xref: /linux-6.15/drivers/rtc/rtc-sun6i.c (revision 8a937203)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * An RTC driver for Allwinner A31/A23
4  *
5  * Copyright (c) 2014, Chen-Yu Tsai <[email protected]>
6  *
7  * based on rtc-sunxi.c
8  *
9  * An RTC driver for Allwinner A10/A20
10  *
11  * Copyright (c) 2013, Carlo Caione <[email protected]>
12  */
13 
14 #include <linux/clk.h>
15 #include <linux/clk-provider.h>
16 #include <linux/delay.h>
17 #include <linux/err.h>
18 #include <linux/fs.h>
19 #include <linux/init.h>
20 #include <linux/interrupt.h>
21 #include <linux/io.h>
22 #include <linux/kernel.h>
23 #include <linux/module.h>
24 #include <linux/of.h>
25 #include <linux/of_address.h>
26 #include <linux/of_device.h>
27 #include <linux/platform_device.h>
28 #include <linux/rtc.h>
29 #include <linux/slab.h>
30 #include <linux/types.h>
31 
32 /* Control register */
33 #define SUN6I_LOSC_CTRL				0x0000
34 #define SUN6I_LOSC_CTRL_KEY			(0x16aa << 16)
35 #define SUN6I_LOSC_CTRL_AUTO_SWT_BYPASS		BIT(15)
36 #define SUN6I_LOSC_CTRL_ALM_DHMS_ACC		BIT(9)
37 #define SUN6I_LOSC_CTRL_RTC_HMS_ACC		BIT(8)
38 #define SUN6I_LOSC_CTRL_RTC_YMD_ACC		BIT(7)
39 #define SUN6I_LOSC_CTRL_EXT_LOSC_EN		BIT(4)
40 #define SUN6I_LOSC_CTRL_EXT_OSC			BIT(0)
41 #define SUN6I_LOSC_CTRL_ACC_MASK		GENMASK(9, 7)
42 
43 #define SUN6I_LOSC_CLK_PRESCAL			0x0008
44 
45 /* RTC */
46 #define SUN6I_RTC_YMD				0x0010
47 #define SUN6I_RTC_HMS				0x0014
48 
49 /* Alarm 0 (counter) */
50 #define SUN6I_ALRM_COUNTER			0x0020
51 /* This holds the remaining alarm seconds on older SoCs (current value) */
52 #define SUN6I_ALRM_COUNTER_HMS			0x0024
53 #define SUN6I_ALRM_EN				0x0028
54 #define SUN6I_ALRM_EN_CNT_EN			BIT(0)
55 #define SUN6I_ALRM_IRQ_EN			0x002c
56 #define SUN6I_ALRM_IRQ_EN_CNT_IRQ_EN		BIT(0)
57 #define SUN6I_ALRM_IRQ_STA			0x0030
58 #define SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND		BIT(0)
59 
60 /* Alarm 1 (wall clock) */
61 #define SUN6I_ALRM1_EN				0x0044
62 #define SUN6I_ALRM1_IRQ_EN			0x0048
63 #define SUN6I_ALRM1_IRQ_STA			0x004c
64 #define SUN6I_ALRM1_IRQ_STA_WEEK_IRQ_PEND	BIT(0)
65 
66 /* Alarm config */
67 #define SUN6I_ALARM_CONFIG			0x0050
68 #define SUN6I_ALARM_CONFIG_WAKEUP		BIT(0)
69 
70 #define SUN6I_LOSC_OUT_GATING			0x0060
71 #define SUN6I_LOSC_OUT_GATING_EN_OFFSET		0
72 
73 /*
74  * Get date values
75  */
76 #define SUN6I_DATE_GET_DAY_VALUE(x)		((x)  & 0x0000001f)
77 #define SUN6I_DATE_GET_MON_VALUE(x)		(((x) & 0x00000f00) >> 8)
78 #define SUN6I_DATE_GET_YEAR_VALUE(x)		(((x) & 0x003f0000) >> 16)
79 #define SUN6I_LEAP_GET_VALUE(x)			(((x) & 0x00400000) >> 22)
80 
81 /*
82  * Get time values
83  */
84 #define SUN6I_TIME_GET_SEC_VALUE(x)		((x)  & 0x0000003f)
85 #define SUN6I_TIME_GET_MIN_VALUE(x)		(((x) & 0x00003f00) >> 8)
86 #define SUN6I_TIME_GET_HOUR_VALUE(x)		(((x) & 0x001f0000) >> 16)
87 
88 /*
89  * Set date values
90  */
91 #define SUN6I_DATE_SET_DAY_VALUE(x)		((x)       & 0x0000001f)
92 #define SUN6I_DATE_SET_MON_VALUE(x)		((x) <<  8 & 0x00000f00)
93 #define SUN6I_DATE_SET_YEAR_VALUE(x)		((x) << 16 & 0x003f0000)
94 #define SUN6I_LEAP_SET_VALUE(x)			((x) << 22 & 0x00400000)
95 
96 /*
97  * Set time values
98  */
99 #define SUN6I_TIME_SET_SEC_VALUE(x)		((x)       & 0x0000003f)
100 #define SUN6I_TIME_SET_MIN_VALUE(x)		((x) <<  8 & 0x00003f00)
101 #define SUN6I_TIME_SET_HOUR_VALUE(x)		((x) << 16 & 0x001f0000)
102 
103 /*
104  * The year parameter passed to the driver is usually an offset relative to
105  * the year 1900. This macro is used to convert this offset to another one
106  * relative to the minimum year allowed by the hardware.
