1 /*
2  * An rtc driver for the Dallas DS1511
3  *
4  * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
5  * Copyright (C) 2007 Andrew Sharp <andy.sharp@lsi.com>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  * Real time clock driver for the Dallas 1511 chip, which also
12  * contains a watchdog timer.  There is a tiny amount of code that
13  * platform code could use to mess with the watchdog device a little
14  * bit, but not a full watchdog driver.
15  */
16 
17 #include <linux/bcd.h>
18 #include <linux/init.h>
19 #include <linux/kernel.h>
20 #include <linux/gfp.h>
21 #include <linux/delay.h>
22 #include <linux/interrupt.h>
23 #include <linux/rtc.h>
24 #include <linux/platform_device.h>
25 #include <linux/io.h>
26 #include <linux/module.h>
27 
28 enum ds1511reg {
29 	DS1511_SEC = 0x0,
30 	DS1511_MIN = 0x1,
31 	DS1511_HOUR = 0x2,
32 	DS1511_DOW = 0x3,
33 	DS1511_DOM = 0x4,
34 	DS1511_MONTH = 0x5,
35 	DS1511_YEAR = 0x6,
36 	DS1511_CENTURY = 0x7,
37 	DS1511_AM1_SEC = 0x8,
38 	DS1511_AM2_MIN = 0x9,
39 	DS1511_AM3_HOUR = 0xa,
40 	DS1511_AM4_DATE = 0xb,
41 	DS1511_WD_MSEC = 0xc,
42 	DS1511_WD_SEC = 0xd,
43 	DS1511_CONTROL_A = 0xe,
44 	DS1511_CONTROL_B = 0xf,
45 	DS1511_RAMADDR_LSB = 0x10,
46 	DS1511_RAMDATA = 0x13
47 };
48 
49 #define DS1511_BLF1	0x80
50 #define DS1511_BLF2	0x40
51 #define DS1511_PRS	0x20
52 #define DS1511_PAB	0x10
53 #define DS1511_TDF	0x08
54 #define DS1511_KSF	0x04
55 #define DS1511_WDF	0x02
56 #define DS1511_IRQF	0x01
57 #define DS1511_TE	0x80
58 #define DS1511_CS	0x40
59 #define DS1511_BME	0x20
60 #define DS1511_TPE	0x10
61 #define DS1511_TIE	0x08
62 #define DS1511_KIE	0x04
63 #define DS1511_WDE	0x02
64 #define DS1511_WDS	0x01
65 #define DS1511_RAM_MAX	0x100
66 
67 #define RTC_CMD		DS1511_CONTROL_B
68 #define RTC_CMD1	DS1511_CONTROL_A
69 
70 #define RTC_ALARM_SEC	DS1511_AM1_SEC
71 #define RTC_ALARM_MIN	DS1511_AM2_MIN
72 #define RTC_ALARM_HOUR	DS1511_AM3_HOUR
73 #define RTC_ALARM_DATE	DS1511_AM4_DATE
74 
75 #define RTC_SEC		DS1511_SEC
76 #define RTC_MIN		DS1511_MIN
77 #define RTC_HOUR	DS1511_HOUR
78 #define RTC_DOW		DS1511_DOW
79 #define RTC_DOM		DS1511_DOM
80 #define RTC_MON		DS1511_MONTH
81 #define RTC_YEAR	DS1511_YEAR
82 #define RTC_CENTURY	DS1511_CENTURY
83 
84 #define RTC_TIE	DS1511_TIE
85 #define RTC_TE	DS1511_TE
86 
87 struct rtc_plat_data {
88 	struct rtc_device *rtc;
89 	void __iomem *ioaddr;		/* virtual base address */
