1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * An rtc driver for the Dallas DS1511
4  *
5  * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
6  * Copyright (C) 2007 Andrew Sharp <andy.sharp@lsi.com>
7  *
8  * Real time clock driver for the Dallas 1511 chip, which also
9  * contains a watchdog timer.  There is a tiny amount of code that
10  * platform code could use to mess with the watchdog device a little
11  * bit, but not a full watchdog driver.
12  */
13 
14 #include <linux/bcd.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/gfp.h>
18 #include <linux/delay.h>
19 #include <linux/interrupt.h>
20 #include <linux/rtc.h>
21 #include <linux/platform_device.h>
22 #include <linux/io.h>
23 #include <linux/module.h>
24 
25 enum ds1511reg {
26 	DS1511_SEC = 0x0,
27 	DS1511_MIN = 0x1,
28 	DS1511_HOUR = 0x2,
29 	DS1511_DOW = 0x3,
30 	DS1511_DOM = 0x4,
31 	DS1511_MONTH = 0x5,
32 	DS1511_YEAR = 0x6,
33 	DS1511_CENTURY = 0x7,
34 	DS1511_AM1_SEC = 0x8,
35 	DS1511_AM2_MIN = 0x9,
36 	DS1511_AM3_HOUR = 0xa,
37 	DS1511_AM4_DATE = 0xb,
38 	DS1511_WD_MSEC = 0xc,
39 	DS1511_WD_SEC = 0xd,
40 	DS1511_CONTROL_A = 0xe,
41 	DS1511_CONTROL_B = 0xf,
42 	DS1511_RAMADDR_LSB = 0x10,
43 	DS1511_RAMDATA = 0x13
44 };
45 
46 #define DS1511_BLF1	0x80
47 #define DS1511_BLF2	0x40
48 #define DS1511_PRS	0x20
49 #define DS1511_PAB	0x10
50 #define DS1511_TDF	0x08
51 #define DS1511_KSF	0x04
52 #define DS1511_WDF	0x02
53 #define DS1511_IRQF	0x01
54 #define DS1511_TE	0x80
55 #define DS1511_CS	0x40
56 #define DS1511_BME	0x20
57 #define DS1511_TPE	0x10
58 #define DS1511_TIE	0x08
59 #define DS1511_KIE	0x04
60 #define DS1511_WDE	0x02
61 #define DS1511_WDS	0x01
62 #define DS1511_RAM_MAX	0x100
63 
64 #define RTC_CMD		DS1511_CONTROL_B
65 #define RTC_CMD1	DS1511_CONTROL_A
66 
67 #define RTC_ALARM_SEC	DS1511_AM1_SEC
68 #define RTC_ALARM_MIN	DS1511_AM2_MIN
69 #define RTC_ALARM_HOUR	DS1511_AM3_HOUR
70 #define RTC_ALARM_DATE	DS1511_AM4_DATE
71 
72 #define RTC_SEC		DS1511_SEC
73 #define RTC_MIN		DS1511_MIN
74 #define RTC_HOUR	DS1511_HOUR
75 #define RTC_DOW		DS1511_DOW
76 #define RTC_DOM		DS1511_DOM
77 #define RTC_MON		DS1511_MONTH
78 #define RTC_YEAR	DS1511_YEAR
79 #define RTC_CENTURY	DS1511_CENTURY
80 
81 #define RTC_TIE	DS1511_TIE
82 #define RTC_TE	DS1511_TE
83 
84 struct rtc_plat_data {
85 	struct rtc_device *rtc;
86 	void __iomem *ioaddr;		/* virtual base address */
87 	int irq;
88 	unsigned int irqen;
89 	int alrm_sec;
90 	int alrm_min;
91 	int alrm_hour;
92 	int alrm_mday;
93 	spinlock_t lock;
94 };
95 
96 static DEFINE_SPINLOCK(ds1511_lock);
97 
98 static __iomem char *ds1511_base;
99 static u32 reg_spacing = 1;
100 
101 static noinline void
rtc_write(uint8_t val,uint32_t reg)102 rtc_write(uint8_t val, uint32_t reg)
103 {
104 	writeb(val, ds1511_base + (reg * reg_spacing));
105 }
106 
107 static noinline uint8_t
rtc_read(enum ds1511reg reg)108 rtc_read(enum ds1511reg reg)
109 {
110 	return readb(ds1511_base + (reg * reg_spacing));
111 }
112 
113 static inline void
rtc_disable_update(void)114 rtc_disable_update(void)
115 {
116 	rtc_write((rtc_read(RTC_CMD) & ~RTC_TE), RTC_CMD);
117 }
118 
119 static void
rtc_enable_update(void)120 rtc_enable_update(void)
121 {
122 	rtc_write((rtc_read(RTC_CMD) | RTC_TE), RTC_CMD);
123 }
124 
125 /*
126  * #define DS1511_WDOG_RESET_SUPPORT
127  *
128  * Uncomment this if you want to use these routines in
129  * some platform code.