107  *
108  * The year range is 1970 - 2033. This range is selected to match Allwinner's
109  * driver, even though it is somewhat limited.
110  */
111 #define SUN6I_YEAR_MIN				1970
112 #define SUN6I_YEAR_OFF				(SUN6I_YEAR_MIN - 1900)
113 
114 #define SECS_PER_DAY				(24 * 3600ULL)
115 
116 /*
117  * There are other differences between models, including:
118  *
119  *   - number of GPIO pins that can be configured to hold a certain level
120  *   - crypto-key related registers (H5, H6)
121  *   - boot process related (super standby, secondary processor entry address)
122  *     registers (R40, H6)
123  *   - SYS power domain controls (R40)
124  *   - DCXO controls (H6)
125  *   - RC oscillator calibration (H6)
126  *
127  * These functions are not covered by this driver.
128  */
129 struct sun6i_rtc_clk_data {
130 	unsigned long rc_osc_rate;
131 	unsigned int fixed_prescaler : 16;
132 	unsigned int has_prescaler : 1;
133 	unsigned int has_out_clk : 1;
134 	unsigned int export_iosc : 1;
135 	unsigned int has_losc_en : 1;
136 	unsigned int has_auto_swt : 1;
137 };
138 
139 #define RTC_LINEAR_DAY	BIT(0)
140 
141 struct sun6i_rtc_dev {
142 	struct rtc_device *rtc;
143 	const struct sun6i_rtc_clk_data *data;
144 	void __iomem *base;
145 	int irq;
146 	time64_t alarm;
147 	unsigned long flags;
148 
149 	struct clk_hw hw;
150 	struct clk_hw *int_osc;
151 	struct clk *losc;
152 	struct clk *ext_losc;
153 
154 	spinlock_t lock;
155 };
156 
157 static struct sun6i_rtc_dev *sun6i_rtc;
158 
159 static unsigned long sun6i_rtc_osc_recalc_rate(struct clk_hw *hw,
160 					       unsigned long parent_rate)
161 {
162 	struct sun6i_rtc_dev *rtc = container_of(hw, struct sun6i_rtc_dev, hw);
163 	u32 val = 0;
164 
165 	val = readl(rtc->base + SUN6I_LOSC_CTRL);
166 	if (val & SUN6I_LOSC_CTRL_EXT_OSC)
167 		return parent_rate;
168 
169 	if (rtc->data->fixed_prescaler)
170 		parent_rate /= rtc->data->fixed_prescaler;
171 
172 	if (rtc->data->has_prescaler) {
173 		val = readl(rtc->base + SUN6I_LOSC_CLK_PRESCAL);
174 		val &= GENMASK(4, 0);
175 	}
176 
177 	return parent_rate / (val + 1);
178 }
179 
180 static u8 sun6i_rtc_osc_get_parent(struct clk_hw *hw)
181 {
182 	struct sun6i_rtc_dev *rtc = container_of(hw, struct sun6i_rtc_dev, hw);
183 
184 	return readl(rtc->base + SUN6I_LOSC_CTRL) & SUN6I_LOSC_CTRL_EXT_OSC;
185 }
186 
187 static int sun6i_rtc_osc_set_parent(struct clk_hw *hw, u8 index)
188 {
189 	struct sun6i_rtc_dev *rtc = container_of(hw, struct sun6i_rtc_dev, hw);
190 	unsigned long flags;
191 	u32 val;
192 
193 	if (index > 1)
194 		return -EINVAL;
195 
196 	spin_lock_irqsave(&rtc->lock, flags);
197 	val = readl(rtc->base + SUN6I_LOSC_CTRL);
198 	val &= ~SUN6I_LOSC_CTRL_EXT_OSC;
199 	val |= SUN6I_LOSC_CTRL_KEY;
200 	val |= index ? SUN6I_LOSC_CTRL_EXT_OSC : 0;
201 	if (rtc->data->has_losc_en) {
202 		val &= ~SUN6I_LOSC_CTRL_EXT_LOSC_EN;
203 		val |= index ? SUN6I_LOSC_CTRL_EXT_LOSC_EN : 0;
204 	}
205 	writel(val, rtc->base + SUN6I_LOSC_CTRL);
