xref: /openbmc/linux/drivers/rtc/rtc-sc27xx.c (revision e620a1e0)
1 /*
2  * Copyright (C) 2017 Spreadtrum Communications Inc.
3  *
4  * SPDX-License-Identifier: GPL-2.0
5  */
6 
7 #include <linux/bitops.h>
8 #include <linux/delay.h>
9 #include <linux/err.h>
10 #include <linux/module.h>
11 #include <linux/of.h>
12 #include <linux/platform_device.h>
13 #include <linux/regmap.h>
14 #include <linux/rtc.h>
15 
16 #define SPRD_RTC_SEC_CNT_VALUE		0x0
17 #define SPRD_RTC_MIN_CNT_VALUE		0x4
18 #define SPRD_RTC_HOUR_CNT_VALUE		0x8
19 #define SPRD_RTC_DAY_CNT_VALUE		0xc
20 #define SPRD_RTC_SEC_CNT_UPD		0x10
21 #define SPRD_RTC_MIN_CNT_UPD		0x14
22 #define SPRD_RTC_HOUR_CNT_UPD		0x18
23 #define SPRD_RTC_DAY_CNT_UPD		0x1c
24 #define SPRD_RTC_SEC_ALM_UPD		0x20
25 #define SPRD_RTC_MIN_ALM_UPD		0x24
26 #define SPRD_RTC_HOUR_ALM_UPD		0x28
27 #define SPRD_RTC_DAY_ALM_UPD		0x2c
28 #define SPRD_RTC_INT_EN			0x30
29 #define SPRD_RTC_INT_RAW_STS		0x34
30 #define SPRD_RTC_INT_CLR		0x38
31 #define SPRD_RTC_INT_MASK_STS		0x3C
32 #define SPRD_RTC_SEC_ALM_VALUE		0x40
33 #define SPRD_RTC_MIN_ALM_VALUE		0x44
34 #define SPRD_RTC_HOUR_ALM_VALUE		0x48
35 #define SPRD_RTC_DAY_ALM_VALUE		0x4c
36 #define SPRD_RTC_SPG_VALUE		0x50
37 #define SPRD_RTC_SPG_UPD		0x54
38 #define SPRD_RTC_PWR_CTRL		0x58
39 #define SPRD_RTC_PWR_STS		0x5c
40 #define SPRD_RTC_SEC_AUXALM_UPD		0x60
41 #define SPRD_RTC_MIN_AUXALM_UPD		0x64
42 #define SPRD_RTC_HOUR_AUXALM_UPD	0x68
43 #define SPRD_RTC_DAY_AUXALM_UPD		0x6c
44 
45 /* BIT & MASK definition for SPRD_RTC_INT_* registers */
46 #define SPRD_RTC_SEC_EN			BIT(0)
47 #define SPRD_RTC_MIN_EN			BIT(1)
48 #define SPRD_RTC_HOUR_EN		BIT(2)
49 #define SPRD_RTC_DAY_EN			BIT(3)
50 #define SPRD_RTC_ALARM_EN		BIT(4)
51 #define SPRD_RTC_HRS_FORMAT_EN		BIT(5)
52 #define SPRD_RTC_AUXALM_EN		BIT(6)
53 #define SPRD_RTC_SPG_UPD_EN		BIT(7)
54 #define SPRD_RTC_SEC_UPD_EN		BIT(8)
55 #define SPRD_RTC_MIN_UPD_EN		BIT(9)
56 #define SPRD_RTC_HOUR_UPD_EN		BIT(10)
57 #define SPRD_RTC_DAY_UPD_EN		BIT(11)
58 #define SPRD_RTC_ALMSEC_UPD_EN		BIT(12)
59 #define SPRD_RTC_ALMMIN_UPD_EN		BIT(13)
60 #define SPRD_RTC_ALMHOUR_UPD_EN		BIT(14)
61 #define SPRD_RTC_ALMDAY_UPD_EN		BIT(15)
62 #define SPRD_RTC_INT_MASK		GENMASK(15, 0)
63 
64 #define SPRD_RTC_TIME_INT_MASK				\
65 	(SPRD_RTC_SEC_UPD_EN | SPRD_RTC_MIN_UPD_EN |	\
66 	 SPRD_RTC_HOUR_UPD_EN | SPRD_RTC_DAY_UPD_EN)
67 
68 #define SPRD_RTC_ALMTIME_INT_MASK				\
69 	(SPRD_RTC_ALMSEC_UPD_EN | SPRD_RTC_ALMMIN_UPD_EN |	\
70 	 SPRD_RTC_ALMHOUR_UPD_EN | SPRD_RTC_ALMDAY_UPD_EN)
71 
72 #define SPRD_RTC_ALM_INT_MASK			\
73 	(SPRD_RTC_SEC_EN | SPRD_RTC_MIN_EN |	\
74 	 SPRD_RTC_HOUR_EN | SPRD_RTC_DAY_EN |	\
75 	 SPRD_RTC_ALARM_EN | SPRD_RTC_AUXALM_EN)
76 
77 /* second/minute/hour/day values mask definition */
78 #define SPRD_RTC_SEC_MASK		GENMASK(5, 0)
79 #define SPRD_RTC_MIN_MASK		GENMASK(5, 0)
80 #define SPRD_RTC_HOUR_MASK		GENMASK(4, 0)
