aboutsummaryrefslogtreecommitdiff
path: root/drivers/rtc/rtc-sc27xx.c
blob: 36810dd40cd3528af29ee5ef72031eb8061052f4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
/*
 * Copyright (C) 2017 Spreadtrum Communications Inc.
 *
 * SPDX-License-Identifier: GPL-2.0
 */

#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/rtc.h>

#define SPRD_RTC_SEC_CNT_VALUE		0x0
#define SPRD_RTC_MIN_CNT_VALUE		0x4
#define SPRD_RTC_HOUR_CNT_VALUE		0x8
#define SPRD_RTC_DAY_CNT_VALUE		0xc
#define SPRD_RTC_SEC_CNT_UPD		0x10
#define SPRD_RTC_MIN_CNT_UPD		0x14
#define SPRD_RTC_HOUR_CNT_UPD		0x18
#define SPRD_RTC_DAY_CNT_UPD		0x1c
#define SPRD_RTC_SEC_ALM_UPD		0x20
#define SPRD_RTC_MIN_ALM_UPD		0x24
#define SPRD_RTC_HOUR_ALM_UPD		0x28
#define SPRD_RTC_DAY_ALM_UPD		0x2c
#define SPRD_RTC_INT_EN			0x30
#define SPRD_RTC_INT_RAW_STS		0x34
#define SPRD_RTC_INT_CLR		0x38
#define SPRD_RTC_INT_MASK_STS		0x3C
#define SPRD_RTC_SEC_ALM_VALUE		0x40
#define SPRD_RTC_MIN_ALM_VALUE		0x44
#define SPRD_RTC_HOUR_ALM_VALUE		0x48
#define SPRD_RTC_DAY_ALM_VALUE		0x4c
#define SPRD_RTC_SPG_VALUE		0x50
#define SPRD_RTC_SPG_UPD		0x54
#define SPRD_RTC_PWR_CTRL		0x58
#define SPRD_RTC_PWR_STS		0x5c
#define SPRD_RTC_SEC_AUXALM_UPD		0x60
#define SPRD_RTC_MIN_AUXALM_UPD		0x64
#define SPRD_RTC_HOUR_AUXALM_UPD	0x68
#define SPRD_RTC_DAY_AUXALM_UPD		0x6c

/* BIT & MASK definition for SPRD_RTC_INT_* registers */
#define SPRD_RTC_SEC_EN			BIT(0)
#define SPRD_RTC_MIN_EN			BIT(1)
#define SPRD_RTC_HOUR_EN		BIT(2)
#define SPRD_RTC_DAY_EN			BIT(3)
#define SPRD_RTC_ALARM_EN		BIT(4)
#define SPRD_RTC_HRS_FORMAT_EN		BIT(5)
#define SPRD_RTC_AUXALM_EN		BIT(6)
#define SPRD_RTC_SPG_UPD_EN		BIT(7)
#define SPRD_RTC_SEC_UPD_EN		BIT(8)
#define SPRD_RTC_MIN_UPD_EN		BIT(9)
#define SPRD_RTC_HOUR_UPD_EN		BIT(10)
#define SPRD_RTC_DAY_UPD_EN		BIT(11)
#define SPRD_RTC_ALMSEC_UPD_EN		BIT(12)
#define SPRD_RTC_ALMMIN_UPD_EN		BIT(13)
#define SPRD_RTC_ALMHOUR_UPD_EN		BIT(14)
#define SPRD_RTC_ALMDAY_UPD_EN		BIT(15)
#define SPRD_RTC_INT_MASK		GENMASK(15, 0)

#define SPRD_RTC_TIME_INT_MASK				\
	(SPRD_RTC_SEC_UPD_EN | SPRD_RTC_MIN_UPD_EN |	\
	 SPRD_RTC_HOUR_UPD_EN | SPRD_RTC_DAY_UPD_EN)

#define SPRD_RTC_ALMTIME_INT_MASK				\
	(SPRD_RTC_ALMSEC_UPD_EN | SPRD_RTC_ALMMIN_UPD_EN |	\
	 SPRD_RTC_ALMHOUR_UPD_EN | SPRD_RTC_ALMDAY_UPD_EN)