206 	spin_unlock_irqrestore(&rtc->lock, flags);
207 
208 	return 0;
209 }
210 
211 static const struct clk_ops sun6i_rtc_osc_ops = {
212 	.recalc_rate	= sun6i_rtc_osc_recalc_rate,
213 
214 	.get_parent	= sun6i_rtc_osc_get_parent,
215 	.set_parent	= sun6i_rtc_osc_set_parent,
216 };
217 
218 static void __init sun6i_rtc_clk_init(struct device_node *node,
219 				      const struct sun6i_rtc_clk_data *data)
220 {
221 	struct clk_hw_onecell_data *clk_data;
222 	struct sun6i_rtc_dev *rtc;
223 	struct clk_init_data init = {
224 		.ops		= &sun6i_rtc_osc_ops,
225 		.name		= "losc",
226 	};
227 	const char *iosc_name = "rtc-int-osc";
228 	const char *clkout_name = "osc32k-out";
229 	const char *parents[2];
230 	u32 reg;
231 
232 	rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
233 	if (!rtc)
234 		return;
235 
236 	rtc->data = data;
237 	clk_data = kzalloc(struct_size(clk_data, hws, 3), GFP_KERNEL);
238 	if (!clk_data) {
239 		kfree(rtc);
240 		return;
241 	}
242 
243 	spin_lock_init(&rtc->lock);
244 
245 	rtc->base = of_io_request_and_map(node, 0, of_node_full_name(node));
246 	if (IS_ERR(rtc->base)) {
247 		pr_crit("Can't map RTC registers");
248 		goto err;
249 	}
250 
251 	reg = SUN6I_LOSC_CTRL_KEY;
252 	if (rtc->data->has_auto_swt) {
253 		/* Bypass auto-switch to int osc, on ext losc failure */
254 		reg |= SUN6I_LOSC_CTRL_AUTO_SWT_BYPASS;
255 		writel(reg, rtc->base + SUN6I_LOSC_CTRL);
256 	}
257 
258 	/* Switch to the external, more precise, oscillator, if present */
259 	if (of_get_property(node, "clocks", NULL)) {
260 		reg |= SUN6I_LOSC_CTRL_EXT_OSC;
261 		if (rtc->data->has_losc_en)
262 			reg |= SUN6I_LOSC_CTRL_EXT_LOSC_EN;
263 	}
264 	writel(reg, rtc->base + SUN6I_LOSC_CTRL);
265 
266 	/* Yes, I know, this is ugly. */
267 	sun6i_rtc = rtc;
268 
269 	/* Only read IOSC name from device tree if it is exported */
270 	if (rtc->data->export_iosc)
271 		of_property_read_string_index(node, "clock-output-names", 2,
272 					      &iosc_name);
273 
274 	rtc->int_osc = clk_hw_register_fixed_rate_with_accuracy(NULL,
275 								iosc_name,
276 								NULL, 0,
277 								rtc->data->rc_osc_rate,
278 								300000000);
279 	if (IS_ERR(rtc->int_osc)) {
280 		pr_crit("Couldn't register the internal oscillator\n");
281 		goto err;
282 	}
283 
284 	parents[0] = clk_hw_get_name(rtc->int_osc);
285 	/* If there is no external oscillator, this will be NULL and ... */
286 	parents[1] = of_clk_get_parent_name(node, 0);
287 
288 	rtc->hw.init = &init;
289 
290 	init.parent_names = parents;
291 	/* ... number of clock parents will be 1. */
292 	init.num_parents = of_clk_get_parent_count(node) + 1;
293 	of_property_read_string_index(node, "clock-output-names", 0,
294 				      &init.name);
295 
296 	rtc->losc = clk_register(NULL, &rtc->hw);
297 	if (IS_ERR(rtc->losc)) {
298 		pr_crit("Couldn't register the LOSC clock\n");
299 		goto err_register;
300 	}
301 
302 	of_property_read_string_index(node, "clock-output-names", 1,