81 #define SPRD_RTC_DAY_MASK		GENMASK(15, 0)
82 
83 /* alarm lock definition for SPRD_RTC_SPG_UPD register */
84 #define SPRD_RTC_ALMLOCK_MASK		GENMASK(7, 0)
85 #define SPRD_RTC_ALM_UNLOCK		0xa5
86 #define SPRD_RTC_ALM_LOCK		(~SPRD_RTC_ALM_UNLOCK &	\
87 					 SPRD_RTC_ALMLOCK_MASK)
88 
89 /* SPG values definition for SPRD_RTC_SPG_UPD register */
90 #define SPRD_RTC_POWEROFF_ALM_FLAG	BIT(8)
91 
92 /* power control/status definition */
93 #define SPRD_RTC_POWER_RESET_VALUE	0x96
94 #define SPRD_RTC_POWER_STS_CLEAR	GENMASK(7, 0)
95 #define SPRD_RTC_POWER_STS_SHIFT	8
96 #define SPRD_RTC_POWER_STS_VALID	\
97 	(~SPRD_RTC_POWER_RESET_VALUE << SPRD_RTC_POWER_STS_SHIFT)
98 
99 /* timeout of synchronizing time and alarm registers (us) */
100 #define SPRD_RTC_POLL_TIMEOUT		200000
101 #define SPRD_RTC_POLL_DELAY_US		20000
102 
103 struct sprd_rtc {
104 	struct rtc_device	*rtc;
105 	struct regmap		*regmap;
106 	struct device		*dev;
107 	u32			base;
108 	int			irq;
109 	bool			valid;
110 };
111 
112 /*
113  * The Spreadtrum RTC controller has 3 groups registers, including time, normal
114  * alarm and auxiliary alarm. The time group registers are used to set RTC time,
115  * the normal alarm registers are used to set normal alarm, and the auxiliary
116  * alarm registers are used to set auxiliary alarm. Both alarm event and
117  * auxiliary alarm event can wake up system from deep sleep, but only alarm
118  * event can power up system from power down status.
119  */
120 enum sprd_rtc_reg_types {
121 	SPRD_RTC_TIME,
122 	SPRD_RTC_ALARM,
123 	SPRD_RTC_AUX_ALARM,
124 };
125 
126 static int sprd_rtc_clear_alarm_ints(struct sprd_rtc *rtc)
127 {
128 	return regmap_write(rtc->regmap, rtc->base + SPRD_RTC_INT_CLR,
129 			    SPRD_RTC_ALM_INT_MASK);
130 }
131 
132 static int sprd_rtc_lock_alarm(struct sprd_rtc *rtc, bool lock)
133 {
134 	int ret;
135 	u32 val;
136 
137 	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_SPG_VALUE, &val);
138 	if (ret)
139 		return ret;
140 
141 	val &= ~SPRD_RTC_ALMLOCK_MASK;
142 	if (lock)
143 		val |= SPRD_RTC_ALM_LOCK;
144 	else
145 		val |= SPRD_RTC_ALM_UNLOCK | SPRD_RTC_POWEROFF_ALM_FLAG;
146 
147 	ret = regmap_write(rtc->regmap, rtc->base + SPRD_RTC_SPG_UPD, val);
148 	if (ret)
149 		return ret;
150 
151 	/* wait until the SPG value is updated successfully */
152 	ret = regmap_read_poll_timeout(rtc->regmap,
153 				       rtc->base + SPRD_RTC_INT_RAW_STS, val,
154 				       (val & SPRD_RTC_SPG_UPD_EN),
155 				       SPRD_RTC_POLL_DELAY_US,
156 				       SPRD_RTC_POLL_TIMEOUT);
157 	if (ret) {
158 		dev_err(rtc->dev, "failed to update SPG value:%d\n", ret);
159 		return ret;
160 	}
161 
162 	return regmap_write(rtc->regmap, rtc->base + SPRD_RTC_INT_CLR,
163 			    SPRD_RTC_SPG_UPD_EN);
164 }
165 
166 static int sprd_rtc_get_secs(struct sprd_rtc *rtc, enum sprd_rtc_reg_types type,
167 			     time64_t *secs)
168 {
169 	u32 sec_reg, min_reg, hour_reg, day_reg;
