->tm_mon = bcd2bin(buf[DS1305_MON]) - 1;
194 time->tm_year = bcd2bin(buf[DS1305_YEAR]) + 100;
195
196 dev_vdbg(dev, "%s secs=%d, mins=%d, "
197 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
198 "read", time->tm_sec, time->tm_min,
199 time->tm_hour, time->tm_mday,
200 time->tm_mon, time->tm_year, time->tm_wday);
201
202 return 0;
203}
204
205static int ds1305_set_time(struct device *dev, struct rtc_time *time)
206{
207 struct ds1305 *ds1305 = dev_get_drvdata(dev);
208 u8 buf[1 + DS1305_RTC_LEN];
209 u8 *bp = buf;
210
211 dev_vdbg(dev, "%s secs=%d, mins=%d, "
212 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
213 "write", time->tm_sec, time->tm_min,
214 time->tm_hour, time->tm_mday,
215 time->tm_mon, time->tm_year, time->tm_wday);
216
217 /* Write registers starting at the first time/date address. */
218 *bp++ = DS1305_WRITE | DS1305_SEC;
219
220 *bp++ = bin2bcd(time->tm_sec);
221 *bp++ = bin2bcd(time->tm_min);
222 *bp++ = hour2bcd(ds1305->hr12, time->tm_hour);
223 *bp++ = (time->tm_wday < 7) ? (time->tm_wday + 1) : 1;
224 *bp++ = bin2bcd(time->tm_mday);
225 *bp++ = bin2bcd(time->tm_mon + 1);
226 *bp++ = bin2bcd(time->tm_year - 100);
227
228 dev_dbg(dev, "%s: %3ph, %4ph\n", "write", &buf[1], &buf[4]);
229
230 /* use write-then-read since dma from stack is nonportable */
231 return spi_write_then_read(ds1305->spi, buf, sizeof(buf),
232 NULL, 0);
233}
234
235/*
236 * Get/set of alarm is a bit funky:
237 *
238 * - First there's the inherent raciness of getting the (partitioned)
239 * status of an alarm that could trigger while we're reading parts
240 * of that status.
241 *
242 * - Second there's its limited range (we could increase it a bit by
243 * relying on WDAY), which means it will easily roll over.
244 *
245 * - Third there's the choice of two alarms and alarm signals.
246 * Here we use ALM0 and expect that nINT0 (open drain) is used;
247 * that's the only real option for DS1306 runtime alarms, and is
248 * natural on DS1305.
249 *
250 * - Fourth, there's also ALM1, and a second interrupt signal:
251 * + On DS1305 ALM1 uses nINT1 (when INTCN=1) else nINT0;
252 * + On DS1306 ALM1 only uses INT1 (an active high pulse)
253 * and it won't work when VCC1 is active.
254 *
255 * So to be most general, we should probably set both alarms to the
256 * same value, letting ALM1 be the wakeup event source on DS1306
257 * and handling several wiring options on DS1305.
258 *
259 * - Fifth, we support the polled mode (as well as possible; why not?)
260 * even when no interrupt line is wired to an IRQ.
261 */
262
263/*
264 * Context: caller holds rtc->ops_lock (to protect ds1305->ctrl)
265 */
266static int ds1305_get_alarm(struct device *dev, struct rtc_wkalrm *alm)
267{
268 struct ds1305 *ds1305 = dev_get_drvdata(dev);
269 struct spi_device *spi = ds1305->spi;
270 u8 addr;
271 int status;
272 u8 buf[DS1305_ALM_LEN];
273
274 /* Refresh control register cache BEFORE reading ALM0 registers,
275 * since reading alarm registers acks any pending IRQ. That
276 * makes returning "pending" status a bit of a lie, but that bit
277 * of EFI status is at best fragile anyway (given IRQ handlers).
