xref: /openbmc/linux/drivers/rtc/rtc-ac100.c (revision 4f6cce39)
1 /*
2  * RTC Driver for X-Powers AC100
3  *
4  * Copyright (c) 2016 Chen-Yu Tsai
5  *
6  * Chen-Yu Tsai <wens@csie.org>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  *
12  * This program is distributed in the hope that it will be useful, but WITHOUT
13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
15  * more details.
16  */
17 
18 #include <linux/bcd.h>
19 #include <linux/clk-provider.h>
20 #include <linux/device.h>
21 #include <linux/interrupt.h>
22 #include <linux/kernel.h>
23 #include <linux/mfd/ac100.h>
24 #include <linux/module.h>
25 #include <linux/mutex.h>
26 #include <linux/of.h>
27 #include <linux/platform_device.h>
28 #include <linux/regmap.h>
29 #include <linux/rtc.h>
30 #include <linux/types.h>
31 
32 /* Control register */
33 #define AC100_RTC_CTRL_24HOUR	BIT(0)
34 
35 /* Clock output register bits */
36 #define AC100_CLKOUT_PRE_DIV_SHIFT	5
37 #define AC100_CLKOUT_PRE_DIV_WIDTH	3
38 #define AC100_CLKOUT_MUX_SHIFT		4
39 #define AC100_CLKOUT_MUX_WIDTH		1
40 #define AC100_CLKOUT_DIV_SHIFT		1
41 #define AC100_CLKOUT_DIV_WIDTH		3
42 #define AC100_CLKOUT_EN			BIT(0)
43 
44 /* RTC */
45 #define AC100_RTC_SEC_MASK	GENMASK(6, 0)
46 #define AC100_RTC_MIN_MASK	GENMASK(6, 0)
47 #define AC100_RTC_HOU_MASK	GENMASK(5, 0)
48 #define AC100_RTC_WEE_MASK	GENMASK(2, 0)
49 #define AC100_RTC_DAY_MASK	GENMASK(5, 0)
50 #define AC100_RTC_MON_MASK	GENMASK(4, 0)
51 #define AC100_RTC_YEA_MASK	GENMASK(7, 0)
52 #define AC100_RTC_YEA_LEAP	BIT(15)
53 #define AC100_RTC_UPD_TRIGGER	BIT(15)
54 
55 /* Alarm (wall clock) */
56 #define AC100_ALM_INT_ENABLE	BIT(0)
57 
58 #define AC100_ALM_SEC_MASK	GENMASK(6, 0)
59 #define AC100_ALM_MIN_MASK	GENMASK(6, 0)
60 #define AC100_ALM_HOU_MASK	GENMASK(5, 0)
61 #define AC100_ALM_WEE_MASK	GENMASK(2, 0)
62 #define AC100_ALM_DAY_MASK	GENMASK(5, 0)
63 #define AC100_ALM_MON_MASK	GENMASK(4, 0)
64 #define AC100_ALM_YEA_MASK	GENMASK(7, 0)
65 #define AC100_ALM_ENABLE_FLAG	BIT(15)
66 #define AC100_ALM_UPD_TRIGGER	BIT(15)
67 
68 /*
69  * The year parameter passed to the driver is usually an offset relative to
70  * the year 1900. This macro is used to convert this offset to another one
71  * relative to the minimum year allowed by the hardware.
72  *
73  * The year range is 1970 - 2069. This range is selected to match Allwinner's
74  * driver.