#define SPRD_RTC_ALM_INT_MASK			\
	(SPRD_RTC_SEC_EN | SPRD_RTC_MIN_EN |	\
	 SPRD_RTC_HOUR_EN | SPRD_RTC_DAY_EN |	\
	 SPRD_RTC_ALARM_EN | SPRD_RTC_AUXALM_EN)

/* second/minute/hour/day values mask definition */
#define SPRD_RTC_SEC_MASK		GENMASK(5, 0)
#define SPRD_RTC_MIN_MASK		GENMASK(5, 0)
#define SPRD_RTC_HOUR_MASK		GENMASK(4, 0)
#define SPRD_RTC_DAY_MASK		GENMASK(15, 0)

/* alarm lock definition for SPRD_RTC_SPG_UPD register */
#define SPRD_RTC_ALMLOCK_MASK		GENMASK(7, 0)
#define SPRD_RTC_ALM_UNLOCK		0xa5
#define SPRD_RTC_ALM_LOCK		(~SPRD_RTC_ALM_UNLOCK &	\
					 SPRD_RTC_ALMLOCK_MASK)

/* SPG values definition for SPRD_RTC_SPG_UPD register */
#define SPRD_RTC_POWEROFF_ALM_FLAG	BIT(8)

/* power control/status definition */
#define SPRD_RTC_POWER_RESET_VALUE	0x96
#define SPRD_RTC_POWER_STS_CLEAR	GENMASK(7, 0)
#define SPRD_RTC_POWER_STS_SHIFT	8
#define SPRD_RTC_POWER_STS_VALID	\
	(~SPRD_RTC_POWER_RESET_VALUE << SPRD_RTC_POWER_STS_SHIFT)

/* timeout of synchronizing time and alarm registers (us) */
#define SPRD_RTC_POLL_TIMEOUT		200000
#define SPRD_RTC_POLL_DELAY_US		20000

struct sprd_rtc {
	struct rtc_device	*rtc;
	struct regmap		*regmap;
	struct device		*dev;
	u32			base;
	int			irq;
	bool			valid;
};

/*
 * The Spreadtrum RTC controller has 3 groups registers, including time, normal
 * alarm and auxiliary alarm. The time group registers are used to set RTC time,
 * the normal alarm registers are used to set normal alarm, and the auxiliary
 * alarm registers are used to set auxiliary alarm. Both alarm event and
 * auxiliary alarm event can wake up system from deep sleep, but only alarm
 * event can power up system from power down status.
 */
enum sprd_rtc_reg_types {
	SPRD_RTC_TIME,
	SPRD_RTC_ALARM,
	SPRD_RTC_AUX_ALARM,
};

static int sprd_rtc_clear_alarm_ints(struct sprd_rtc *rtc)
{
	return regmap_write(rtc->regmap, rtc->base + SPRD_RTC_INT_CLR,
			    SPRD_RTC_ALM_INT_MASK);
}

static int sprd_rtc_lock_alarm(struct sprd_rtc *rtc, bool lock)
{
	int ret;
	u32 val;

	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_SPG_VALUE, &val);
	if (ret)
		return ret;

	val &= ~SPRD_RTC_ALMLOCK_MASK;
	if (lock)
		val |= SPRD_RTC_ALM_LOCK;
	else
		val |= SPRD_RTC_ALM_UNLOCK | SPRD_RTC_POWEROFF_ALM_FLAG;

	ret = regmap_write(rtc->regmap, rtc->base + SPRD_RTC_SPG_UPD, val);
	if (ret)
		return ret;

	/* wait until the SPG value is updated successfully */
	ret = regmap_read_poll_timeout(rtc->regmap,
				       rtc->base + SPRD_RTC_INT_RAW_STS, val,
				       (val & SPRD_RTC_SPG_UPD_EN),
				       SPRD_RTC_POLL_DELAY_US,
				       SPRD_RTC_POLL_TIMEOUT);
	if (ret) {
		dev_err(rtc->dev, "failed to update SPG value:%d\n", ret);
		return ret;
	}

	return regmap_write(rtc->regmap, rtc->base + SPRD_RTC_INT_CLR,
			    SPRD_RTC_SPG_UPD_EN);
}

static int sprd_rtc_get_secs(struct sprd_rtc *rtc, enum sprd_rtc_reg_types type,
			     time64_t *secs)
{
	u32 sec_reg, min_reg, hour_reg, day_reg;
	u32 val, sec, min, hour, day;
	int ret;