303 				      &clkout_name);
304 	rtc->ext_losc = clk_register_gate(NULL, clkout_name, init.name,
305 					  0, rtc->base + SUN6I_LOSC_OUT_GATING,
306 					  SUN6I_LOSC_OUT_GATING_EN_OFFSET, 0,
307 					  &rtc->lock);
308 	if (IS_ERR(rtc->ext_losc)) {
309 		pr_crit("Couldn't register the LOSC external gate\n");
310 		goto err_register;
311 	}
312 
313 	clk_data->num = 2;
314 	clk_data->hws[0] = &rtc->hw;
315 	clk_data->hws[1] = __clk_get_hw(rtc->ext_losc);
316 	if (rtc->data->export_iosc) {
317 		clk_data->hws[2] = rtc->int_osc;
318 		clk_data->num = 3;
319 	}
320 	of_clk_add_hw_provider(node, of_clk_hw_onecell_get, clk_data);
321 	return;
322 
323 err_register:
324 	clk_hw_unregister_fixed_rate(rtc->int_osc);
325 err:
326 	kfree(clk_data);
327 }
328 
329 static const struct sun6i_rtc_clk_data sun6i_a31_rtc_data = {
330 	.rc_osc_rate = 667000, /* datasheet says 600 ~ 700 KHz */
331 	.has_prescaler = 1,
332 };
333 
334 static void __init sun6i_a31_rtc_clk_init(struct device_node *node)
335 {
336 	sun6i_rtc_clk_init(node, &sun6i_a31_rtc_data);
337 }
338 CLK_OF_DECLARE_DRIVER(sun6i_a31_rtc_clk, "allwinner,sun6i-a31-rtc",
339 		      sun6i_a31_rtc_clk_init);
340 
341 static const struct sun6i_rtc_clk_data sun8i_a23_rtc_data = {
342 	.rc_osc_rate = 667000, /* datasheet says 600 ~ 700 KHz */
343 	.has_prescaler = 1,
344 	.has_out_clk = 1,
345 };
346 
347 static void __init sun8i_a23_rtc_clk_init(struct device_node *node)
348 {
349 	sun6i_rtc_clk_init(node, &sun8i_a23_rtc_data);
350 }
351 CLK_OF_DECLARE_DRIVER(sun8i_a23_rtc_clk, "allwinner,sun8i-a23-rtc",
352 		      sun8i_a23_rtc_clk_init);
353 
354 static const struct sun6i_rtc_clk_data sun8i_h3_rtc_data = {
355 	.rc_osc_rate = 16000000,
356 	.fixed_prescaler = 32,
357 	.has_prescaler = 1,
358 	.has_out_clk = 1,
359 	.export_iosc = 1,
360 };
361 
362 static void __init sun8i_h3_rtc_clk_init(struct device_node *node)
363 {
364 	sun6i_rtc_clk_init(node, &sun8i_h3_rtc_data);
365 }
366 CLK_OF_DECLARE_DRIVER(sun8i_h3_rtc_clk, "allwinner,sun8i-h3-rtc",
367 		      sun8i_h3_rtc_clk_init);
368 /* As far as we are concerned, clocks for H5 are the same as H3 */
369 CLK_OF_DECLARE_DRIVER(sun50i_h5_rtc_clk, "allwinner,sun50i-h5-rtc",
370 		      sun8i_h3_rtc_clk_init);
371 
372 static const struct sun6i_rtc_clk_data sun50i_h6_rtc_data = {
373 	.rc_osc_rate = 16000000,
374 	.fixed_prescaler = 32,
375 	.has_prescaler = 1,
376 	.has_out_clk = 1,
377 	.export_iosc = 1,
378 	.has_losc_en = 1,
379 	.has_auto_swt = 1,
380 };
381 
382 static void __init sun50i_h6_rtc_clk_init(struct device_node *node)
383 {
384 	sun6i_rtc_clk_init(node, &sun50i_h6_rtc_data);
385 }
386 CLK_OF_DECLARE_DRIVER(sun50i_h6_rtc_clk, "allwinner,sun50i-h6-rtc",
387 		      sun50i_h6_rtc_clk_init);
388 
389 /*
390  * The R40 user manual is self-conflicting on whether the prescaler is
391  * fixed or configurable. The clock diagram shows it as fixed, but there
392  * is also a configurable divider in the RTC block.