170 	u32 val, sec, min, hour, day;
171 	int ret;
172 
173 	switch (type) {
174 	case SPRD_RTC_TIME:
175 		sec_reg = SPRD_RTC_SEC_CNT_VALUE;
176 		min_reg = SPRD_RTC_MIN_CNT_VALUE;
177 		hour_reg = SPRD_RTC_HOUR_CNT_VALUE;
178 		day_reg = SPRD_RTC_DAY_CNT_VALUE;
179 		break;
180 	case SPRD_RTC_ALARM:
181 		sec_reg = SPRD_RTC_SEC_ALM_VALUE;
182 		min_reg = SPRD_RTC_MIN_ALM_VALUE;
183 		hour_reg = SPRD_RTC_HOUR_ALM_VALUE;
184 		day_reg = SPRD_RTC_DAY_ALM_VALUE;
185 		break;
186 	case SPRD_RTC_AUX_ALARM:
187 		sec_reg = SPRD_RTC_SEC_AUXALM_UPD;
188 		min_reg = SPRD_RTC_MIN_AUXALM_UPD;
189 		hour_reg = SPRD_RTC_HOUR_AUXALM_UPD;
190 		day_reg = SPRD_RTC_DAY_AUXALM_UPD;
191 		break;
192 	default:
193 		return -EINVAL;
194 	}
195 
196 	ret = regmap_read(rtc->regmap, rtc->base + sec_reg, &val);
197 	if (ret)
198 		return ret;
199 
200 	sec = val & SPRD_RTC_SEC_MASK;
201 
202 	ret = regmap_read(rtc->regmap, rtc->base + min_reg, &val);
203 	if (ret)
204 		return ret;
205 
206 	min = val & SPRD_RTC_MIN_MASK;
207 
208 	ret = regmap_read(rtc->regmap, rtc->base + hour_reg, &val);
209 	if (ret)
210 		return ret;
211 
212 	hour = val & SPRD_RTC_HOUR_MASK;
213 
214 	ret = regmap_read(rtc->regmap, rtc->base + day_reg, &val);
215 	if (ret)
216 		return ret;
217 
218 	day = val & SPRD_RTC_DAY_MASK;
219 	*secs = (((time64_t)(day * 24) + hour) * 60 + min) * 60 + sec;
220 	return 0;
221 }
222 
223 static int sprd_rtc_set_secs(struct sprd_rtc *rtc, enum sprd_rtc_reg_types type,
224 			     time64_t secs)
225 {
226 	u32 sec_reg, min_reg, hour_reg, day_reg, sts_mask;
227 	u32 sec, min, hour, day, val;
228 	int ret, rem;
229 
230 	/* convert seconds to RTC time format */
231 	day = div_s64_rem(secs, 86400, &rem);
232 	hour = rem / 3600;
233 	rem -= hour * 3600;
234 	min = rem / 60;
235 	sec = rem - min * 60;
236 
237 	switch (type) {
238 	case SPRD_RTC_TIME:
239 		sec_reg = SPRD_RTC_SEC_CNT_UPD;
240 		min_reg = SPRD_RTC_MIN_CNT_UPD;
241 		hour_reg = SPRD_RTC_HOUR_CNT_UPD;
242 		day_reg = SPRD_RTC_DAY_CNT_UPD;
243 		sts_mask = SPRD_RTC_TIME_INT_MASK;
244 		break;
245 	case SPRD_RTC_ALARM:
246 		sec_reg = SPRD_RTC_SEC_ALM_UPD;
247 		min_reg = SPRD_RTC_MIN_ALM_UPD;
248 		hour_reg = SPRD_RTC_HOUR_ALM_UPD;
249 		day_reg = SPRD_RTC_DAY_ALM_UPD;
250 		sts_mask = SPRD_RTC_ALMTIME_INT_MASK;
251 		break;
252 	case SPRD_RTC_AUX_ALARM:
253 		sec_reg = SPRD_RTC_SEC_AUXALM_UPD;
254 		min_reg = SPRD_RTC_MIN_AUXALM_UPD;
255 		hour_reg = SPRD_RTC_HOUR_AUXALM_UPD;
256 		day_reg = SPRD_RTC_DAY_AUXALM_UPD;
257 		sts_mask = 0;
258 		break;
259 	default:
260 		return -EINVAL;
261 	}
262 
263 	ret = regmap_write(rtc->regmap, rtc->base + sec_reg, sec);
264 	if (ret)
265 		return ret;
266 
267 	ret = regmap_write(rtc->regmap, rtc->base + min_reg, min);
268 	if (ret)
269 		return ret;
270 
271 	ret = regmap_write(rtc->regmap, rtc->base + hour_reg, hour);
272 	if (ret)
273 		return ret;