	switch (type) {
	case SPRD_RTC_TIME:
		sec_reg = SPRD_RTC_SEC_CNT_VALUE;
		min_reg = SPRD_RTC_MIN_CNT_VALUE;
		hour_reg = SPRD_RTC_HOUR_CNT_VALUE;
		day_reg = SPRD_RTC_DAY_CNT_VALUE;
		break;
	case SPRD_RTC_ALARM:
		sec_reg = SPRD_RTC_SEC_ALM_VALUE;
		min_reg = SPRD_RTC_MIN_ALM_VALUE;
		hour_reg = SPRD_RTC_HOUR_ALM_VALUE;
		day_reg = SPRD_RTC_DAY_ALM_VALUE;
		break;
	case SPRD_RTC_AUX_ALARM:
		sec_reg = SPRD_RTC_SEC_AUXALM_UPD;
		min_reg = SPRD_RTC_MIN_AUXALM_UPD;
		hour_reg = SPRD_RTC_HOUR_AUXALM_UPD;
		day_reg = SPRD_RTC_DAY_AUXALM_UPD;
		break;
	default:
		return -EINVAL;
	}

	ret = regmap_read(rtc->regmap, rtc->base + sec_reg, &val);
	if (ret)
		return ret;

	sec = val & SPRD_RTC_SEC_MASK;

	ret = regmap_read(rtc->regmap, rtc->base + min_reg, &val);
	if (ret)
		return ret;

	min = val & SPRD_RTC_MIN_MASK;

	ret = regmap_read(rtc->regmap, rtc->base + hour_reg, &val);
	if (ret)
		return ret;

	hour = val & SPRD_RTC_HOUR_MASK;

	ret = regmap_read(rtc->regmap, rtc->base + day_reg, &val);
	if (ret)
		return ret;

	day = val & SPRD_RTC_DAY_MASK;
	*secs = (((time64_t)(day * 24) + hour) * 60 + min) * 60 + sec;
	return 0;
}

static int sprd_rtc_set_secs(struct sprd_rtc *rtc, enum sprd_rtc_reg_types type,
			     time64_t secs)
{
	u32 sec_reg, min_reg, hour_reg, day_reg, sts_mask;
	u32 sec, min, hour, day, val;
	int ret, rem;

	/* convert seconds to RTC time format */
	day = div_s64_rem(secs, 86400, &rem);
	hour = rem / 3600;
	rem -= hour * 3600;
	min = rem / 60;
	sec = rem - min * 60;

	switch (type) {
	case SPRD_RTC_TIME:
		sec_reg = SPRD_RTC_SEC_CNT_UPD;
		min_reg = SPRD_RTC_MIN_CNT_UPD;
		hour_reg = SPRD_RTC_HOUR_CNT_UPD;
		day_reg = SPRD_RTC_DAY_CNT_UPD;
		sts_mask = SPRD_RTC_TIME_INT_MASK;
		break;
	case SPRD_RTC_ALARM:
		sec_reg = SPRD_RTC_SEC_ALM_UPD;
		min_reg = SPRD_RTC_MIN_ALM_UPD;
		hour_reg = SPRD_RTC_HOUR_ALM_UPD;
		day_reg = SPRD_RTC_DAY_ALM_UPD;
		sts_mask = SPRD_RTC_ALMTIME_INT_MASK;
		break;
	case SPRD_RTC_AUX_ALARM:
		sec_reg = SPRD_RTC_SEC_AUXALM_UPD;
		min_reg = SPRD_RTC_MIN_AUXALM_UPD;
		hour_reg = SPRD_RTC_HOUR_AUXALM_UPD;
		day_reg = SPRD_RTC_DAY_AUXALM_UPD;
		sts_mask = 0;
		break;
	default:
		return -EINVAL;
	}

	ret = regmap_write(rtc->regmap, rtc->base + sec_reg, sec);
	if (ret)
		return ret;

	ret = regmap_write(rtc->regmap, rtc->base + min_reg, min);
	if (ret)
		return ret;

	ret = regmap_write(rtc->regmap, rtc->base + hour_reg, hour);
	if (ret)
		return ret;

	ret = regmap_write(rtc->regmap, rtc->base + day_reg, day);
	if (ret)
		return ret;

	if (type == SPRD_RTC_AUX_ALARM)
		return 0;

