xref: /linux/drivers/rtc/rtc-ac100.c (revision 2363088eba2ecccfb643725e4864af73c4226a04)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * RTC Driver for X-Powers AC100
4  *
5  * Copyright (c) 2016 Chen-Yu Tsai
6  *
7  * Chen-Yu Tsai <wens@csie.org>
8  */
9 
10 #include <linux/bcd.h>
11 #include <linux/clk-provider.h>
12 #include <linux/device.h>
13 #include <linux/interrupt.h>
14 #include <linux/kernel.h>
15 #include <linux/mfd/ac100.h>
16 #include <linux/module.h>
17 #include <linux/mutex.h>
18 #include <linux/of.h>
19 #include <linux/platform_device.h>
20 #include <linux/regmap.h>
21 #include <linux/rtc.h>
22 #include <linux/types.h>
23 
24 /* Control register */
25 #define AC100_RTC_CTRL_24HOUR	BIT(0)
26 
27 /* Clock output register bits */
28 #define AC100_CLKOUT_PRE_DIV_SHIFT	5
29 #define AC100_CLKOUT_PRE_DIV_WIDTH	3
30 #define AC100_CLKOUT_MUX_SHIFT		4
31 #define AC100_CLKOUT_MUX_WIDTH		1
32 #define AC100_CLKOUT_DIV_SHIFT		1
33 #define AC100_CLKOUT_DIV_WIDTH		3
34 #define AC100_CLKOUT_EN			BIT(0)
35 
36 /* RTC */
37 #define AC100_RTC_SEC_MASK	GENMASK(6, 0)
38 #define AC100_RTC_MIN_MASK	GENMASK(6, 0)
39 #define AC100_RTC_HOU_MASK	GENMASK(5, 0)
40 #define AC100_RTC_WEE_MASK	GENMASK(2, 0)
41 #define AC100_RTC_DAY_MASK	GENMASK(5, 0)
42 #define AC100_RTC_MON_MASK	GENMASK(4, 0)
43 #define AC100_RTC_YEA_MASK	GENMASK(7, 0)
44 #define AC100_RTC_YEA_LEAP	BIT(15)
45 #define AC100_RTC_UPD_TRIGGER	BIT(15)
46 
47 /* Alarm (wall clock) */
48 #define AC100_ALM_INT_ENABLE	BIT(0)
49 
50 #define AC100_ALM_SEC_MASK	GENMASK(6, 0)
51 #define AC100_ALM_MIN_MASK	GENMASK(6, 0)
52 #define AC100_ALM_HOU_MASK	GENMASK(5, 0)
53 #define AC100_ALM_WEE_MASK	GENMASK(2, 0)
54 #define AC100_ALM_DAY_MASK	GENMASK(5, 0)
55 #define AC100_ALM_MON_MASK	GENMASK(4, 0)
56 #define AC100_ALM_YEA_MASK	GENMASK(7, 0)
57 #define AC100_ALM_ENABLE_FLAG	BIT(15)
58 #define AC100_ALM_UPD_TRIGGER	BIT(15)
59 
60 /*
61  * The year parameter passed to the driver is usually an offset relative to
62  * the year 1900. This macro is used to convert this offset to another one
63  * relative to the minimum year allowed by the hardware.
64  *
65  * The year range is 1970 - 2069. This range is selected to match Allwinner's
66  * driver.