75  */
76 #define AC100_YEAR_MIN				1970
77 #define AC100_YEAR_MAX				2069
78 #define AC100_YEAR_OFF				(AC100_YEAR_MIN - 1900)
79 
80 struct ac100_clkout {
81 	struct clk_hw hw;
82 	struct regmap *regmap;
83 	u8 offset;
84 };
85 
86 #define to_ac100_clkout(_hw) container_of(_hw, struct ac100_clkout, hw)
87 
88 #define AC100_RTC_32K_NAME	"ac100-rtc-32k"
89 #define AC100_RTC_32K_RATE	32768
90 #define AC100_CLKOUT_NUM	3
91 
92 static const char * const ac100_clkout_names[AC100_CLKOUT_NUM] = {
93 	"ac100-cko1-rtc",
94 	"ac100-cko2-rtc",
95 	"ac100-cko3-rtc",
96 };
97 
98 struct ac100_rtc_dev {
99 	struct rtc_device *rtc;
100 	struct device *dev;
101 	struct regmap *regmap;
102 	int irq;
103 	unsigned long alarm;
104 
105 	struct clk_hw *rtc_32k_clk;
106 	struct ac100_clkout clks[AC100_CLKOUT_NUM];
107 	struct clk_hw_onecell_data *clk_data;
108 };
109 
110 /**
111  * Clock controls for 3 clock output pins
112  */
113 
114 static const struct clk_div_table ac100_clkout_prediv[] = {
115 	{ .val = 0, .div = 1 },
116 	{ .val = 1, .div = 2 },
117 	{ .val = 2, .div = 4 },
118 	{ .val = 3, .div = 8 },
119 	{ .val = 4, .div = 16 },
120 	{ .val = 5, .div = 32 },
121 	{ .val = 6, .div = 64 },
122 	{ .val = 7, .div = 122 },
123 	{ },
124 };
125 
126 /* Abuse the fact that one parent is 32768 Hz, and the other is 4 MHz */
127 static unsigned long ac100_clkout_recalc_rate(struct clk_hw *hw,
128 					      unsigned long prate)
129 {
130 	struct ac100_clkout *clk = to_ac100_clkout(hw);
131 	unsigned int reg, div;
132 
133 	regmap_read(clk->regmap, clk->offset, &reg);
134 
135 	/* Handle pre-divider first */
136 	if (prate != AC100_RTC_32K_RATE) {
137 		div = (reg >> AC100_CLKOUT_PRE_DIV_SHIFT) &
138 			((1 << AC100_CLKOUT_PRE_DIV_WIDTH) - 1);
139 		prate = divider_recalc_rate(hw, prate, div,
140 					    ac100_clkout_prediv, 0);
141 	}
142 
143 	div = (reg >> AC100_CLKOUT_DIV_SHIFT) &
144 		(BIT(AC100_CLKOUT_DIV_WIDTH) - 1);
145 	return divider_recalc_rate(hw, prate, div, NULL,
146 				   CLK_DIVIDER_POWER_OF_TWO);
147 }
148 
149 static long ac100_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
150 				    unsigned long prate)
151 {
152 	unsigned long best_rate = 0, tmp_rate, tmp_prate;
153 	int i;
154 
155 	if (prate == AC100_RTC_32K_RATE)
156 		return divider_round_rate(hw, rate, &prate, NULL,
157 					  AC100_CLKOUT_DIV_WIDTH,
158 					  CLK_DIVIDER_POWER_OF_TWO);
159 
160 	for (i = 0; ac100_clkout_prediv[i].div; i++) {
161 		tmp_prate = DIV_ROUND_UP(prate, ac100_clkout_prediv[i].val);
162 		tmp_rate = divider_round_rate(hw, rate, &tmp_prate, NULL,
163 					      AC100_CLKOUT_DIV_WIDTH,
164 					      CLK_DIVIDER_POWER_OF_TWO);
165 
166 		if (tmp_rate > rate)
167 			continue;
168 		if (rate - tmp_rate < best_rate - tmp_rate)
169 			best_rate = tmp_rate;
170 	}
171 