393  */
394 static const struct sun6i_rtc_clk_data sun8i_r40_rtc_data = {
395 	.rc_osc_rate = 16000000,
396 	.fixed_prescaler = 512,
397 };
398 static void __init sun8i_r40_rtc_clk_init(struct device_node *node)
399 {
400 	sun6i_rtc_clk_init(node, &sun8i_r40_rtc_data);
401 }
402 CLK_OF_DECLARE_DRIVER(sun8i_r40_rtc_clk, "allwinner,sun8i-r40-rtc",
403 		      sun8i_r40_rtc_clk_init);
404 
405 static const struct sun6i_rtc_clk_data sun8i_v3_rtc_data = {
406 	.rc_osc_rate = 32000,
407 	.has_out_clk = 1,
408 };
409 
410 static void __init sun8i_v3_rtc_clk_init(struct device_node *node)
411 {
412 	sun6i_rtc_clk_init(node, &sun8i_v3_rtc_data);
413 }
414 CLK_OF_DECLARE_DRIVER(sun8i_v3_rtc_clk, "allwinner,sun8i-v3-rtc",
415 		      sun8i_v3_rtc_clk_init);
416 
417 static irqreturn_t sun6i_rtc_alarmirq(int irq, void *id)
418 {
419 	struct sun6i_rtc_dev *chip = (struct sun6i_rtc_dev *) id;
420 	irqreturn_t ret = IRQ_NONE;
421 	u32 val;
422 
423 	spin_lock(&chip->lock);
424 	val = readl(chip->base + SUN6I_ALRM_IRQ_STA);
425 
426 	if (val & SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND) {
427 		val |= SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND;
428 		writel(val, chip->base + SUN6I_ALRM_IRQ_STA);
429 
430 		rtc_update_irq(chip->rtc, 1, RTC_AF | RTC_IRQF);
431 
432 		ret = IRQ_HANDLED;
433 	}
434 	spin_unlock(&chip->lock);
435 
436 	return ret;
437 }
438 
439 static void sun6i_rtc_setaie(int to, struct sun6i_rtc_dev *chip)
440 {
441 	u32 alrm_val = 0;
442 	u32 alrm_irq_val = 0;
443 	u32 alrm_wake_val = 0;
444 	unsigned long flags;
445 
446 	if (to) {
447 		alrm_val = SUN6I_ALRM_EN_CNT_EN;
448 		alrm_irq_val = SUN6I_ALRM_IRQ_EN_CNT_IRQ_EN;
449 		alrm_wake_val = SUN6I_ALARM_CONFIG_WAKEUP;
450 	} else {
451 		writel(SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND,
452 		       chip->base + SUN6I_ALRM_IRQ_STA);
453 	}
454 
455 	spin_lock_irqsave(&chip->lock, flags);
456 	writel(alrm_val, chip->base + SUN6I_ALRM_EN);
457 	writel(alrm_irq_val, chip->base + SUN6I_ALRM_IRQ_EN);
458 	writel(alrm_wake_val, chip->base + SUN6I_ALARM_CONFIG);
459 	spin_unlock_irqrestore(&chip->lock, flags);
460 }
461 
462 static int sun6i_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
463 {
464 	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
465 	u32 date, time;
466 
467 	/*
468 	 * read again in case it changes
469 	 */
470 	do {
471 		date = readl(chip->base + SUN6I_RTC_YMD);
472 		time = readl(chip->base + SUN6I_RTC_HMS);
473 	} while ((date != readl(chip->base + SUN6I_RTC_YMD)) ||
474 		 (time != readl(chip->base + SUN6I_RTC_HMS)));
475 
476 	if (chip->flags & RTC_LINEAR_DAY) {
477 		/*
478 		 * Newer chips store a linear day number, the manual
479 		 * does not mandate any epoch base. The BSP driver uses
480 		 * the UNIX epoch, let's just copy that, as it's the
481 		 * easiest anyway.