67  */
68 #define AC100_YEAR_MIN				1970
69 #define AC100_YEAR_MAX				2069
70 #define AC100_YEAR_OFF				(AC100_YEAR_MIN - 1900)
71 
72 struct ac100_clkout {
73 	struct clk_hw hw;
74 	struct regmap *regmap;
75 	u8 offset;
76 };
77 
78 #define to_ac100_clkout(_hw) container_of(_hw, struct ac100_clkout, hw)
79 
80 #define AC100_RTC_32K_NAME	"ac100-rtc-32k"
81 #define AC100_RTC_32K_RATE	32768
82 #define AC100_CLKOUT_NUM	3
83 
84 static const char * const ac100_clkout_names[AC100_CLKOUT_NUM] = {
85 	"ac100-cko1-rtc",
86 	"ac100-cko2-rtc",
87 	"ac100-cko3-rtc",
88 };
89 
90 struct ac100_rtc_dev {
91 	struct rtc_device *rtc;
92 	struct device *dev;
93 	struct regmap *regmap;
94 	int irq;
95 	unsigned long alarm;
96 
97 	struct clk_hw *rtc_32k_clk;
98 	struct ac100_clkout clks[AC100_CLKOUT_NUM];
99 	struct clk_hw_onecell_data *clk_data;
100 };
101 
102 /**
103  * Clock controls for 3 clock output pins
104  */
105 
106 static const struct clk_div_table ac100_clkout_prediv[] = {
107 	{ .val = 0, .div = 1 },
108 	{ .val = 1, .div = 2 },
109 	{ .val = 2, .div = 4 },
110 	{ .val = 3, .div = 8 },
111 	{ .val = 4, .div = 16 },
112 	{ .val = 5, .div = 32 },
113 	{ .val = 6, .div = 64 },
114 	{ .val = 7, .div = 122 },
115 	{ },
116 };
117 
118 /* Abuse the fact that one parent is 32768 Hz, and the other is 4 MHz */
119 static unsigned long ac100_clkout_recalc_rate(struct clk_hw *hw,
120 					      unsigned long prate)
121 {
122 	struct ac100_clkout *clk = to_ac100_clkout(hw);
123 	unsigned int reg, div;
124 
125 	regmap_read(clk->regmap, clk->offset, &reg);
126 
127 	/* Handle pre-divider first */
128 	if (prate != AC100_RTC_32K_RATE) {
129 		div = (reg >> AC100_CLKOUT_PRE_DIV_SHIFT) &
130 			((1 << AC100_CLKOUT_PRE_DIV_WIDTH) - 1);
131 		prate = divider_recalc_rate(hw, prate, div,
132 					    ac100_clkout_prediv, 0,
133 					    AC100_CLKOUT_PRE_DIV_WIDTH);
134 	}
135 
136 	div = (reg >> AC100_CLKOUT_DIV_SHIFT) &
137 		(BIT(AC100_CLKOUT_DIV_WIDTH) - 1);
138 	return divider_recalc_rate(hw, prate, div, NULL,
139 				   CLK_DIVIDER_POWER_OF_TWO,
140 				   AC100_CLKOUT_DIV_WIDTH);
141 }
142 
143 static long ac100_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
144 				    unsigned long prate)
145 {
146 	unsigned long best_rate = 0, tmp_rate, tmp_prate;
147 	int i;
148 
149 	if (prate == AC100_RTC_32K_RATE)
150 		return divider_round_rate(hw, rate, &prate, NULL,
151 					  AC100_CLKOUT_DIV_WIDTH,
152 					  CLK_DIVIDER_POWER_OF_TWO);
153 
154 	for (i = 0; ac100_clkout_prediv[i].div; i++) {
155 		tmp_prate = DIV_ROUND_UP(prate, ac100_clkout_prediv[i].val);
156 		tmp_rate = divider_round_rate(hw, rate, &tmp_prate, NULL,
157 					      AC100_CLKOUT_DIV_WIDTH,
158 					      CLK_DIVIDER_POWER_OF_TWO);
159 
160 		if (tmp_rate > rate)
161 			continue;
162 		if (rate - tmp_rate < best_rate - tmp_rate)
163 			best_rate = tmp_rate;
164 	}
165 
166 	return best_rate;
167 }
168 
169 static int ac100_clkout_determine_rate(struct clk_hw *hw,
170 				       struct clk_rate_request *req)
171 {
172 	struct clk_hw *best_parent;
173 	unsigned long best = 0;
174 	int i, num_parents = clk_hw_get_num_parents(hw);
175 
176 	for (i = 0; i < num_parents; i++) {
177 		struct clk_hw *parent = clk_hw_get_parent_by_index(hw, i);
178 		unsigned long tmp, prate;
179 
180 		/*
181 		 * The clock has two parents, one is a fixed clock which is
182 		 * internally registered by the ac100 driver. The other parent
183 		 * is a clock from the codec side of the chip, which we
184 		 * properly declare and reference in the devicetree and is
185 		 * not implemented in any driver right now.