90 	int irq;
91 	unsigned int irqen;
92 	int alrm_sec;
93 	int alrm_min;
94 	int alrm_hour;
95 	int alrm_mday;
96 	spinlock_t lock;
97 };
98 
99 static DEFINE_SPINLOCK(ds1511_lock);
100 
101 static __iomem char *ds1511_base;
102 static u32 reg_spacing = 1;
103 
104 static noinline void
rtc_write(uint8_t val,uint32_t reg)105 rtc_write(uint8_t val, uint32_t reg)
106 {
107 	writeb(val, ds1511_base + (reg * reg_spacing));
108 }
109 
110 static inline void
rtc_write_alarm(uint8_t val,enum ds1511reg reg)111 rtc_write_alarm(uint8_t val, enum ds1511reg reg)
112 {
113 	rtc_write((val | 0x80), reg);
114 }
115 
116 static noinline uint8_t
rtc_read(enum ds1511reg reg)117 rtc_read(enum ds1511reg reg)
118 {
119 	return readb(ds1511_base + (reg * reg_spacing));
120 }
121 
122 static inline void
rtc_disable_update(void)123 rtc_disable_update(void)
124 {
125 	rtc_write((rtc_read(RTC_CMD) & ~RTC_TE), RTC_CMD);
126 }
127 
128 static void
rtc_enable_update(void)129 rtc_enable_update(void)
130 {
131 	rtc_write((rtc_read(RTC_CMD) | RTC_TE), RTC_CMD);
132 }
133 
134 /*
135  * #define DS1511_WDOG_RESET_SUPPORT
136  *
137  * Uncomment this if you want to use these routines in
138  * some platform code.
139  */
140 #ifdef DS1511_WDOG_RESET_SUPPORT
141 /*
142  * just enough code to set the watchdog timer so that it
143  * will reboot the system
144  */
145 void
ds1511_wdog_set(unsigned long deciseconds)146 ds1511_wdog_set(unsigned long deciseconds)
147 {
148 	/*
149 	 * the wdog timer can take 99.99 seconds
150 	 */
151 	deciseconds %= 10000;
152 	/*
153 	 * set the wdog values in the wdog registers
154 	 */
155 	rtc_write(bin2bcd(deciseconds % 100), DS1511_WD_MSEC);
156 	rtc_write(bin2bcd(deciseconds / 100), DS1511_WD_SEC);
157 	/*
158 	 * set wdog enable and wdog 'steering' bit to issue a reset
159 	 */
160 	rtc_write(rtc_read(RTC_CMD) | DS1511_WDE | DS1511_WDS, RTC_CMD);
161 }
162 
163 void
ds1511_wdog_disable(void)164 ds1511_wdog_disable(void)
165 {
166 	/*
167 	 * clear wdog enable and wdog 'steering' bits
168 	 */
169 	rtc_write(rtc_read(RTC_CMD) & ~(DS1511_WDE | DS1511_WDS), RTC_CMD);
170 	/*
171 	 * clear the wdog counter
172 	 */
173 	rtc_write(0, DS1511_WD_MSEC);
174 	rtc_write(0, DS1511_WD_SEC);
175 }
176 #endif
177 
178 /*
179  * set the rtc chip's idea of the time.
180  * stupidly, some callers call with year unmolested;
181  * and some call with  year = year - 1900.  thanks.