482 		 */
483 		rtc_time64_to_tm((date & 0xffff) * SECS_PER_DAY, rtc_tm);
484 	} else {
485 		rtc_tm->tm_mday = SUN6I_DATE_GET_DAY_VALUE(date);
486 		rtc_tm->tm_mon  = SUN6I_DATE_GET_MON_VALUE(date) - 1;
487 		rtc_tm->tm_year = SUN6I_DATE_GET_YEAR_VALUE(date);
488 
489 		/*
490 		 * switch from (data_year->min)-relative offset to
491 		 * a (1900)-relative one
492 		 */
493 		rtc_tm->tm_year += SUN6I_YEAR_OFF;
494 	}
495 
496 	rtc_tm->tm_sec  = SUN6I_TIME_GET_SEC_VALUE(time);
497 	rtc_tm->tm_min  = SUN6I_TIME_GET_MIN_VALUE(time);
498 	rtc_tm->tm_hour = SUN6I_TIME_GET_HOUR_VALUE(time);
499 
500 	return 0;
501 }
502 
503 static int sun6i_rtc_getalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
504 {
505 	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
506 	unsigned long flags;
507 	u32 alrm_st;
508 	u32 alrm_en;
509 
510 	spin_lock_irqsave(&chip->lock, flags);
511 	alrm_en = readl(chip->base + SUN6I_ALRM_IRQ_EN);
512 	alrm_st = readl(chip->base + SUN6I_ALRM_IRQ_STA);
513 	spin_unlock_irqrestore(&chip->lock, flags);
514 
515 	wkalrm->enabled = !!(alrm_en & SUN6I_ALRM_EN_CNT_EN);
516 	wkalrm->pending = !!(alrm_st & SUN6I_ALRM_EN_CNT_EN);
517 	rtc_time64_to_tm(chip->alarm, &wkalrm->time);
518 
519 	return 0;
520 }
521 
522 static int sun6i_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
523 {
524 	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
525 	struct rtc_time *alrm_tm = &wkalrm->time;
526 	struct rtc_time tm_now;
527 	time64_t time_set;
528 	u32 counter_val, counter_val_hms;
529 	int ret;
530 
531 	time_set = rtc_tm_to_time64(alrm_tm);
532 
533 	if (chip->flags & RTC_LINEAR_DAY) {
534 		/*
535 		 * The alarm registers hold the actual alarm time, encoded
536 		 * in the same way (linear day + HMS) as the current time.
537 		 */
538 		counter_val_hms = SUN6I_TIME_SET_SEC_VALUE(alrm_tm->tm_sec)  |
539 				  SUN6I_TIME_SET_MIN_VALUE(alrm_tm->tm_min)  |
540 				  SUN6I_TIME_SET_HOUR_VALUE(alrm_tm->tm_hour);
541 		/* The division will cut off the H:M:S part of alrm_tm. */
542 		counter_val = div_u64(rtc_tm_to_time64(alrm_tm), SECS_PER_DAY);
543 	} else {
544 		/* The alarm register holds the number of seconds left. */
545 		time64_t time_now;
546 
547 		ret = sun6i_rtc_gettime(dev, &tm_now);
548 		if (ret < 0) {
549 			dev_err(dev, "Error in getting time\n");
550 			return -EINVAL;
551 		}
552 
553 		time_now = rtc_tm_to_time64(&tm_now);
554 		if (time_set <= time_now) {
555 			dev_err(dev, "Date to set in the past\n");
556 			return -EINVAL;
557 		}
558 		if ((time_set - time_now) > U32_MAX) {
559 			dev_err(dev, "Date too far in the future\n");
560 			return -EINVAL;
561 		}
562 
563 		counter_val = time_set - time_now;
564 	}
565 
566 	sun6i_rtc_setaie(0, chip);
567 	writel(0, chip->base + SUN6I_ALRM_COUNTER);
568 	if (chip->flags & RTC_LINEAR_DAY)
569 		writel(0, chip->base + SUN6I_ALRM_COUNTER_HMS);
570 	usleep_range(100, 300);
571 
572 	writel(counter_val, chip->base + SUN6I_ALRM_COUNTER);
573 	if (chip->flags & RTC_LINEAR_DAY)
574 		writel(counter_val_hms, chip->base + SUN6I_ALRM_COUNTER_HMS);
575 	chip->alarm = time_set;
576 
577 	sun6i_rtc_setaie(wkalrm->enabled, chip);
578 
579 	return 0;
580 }
581 
582 static int sun6i_rtc_wait(struct sun6i_rtc_dev *chip, int offset,
583 			  unsigned int mask, unsigned int ms_timeout)
584 {
585 	const unsigned long timeout = jiffies + msecs_to_jiffies(ms_timeout);
586 	u32 reg;
587 
588 	do {
589 		reg = readl(chip->base + offset);
590 		reg &= mask;
591 
592 		if (!reg)
593 			return 0;
594 
595 	} while (time_before(jiffies, timeout));
596 
597 	return -ETIMEDOUT;