278 */
279 addr = DS1305_CONTROL;
280 status = spi_write_then_read(spi, &addr, sizeof(addr),
281 ds1305->ctrl, sizeof(ds1305->ctrl));
282 if (status < 0)
283 return status;
284
285 alm->enabled = !!(ds1305->ctrl[0] & DS1305_AEI0);
286 alm->pending = !!(ds1305->ctrl[1] & DS1305_AEI0);
287
288 /* get and check ALM0 registers */
289 addr = DS1305_ALM0(DS1305_SEC);
290 status = spi_write_then_read(spi, &addr, sizeof(addr),
291 buf, sizeof(buf));
292 if (status < 0)
293 return status;
294
295 dev_vdbg(dev, "%s: %02x %02x %02x %02x\n",
296 "alm0 read", buf[DS1305_SEC], buf[DS1305_MIN],
297 buf[DS1305_HOUR], buf[DS1305_WDAY]);
298
299 if ((DS1305_ALM_DISABLE & buf[DS1305_SEC])
300 || (DS1305_ALM_DISABLE & buf[DS1305_MIN])
301 || (DS1305_ALM_DISABLE & buf[DS1305_HOUR]))
302 return -EIO;
303
304 /* Stuff these values into alm->time and let RTC framework code
305 * fill in the rest ... and also handle rollover to tomorrow when
306 * that's needed.
307 */
308 alm->time.tm_sec = bcd2bin(buf[DS1305_SEC]);
309 alm->time.tm_min = bcd2bin(buf[DS1305_MIN]);
310 alm->time.tm_hour = bcd2hour(buf[DS1305_HOUR]);
311
312 return 0;
313}
314
315/*
316 * Context: caller holds rtc->ops_lock (to protect ds1305->ctrl)
317 */
318static int ds1305_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
319{
320 struct ds1305 *ds1305 = dev_get_drvdata(dev);
321 struct spi_device *spi = ds1305->spi;
322 unsigned long now, later;
323 struct rtc_time tm;
324 int status;
325 u8 buf[1 + DS1305_ALM_LEN];
326
327 /* convert desired alarm to time_t */
328 later = rtc_tm_to_time64(&alm->time);
329
330 /* Read current time as time_t */
331 status = ds1305_get_time(dev, &tm);
332 if (status < 0)
333 return status;
334 now = rtc_tm_to_time64(&tm);
335
336 /* make sure alarm fires within the next 24 hours */
337 if (later <= now)
338 return -EINVAL;
339 if ((later - now) > 24 * 60 * 60)
340 return -EDOM;
341
342 /* disable alarm if needed */
343 if (ds1305->ctrl[0] & DS1305_AEI0) {
344 ds1305->ctrl[0] &= ~DS1305_AEI0;
345
346 buf[0] = DS1305_WRITE | DS1305_CONTROL;
347 buf[1] = ds1305->ctrl[0];
348 status = spi_write_then_read(ds1305->spi, buf, 2, NULL, 0);
349 if (status < 0)
350 return status;
351 }
352
353 /* write alarm */
354 buf[0] = DS1305_WRITE | DS1305_ALM0(DS1305_SEC);
355 buf[1 + DS1305_SEC] = bin2bcd(alm->time.tm_sec);
356 buf[1 + DS1305_MIN] = bin2bcd(alm->time.tm_min);
357 buf[1 + DS1305_HOUR] = hour2bcd(ds1305->hr12, alm->time.tm_hour);
358 buf[1 + DS1305_WDAY] = DS1305_ALM_DISABLE;
359
360 dev_dbg(dev, "%s: %02x %02x %02x %02x\n",
361 "alm0 write", buf[1 + DS1305_SEC], buf[1 + DS1305_MIN],
362 buf[1 + DS1305_HOUR], buf[1 + DS1305_WDAY]);
363
364 status = spi_write_then_read(spi, buf, sizeof(buf), NULL, 0);
365 if (status < 0)
366 return status;
367
368 /* enable alarm if requested */
369 if (alm->enabled) {
370 ds1305->ctrl[0] |= DS1305_AEI0;
371
372 buf[0] = DS1305_WRITE | DS1305_CONTROL;
373 buf[1] = ds1305->ctrl[0];
374 status = spi_write_then_read(ds1305->spi, buf, 2, NULL, 0);
375 }
376
377 return status;
378}
379
380#ifdef CONFIG_PROC_FS
381
382static int ds1305_proc(struct device *dev, struct seq_file *seq)
383{
384 struct ds1305 *ds1305 = dev_get_drvdata(dev);
385 char *diodes = "no";
386 char *resistors = "";
387
388 /* ctrl[2] is treated as read-only; no locking needed */
389 if ((ds1305->ctrl[2] & 0xf0) == DS1305_TRICKLE_MAGIC) {
390 switch (ds1305->ctrl[2] & 0x0c) {
391 case DS1305_TRICKLE_DS2:
392 diodes = "2 diodes, ";
393 break;
394 case DS1305_TRICKLE_DS1:
395 diodes = "1 diode, ";
396 break;
397 default:
398 goto done;
399 }
400 switch (ds1305->ctrl[2] & 0x03) {
401 case DS1305_TRICKLE_2K:
402 resistors = "2k Ohm";
403 break;
404 case DS1305_TRICKLE_4K:
405 resistors = "4k Ohm";
406 break;
407 case DS1305_TRICKLE_8K:
408 resistors = "8k Ohm";
409 break;
410 default:
411 diodes = "no";
412 break;