172 	return best_rate;
173 }
174 
175 static int ac100_clkout_determine_rate(struct clk_hw *hw,
176 				       struct clk_rate_request *req)
177 {
178 	struct clk_hw *best_parent;
179 	unsigned long best = 0;
180 	int i, num_parents = clk_hw_get_num_parents(hw);
181 
182 	for (i = 0; i < num_parents; i++) {
183 		struct clk_hw *parent = clk_hw_get_parent_by_index(hw, i);
184 		unsigned long tmp, prate = clk_hw_get_rate(parent);
185 
186 		tmp = ac100_clkout_round_rate(hw, req->rate, prate);
187 
188 		if (tmp > req->rate)
189 			continue;
190 		if (req->rate - tmp < req->rate - best) {
191 			best = tmp;
192 			best_parent = parent;
193 		}
194 	}
195 
196 	if (!best)
197 		return -EINVAL;
198 
199 	req->best_parent_hw = best_parent;
200 	req->best_parent_rate = best;
201 	req->rate = best;
202 
203 	return 0;
204 }
205 
206 static int ac100_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
207 				 unsigned long prate)
208 {
209 	struct ac100_clkout *clk = to_ac100_clkout(hw);
210 	int div = 0, pre_div = 0;
211 
212 	do {
213 		div = divider_get_val(rate * ac100_clkout_prediv[pre_div].div,
214 				      prate, NULL, AC100_CLKOUT_DIV_WIDTH,
215 				      CLK_DIVIDER_POWER_OF_TWO);
216 		if (div >= 0)
217 			break;
218 	} while (prate != AC100_RTC_32K_RATE &&
219 		 ac100_clkout_prediv[++pre_div].div);
220 
221 	if (div < 0)
222 		return div;
223 
224 	pre_div = ac100_clkout_prediv[pre_div].val;
225 
226 	regmap_update_bits(clk->regmap, clk->offset,
227 			   ((1 << AC100_CLKOUT_DIV_WIDTH) - 1) << AC100_CLKOUT_DIV_SHIFT |
228 			   ((1 << AC100_CLKOUT_PRE_DIV_WIDTH) - 1) << AC100_CLKOUT_PRE_DIV_SHIFT,
229 			   (div - 1) << AC100_CLKOUT_DIV_SHIFT |
230 			   (pre_div - 1) << AC100_CLKOUT_PRE_DIV_SHIFT);
231 
232 	return 0;
233 }
234 
235 static int ac100_clkout_prepare(struct clk_hw *hw)
236 {
237 	struct ac100_clkout *clk = to_ac100_clkout(hw);
238 
239 	return regmap_update_bits(clk->regmap, clk->offset, AC100_CLKOUT_EN,
240 				  AC100_CLKOUT_EN);
241 }
242 
243 static void ac100_clkout_unprepare(struct clk_hw *hw)
244 {
245 	struct ac100_clkout *clk = to_ac100_clkout(hw);
246 
247 	regmap_update_bits(clk->regmap, clk->offset, AC100_CLKOUT_EN, 0);
248 }
249 
250 static int ac100_clkout_is_prepared(struct clk_hw *hw)
251 {
252 	struct ac100_clkout *clk = to_ac100_clkout(hw);
253 	unsigned int reg;
254 
255 	regmap_read(clk->regmap, clk->offset, &reg);
256 
257 	return reg & AC100_CLKOUT_EN;
258 }
259 
260 static u8 ac100_clkout_get_parent(struct clk_hw *hw)
261 {
262 	struct ac100_clkout *clk = to_ac100_clkout(hw);
263 	unsigned int reg;
264 
265 	regmap_read(clk->regmap, clk->offset, &reg);
266 
267 	return (reg >> AC100_CLKOUT_MUX_SHIFT) & 0x1;
268 }
269 
270 static int ac100_clkout_set_parent(struct clk_hw *hw, u8 index)
271 {
272 	struct ac100_clkout *clk = to_ac100_clkout(hw);