130  */
131 #ifdef DS1511_WDOG_RESET_SUPPORT
132 /*
133  * just enough code to set the watchdog timer so that it
134  * will reboot the system
135  */
136 void
ds1511_wdog_set(unsigned long deciseconds)137 ds1511_wdog_set(unsigned long deciseconds)
138 {
139 	/*
140 	 * the wdog timer can take 99.99 seconds
141 	 */
142 	deciseconds %= 10000;
143 	/*
144 	 * set the wdog values in the wdog registers
145 	 */
146 	rtc_write(bin2bcd(deciseconds % 100), DS1511_WD_MSEC);
147 	rtc_write(bin2bcd(deciseconds / 100), DS1511_WD_SEC);
148 	/*
149 	 * set wdog enable and wdog 'steering' bit to issue a reset
150 	 */
151 	rtc_write(rtc_read(RTC_CMD) | DS1511_WDE | DS1511_WDS, RTC_CMD);
152 }
153 
154 void
ds1511_wdog_disable(void)155 ds1511_wdog_disable(void)
156 {
157 	/*
158 	 * clear wdog enable and wdog 'steering' bits
159 	 */
160 	rtc_write(rtc_read(RTC_CMD) & ~(DS1511_WDE | DS1511_WDS), RTC_CMD);
161 	/*
162 	 * clear the wdog counter
163 	 */
164 	rtc_write(0, DS1511_WD_MSEC);
165 	rtc_write(0, DS1511_WD_SEC);
166 }
167 #endif
168 
169 /*
170  * set the rtc chip's idea of the time.
171  * stupidly, some callers call with year unmolested;
172  * and some call with  year = year - 1900.  thanks.
173  */
ds1511_rtc_set_time(struct device * dev,struct rtc_time * rtc_tm)174 static int ds1511_rtc_set_time(struct device *dev, struct rtc_time *rtc_tm)
175 {
176 	u8 mon, day, dow, hrs, min, sec, yrs, cen;
177 	unsigned long flags;
178 
179 	/*
180 	 * won't have to change this for a while
181 	 */
182 	if (rtc_tm->tm_year < 1900)
183 		rtc_tm->tm_year += 1900;
184 
185 	if (rtc_tm->tm_year < 1970)
186 		return -EINVAL;
187 
188 	yrs = rtc_tm->tm_year % 100;
189 	cen = rtc_tm->tm_year / 100;
190 	mon = rtc_tm->tm_mon + 1;   /* tm_mon starts at zero */
191 	day = rtc_tm->tm_mday;
192 	dow = rtc_tm->tm_wday & 0x7; /* automatic BCD */
193 	hrs = rtc_tm->tm_hour;
194 	min = rtc_tm->tm_min;
195 	sec = rtc_tm->tm_sec;
196 
197 	if ((mon > 12) || (day == 0))
198 		return -EINVAL;
199 
200 	if (day > rtc_month_days(rtc_tm->tm_mon, rtc_tm->tm_year))
201 		return -EINVAL;
202 
203 	if ((hrs >= 24) || (min >= 60) || (sec >= 60))
204 		return -EINVAL;
205 
206 	/*
207 	 * each register is a different number of valid bits
208 	 */
209 	sec = bin2bcd(sec) & 0x7f;
210 	min = bin2bcd(min) & 0x7f;
211 	hrs = bin2bcd(hrs) & 0x3f;