413 }
414 }
415
416done:
417 seq_printf(seq, "trickle_charge\t: %s%s\n", diodes, resistors);
418
419 return 0;
420}
421
422#else
423#define ds1305_proc NULL
424#endif
425
426static const struct rtc_class_ops ds1305_ops = {
427 .read_time = ds1305_get_time,
428 .set_time = ds1305_set_time,
429 .read_alarm = ds1305_get_alarm,
430 .set_alarm = ds1305_set_alarm,
431 .proc = ds1305_proc,
432 .alarm_irq_enable = ds1305_alarm_irq_enable,
433};
434
435static void ds1305_work(struct work_struct *work)
436{
437 struct ds1305 *ds1305 = container_of(work, struct ds1305, work);
438 struct mutex *lock = &ds1305->rtc->ops_lock;
439 struct spi_device *spi = ds1305->spi;
440 u8 buf[3];
441 int status;
442
443 /* lock to protect ds1305->ctrl */
444 mutex_lock(lock);
445
446 /* Disable the IRQ, and clear its status ... for now, we "know"
447 * that if more than one alarm is active, they're in sync.
448 * Note that reading ALM data registers also clears IRQ status.
449 */
450 ds1305->ctrl[0] &= ~(DS1305_AEI1 | DS1305_AEI0);
451 ds1305->ctrl[1] = 0;
452
453 buf[0] = DS1305_WRITE | DS1305_CONTROL;
454 buf[1] = ds1305->ctrl[0];
455 buf[2] = 0;
456
457 status = spi_write_then_read(spi, buf, sizeof(buf),
458 NULL, 0);
459 if (status < 0)
460 dev_dbg(&spi->dev, "clear irq --> %d\n", status);
461
462 mutex_unlock(lock);
463
464 if (!test_bit(FLAG_EXITING, &ds1305->flags))
465 enable_irq(spi->irq);
466
467 rtc_update_irq(ds1305->rtc, 1, RTC_AF | RTC_IRQF);
468}
469
470/*
471 * This "real" IRQ handler hands off to a workqueue mostly to allow
472 * mutex locking for ds1305->ctrl ... unlike I2C, we could issue async
473 * I/O requests in IRQ context (to clear the IRQ status).
474 */
475static irqreturn_t ds1305_irq(int irq, void *p)
476{
477 struct ds1305 *ds1305 = p;
478
479 disable_irq(irq);
480 schedule_work(&ds1305->work);
481 return IRQ_HANDLED;
482}
483
484/*----------------------------------------------------------------------*/
485
486/*
487 * Interface for NVRAM
488 */
489
490static void msg_init(struct spi_message *m, struct spi_transfer *x,
491 u8 *addr, size_t count, char *tx, char *rx)
492{
493 spi_message_init(m);
494 memset(x, 0, 2 * sizeof(*x));
495
496 x->tx_buf = addr;
497 x->len = 1;
498 spi_message_add_tail(x, m);
499
500 x++;
501
502 x->tx_buf = tx;
503 x->rx_buf = rx;
504 x->len = count;
505 spi_message_add_tail(x, m);
506}
507
508static int ds1305_nvram_read(void *priv, unsigned int off, void *buf,
509 size_t count)
510{
511 struct ds1305 *ds1305 = priv;
512 struct spi_device *spi = ds1305->spi;
513 u8 addr;
514 struct spi_message m;
515 struct spi_transfer x[2];
516
517 addr = DS1305_NVRAM + off;
518 msg_init(&m, x, &addr, count, NULL, buf);
519
520 return spi_sync(spi, &m);
521}
522
523static int ds1305_nvram_write(void *priv, unsigned int off, void *buf,
524 size_t count)
525{
526 struct ds1305 *ds1305 = priv;
527 struct spi_device *spi = ds1305->spi;
528 u8 addr;
529 struct spi_message m;
530 struct spi_transfer x[2];
531
532 addr = (DS1305_WRITE | DS1305_NVRAM) + off;
533 msg_init(&m, x, &addr, count, buf, NULL);
534
535 return spi_sync(spi, &m);
536}
537
538/*----------------------------------------------------------------------*/
539
540/*
541 * Interface to SPI stack
542 */
543
544static int ds1305_probe(struct spi_device *spi)
545{
546 struct ds1305 *ds1305;
547 int status;
548 u8 addr, value;
549 struct ds1305_platform_data *pdata = dev_get_platdata(&spi->dev);
550 bool write_ctrl = false;
551 struct nvmem_config ds1305_nvmem_cfg = {
552 .name = "ds1305_nvram",
553 .word_size = 1,
554 .stride = 1,
555 .size = DS1305_NVRAM_LEN,
556 .reg_read = ds1305_nvram_read,
557 .reg_write = ds1305_nvram_write,
558 };
559
560 /* Sanity check board setup data. This may be hooked up
561 * in 3wire mode, but we don't care. Note that unless
562 * there's an inverter in place, this needs SPI_CS_HIGH!