273 
274 	return regmap_update_bits(clk->regmap, clk->offset,
275 				  BIT(AC100_CLKOUT_MUX_SHIFT),
276 				  index ? BIT(AC100_CLKOUT_MUX_SHIFT) : 0);
277 }
278 
279 static const struct clk_ops ac100_clkout_ops = {
280 	.prepare	= ac100_clkout_prepare,
281 	.unprepare	= ac100_clkout_unprepare,
282 	.is_prepared	= ac100_clkout_is_prepared,
283 	.recalc_rate	= ac100_clkout_recalc_rate,
284 	.determine_rate	= ac100_clkout_determine_rate,
285 	.get_parent	= ac100_clkout_get_parent,
286 	.set_parent	= ac100_clkout_set_parent,
287 	.set_rate	= ac100_clkout_set_rate,
288 };
289 
290 static int ac100_rtc_register_clks(struct ac100_rtc_dev *chip)
291 {
292 	struct device_node *np = chip->dev->of_node;
293 	const char *parents[2] = {AC100_RTC_32K_NAME};
294 	int i, ret;
295 
296 	chip->clk_data = devm_kzalloc(chip->dev, sizeof(*chip->clk_data) +
297 						 sizeof(*chip->clk_data->hws) *
298 						 AC100_CLKOUT_NUM,
299 						 GFP_KERNEL);
300 	if (!chip->clk_data)
301 		return -ENOMEM;
302 
303 	chip->rtc_32k_clk = clk_hw_register_fixed_rate(chip->dev,
304 						       AC100_RTC_32K_NAME,
305 						       NULL, 0,
306 						       AC100_RTC_32K_RATE);
307 	if (IS_ERR(chip->rtc_32k_clk)) {
308 		ret = PTR_ERR(chip->rtc_32k_clk);
309 		dev_err(chip->dev, "Failed to register RTC-32k clock: %d\n",
310 			ret);
311 		return ret;
312 	}
313 
314 	parents[1] = of_clk_get_parent_name(np, 0);
315 	if (!parents[1]) {
316 		dev_err(chip->dev, "Failed to get ADDA 4M clock\n");
317 		return -EINVAL;
318 	}
319 
320 	for (i = 0; i < AC100_CLKOUT_NUM; i++) {
321 		struct ac100_clkout *clk = &chip->clks[i];
322 		struct clk_init_data init = {
323 			.name = ac100_clkout_names[i],
324 			.ops = &ac100_clkout_ops,
325 			.parent_names = parents,
326 			.num_parents = ARRAY_SIZE(parents),
327 			.flags = 0,
328 		};
329 
330 		of_property_read_string_index(np, "clock-output-names",
331 					      i, &init.name);
332 		clk->regmap = chip->regmap;
333 		clk->offset = AC100_CLKOUT_CTRL1 + i;
334 		clk->hw.init = &init;
335 
336 		ret = devm_clk_hw_register(chip->dev, &clk->hw);
337 		if (ret) {
338 			dev_err(chip->dev, "Failed to register clk '%s': %d\n",
339 				init.name, ret);
340 			goto err_unregister_rtc_32k;
341 		}
342 
343 		chip->clk_data->hws[i] = &clk->hw;
344 	}
345 
346 	chip->clk_data->num = i;
347 	ret = of_clk_add_hw_provider(np, of_clk_hw_onecell_get, chip->clk_data);
348 	if (ret)
349 		goto err_unregister_rtc_32k;
350 
351 	return 0;
352 
353 err_unregister_rtc_32k:
354 	clk_unregister_fixed_rate(chip->rtc_32k_clk->clk);
355 
356 	return ret;
357 }
358 
359 static void ac100_rtc_unregister_clks(struct ac100_rtc_dev *chip)
360 {
361 	of_clk_del_provider(chip->dev->of_node);
362 	clk_unregister_fixed_rate(chip->rtc_32k_clk->clk);
363 }
364 
365 /**