598 }
599 
600 static int sun6i_rtc_settime(struct device *dev, struct rtc_time *rtc_tm)
601 {
602 	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
603 	u32 date = 0;
604 	u32 time = 0;
605 
606 	time = SUN6I_TIME_SET_SEC_VALUE(rtc_tm->tm_sec)  |
607 		SUN6I_TIME_SET_MIN_VALUE(rtc_tm->tm_min)  |
608 		SUN6I_TIME_SET_HOUR_VALUE(rtc_tm->tm_hour);
609 
610 	if (chip->flags & RTC_LINEAR_DAY) {
611 		/* The division will cut off the H:M:S part of rtc_tm. */
612 		date = div_u64(rtc_tm_to_time64(rtc_tm), SECS_PER_DAY);
613 	} else {
614 		rtc_tm->tm_year -= SUN6I_YEAR_OFF;
615 		rtc_tm->tm_mon += 1;
616 
617 		date = SUN6I_DATE_SET_DAY_VALUE(rtc_tm->tm_mday) |
618 			SUN6I_DATE_SET_MON_VALUE(rtc_tm->tm_mon)  |
619 			SUN6I_DATE_SET_YEAR_VALUE(rtc_tm->tm_year);
620 
621 		if (is_leap_year(rtc_tm->tm_year + SUN6I_YEAR_MIN))
622 			date |= SUN6I_LEAP_SET_VALUE(1);
623 	}
624 
625 	/* Check whether registers are writable */
626 	if (sun6i_rtc_wait(chip, SUN6I_LOSC_CTRL,
627 			   SUN6I_LOSC_CTRL_ACC_MASK, 50)) {
628 		dev_err(dev, "rtc is still busy.\n");
629 		return -EBUSY;
630 	}
631 
632 	writel(time, chip->base + SUN6I_RTC_HMS);
633 
634 	/*
635 	 * After writing the RTC HH-MM-SS register, the
636 	 * SUN6I_LOSC_CTRL_RTC_HMS_ACC bit is set and it will not
637 	 * be cleared until the real writing operation is finished
638 	 */
639 
640 	if (sun6i_rtc_wait(chip, SUN6I_LOSC_CTRL,
641 			   SUN6I_LOSC_CTRL_RTC_HMS_ACC, 50)) {
642 		dev_err(dev, "Failed to set rtc time.\n");
643 		return -ETIMEDOUT;
644 	}
645 
646 	writel(date, chip->base + SUN6I_RTC_YMD);
647 
648 	/*
649 	 * After writing the RTC YY-MM-DD register, the
650 	 * SUN6I_LOSC_CTRL_RTC_YMD_ACC bit is set and it will not
651 	 * be cleared until the real writing operation is finished
652 	 */
653 
654 	if (sun6i_rtc_wait(chip, SUN6I_LOSC_CTRL,
655 			   SUN6I_LOSC_CTRL_RTC_YMD_ACC, 50)) {
656 		dev_err(dev, "Failed to set rtc time.\n");
657 		return -ETIMEDOUT;
658 	}
659 
660 	return 0;
661 }
662 
663 static int sun6i_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
664 {
665 	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
666 
667 	if (!enabled)
668 		sun6i_rtc_setaie(enabled, chip);
669 
670 	return 0;
671 }
672 
673 static const struct rtc_class_ops sun6i_rtc_ops = {
674 	.read_time		= sun6i_rtc_gettime,
675 	.set_time		= sun6i_rtc_settime,
676 	.read_alarm		= sun6i_rtc_getalarm,
677 	.set_alarm		= sun6i_rtc_setalarm,
678 	.alarm_irq_enable	= sun6i_rtc_alarm_irq_enable
679 };
680 
681 #ifdef CONFIG_PM_SLEEP
682 /* Enable IRQ wake on suspend, to wake up from RTC. */
683 static int sun6i_rtc_suspend(struct device *dev)
684 {
685 	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
686 
687 	if (device_may_wakeup(dev))
688 		enable_irq_wake(chip->irq);
689 
690 	return 0;
691 }
692 
693 /* Disable IRQ wake on resume. */
694 static int sun6i_rtc_resume(struct device *dev)
695 {
696 	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
697 
698 	if (device_may_wakeup(dev))
699 		disable_irq_wake(chip->irq);
700 
701 	return 0;
702 }
703 #endif
704 
705 static SIMPLE_DEV_PM_OPS(sun6i_rtc_pm_ops,
706 	sun6i_rtc_suspend, sun6i_rtc_resume);
707 
708 static void sun6i_rtc_bus_clk_cleanup(void *data)
709 {
710 	struct clk *bus_clk = data;
711 
712 	clk_disable_unprepare(bus_clk);
713 }
714 
715 static int sun6i_rtc_probe(struct platform_device *pdev)
716 {
717 	struct sun6i_rtc_dev *chip = sun6i_rtc;
718 	struct device *dev = &pdev->dev;
719 	struct clk *bus_clk;
720 	int ret;
721 
722 	bus_clk = devm_clk_get_optional(dev, "bus");
723 	if (IS_ERR(bus_clk))