186 		 * If the clock core looks for the parent of that second
187 		 * missing clock, it can't find one that is registered and
188 		 * returns NULL.
189 		 * So we end up in a situation where clk_hw_get_num_parents
190 		 * returns the amount of clocks we can be parented to, but
191 		 * clk_hw_get_parent_by_index will not return the orphan
192 		 * clocks.
193 		 * Thus we need to check if the parent exists before
194 		 * we get the parent rate, so we could use the RTC
195 		 * without waiting for the codec to be supported.
196 		 */
197 		if (!parent)
198 			continue;
199 
200 		prate = clk_hw_get_rate(parent);
201 
202 		tmp = ac100_clkout_round_rate(hw, req->rate, prate);
203 
204 		if (tmp > req->rate)
205 			continue;
206 		if (req->rate - tmp < req->rate - best) {
207 			best = tmp;
208 			best_parent = parent;
209 		}
210 	}
211 
212 	if (!best)
213 		return -EINVAL;
214 
215 	req->best_parent_hw = best_parent;
216 	req->best_parent_rate = best;
217 	req->rate = best;
218 
219 	return 0;
220 }
221 
222 static int ac100_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
223 				 unsigned long prate)
224 {
225 	struct ac100_clkout *clk = to_ac100_clkout(hw);
226 	int div = 0, pre_div = 0;
227 
228 	do {
229 		div = divider_get_val(rate * ac100_clkout_prediv[pre_div].div,
230 				      prate, NULL, AC100_CLKOUT_DIV_WIDTH,
231 				      CLK_DIVIDER_POWER_OF_TWO);
232 		if (div >= 0)
233 			break;
234 	} while (prate != AC100_RTC_32K_RATE &&
235 		 ac100_clkout_prediv[++pre_div].div);
236 
237 	if (div < 0)
238 		return div;
239 
240 	pre_div = ac100_clkout_prediv[pre_div].val;
241 
242 	regmap_update_bits(clk->regmap, clk->offset,
243 			   ((1 << AC100_CLKOUT_DIV_WIDTH) - 1) << AC100_CLKOUT_DIV_SHIFT |
244 			   ((1 << AC100_CLKOUT_PRE_DIV_WIDTH) - 1) << AC100_CLKOUT_PRE_DIV_SHIFT,
245 			   (div - 1) << AC100_CLKOUT_DIV_SHIFT |
246 			   (pre_div - 1) << AC100_CLKOUT_PRE_DIV_SHIFT);
247 
248 	return 0;
249 }
250 
251 static int ac100_clkout_prepare(struct clk_hw *hw)
252 {
253 	struct ac100_clkout *clk = to_ac100_clkout(hw);
254 
255 	return regmap_update_bits(clk->regmap, clk->offset, AC100_CLKOUT_EN,
256 				  AC100_CLKOUT_EN);
257 }
258 
259 static void ac100_clkout_unprepare(struct clk_hw *hw)
260 {
261 	struct ac100_clkout *clk = to_ac100_clkout(hw);
262 
263 	regmap_update_bits(clk->regmap, clk->offset, AC100_CLKOUT_EN, 0);
264 }
265 
266 static int ac100_clkout_is_prepared(struct clk_hw *hw)
267 {
268 	struct ac100_clkout *clk = to_ac100_clkout(hw);
269 	unsigned int reg;
270 
271 	regmap_read(clk->regmap, clk->offset, &reg);
272 
273 	return reg & AC100_CLKOUT_EN;
274 }
275 
276 static u8 ac100_clkout_get_parent(struct clk_hw *hw)
277 {
278 	struct ac100_clkout *clk = to_ac100_clkout(hw);
279 	unsigned int reg;
280 