274 
275 	ret = regmap_write(rtc->regmap, rtc->base + day_reg, day);
276 	if (ret)
277 		return ret;
278 
279 	if (type == SPRD_RTC_AUX_ALARM)
280 		return 0;
281 
282 	/*
283 	 * Since the time and normal alarm registers are put in always-power-on
284 	 * region supplied by VDDRTC, then these registers changing time will
285 	 * be very long, about 125ms. Thus here we should wait until all
286 	 * values are updated successfully.
287 	 */
288 	ret = regmap_read_poll_timeout(rtc->regmap,
289 				       rtc->base + SPRD_RTC_INT_RAW_STS, val,
290 				       ((val & sts_mask) == sts_mask),
291 				       SPRD_RTC_POLL_DELAY_US,
292 				       SPRD_RTC_POLL_TIMEOUT);
293 	if (ret < 0) {
294 		dev_err(rtc->dev, "set time/alarm values timeout\n");
295 		return ret;
296 	}
297 
298 	return regmap_write(rtc->regmap, rtc->base + SPRD_RTC_INT_CLR,
299 			    sts_mask);
300 }
301 
302 static int sprd_rtc_read_aux_alarm(struct device *dev, struct rtc_wkalrm *alrm)
303 {
304 	struct sprd_rtc *rtc = dev_get_drvdata(dev);
305 	time64_t secs;
306 	u32 val;
307 	int ret;
308 
309 	ret = sprd_rtc_get_secs(rtc, SPRD_RTC_AUX_ALARM, &secs);
310 	if (ret)
311 		return ret;
312 
313 	rtc_time64_to_tm(secs, &alrm->time);
314 
315 	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_INT_EN, &val);
316 	if (ret)
317 		return ret;
318 
319 	alrm->enabled = !!(val & SPRD_RTC_AUXALM_EN);
320 
321 	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_INT_RAW_STS, &val);
322 	if (ret)
323 		return ret;
324 
325 	alrm->pending = !!(val & SPRD_RTC_AUXALM_EN);
326 	return 0;
327 }
328 
329 static int sprd_rtc_set_aux_alarm(struct device *dev, struct rtc_wkalrm *alrm)
330 {
331 	struct sprd_rtc *rtc = dev_get_drvdata(dev);
332 	time64_t secs = rtc_tm_to_time64(&alrm->time);
333 	int ret;
334 
335 	/* clear the auxiliary alarm interrupt status */
336 	ret = regmap_write(rtc->regmap, rtc->base + SPRD_RTC_INT_CLR,
337 			   SPRD_RTC_AUXALM_EN);
338 	if (ret)
339 		return ret;
340 
341 	ret = sprd_rtc_set_secs(rtc, SPRD_RTC_AUX_ALARM, secs);
342 	if (ret)
343 		return ret;
344 
345 	if (alrm->enabled) {
346 		ret = regmap_update_bits(rtc->regmap,
347 					 rtc->base + SPRD_RTC_INT_EN,
348 					 SPRD_RTC_AUXALM_EN,
349 					 SPRD_RTC_AUXALM_EN);
350 	} else {
351 		ret = regmap_update_bits(rtc->regmap,
352 					 rtc->base + SPRD_RTC_INT_EN,
353 					 SPRD_RTC_AUXALM_EN, 0);
354 	}
355 
356 	return ret;
357 }
358 
359 static int sprd_rtc_read_time(struct device *dev, struct rtc_time *tm)
360 {
361 	struct sprd_rtc *rtc = dev_get_drvdata(dev);
362 	time64_t secs;
363 	int ret;
364 
365 	if (!rtc->valid) {
366 		dev_warn(dev, "RTC values are invalid\n");
367 		return -EINVAL;
368 	}
369 
370 	ret = sprd_rtc_get_secs(rtc, SPRD_RTC_TIME, &secs);
371 	if (ret)
372 		return ret;
373 
374 	rtc_time64_to_tm(secs, tm);
375 	return 0;
376 }
377 
378 static int sprd_rtc_set_time(struct device *dev, struct rtc_time *tm)