212 	day = bin2bcd(day) & 0x3f;
213 	mon = bin2bcd(mon) & 0x1f;
214 	yrs = bin2bcd(yrs) & 0xff;
215 	cen = bin2bcd(cen) & 0xff;
216 
217 	spin_lock_irqsave(&ds1511_lock, flags);
218 	rtc_disable_update();
219 	rtc_write(cen, RTC_CENTURY);
220 	rtc_write(yrs, RTC_YEAR);
221 	rtc_write((rtc_read(RTC_MON) & 0xe0) | mon, RTC_MON);
222 	rtc_write(day, RTC_DOM);
223 	rtc_write(hrs, RTC_HOUR);
224 	rtc_write(min, RTC_MIN);
225 	rtc_write(sec, RTC_SEC);
226 	rtc_write(dow, RTC_DOW);
227 	rtc_enable_update();
228 	spin_unlock_irqrestore(&ds1511_lock, flags);
229 
230 	return 0;
231 }
232 
ds1511_rtc_read_time(struct device * dev,struct rtc_time * rtc_tm)233 static int ds1511_rtc_read_time(struct device *dev, struct rtc_time *rtc_tm)
234 {
235 	unsigned int century;
236 	unsigned long flags;
237 
238 	spin_lock_irqsave(&ds1511_lock, flags);
239 	rtc_disable_update();
240 
241 	rtc_tm->tm_sec = rtc_read(RTC_SEC) & 0x7f;
242 	rtc_tm->tm_min = rtc_read(RTC_MIN) & 0x7f;
243 	rtc_tm->tm_hour = rtc_read(RTC_HOUR) & 0x3f;
244 	rtc_tm->tm_mday = rtc_read(RTC_DOM) & 0x3f;
245 	rtc_tm->tm_wday = rtc_read(RTC_DOW) & 0x7;
246 	rtc_tm->tm_mon = rtc_read(RTC_MON) & 0x1f;
247 	rtc_tm->tm_year = rtc_read(RTC_YEAR) & 0x7f;
248 	century = rtc_read(RTC_CENTURY);
249 
250 	rtc_enable_update();
251 	spin_unlock_irqrestore(&ds1511_lock, flags);
252 
253 	rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
254 	rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
255 	rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
256 	rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
257 	rtc_tm->tm_wday = bcd2bin(rtc_tm->tm_wday);
258 	rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
259 	rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
260 	century = bcd2bin(century) * 100;
261 
262 	/*
263 	 * Account for differences between how the RTC uses the values
264 	 * and how they are defined in a struct rtc_time;
265 	 */
266 	century += rtc_tm->tm_year;
267 	rtc_tm->tm_year = century - 1900;
268 
269 	rtc_tm->tm_mon--;
270 
271 	return 0;
272 }
273 
274 /*
275  * write the alarm register settings
276  *
277  * we only have the use to interrupt every second, otherwise
278  * known as the update interrupt, or the interrupt if the whole
279  * date/hours/mins/secs matches.  the ds1511 has many more
280  * permutations, but the kernel doesn't.