366  * RTC related bits
367  */
368 static int ac100_rtc_get_time(struct device *dev, struct rtc_time *rtc_tm)
369 {
370 	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
371 	struct regmap *regmap = chip->regmap;
372 	u16 reg[7];
373 	int ret;
374 
375 	ret = regmap_bulk_read(regmap, AC100_RTC_SEC, reg, 7);
376 	if (ret)
377 		return ret;
378 
379 	rtc_tm->tm_sec  = bcd2bin(reg[0] & AC100_RTC_SEC_MASK);
380 	rtc_tm->tm_min  = bcd2bin(reg[1] & AC100_RTC_MIN_MASK);
381 	rtc_tm->tm_hour = bcd2bin(reg[2] & AC100_RTC_HOU_MASK);
382 	rtc_tm->tm_wday = bcd2bin(reg[3] & AC100_RTC_WEE_MASK);
383 	rtc_tm->tm_mday = bcd2bin(reg[4] & AC100_RTC_DAY_MASK);
384 	rtc_tm->tm_mon  = bcd2bin(reg[5] & AC100_RTC_MON_MASK) - 1;
385 	rtc_tm->tm_year = bcd2bin(reg[6] & AC100_RTC_YEA_MASK) +
386 			  AC100_YEAR_OFF;
387 
388 	return rtc_valid_tm(rtc_tm);
389 }
390 
391 static int ac100_rtc_set_time(struct device *dev, struct rtc_time *rtc_tm)
392 {
393 	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
394 	struct regmap *regmap = chip->regmap;
395 	int year;
396 	u16 reg[8];
397 
398 	/* our RTC has a limited year range... */
399 	year = rtc_tm->tm_year - AC100_YEAR_OFF;
400 	if (year < 0 || year > (AC100_YEAR_MAX - 1900)) {
401 		dev_err(dev, "rtc only supports year in range %d - %d\n",
402 			AC100_YEAR_MIN, AC100_YEAR_MAX);
403 		return -EINVAL;
404 	}
405 
406 	/* convert to BCD */
407 	reg[0] = bin2bcd(rtc_tm->tm_sec)     & AC100_RTC_SEC_MASK;
408 	reg[1] = bin2bcd(rtc_tm->tm_min)     & AC100_RTC_MIN_MASK;
409 	reg[2] = bin2bcd(rtc_tm->tm_hour)    & AC100_RTC_HOU_MASK;
410 	reg[3] = bin2bcd(rtc_tm->tm_wday)    & AC100_RTC_WEE_MASK;
411 	reg[4] = bin2bcd(rtc_tm->tm_mday)    & AC100_RTC_DAY_MASK;
412 	reg[5] = bin2bcd(rtc_tm->tm_mon + 1) & AC100_RTC_MON_MASK;
413 	reg[6] = bin2bcd(year)		     & AC100_RTC_YEA_MASK;
414 	/* trigger write */
415 	reg[7] = AC100_RTC_UPD_TRIGGER;
416 
417 	/* Is it a leap year? */
418 	if (is_leap_year(year + AC100_YEAR_OFF + 1900))
419 		reg[6] |= AC100_RTC_YEA_LEAP;
420 
421 	return regmap_bulk_write(regmap, AC100_RTC_SEC, reg, 8);
422 }
423 
424 static int ac100_rtc_alarm_irq_enable(struct device *dev, unsigned int en)
425 {
426 	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
427 	struct regmap *regmap = chip->regmap;
428 	unsigned int val;
429 
430 	val = en ? AC100_ALM_INT_ENABLE : 0;
431 
432 	return regmap_write(regmap, AC100_ALM_INT_ENA, val);
433 }
434 
435 static int ac100_rtc_get_alarm(struct device *dev, struct rtc_wkalrm *alrm)
436 {
437 	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
438 	struct regmap *regmap = chip->regmap;
439 	struct rtc_time *alrm_tm = &alrm->time;
440 	u16 reg[7];
441 	unsigned int val;
442 	int ret;
443 
444 	ret = regmap_read(regmap, AC100_ALM_INT_ENA, &val);
445 	if (ret)
446 		return ret;
447 