379 {
380 	struct sprd_rtc *rtc = dev_get_drvdata(dev);
381 	time64_t secs = rtc_tm_to_time64(tm);
382 	int ret;
383 
384 	ret = sprd_rtc_set_secs(rtc, SPRD_RTC_TIME, secs);
385 	if (ret)
386 		return ret;
387 
388 	if (!rtc->valid) {
389 		/* Clear RTC power status firstly */
390 		ret = regmap_write(rtc->regmap, rtc->base + SPRD_RTC_PWR_CTRL,
391 				   SPRD_RTC_POWER_STS_CLEAR);
392 		if (ret)
393 			return ret;
394 
395 		/*
396 		 * Set RTC power status to indicate now RTC has valid time
397 		 * values.
398 		 */
399 		ret = regmap_write(rtc->regmap, rtc->base + SPRD_RTC_PWR_CTRL,
400 				   SPRD_RTC_POWER_STS_VALID);
401 		if (ret)
402 			return ret;
403 
404 		rtc->valid = true;
405 	}
406 
407 	return 0;
408 }
409 
410 static int sprd_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
411 {
412 	struct sprd_rtc *rtc = dev_get_drvdata(dev);
413 	time64_t secs;
414 	int ret;
415 	u32 val;
416 
417 	/*
418 	 * Before RTC device is registered, it will check to see if there is an
419 	 * alarm already set in RTC hardware, and we always read the normal
420 	 * alarm at this time.
421 	 *
422 	 * Or if aie_timer is enabled, we should get the normal alarm time.
423 	 * Otherwise we should get auxiliary alarm time.
424 	 */
425 	if (rtc->rtc && rtc->rtc->registered && rtc->rtc->aie_timer.enabled == 0)
426 		return sprd_rtc_read_aux_alarm(dev, alrm);
427 
428 	ret = sprd_rtc_get_secs(rtc, SPRD_RTC_ALARM, &secs);
429 	if (ret)
430 		return ret;
431 
432 	rtc_time64_to_tm(secs, &alrm->time);
433 
434 	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_INT_EN, &val);
435 	if (ret)
436 		return ret;
437 
438 	alrm->enabled = !!(val & SPRD_RTC_ALARM_EN);
439 
440 	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_INT_RAW_STS, &val);
441 	if (ret)
442 		return ret;
443 
444 	alrm->pending = !!(val & SPRD_RTC_ALARM_EN);
445 	return 0;
446 }
447 
448 static int sprd_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
449 {
450 	struct sprd_rtc *rtc = dev_get_drvdata(dev);
451 	time64_t secs = rtc_tm_to_time64(&alrm->time);
452 	struct rtc_time aie_time =
453 		rtc_ktime_to_tm(rtc->rtc->aie_timer.node.expires);
454 	int ret;
455 
456 	/*
457 	 * We have 2 groups alarms: normal alarm and auxiliary alarm. Since
458 	 * both normal alarm event and auxiliary alarm event can wake up system
459 	 * from deep sleep, but only alarm event can power up system from power
460 	 * down status. Moreover we do not need to poll about 125ms when
461 	 * updating auxiliary alarm registers. Thus we usually set auxiliary
462 	 * alarm when wake up system from deep sleep, and for other scenarios,
463 	 * we should set normal alarm with polling status.
464 	 *
465 	 * So here we check if the alarm time is set by aie_timer, if yes, we
466 	 * should set normal alarm, if not, we should set auxiliary alarm which
467 	 * means it is just a wake event.