724 		return PTR_ERR(bus_clk);
725 
726 	if (bus_clk) {
727 		ret = clk_prepare_enable(bus_clk);
728 		if (ret)
729 			return ret;
730 
731 		ret = devm_add_action_or_reset(dev, sun6i_rtc_bus_clk_cleanup,
732 					       bus_clk);
733 		if (ret)
734 			return ret;
735 	}
736 
737 	if (!chip) {
738 		chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
739 		if (!chip)
740 			return -ENOMEM;
741 
742 		spin_lock_init(&chip->lock);
743 
744 		chip->base = devm_platform_ioremap_resource(pdev, 0);
745 		if (IS_ERR(chip->base))
746 			return PTR_ERR(chip->base);
747 	}
748 
749 	platform_set_drvdata(pdev, chip);
750 
751 	chip->flags = (unsigned long)of_device_get_match_data(&pdev->dev);
752 
753 	chip->irq = platform_get_irq(pdev, 0);
754 	if (chip->irq < 0)
755 		return chip->irq;
756 
757 	ret = devm_request_irq(&pdev->dev, chip->irq, sun6i_rtc_alarmirq,
758 			       0, dev_name(&pdev->dev), chip);
759 	if (ret) {
760 		dev_err(&pdev->dev, "Could not request IRQ\n");
761 		return ret;
762 	}
763 
764 	/* clear the alarm counter value */
765 	writel(0, chip->base + SUN6I_ALRM_COUNTER);
766 
767 	/* disable counter alarm */
768 	writel(0, chip->base + SUN6I_ALRM_EN);
769 
770 	/* disable counter alarm interrupt */
771 	writel(0, chip->base + SUN6I_ALRM_IRQ_EN);
772 
773 	/* disable week alarm */
774 	writel(0, chip->base + SUN6I_ALRM1_EN);
775 
776 	/* disable week alarm interrupt */
777 	writel(0, chip->base + SUN6I_ALRM1_IRQ_EN);
778 
779 	/* clear counter alarm pending interrupts */
780 	writel(SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND,
781 	       chip->base + SUN6I_ALRM_IRQ_STA);
782 
783 	/* clear week alarm pending interrupts */
784 	writel(SUN6I_ALRM1_IRQ_STA_WEEK_IRQ_PEND,
785 	       chip->base + SUN6I_ALRM1_IRQ_STA);
786 
787 	/* disable alarm wakeup */
788 	writel(0, chip->base + SUN6I_ALARM_CONFIG);
789 
790 	clk_prepare_enable(chip->losc);
791 
792 	device_init_wakeup(&pdev->dev, 1);
793 
794 	chip->rtc = devm_rtc_allocate_device(&pdev->dev);
795 	if (IS_ERR(chip->rtc))
796 		return PTR_ERR(chip->rtc);
797 
798 	chip->rtc->ops = &sun6i_rtc_ops;
799 	if (chip->flags & RTC_LINEAR_DAY)
800 		chip->rtc->range_max = (65536 * SECS_PER_DAY) - 1;
801 	else
802 		chip->rtc->range_max = 2019686399LL; /* 2033-12-31 23:59:59 */
803 
804 	ret = devm_rtc_register_device(chip->rtc);
805 	if (ret)
806 		return ret;
807 
808 	dev_info(&pdev->dev, "RTC enabled\n");
809 
810 	return 0;
811 }
812 
813 /*
814  * As far as RTC functionality goes, all models are the same. The
815  * datasheets claim that different models have different number of
816  * registers available for non-volatile storage, but experiments show
817  * that all SoCs have 16 registers available for this purpose.
818  */
819 static const struct of_device_id sun6i_rtc_dt_ids[] = {
820 	{ .compatible = "allwinner,sun6i-a31-rtc" },
821 	{ .compatible = "allwinner,sun8i-a23-rtc" },
822 	{ .compatible = "allwinner,sun8i-h3-rtc" },
823 	{ .compatible = "allwinner,sun8i-r40-rtc" },
824 	{ .compatible = "allwinner,sun8i-v3-rtc" },
825 	{ .compatible = "allwinner,sun50i-h5-rtc" },
826 	{ .compatible = "allwinner,sun50i-h6-rtc" },
827 	{ .compatible = "allwinner,sun50i-h616-rtc",
828 		.data = (void *)RTC_LINEAR_DAY },
829 	{ /* sentinel */ },
830 };
831 MODULE_DEVICE_TABLE(of, sun6i_rtc_dt_ids);
832 
833 static struct platform_driver sun6i_rtc_driver = {
834 	.probe		= sun6i_rtc_probe,
835 	.driver		= {
836 		.name		= "sun6i-rtc",
837 		.of_match_table = sun6i_rtc_dt_ids,
838 		.pm = &sun6i_rtc_pm_ops,
839 	},
840 };
841 builtin_platform_driver(sun6i_rtc_driver);
842