281 	regmap_read(clk->regmap, clk->offset, &reg);
282 
283 	return (reg >> AC100_CLKOUT_MUX_SHIFT) & 0x1;
284 }
285 
286 static int ac100_clkout_set_parent(struct clk_hw *hw, u8 index)
287 {
288 	struct ac100_clkout *clk = to_ac100_clkout(hw);
289 
290 	return regmap_update_bits(clk->regmap, clk->offset,
291 				  BIT(AC100_CLKOUT_MUX_SHIFT),
292 				  index ? BIT(AC100_CLKOUT_MUX_SHIFT) : 0);
293 }
294 
295 static const struct clk_ops ac100_clkout_ops = {
296 	.prepare	= ac100_clkout_prepare,
297 	.unprepare	= ac100_clkout_unprepare,
298 	.is_prepared	= ac100_clkout_is_prepared,
299 	.recalc_rate	= ac100_clkout_recalc_rate,
300 	.determine_rate	= ac100_clkout_determine_rate,
301 	.get_parent	= ac100_clkout_get_parent,
302 	.set_parent	= ac100_clkout_set_parent,
303 	.set_rate	= ac100_clkout_set_rate,
304 };
305 
306 static int ac100_rtc_register_clks(struct ac100_rtc_dev *chip)
307 {
308 	struct device_node *np = chip->dev->of_node;
309 	const char *parents[2] = {AC100_RTC_32K_NAME};
310 	int i, ret;
311 
312 	chip->clk_data = devm_kzalloc(chip->dev,
313 				      struct_size(chip->clk_data, hws,
314 						  AC100_CLKOUT_NUM),
315 				      GFP_KERNEL);
316 	if (!chip->clk_data)
317 		return -ENOMEM;
318 
319 	chip->rtc_32k_clk = clk_hw_register_fixed_rate(chip->dev,
320 						       AC100_RTC_32K_NAME,
321 						       NULL, 0,
322 						       AC100_RTC_32K_RATE);
323 	if (IS_ERR(chip->rtc_32k_clk)) {
324 		ret = PTR_ERR(chip->rtc_32k_clk);
325 		dev_err(chip->dev, "Failed to register RTC-32k clock: %d\n",
326 			ret);
327 		return ret;
328 	}
329 
330 	parents[1] = of_clk_get_parent_name(np, 0);
331 	if (!parents[1]) {
332 		dev_err(chip->dev, "Failed to get ADDA 4M clock\n");
333 		return -EINVAL;
334 	}
335 
336 	for (i = 0; i < AC100_CLKOUT_NUM; i++) {
337 		struct ac100_clkout *clk = &chip->clks[i];
338 		struct clk_init_data init = {
339 			.name = ac100_clkout_names[i],
340 			.ops = &ac100_clkout_ops,
341 			.parent_names = parents,
342 			.num_parents = ARRAY_SIZE(parents),
343 			.flags = 0,
344 		};
345 
346 		of_property_read_string_index(np, "clock-output-names",
347 					      i, &init.name);
348 		clk->regmap = chip->regmap;
349 		clk->offset = AC100_CLKOUT_CTRL1 + i;
350 		clk->hw.init = &init;
351 
352 		ret = devm_clk_hw_register(chip->dev, &clk->hw);
353 		if (ret) {
354 			dev_err(chip->dev, "Failed to register clk '%s': %d\n",
355 				init.name, ret);
356 			goto err_unregister_rtc_32k;
357 		}
358 
359 		chip->clk_data->hws[i] = &clk->hw;
360 	}
361 
362 	chip->clk_data->num = i;
363 	ret = of_clk_add_hw_provider(np, of_clk_hw_onecell_get, chip->clk_data);
364 	if (ret)
365 		goto err_unregister_rtc_32k;
366 
367 	return 0;
368 
369 err_unregister_rtc_32k:
370 	clk_unregister_fixed_rate(chip->rtc_32k_clk->clk);
371 
372 	return ret;
373 }
374 