448 	alrm->enabled = !!(val & AC100_ALM_INT_ENABLE);
449 
450 	ret = regmap_bulk_read(regmap, AC100_ALM_SEC, reg, 7);
451 	if (ret)
452 		return ret;
453 
454 	alrm_tm->tm_sec  = bcd2bin(reg[0] & AC100_ALM_SEC_MASK);
455 	alrm_tm->tm_min  = bcd2bin(reg[1] & AC100_ALM_MIN_MASK);
456 	alrm_tm->tm_hour = bcd2bin(reg[2] & AC100_ALM_HOU_MASK);
457 	alrm_tm->tm_wday = bcd2bin(reg[3] & AC100_ALM_WEE_MASK);
458 	alrm_tm->tm_mday = bcd2bin(reg[4] & AC100_ALM_DAY_MASK);
459 	alrm_tm->tm_mon  = bcd2bin(reg[5] & AC100_ALM_MON_MASK) - 1;
460 	alrm_tm->tm_year = bcd2bin(reg[6] & AC100_ALM_YEA_MASK) +
461 			   AC100_YEAR_OFF;
462 
463 	return 0;
464 }
465 
466 static int ac100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
467 {
468 	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
469 	struct regmap *regmap = chip->regmap;
470 	struct rtc_time *alrm_tm = &alrm->time;
471 	u16 reg[8];
472 	int year;
473 	int ret;
474 
475 	/* our alarm has a limited year range... */
476 	year = alrm_tm->tm_year - AC100_YEAR_OFF;
477 	if (year < 0 || year > (AC100_YEAR_MAX - 1900)) {
478 		dev_err(dev, "alarm only supports year in range %d - %d\n",
479 			AC100_YEAR_MIN, AC100_YEAR_MAX);
480 		return -EINVAL;
481 	}
482 
483 	/* convert to BCD */
484 	reg[0] = (bin2bcd(alrm_tm->tm_sec)  & AC100_ALM_SEC_MASK) |
485 			AC100_ALM_ENABLE_FLAG;
486 	reg[1] = (bin2bcd(alrm_tm->tm_min)  & AC100_ALM_MIN_MASK) |
487 			AC100_ALM_ENABLE_FLAG;
488 	reg[2] = (bin2bcd(alrm_tm->tm_hour) & AC100_ALM_HOU_MASK) |
489 			AC100_ALM_ENABLE_FLAG;
490 	/* Do not enable weekday alarm */
491 	reg[3] = bin2bcd(alrm_tm->tm_wday) & AC100_ALM_WEE_MASK;
492 	reg[4] = (bin2bcd(alrm_tm->tm_mday) & AC100_ALM_DAY_MASK) |
493 			AC100_ALM_ENABLE_FLAG;
494 	reg[5] = (bin2bcd(alrm_tm->tm_mon + 1)  & AC100_ALM_MON_MASK) |
495 			AC100_ALM_ENABLE_FLAG;
496 	reg[6] = (bin2bcd(year) & AC100_ALM_YEA_MASK) |
497 			AC100_ALM_ENABLE_FLAG;
498 	/* trigger write */
499 	reg[7] = AC100_ALM_UPD_TRIGGER;
500 
501 	ret = regmap_bulk_write(regmap, AC100_ALM_SEC, reg, 8);
502 	if (ret)
503 		return ret;
504 
505 	return ac100_rtc_alarm_irq_enable(dev, alrm->enabled);
506 }
507 
508 static irqreturn_t ac100_rtc_irq(int irq, void *data)
509 {
510 	struct ac100_rtc_dev *chip = data;
511 	struct regmap *regmap = chip->regmap;
512 	unsigned int val = 0;
513 	int ret;
514 
515 	mutex_lock(&chip->rtc->ops_lock);
516 
517 	/* read status */
518 	ret = regmap_read(regmap, AC100_ALM_INT_STA, &val);
519 	if (ret)
520 		goto out;
521 
522 	if (val & AC100_ALM_INT_ENABLE) {
523 		/* signal rtc framework */
524 		rtc_update_irq(chip->rtc, 1, RTC_AF | RTC_IRQF);
525 
526 		/* clear status */
527 		ret = regmap_write(regmap, AC100_ALM_INT_STA, val);
528 		if (ret)
529 			goto out;
530 
531 		/* disable interrupt */
532 		ret = ac100_rtc_alarm_irq_enable(chip->dev, 0);