	/*
	 * Since the time and normal alarm registers are put in always-power-on
	 * region supplied by VDDRTC, then these registers changing time will
	 * be very long, about 125ms. Thus here we should wait until all
	 * values are updated successfully.
	 */
	ret = regmap_read_poll_timeout(rtc->regmap,
				       rtc->base + SPRD_RTC_INT_RAW_STS, val,
				       ((val & sts_mask) == sts_mask),
				       SPRD_RTC_POLL_DELAY_US,
				       SPRD_RTC_POLL_TIMEOUT);
	if (ret < 0) {
		dev_err(rtc->dev, "set time/alarm values timeout\n");
		return ret;
	}

	return regmap_write(rtc->regmap, rtc->base + SPRD_RTC_INT_CLR,
			    sts_mask);
}

static int sprd_rtc_read_aux_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct sprd_rtc *rtc = dev_get_drvdata(dev);
	time64_t secs;
	u32 val;
	int ret;

	ret = sprd_rtc_get_secs(rtc, SPRD_RTC_AUX_ALARM, &secs);
	if (ret)
		return ret;

	rtc_time64_to_tm(secs, &alrm->time);

	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_INT_EN, &val);
	if (ret)
		return ret;

	alrm->enabled = !!(val & SPRD_RTC_AUXALM_EN);

	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_INT_RAW_STS, &val);
	if (ret)
		return ret;

	alrm->pending = !!(val & SPRD_RTC_AUXALM_EN);
	return 0;
}

static int sprd_rtc_set_aux_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct sprd_rtc *rtc = dev_get_drvdata(dev);
	time64_t secs = rtc_tm_to_time64(&alrm->time);
	int ret;

	/* clear the auxiliary alarm interrupt status */
	ret = regmap_write(rtc->regmap, rtc->base + SPRD_RTC_INT_CLR,
			   SPRD_RTC_AUXALM_EN);
	if (ret)
		return ret;

	ret = sprd_rtc_set_secs(rtc, SPRD_RTC_AUX_ALARM, secs);
	if (ret)
		return ret;

	if (alrm->enabled) {
		ret = regmap_update_bits(rtc->regmap,
					 rtc->base + SPRD_RTC_INT_EN,
					 SPRD_RTC_AUXALM_EN,
					 SPRD_RTC_AUXALM_EN);
	} else {
		ret = regmap_update_bits(rtc->regmap,
					 rtc->base + SPRD_RTC_INT_EN,
					 SPRD_RTC_AUXALM_EN, 0);
	}

	return ret;
}

static int sprd_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	struct sprd_rtc *rtc = dev_get_drvdata(dev);
	time64_t secs;
	int ret;

	if (!rtc->valid) {
		dev_warn(dev, "RTC values are invalid\n");
		return -EINVAL;
	}

	ret = sprd_rtc_get_secs(rtc, SPRD_RTC_TIME, &secs);
	if (ret)
		return ret;

	rtc_time64_to_tm(secs, tm);
	return 0;
}

static int sprd_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	struct sprd_rtc *rtc = dev_get_drvdata(dev);
	time64_t secs = rtc_tm_to_time64(tm);
	int ret;

	ret = sprd_rtc_set_secs(rtc, SPRD_RTC_TIME, secs);
	if (ret)
		return ret;

	if (!rtc->valid) {
		/* Clear RTC power status firstly */
		ret = regmap_write(rtc->regmap, rtc->base + SPRD_RTC_PWR_CTRL,
				   SPRD_RTC_POWER_STS_CLEAR);
		if (ret)
			return ret;

		/*
		 * Set RTC power status to indicate now RTC has valid time
		 * values.
		 */
		ret = regmap_write(rtc->regmap, rtc->base + SPRD_RTC_PWR_CTRL,
				   SPRD_RTC_POWER_STS_VALID);
		if (ret)
			return ret;

		rtc->valid = true;
	}

	return 0;
}

static int sprd_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct sprd_rtc *rtc = dev_get_drvdata(dev);
	time64_t secs;
	int ret;
	u32 val;