468 	 */
469 	if (!rtc->rtc->aie_timer.enabled || rtc_tm_sub(&aie_time, &alrm->time))
470 		return sprd_rtc_set_aux_alarm(dev, alrm);
471 
472 	/* clear the alarm interrupt status firstly */
473 	ret = regmap_write(rtc->regmap, rtc->base + SPRD_RTC_INT_CLR,
474 			   SPRD_RTC_ALARM_EN);
475 	if (ret)
476 		return ret;
477 
478 	ret = sprd_rtc_set_secs(rtc, SPRD_RTC_ALARM, secs);
479 	if (ret)
480 		return ret;
481 
482 	if (alrm->enabled) {
483 		ret = regmap_update_bits(rtc->regmap,
484 					 rtc->base + SPRD_RTC_INT_EN,
485 					 SPRD_RTC_ALARM_EN,
486 					 SPRD_RTC_ALARM_EN);
487 		if (ret)
488 			return ret;
489 
490 		/* unlock the alarm to enable the alarm function. */
491 		ret = sprd_rtc_lock_alarm(rtc, false);
492 	} else {
493 		regmap_update_bits(rtc->regmap,
494 				   rtc->base + SPRD_RTC_INT_EN,
495 				   SPRD_RTC_ALARM_EN, 0);
496 
497 		/*
498 		 * Lock the alarm function in case fake alarm event will power
499 		 * up systems.
500 		 */
501 		ret = sprd_rtc_lock_alarm(rtc, true);
502 	}
503 
504 	return ret;
505 }
506 
507 static int sprd_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
508 {
509 	struct sprd_rtc *rtc = dev_get_drvdata(dev);
510 	int ret;
511 
512 	if (enabled) {
513 		ret = regmap_update_bits(rtc->regmap,
514 					 rtc->base + SPRD_RTC_INT_EN,
515 					 SPRD_RTC_ALARM_EN | SPRD_RTC_AUXALM_EN,
516 					 SPRD_RTC_ALARM_EN | SPRD_RTC_AUXALM_EN);
517 		if (ret)
518 			return ret;
519 
520 		ret = sprd_rtc_lock_alarm(rtc, false);
521 	} else {
522 		regmap_update_bits(rtc->regmap, rtc->base + SPRD_RTC_INT_EN,
523 				   SPRD_RTC_ALARM_EN | SPRD_RTC_AUXALM_EN, 0);
524 
525 		ret = sprd_rtc_lock_alarm(rtc, true);
526 	}
527 
528 	return ret;
529 }
530 
531 static const struct rtc_class_ops sprd_rtc_ops = {
532 	.read_time = sprd_rtc_read_time,
533 	.set_time = sprd_rtc_set_time,
534 	.read_alarm = sprd_rtc_read_alarm,
535 	.set_alarm = sprd_rtc_set_alarm,
536 	.alarm_irq_enable = sprd_rtc_alarm_irq_enable,
537 };
538 
539 static irqreturn_t sprd_rtc_handler(int irq, void *dev_id)
540 {
541 	struct sprd_rtc *rtc = dev_id;
542 	int ret;
543 
544 	ret = sprd_rtc_clear_alarm_ints(rtc);
545 	if (ret)
546 		return IRQ_RETVAL(ret);
547 
548 	rtc_update_irq(rtc->rtc, 1, RTC_AF | RTC_IRQF);
549 	return IRQ_HANDLED;
550 }
551 
552 static int sprd_rtc_check_power_down(struct sprd_rtc *rtc)
553 {
554 	u32 val;
555 	int ret;
556 
557 	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_PWR_STS, &val);
558 	if (ret)
559 		return ret;
560 
561 	/*
562 	 * If the RTC power status value is SPRD_RTC_POWER_RESET_VALUE, which
563 	 * means the RTC has been powered down, so the RTC time values are
564 	 * invalid.
565 	 */
566 	rtc->valid = val == SPRD_RTC_POWER_RESET_VALUE ? false : true;
567 	return 0;
568 }
569 
570 static int sprd_rtc_check_alarm_int(struct sprd_rtc *rtc)
571 {
572 	u32 val;
573 	int ret;
574 
575 	ret = regmap_read(rtc->regmap, rtc->base + SPRD_RTC_SPG_VALUE, &val);
576 	if (ret)
577 		return ret;
578 
579 	/*
580 	 * The SPRD_RTC_INT_EN register is not put in always-power-on region
581 	 * supplied by VDDRTC, so we should check if we need enable the alarm
582 	 * interrupt when system booting.