375 static void ac100_rtc_unregister_clks(struct ac100_rtc_dev *chip)
376 {
377 	of_clk_del_provider(chip->dev->of_node);
378 	clk_unregister_fixed_rate(chip->rtc_32k_clk->clk);
379 }
380 
381 /**
382  * RTC related bits
383  */
384 static int ac100_rtc_get_time(struct device *dev, struct rtc_time *rtc_tm)
385 {
386 	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
387 	struct regmap *regmap = chip->regmap;
388 	u16 reg[7];
389 	int ret;
390 
391 	ret = regmap_bulk_read(regmap, AC100_RTC_SEC, reg, 7);
392 	if (ret)
393 		return ret;
394 
395 	rtc_tm->tm_sec  = bcd2bin(reg[0] & AC100_RTC_SEC_MASK);
396 	rtc_tm->tm_min  = bcd2bin(reg[1] & AC100_RTC_MIN_MASK);
397 	rtc_tm->tm_hour = bcd2bin(reg[2] & AC100_RTC_HOU_MASK);
398 	rtc_tm->tm_wday = bcd2bin(reg[3] & AC100_RTC_WEE_MASK);
399 	rtc_tm->tm_mday = bcd2bin(reg[4] & AC100_RTC_DAY_MASK);
400 	rtc_tm->tm_mon  = bcd2bin(reg[5] & AC100_RTC_MON_MASK) - 1;
401 	rtc_tm->tm_year = bcd2bin(reg[6] & AC100_RTC_YEA_MASK) +
402 			  AC100_YEAR_OFF;
403 
404 	return 0;
405 }
406 
407 static int ac100_rtc_set_time(struct device *dev, struct rtc_time *rtc_tm)
408 {
409 	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
410 	struct regmap *regmap = chip->regmap;
411 	int year;
412 	u16 reg[8];
413 
414 	/* our RTC has a limited year range... */
415 	year = rtc_tm->tm_year - AC100_YEAR_OFF;
416 	if (year < 0 || year > (AC100_YEAR_MAX - 1900)) {
417 		dev_err(dev, "rtc only supports year in range %d - %d\n",
418 			AC100_YEAR_MIN, AC100_YEAR_MAX);
419 		return -EINVAL;
420 	}
421 
422 	/* convert to BCD */
423 	reg[0] = bin2bcd(rtc_tm->tm_sec)     & AC100_RTC_SEC_MASK;
424 	reg[1] = bin2bcd(rtc_tm->tm_min)     & AC100_RTC_MIN_MASK;
425 	reg[2] = bin2bcd(rtc_tm->tm_hour)    & AC100_RTC_HOU_MASK;
426 	reg[3] = bin2bcd(rtc_tm->tm_wday)    & AC100_RTC_WEE_MASK;
427 	reg[4] = bin2bcd(rtc_tm->tm_mday)    & AC100_RTC_DAY_MASK;
428 	reg[5] = bin2bcd(rtc_tm->tm_mon + 1) & AC100_RTC_MON_MASK;
429 	reg[6] = bin2bcd(year)		     & AC100_RTC_YEA_MASK;
430 	/* trigger write */
431 	reg[7] = AC100_RTC_UPD_TRIGGER;
432 
433 	/* Is it a leap year? */
434 	if (is_leap_year(year + AC100_YEAR_OFF + 1900))
435 		reg[6] |= AC100_RTC_YEA_LEAP;
436 
437 	return regmap_bulk_write(regmap, AC100_RTC_SEC, reg, 8);
438 }
439 
440 static int ac100_rtc_alarm_irq_enable(struct device *dev, unsigned int en)
441 {
442 	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
443 	struct regmap *regmap = chip->regmap;
444 	unsigned int val;
445 
446 	val = en ? AC100_ALM_INT_ENABLE : 0;
447 
448 	return regmap_write(regmap, AC100_ALM_INT_ENA, val);
449 }
450 
451 static int ac100_rtc_get_alarm(struct device *dev, struct rtc_wkalrm *alrm)
452 {
453 	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
454 	struct regmap *regmap = chip->regmap;
455 	struct rtc_time *alrm_tm = &alrm->time;