	/*
	 * Before RTC device is registered, it will check to see if there is an
	 * alarm already set in RTC hardware, and we always read the normal
	 * alarm at this time.
	 *
	 * Or if aie_timer is enabled, we should get the normal alarm time.
	 * Otherwise we should get auxiliary alarm time.
	 */
	if (rtc->rtc && rtc->rtc->registered && rtc->rtc->aie_timer.enabled == 0)
		return sprd_rtc_read_aux_alarm(dev, alrm);

	ret = sprd_rtc_get_secs(rtc, SPRD_RTC_ALARM, &secs);
	if (ret)
		return ret;

	rtc_time64_to_tm(secs, &alrm->time);

	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_INT_EN, &val);
	if (ret)
		return ret;

	alrm->enabled = !!(val & SPRD_RTC_ALARM_EN);

	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_INT_RAW_STS, &val);
	if (ret)
		return ret;

	alrm->pending = !!(val & SPRD_RTC_ALARM_EN);
	return 0;
}

static int sprd_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct sprd_rtc *rtc = dev_get_drvdata(dev);
	time64_t secs = rtc_tm_to_time64(&alrm->time);
	struct rtc_time aie_time =
		rtc_ktime_to_tm(rtc->rtc->aie_timer.node.expires);
	int ret;

	/*
	 * We have 2 groups alarms: normal alarm and auxiliary alarm. Since
	 * both normal alarm event and auxiliary alarm event can wake up system
	 * from deep sleep, but only alarm event can power up system from power
	 * down status. Moreover we do not need to poll about 125ms when
	 * updating auxiliary alarm registers. Thus we usually set auxiliary
	 * alarm when wake up system from deep sleep, and for other scenarios,
	 * we should set normal alarm with polling status.
	 *
	 * So here we check if the alarm time is set by aie_timer, if yes, we
	 * should set normal alarm, if not, we should set auxiliary alarm which
	 * means it is just a wake event.
	 */
	if (!rtc->rtc->aie_timer.enabled || rtc_tm_sub(&aie_time, &alrm->time))
		return sprd_rtc_set_aux_alarm(dev, alrm);

	/* clear the alarm interrupt status firstly */
	ret = regmap_write(rtc->regmap, rtc->base + SPRD_RTC_INT_CLR,
			   SPRD_RTC_ALARM_EN);
	if (ret)
		return ret;

	ret = sprd_rtc_set_secs(rtc, SPRD_RTC_ALARM, secs);
	if (ret)
		return ret;

	if (alrm->enabled) {
		ret = regmap_update_bits(rtc->regmap,
					 rtc->base + SPRD_RTC_INT_EN,
					 SPRD_RTC_ALARM_EN,
					 SPRD_RTC_ALARM_EN);
		if (ret)
			return ret;

		/* unlock the alarm to enable the alarm function. */
		ret = sprd_rtc_lock_alarm(rtc, false);
	} else {
		regmap_update_bits(rtc->regmap,
				   rtc->base + SPRD_RTC_INT_EN,
				   SPRD_RTC_ALARM_EN, 0);

		/*
		 * Lock the alarm function in case fake alarm event will power
		 * up systems.
		 */
		ret = sprd_rtc_lock_alarm(rtc, true);
	}

	return ret;
}

static int sprd_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
	struct sprd_rtc *rtc = dev_get_drvdata(dev);
	int ret;

	if (enabled) {
		ret = regmap_update_bits(rtc->regmap,
					 rtc->base + SPRD_RTC_INT_EN,
					 SPRD_RTC_ALARM_EN | SPRD_RTC_AUXALM_EN,
					 SPRD_RTC_ALARM_EN | SPRD_RTC_AUXALM_EN);
		if (ret)
			return ret;

		ret = sprd_rtc_lock_alarm(rtc, false);
	} else {
		regmap_update_bits(rtc->regmap, rtc->base + SPRD_RTC_INT_EN,
				   SPRD_RTC_ALARM_EN | SPRD_RTC_AUXALM_EN, 0);

		ret = sprd_rtc_lock_alarm(rtc, true);
	}

	return ret;
}

static const struct rtc_class_ops sprd_rtc_ops = {
	.read_time = sprd_rtc_read_time,
	.set_time = sprd_rtc_set_time,
	.read_alarm = sprd_rtc_read_alarm,
	.set_alarm = sprd_rtc_set_alarm,
	.alarm_irq_enable = sprd_rtc_alarm_irq_enable,
};

static irqreturn_t sprd_rtc_handler(int irq, void *dev_id)
{
	struct sprd_rtc *rtc = dev_id;
	int ret;

	ret = sprd_rtc_clear_alarm_ints(rtc);
	if (ret)
		return IRQ_RETVAL(ret);

	rtc_update_irq(rtc->rtc, 1, RTC_AF | RTC_IRQF);
	return IRQ_HANDLED;
}

static int sprd_rtc_check_power_down(struct sprd_rtc *rtc)
{
	u32 val;
	int ret;