563 */
564 if ((spi->bits_per_word && spi->bits_per_word != 8)
565 || (spi->max_speed_hz > 2000000)
566 || !(spi->mode & SPI_CPHA))
567 return -EINVAL;
568
569 /* set up driver data */
570 ds1305 = devm_kzalloc(&spi->dev, sizeof(*ds1305), GFP_KERNEL);
571 if (!ds1305)
572 return -ENOMEM;
573 ds1305->spi = spi;
574 spi_set_drvdata(spi, ds1305);
575
576 /* read and cache control registers */
577 addr = DS1305_CONTROL;
578 status = spi_write_then_read(spi, &addr, sizeof(addr),
579 ds1305->ctrl, sizeof(ds1305->ctrl));
580 if (status < 0) {
581 dev_dbg(&spi->dev, "can't %s, %d\n",
582 "read", status);
583 return status;
584 }
585
586 dev_dbg(&spi->dev, "ctrl %s: %3ph\n", "read", ds1305->ctrl);
587
588 /* Sanity check register values ... partially compensating for the
589 * fact that SPI has no device handshake. A pullup on MISO would
590 * make these tests fail; but not all systems will have one. If
591 * some register is neither 0x00 nor 0xff, a chip is likely there.
592 */
593 if ((ds1305->ctrl[0] & 0x38) != 0 || (ds1305->ctrl[1] & 0xfc) != 0) {
594 dev_dbg(&spi->dev, "RTC chip is not present\n");
595 return -ENODEV;
596 }
597 if (ds1305->ctrl[2] == 0)
598 dev_dbg(&spi->dev, "chip may not be present\n");
599
600 /* enable writes if needed ... if we were paranoid it would
601 * make sense to enable them only when absolutely necessary.
602 */
603 if (ds1305->ctrl[0] & DS1305_WP) {
604 u8 buf[2];
605
606 ds1305->ctrl[0] &= ~DS1305_WP;
607
608 buf[0] = DS1305_WRITE | DS1305_CONTROL;
609 buf[1] = ds1305->ctrl[0];
610 status = spi_write_then_read(spi, buf, sizeof(buf), NULL, 0);
611
612 dev_dbg(&spi->dev, "clear WP --> %d\n", status);
613 if (status < 0)
614 return status;
615 }
616
617 /* on DS1305, maybe start oscillator; like most low power
618 * oscillators, it may take a second to stabilize
619 */
620 if (ds1305->ctrl[0] & DS1305_nEOSC) {
621 ds1305->ctrl[0] &= ~DS1305_nEOSC;
622 write_ctrl = true;
623 dev_warn(&spi->dev, "SET TIME!\n");
624 }
625
626 /* ack any pending IRQs */
627 if (ds1305->ctrl[1]) {
628 ds1305->ctrl[1] = 0;
629 write_ctrl = true;
630 }
631
632 /* this may need one-time (re)init */
633 if (pdata) {
634 /* maybe enable trickle charge */
635 if (((ds1305->ctrl[2] & 0xf0) != DS1305_TRICKLE_MAGIC)) {
636 ds1305->ctrl[2] = DS1305_TRICKLE_MAGIC
637 | pdata->trickle;
638 write_ctrl = true;
639 }
640
641 /* on DS1306, configure 1 Hz signal */
642 if (pdata->is_ds1306) {
643 if (pdata->en_1hz) {
644 if (!(ds1305->ctrl[0] & DS1306_1HZ)) {
645 ds1305->ctrl[0] |= DS1306_1HZ;
646 write_ctrl = true;
647 }
648 } else {
649 if (ds1305->ctrl[0] & DS1306_1HZ) {
650 ds1305->ctrl[0] &= ~DS1306_1HZ;
651 write_ctrl = true;
652 }
653 }
654 }
655 }
656
657 if (write_ctrl) {
658 u8 buf[4];
659