281  */
282 static void
ds1511_rtc_update_alarm(struct rtc_plat_data * pdata)283 ds1511_rtc_update_alarm(struct rtc_plat_data *pdata)
284 {
285 	unsigned long flags;
286 
287 	spin_lock_irqsave(&pdata->lock, flags);
288 	rtc_write(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
289 	       0x80 : bin2bcd(pdata->alrm_mday) & 0x3f,
290 	       RTC_ALARM_DATE);
291 	rtc_write(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
292 	       0x80 : bin2bcd(pdata->alrm_hour) & 0x3f,
293 	       RTC_ALARM_HOUR);
294 	rtc_write(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
295 	       0x80 : bin2bcd(pdata->alrm_min) & 0x7f,
296 	       RTC_ALARM_MIN);
297 	rtc_write(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
298 	       0x80 : bin2bcd(pdata->alrm_sec) & 0x7f,
299 	       RTC_ALARM_SEC);
300 	rtc_write(rtc_read(RTC_CMD) | (pdata->irqen ? RTC_TIE : 0), RTC_CMD);
301 	rtc_read(RTC_CMD1);	/* clear interrupts */
302 	spin_unlock_irqrestore(&pdata->lock, flags);
303 }
304 
305 static int
ds1511_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alrm)306 ds1511_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
307 {
308 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
309 
310 	if (pdata->irq <= 0)
311 		return -EINVAL;
312 
313 	pdata->alrm_mday = alrm->time.tm_mday;
314 	pdata->alrm_hour = alrm->time.tm_hour;
315 	pdata->alrm_min = alrm->time.tm_min;
316 	pdata->alrm_sec = alrm->time.tm_sec;
317 	if (alrm->enabled)
318 		pdata->irqen |= RTC_AF;
319 
320 	ds1511_rtc_update_alarm(pdata);
321 	return 0;
322 }
323 
324 static int
ds1511_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alrm)325 ds1511_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
326 {
327 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
328 
329 	if (pdata->irq <= 0)
330 		return -EINVAL;
331 
332 	alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
333 	alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
334 	alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
335 	alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
336 	alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
337 	return 0;
338 }
339 
340 static irqreturn_t
ds1511_interrupt(int irq,void * dev_id)341 ds1511_interrupt(int irq, void *dev_id)
342 {
343 	struct platform_device *pdev = dev_id;
344 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
345 	unsigned long events = 0;
346 
347 	spin_lock(&pdata->lock);
348 	/*
349 	 * read and clear interrupt
350 	 */
351 	if (rtc_read(RTC_CMD1) & DS1511_IRQF) {
352 		events = RTC_IRQF;
353 		if (rtc_read(RTC_ALARM_SEC) & 0x80)
354 			events |= RTC_UF;
355 		else
356 			events |= RTC_AF;
357 		rtc_update_irq(pdata->rtc, 1, events);
358 	}
359 	spin_unlock(&pdata->lock);
360 	return events ? IRQ_HANDLED : IRQ_NONE;
361 }
362 
ds1511_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)363 static int ds1511_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
364 {
365 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
366 
367 	if (pdata->irq <= 0)
368 		return -EINVAL;
369 	if (enabled)
370 		pdata->irqen |= RTC_AF;
371 	else
372 		pdata->irqen &= ~RTC_AF;
373 	ds1511_rtc_update_alarm(pdata);
374 	return 0;
375 }
376 
377 static const struct rtc_class_ops ds1511_rtc_ops = {
378 	.read_time		= ds1511_rtc_read_time,