533 		if (ret)
534 			goto out;
535 	}
536 
537 out:
538 	mutex_unlock(&chip->rtc->ops_lock);
539 	return IRQ_HANDLED;
540 }
541 
542 static const struct rtc_class_ops ac100_rtc_ops = {
543 	.read_time	  = ac100_rtc_get_time,
544 	.set_time	  = ac100_rtc_set_time,
545 	.read_alarm	  = ac100_rtc_get_alarm,
546 	.set_alarm	  = ac100_rtc_set_alarm,
547 	.alarm_irq_enable = ac100_rtc_alarm_irq_enable,
548 };
549 
550 static int ac100_rtc_probe(struct platform_device *pdev)
551 {
552 	struct ac100_dev *ac100 = dev_get_drvdata(pdev->dev.parent);
553 	struct ac100_rtc_dev *chip;
554 	int ret;
555 
556 	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
557 	if (!chip)
558 		return -ENOMEM;
559 
560 	platform_set_drvdata(pdev, chip);
561 	chip->dev = &pdev->dev;
562 	chip->regmap = ac100->regmap;
563 
564 	chip->irq = platform_get_irq(pdev, 0);
565 	if (chip->irq < 0) {
566 		dev_err(&pdev->dev, "No IRQ resource\n");
567 		return chip->irq;
568 	}
569 
570 	ret = devm_request_threaded_irq(&pdev->dev, chip->irq, NULL,
571 					ac100_rtc_irq,
572 					IRQF_SHARED | IRQF_ONESHOT,
573 					dev_name(&pdev->dev), chip);
574 	if (ret) {
575 		dev_err(&pdev->dev, "Could not request IRQ\n");
576 		return ret;
577 	}
578 
579 	/* always use 24 hour mode */
580 	regmap_write_bits(chip->regmap, AC100_RTC_CTRL, AC100_RTC_CTRL_24HOUR,
581 			  AC100_RTC_CTRL_24HOUR);
582 
583 	/* disable counter alarm interrupt */
584 	regmap_write(chip->regmap, AC100_ALM_INT_ENA, 0);
585 
586 	/* clear counter alarm pending interrupts */
587 	regmap_write(chip->regmap, AC100_ALM_INT_STA, AC100_ALM_INT_ENABLE);
588 
589 	chip->rtc = devm_rtc_device_register(&pdev->dev, "rtc-ac100",
590 					     &ac100_rtc_ops, THIS_MODULE);
591 	if (IS_ERR(chip->rtc)) {
592 		dev_err(&pdev->dev, "unable to register device\n");
593 		return PTR_ERR(chip->rtc);
594 	}
595 
596 	ret = ac100_rtc_register_clks(chip);
597 	if (ret)
598 		return ret;
599 
600 	dev_info(&pdev->dev, "RTC enabled\n");
601 
602 	return 0;
603 }
604 
605 static int ac100_rtc_remove(struct platform_device *pdev)
606 {
607 	struct ac100_rtc_dev *chip = platform_get_drvdata(pdev);
608 
609 	ac100_rtc_unregister_clks(chip);
610 
611 	return 0;
612 }
613 
614 static const struct of_device_id ac100_rtc_match[] = {
615 	{ .compatible = "x-powers,ac100-rtc" },
616 	{ },
617 };
618 MODULE_DEVICE_TABLE(of, ac100_rtc_match);
619 
620 static struct platform_driver ac100_rtc_driver = {
621 	.probe		= ac100_rtc_probe,
622 	.remove		= ac100_rtc_remove,
623 	.driver		= {
624 		.name		= "ac100-rtc",
625 		.of_match_table	= of_match_ptr(ac100_rtc_match),
626 	},
627 };
628 module_platform_driver(ac100_rtc_driver);
629 
630 MODULE_DESCRIPTION("X-Powers AC100 RTC driver");
631 MODULE_AUTHOR("Chen-Yu Tsai <wens@csie.org>");
632 MODULE_LICENSE("GPL v2");
633