456 	u16 reg[7];
457 	unsigned int val;
458 	int ret;
459 
460 	ret = regmap_read(regmap, AC100_ALM_INT_ENA, &val);
461 	if (ret)
462 		return ret;
463 
464 	alrm->enabled = !!(val & AC100_ALM_INT_ENABLE);
465 
466 	ret = regmap_bulk_read(regmap, AC100_ALM_SEC, reg, 7);
467 	if (ret)
468 		return ret;
469 
470 	alrm_tm->tm_sec  = bcd2bin(reg[0] & AC100_ALM_SEC_MASK);
471 	alrm_tm->tm_min  = bcd2bin(reg[1] & AC100_ALM_MIN_MASK);
472 	alrm_tm->tm_hour = bcd2bin(reg[2] & AC100_ALM_HOU_MASK);
473 	alrm_tm->tm_wday = bcd2bin(reg[3] & AC100_ALM_WEE_MASK);
474 	alrm_tm->tm_mday = bcd2bin(reg[4] & AC100_ALM_DAY_MASK);
475 	alrm_tm->tm_mon  = bcd2bin(reg[5] & AC100_ALM_MON_MASK) - 1;
476 	alrm_tm->tm_year = bcd2bin(reg[6] & AC100_ALM_YEA_MASK) +
477 			   AC100_YEAR_OFF;
478 
479 	return 0;
480 }
481 
482 static int ac100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
483 {
484 	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
485 	struct regmap *regmap = chip->regmap;
486 	struct rtc_time *alrm_tm = &alrm->time;
487 	u16 reg[8];
488 	int year;
489 	int ret;
490 
491 	/* our alarm has a limited year range... */
492 	year = alrm_tm->tm_year - AC100_YEAR_OFF;
493 	if (year < 0 || year > (AC100_YEAR_MAX - 1900)) {
494 		dev_err(dev, "alarm only supports year in range %d - %d\n",
495 			AC100_YEAR_MIN, AC100_YEAR_MAX);
496 		return -EINVAL;
497 	}
498 
499 	/* convert to BCD */
500 	reg[0] = (bin2bcd(alrm_tm->tm_sec)  & AC100_ALM_SEC_MASK) |
501 			AC100_ALM_ENABLE_FLAG;
502 	reg[1] = (bin2bcd(alrm_tm->tm_min)  & AC100_ALM_MIN_MASK) |
503 			AC100_ALM_ENABLE_FLAG;
504 	reg[2] = (bin2bcd(alrm_tm->tm_hour) & AC100_ALM_HOU_MASK) |
505 			AC100_ALM_ENABLE_FLAG;
506 	/* Do not enable weekday alarm */
507 	reg[3] = bin2bcd(alrm_tm->tm_wday) & AC100_ALM_WEE_MASK;
508 	reg[4] = (bin2bcd(alrm_tm->tm_mday) & AC100_ALM_DAY_MASK) |
509 			AC100_ALM_ENABLE_FLAG;
510 	reg[5] = (bin2bcd(alrm_tm->tm_mon + 1)  & AC100_ALM_MON_MASK) |
511 			AC100_ALM_ENABLE_FLAG;
512 	reg[6] = (bin2bcd(year) & AC100_ALM_YEA_MASK) |
513 			AC100_ALM_ENABLE_FLAG;
514 	/* trigger write */
515 	reg[7] = AC100_ALM_UPD_TRIGGER;
516 
517 	ret = regmap_bulk_write(regmap, AC100_ALM_SEC, reg, 8);
518 	if (ret)
519 		return ret;
520 
521 	return ac100_rtc_alarm_irq_enable(dev, alrm->enabled);
522 }
523 
524 static irqreturn_t ac100_rtc_irq(int irq, void *data)
525 {
526 	struct ac100_rtc_dev *chip = data;
527 	struct regmap *regmap = chip->regmap;
528 	unsigned int val = 0;
529 	int ret;
530 
531 	rtc_lock(chip->rtc);
532 
533 	/* read status */
534 	ret = regmap_read(regmap, AC100_ALM_INT_STA, &val);
535 	if (ret)
536 		goto out;
537 
538 	if (val & AC100_ALM_INT_ENABLE) {
539 		/* signal rtc framework */
540 		rtc_update_irq(chip->rtc, 1, RTC_AF | RTC_IRQF);
541 
542 		/* clear status */