379 	.set_time		= ds1511_rtc_set_time,
380 	.read_alarm		= ds1511_rtc_read_alarm,
381 	.set_alarm		= ds1511_rtc_set_alarm,
382 	.alarm_irq_enable	= ds1511_rtc_alarm_irq_enable,
383 };
384 
ds1511_nvram_read(void * priv,unsigned int pos,void * buf,size_t size)385 static int ds1511_nvram_read(void *priv, unsigned int pos, void *buf,
386 			     size_t size)
387 {
388 	int i;
389 
390 	rtc_write(pos, DS1511_RAMADDR_LSB);
391 	for (i = 0; i < size; i++)
392 		*(char *)buf++ = rtc_read(DS1511_RAMDATA);
393 
394 	return 0;
395 }
396 
ds1511_nvram_write(void * priv,unsigned int pos,void * buf,size_t size)397 static int ds1511_nvram_write(void *priv, unsigned int pos, void *buf,
398 			      size_t size)
399 {
400 	int i;
401 
402 	rtc_write(pos, DS1511_RAMADDR_LSB);
403 	for (i = 0; i < size; i++)
404 		rtc_write(*(char *)buf++, DS1511_RAMDATA);
405 
406 	return 0;
407 }
408 
ds1511_rtc_probe(struct platform_device * pdev)409 static int ds1511_rtc_probe(struct platform_device *pdev)
410 {
411 	struct rtc_plat_data *pdata;
412 	int ret = 0;
413 	struct nvmem_config ds1511_nvmem_cfg = {
414 		.name = "ds1511_nvram",
415 		.word_size = 1,
416 		.stride = 1,
417 		.size = DS1511_RAM_MAX,
418 		.reg_read = ds1511_nvram_read,
419 		.reg_write = ds1511_nvram_write,
420 		.priv = &pdev->dev,
421 	};
422 
423 	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
424 	if (!pdata)
425 		return -ENOMEM;
426 
427 	ds1511_base = devm_platform_ioremap_resource(pdev, 0);
428 	if (IS_ERR(ds1511_base))
429 		return PTR_ERR(ds1511_base);
430 	pdata->ioaddr = ds1511_base;
431 	pdata->irq = platform_get_irq(pdev, 0);
432 
433 	/*
434 	 * turn on the clock and the crystal, etc.
435 	 */
436 	rtc_write(DS1511_BME, RTC_CMD);
437 	rtc_write(0, RTC_CMD1);
438 	/*
439 	 * clear the wdog counter
440 	 */
441 	rtc_write(0, DS1511_WD_MSEC);
442 	rtc_write(0, DS1511_WD_SEC);
443 	/*
444 	 * start the clock
445 	 */
446 	rtc_enable_update();
447 
448 	/*
449 	 * check for a dying bat-tree
450 	 */
451 	if (rtc_read(RTC_CMD1) & DS1511_BLF1)
452 		dev_warn(&pdev->dev, "voltage-low detected.\n");
453 
454 	spin_lock_init(&pdata->lock);
455 	platform_set_drvdata(pdev, pdata);
456 
457 	pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
458 	if (IS_ERR(pdata->rtc))
459 		return PTR_ERR(pdata->rtc);
460 
461 	pdata->rtc->ops = &ds1511_rtc_ops;
462 
463 	ret = devm_rtc_register_device(pdata->rtc);
464 	if (ret)
465 		return ret;
466 
467 	devm_rtc_nvmem_register(pdata->rtc, &ds1511_nvmem_cfg);
468 
469 	/*
470 	 * if the platform has an interrupt in mind for this device,
471 	 * then by all means, set it
472 	 */
473 	if (pdata->irq > 0) {
474 		rtc_read(RTC_CMD1);
475 		if (devm_request_irq(&pdev->dev, pdata->irq, ds1511_interrupt,
476 			IRQF_SHARED, pdev->name, pdev) < 0) {
477 
478 			dev_warn(&pdev->dev, "interrupt not available.\n");
479 			pdata->irq = 0;
480 		}
481 	}
482 
483 	return 0;
484 }
485 
486 /* work with hotplug and coldplug */
487 MODULE_ALIAS("platform:ds1511");
488 
489 static struct platform_driver ds1511_rtc_driver = {
490 	.probe		= ds1511_rtc_probe,
491 	.driver		= {
492 		.name	= "ds1511",
493 	},
494 };
495 
496 module_platform_driver(ds1511_rtc_driver);
497 
498 MODULE_AUTHOR("Andrew Sharp <andy.sharp@lsi.com>");
499 MODULE_DESCRIPTION("Dallas DS1511 RTC driver");
500 MODULE_LICENSE("GPL");
501