	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_PWR_STS, &val);
	if (ret)
		return ret;

	/*
	 * If the RTC power status value is SPRD_RTC_POWER_RESET_VALUE, which
	 * means the RTC has been powered down, so the RTC time values are
	 * invalid.
	 */
	rtc->valid = val == SPRD_RTC_POWER_RESET_VALUE ? false : true;
	return 0;
}

static int sprd_rtc_check_alarm_int(struct sprd_rtc *rtc)
{
	u32 val;
	int ret;

	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_SPG_VALUE, &val);
	if (ret)
		return ret;

	/*
	 * The SPRD_RTC_INT_EN register is not put in always-power-on region
	 * supplied by VDDRTC, so we should check if we need enable the alarm
	 * interrupt when system booting.
	 *
	 * If we have set SPRD_RTC_POWEROFF_ALM_FLAG which is saved in
	 * always-power-on region, that means we have set one alarm last time,
	 * so we should enable the alarm interrupt to help RTC core to see if
	 * there is an alarm already set in RTC hardware.
	 */
	if (!(val & SPRD_RTC_POWEROFF_ALM_FLAG))
		return 0;

	return regmap_update_bits(rtc->regmap, rtc->base + SPRD_RTC_INT_EN,
				  SPRD_RTC_ALARM_EN, SPRD_RTC_ALARM_EN);
}

static int sprd_rtc_probe(struct platform_device *pdev)
{
	struct device_node *node = pdev->dev.of_node;
	struct sprd_rtc *rtc;
	int ret;

	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
	if (!rtc)
		return -ENOMEM;

	rtc->regmap = dev_get_regmap(pdev->dev.parent, NULL);
	if (!rtc->regmap)
		return -ENODEV;

	ret = of_property_read_u32(node, "reg", &rtc->base);
	if (ret) {
		dev_err(&pdev->dev, "failed to get RTC base address\n");
		return ret;
	}

	rtc->irq = platform_get_irq(pdev, 0);
	if (rtc->irq < 0)
		return rtc->irq;

	rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
	if (IS_ERR(rtc->rtc))
		return PTR_ERR(rtc->rtc);

	rtc->dev = &pdev->dev;
	platform_set_drvdata(pdev, rtc);

	/* check if we need set the alarm interrupt */
	ret = sprd_rtc_check_alarm_int(rtc);
	if (ret) {
		dev_err(&pdev->dev, "failed to check RTC alarm interrupt\n");
		return ret;
	}

	/* check if RTC time values are valid */
	ret = sprd_rtc_check_power_down(rtc);
	if (ret) {
		dev_err(&pdev->dev, "failed to check RTC time values\n");
		return ret;
	}

	ret = devm_request_threaded_irq(&pdev->dev, rtc->irq, NULL,
					sprd_rtc_handler,
					IRQF_ONESHOT | IRQF_EARLY_RESUME,
					pdev->name, rtc);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to request RTC irq\n");
		return ret;
	}

	device_init_wakeup(&pdev->dev, 1);

	rtc->rtc->ops = &sprd_rtc_ops;
	rtc->rtc->range_min = 0;
	rtc->rtc->range_max = 5662310399LL;
	ret = rtc_register_device(rtc->rtc);
	if (ret) {
		device_init_wakeup(&pdev->dev, 0);
		return ret;
	}

	return 0;
}

static const struct of_device_id sprd_rtc_of_match[] = {
	{ .compatible = "sprd,sc2731-rtc", },
	{ },
};
MODULE_DEVICE_TABLE(of, sprd_rtc_of_match);

static struct platform_driver sprd_rtc_driver = {
	.driver = {
		.name = "sprd-rtc",
		.of_match_table = sprd_rtc_of_match,
	},
	.probe	= sprd_rtc_probe,
};
module_platform_driver(sprd_rtc_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Spreadtrum RTC Device Driver");
MODULE_AUTHOR("Baolin Wang <baolin.wang@spreadtrum.com>");