543 		ret = regmap_write(regmap, AC100_ALM_INT_STA, val);
544 		if (ret)
545 			goto out;
546 
547 		/* disable interrupt */
548 		ret = ac100_rtc_alarm_irq_enable(chip->dev, 0);
549 		if (ret)
550 			goto out;
551 	}
552 
553 out:
554 	rtc_unlock(chip->rtc);
555 	return IRQ_HANDLED;
556 }
557 
558 static const struct rtc_class_ops ac100_rtc_ops = {
559 	.read_time	  = ac100_rtc_get_time,
560 	.set_time	  = ac100_rtc_set_time,
561 	.read_alarm	  = ac100_rtc_get_alarm,
562 	.set_alarm	  = ac100_rtc_set_alarm,
563 	.alarm_irq_enable = ac100_rtc_alarm_irq_enable,
564 };
565 
566 static int ac100_rtc_probe(struct platform_device *pdev)
567 {
568 	struct ac100_dev *ac100 = dev_get_drvdata(pdev->dev.parent);
569 	struct ac100_rtc_dev *chip;
570 	int ret;
571 
572 	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
573 	if (!chip)
574 		return -ENOMEM;
575 
576 	platform_set_drvdata(pdev, chip);
577 	chip->dev = &pdev->dev;
578 	chip->regmap = ac100->regmap;
579 
580 	chip->irq = platform_get_irq(pdev, 0);
581 	if (chip->irq < 0)
582 		return chip->irq;
583 
584 	chip->rtc = devm_rtc_allocate_device(&pdev->dev);
585 	if (IS_ERR(chip->rtc))
586 		return PTR_ERR(chip->rtc);
587 
588 	chip->rtc->ops = &ac100_rtc_ops;
589 
590 	ret = devm_request_threaded_irq(&pdev->dev, chip->irq, NULL,
591 					ac100_rtc_irq,
592 					IRQF_SHARED | IRQF_ONESHOT,
593 					dev_name(&pdev->dev), chip);
594 	if (ret) {
595 		dev_err(&pdev->dev, "Could not request IRQ\n");
596 		return ret;
597 	}
598 
599 	/* always use 24 hour mode */
600 	regmap_write_bits(chip->regmap, AC100_RTC_CTRL, AC100_RTC_CTRL_24HOUR,
601 			  AC100_RTC_CTRL_24HOUR);
602 
603 	/* disable counter alarm interrupt */
604 	regmap_write(chip->regmap, AC100_ALM_INT_ENA, 0);
605 
606 	/* clear counter alarm pending interrupts */
607 	regmap_write(chip->regmap, AC100_ALM_INT_STA, AC100_ALM_INT_ENABLE);
608 
609 	ret = ac100_rtc_register_clks(chip);
610 	if (ret)
611 		return ret;
612 
613 	return devm_rtc_register_device(chip->rtc);
614 }
615 
616 static void ac100_rtc_remove(struct platform_device *pdev)
617 {
618 	struct ac100_rtc_dev *chip = platform_get_drvdata(pdev);
619 
620 	ac100_rtc_unregister_clks(chip);
621 }
622 
623 static const struct of_device_id ac100_rtc_match[] = {
624 	{ .compatible = "x-powers,ac100-rtc" },
625 	{ },
626 };
627 MODULE_DEVICE_TABLE(of, ac100_rtc_match);
628 
629 static struct platform_driver ac100_rtc_driver = {
630 	.probe		= ac100_rtc_probe,
631 	.remove_new	= ac100_rtc_remove,
632 	.driver		= {
633 		.name		= "ac100-rtc",
634 		.of_match_table	= of_match_ptr(ac100_rtc_match),
635 	},
636 };
637 module_platform_driver(ac100_rtc_driver);
638 
639 MODULE_DESCRIPTION("X-Powers AC100 RTC driver");
640 MODULE_AUTHOR("Chen-Yu Tsai <wens@csie.org>");
641 MODULE_LICENSE("GPL v2");
642