660 buf[0] = DS1305_WRITE | DS1305_CONTROL;
661 buf[1] = ds1305->ctrl[0];
662 buf[2] = ds1305->ctrl[1];
663 buf[3] = ds1305->ctrl[2];
664 status = spi_write_then_read(spi, buf, sizeof(buf), NULL, 0);
665 if (status < 0) {
666 dev_dbg(&spi->dev, "can't %s, %d\n",
667 "write", status);
668 return status;
669 }
670
671 dev_dbg(&spi->dev, "ctrl %s: %3ph\n", "write", ds1305->ctrl);
672 }
673
674 /* see if non-Linux software set up AM/PM mode */
675 addr = DS1305_HOUR;
676 status = spi_write_then_read(spi, &addr, sizeof(addr),
677 &value, sizeof(value));
678 if (status < 0) {
679 dev_dbg(&spi->dev, "read HOUR --> %d\n", status);
680 return status;
681 }
682
683 ds1305->hr12 = (DS1305_HR_12 & value) != 0;
684 if (ds1305->hr12)
685 dev_dbg(&spi->dev, "AM/PM\n");
686
687 /* register RTC ... from here on, ds1305->ctrl needs locking */
688 ds1305->rtc = devm_rtc_allocate_device(&spi->dev);
689 if (IS_ERR(ds1305->rtc))
690 return PTR_ERR(ds1305->rtc);
691
692 ds1305->rtc->ops = &ds1305_ops;
693 ds1305->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
694 ds1305->rtc->range_max = RTC_TIMESTAMP_END_2099;
695
696 ds1305_nvmem_cfg.priv = ds1305;
697 ds1305->rtc->nvram_old_abi = true;
698 status = rtc_register_device(ds1305->rtc);
699 if (status)
700 return status;
701
702 rtc_nvmem_register(ds1305->rtc, &ds1305_nvmem_cfg);
703
704 /* Maybe set up alarm IRQ; be ready to handle it triggering right
705 * away. NOTE that we don't share this. The signal is active low,
706 * and we can't ack it before a SPI message delay. We temporarily
707 * disable the IRQ until it's acked, which lets us work with more
708 * IRQ trigger modes (not all IRQ controllers can do falling edge).
709 */
710 if (spi->irq) {
711 INIT_WORK(&ds1305->work, ds1305_work);
712 status = devm_request_irq(&spi->dev, spi->irq, ds1305_irq,
713 0, dev_name(&ds1305->rtc->dev), ds1305);
714 if (status < 0) {
715 dev_err(&spi->dev, "request_irq %d --> %d\n",
716 spi->irq, status);
717 } else {
718 device_set_wakeup_capable(&spi->dev, 1);
719 }
720 }
721
722 return 0;
723}
724
725static int ds1305_remove(struct spi_device *spi)
726{
727 struct ds1305 *ds1305 = spi_get_drvdata(spi);
728
729 /* carefully shut down irq and workqueue, if present */
730 if (spi->irq) {
731 set_bit(FLAG_EXITING, &ds1305->flags);
732 devm_free_irq(&spi->dev, spi->irq, ds1305);
733 cancel_work_sync(&ds1305->work);
734 }
735
736 return 0;
737}
738
739static struct spi_driver ds1305_driver = {
740 .driver.name = "rtc-ds1305",
741 .probe = ds1305_probe,
742 .remove = ds1305_remove,
743 /* REVISIT add suspend/resume */
744};
745
746module_spi_driver(ds1305_driver);
747
748MODULE_DESCRIPTION("RTC driver for DS1305 and DS1306 chips");
749MODULE_LICENSE("GPL");
750MODULE_ALIAS("spi:rtc-ds1305");