583 	 *
584 	 * If we have set SPRD_RTC_POWEROFF_ALM_FLAG which is saved in
585 	 * always-power-on region, that means we have set one alarm last time,
586 	 * so we should enable the alarm interrupt to help RTC core to see if
587 	 * there is an alarm already set in RTC hardware.
588 	 */
589 	if (!(val & SPRD_RTC_POWEROFF_ALM_FLAG))
590 		return 0;
591 
592 	return regmap_update_bits(rtc->regmap, rtc->base + SPRD_RTC_INT_EN,
593 				  SPRD_RTC_ALARM_EN, SPRD_RTC_ALARM_EN);
594 }
595 
596 static int sprd_rtc_probe(struct platform_device *pdev)
597 {
598 	struct device_node *node = pdev->dev.of_node;
599 	struct sprd_rtc *rtc;
600 	int ret;
601 
602 	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
603 	if (!rtc)
604 		return -ENOMEM;
605 
606 	rtc->regmap = dev_get_regmap(pdev->dev.parent, NULL);
607 	if (!rtc->regmap)
608 		return -ENODEV;
609 
610 	ret = of_property_read_u32(node, "reg", &rtc->base);
611 	if (ret) {
612 		dev_err(&pdev->dev, "failed to get RTC base address\n");
613 		return ret;
614 	}
615 
616 	rtc->irq = platform_get_irq(pdev, 0);
617 	if (rtc->irq < 0)
618 		return rtc->irq;
619 
620 	rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
621 	if (IS_ERR(rtc->rtc))
622 		return PTR_ERR(rtc->rtc);
623 
624 	rtc->dev = &pdev->dev;
625 	platform_set_drvdata(pdev, rtc);
626 
627 	/* check if we need set the alarm interrupt */
628 	ret = sprd_rtc_check_alarm_int(rtc);
629 	if (ret) {
630 		dev_err(&pdev->dev, "failed to check RTC alarm interrupt\n");
631 		return ret;
632 	}
633 
634 	/* check if RTC time values are valid */
635 	ret = sprd_rtc_check_power_down(rtc);
636 	if (ret) {
637 		dev_err(&pdev->dev, "failed to check RTC time values\n");
638 		return ret;
639 	}
640 
641 	ret = devm_request_threaded_irq(&pdev->dev, rtc->irq, NULL,
642 					sprd_rtc_handler,
643 					IRQF_ONESHOT | IRQF_EARLY_RESUME,
644 					pdev->name, rtc);
645 	if (ret < 0) {
646 		dev_err(&pdev->dev, "failed to request RTC irq\n");
647 		return ret;
648 	}
649 
650 	device_init_wakeup(&pdev->dev, 1);
651 
652 	rtc->rtc->ops = &sprd_rtc_ops;
653 	rtc->rtc->range_min = 0;
654 	rtc->rtc->range_max = 5662310399LL;
655 	ret = rtc_register_device(rtc->rtc);
656 	if (ret) {
657 		device_init_wakeup(&pdev->dev, 0);
658 		return ret;
659 	}
660 
661 	return 0;
662 }
663 
664 static int sprd_rtc_remove(struct platform_device *pdev)
665 {
666 	device_init_wakeup(&pdev->dev, 0);
667 	return 0;
668 }
669 
670 static const struct of_device_id sprd_rtc_of_match[] = {
671 	{ .compatible = "sprd,sc2731-rtc", },
672 	{ },
673 };
674 MODULE_DEVICE_TABLE(of, sprd_rtc_of_match);
675 
676 static struct platform_driver sprd_rtc_driver = {
677 	.driver = {
678 		.name = "sprd-rtc",
679 		.of_match_table = sprd_rtc_of_match,
680 	},
681 	.probe	= sprd_rtc_probe,
682 	.remove = sprd_rtc_remove,
683 };
684 module_platform_driver(sprd_rtc_driver);
685 
686 MODULE_LICENSE("GPL v2");
687 MODULE_DESCRIPTION("Spreadtrum RTC Device Driver");
688 MODULE_AUTHOR("Baolin Wang <baolin.wang@spreadtrum.com>");
689