182  */
ds1511_rtc_set_time(struct device * dev,struct rtc_time * rtc_tm)183 static int ds1511_rtc_set_time(struct device *dev, struct rtc_time *rtc_tm)
184 {
185 	u8 mon, day, dow, hrs, min, sec, yrs, cen;
186 	unsigned long flags;
187 
188 	/*
189 	 * won't have to change this for a while
190 	 */
191 	if (rtc_tm->tm_year < 1900)
192 		rtc_tm->tm_year += 1900;
193 
194 	if (rtc_tm->tm_year < 1970)
195 		return -EINVAL;
196 
197 	yrs = rtc_tm->tm_year % 100;
198 	cen = rtc_tm->tm_year / 100;
199 	mon = rtc_tm->tm_mon + 1;   /* tm_mon starts at zero */
200 	day = rtc_tm->tm_mday;
201 	dow = rtc_tm->tm_wday & 0x7; /* automatic BCD */
202 	hrs = rtc_tm->tm_hour;
203 	min = rtc_tm->tm_min;
204 	sec = rtc_tm->tm_sec;
205 
206 	if ((mon > 12) || (day == 0))
207 		return -EINVAL;
208 
209 	if (day > rtc_month_days(rtc_tm->tm_mon, rtc_tm->tm_year))
210 		return -EINVAL;
211 
212 	if ((hrs >= 24) || (min >= 60) || (sec >= 60))
213 		return -EINVAL;
214 
215 	/*
216 	 * each register is a different number of valid bits
217 	 */
218 	sec = bin2bcd(sec) & 0x7f;
219 	min = bin2bcd(min) & 0x7f;
220 	hrs = bin2bcd(hrs) & 0x3f;
221 	day = bin2bcd(day) & 0x3f;
222 	mon = bin2bcd(mon) & 0x1f;
223 	yrs = bin2bcd(yrs) & 0xff;
224 	cen = bin2bcd(cen) & 0xff;
225 
226 	spin_lock_irqsave(&ds1511_lock, flags);
227 	rtc_disable_update();
228 	rtc_write(cen, RTC_CENTURY);
229 	rtc_write(yrs, RTC_YEAR);
230 	rtc_write((rtc_read(RTC_MON) & 0xe0) | mon, RTC_MON);
231 	rtc_write(day, RTC_DOM);
232 	rtc_write(hrs, RTC_HOUR);
233 	rtc_write(min, RTC_MIN);
234 	rtc_write(sec, RTC_SEC);
235 	rtc_write(dow, RTC_DOW);
236 	rtc_enable_update();
237 	spin_unlock_irqrestore(&ds1511_lock, flags);
238 
239 	return 0;
240 }
241 
ds1511_rtc_read_time(struct device * dev,struct rtc_time * rtc_tm)242 static int ds1511_rtc_read_time(struct device *dev, struct rtc_time *rtc_tm)
243 {
244 	unsigned int century;
245 	unsigned long flags;
246 
247 	spin_lock_irqsave(&ds1511_lock, flags);
248 	rtc_disable_update();
249 
250 	rtc_tm->tm_sec = rtc_read(RTC_SEC) & 0x7f;
251 	rtc_tm->tm_min = rtc_read(RTC_MIN) & 0x7f;
252 	rtc_tm->tm_hour = rtc_read(RTC_HOUR) & 0x3f;
253 	rtc_tm->tm_mday = rtc_read(RTC_DOM) & 0x3f;
254 	rtc_tm->tm_wday = rtc_read(RTC_DOW) & 0x7;
255 	rtc_tm->tm_mon = rtc_read(RTC_MON) & 0x1f;
256 	rtc_tm->tm_year = rtc_read(RTC_YEAR) & 0x7f;
257 	century = rtc_read(RTC_CENTURY);
258 
259 	rtc_enable_update();
260 	spin_unlock_irqrestore(&ds1511_lock, flags);
261 
262 	rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
263 	rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
264 	rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
265 	rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
266 	rtc_tm->tm_wday = bcd2bin(rtc_tm->tm_wday);
267 	rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
268 	rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
269 	century = bcd2bin(century) * 100;
270 
271 	/*
272 	 * Account for differences between how the RTC uses the values
273 	 * and how they are defined in a struct rtc_time;
274 	 */
275 	century += rtc_tm->tm_year;
276 	rtc_tm->tm_year = century - 1900;
277 
278 	rtc_tm->tm_mon--;
279 
280 	return 0;
281 }
282 
283 /*
284  * write the alarm register settings
285  *
286  * we only have the use to interrupt every second, otherwise
287  * known as the update interrupt, or the interrupt if the whole
288  * date/hours/mins/secs matches.  the ds1511 has many more
289  * permutations, but the kernel doesn't.
290  */
291 static void
ds1511_rtc_update_alarm(struct rtc_plat_data * pdata)292 ds1511_rtc_update_alarm(struct rtc_plat_data *pdata)
293 {
294 	unsigned long flags;
295 
296 	spin_lock_irqsave(&pdata->lock, flags);
297 	rtc_write(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
298 	       0x80 : bin2bcd(pdata->alrm_mday) & 0x3f,
299 	       RTC_ALARM_DATE);
300 	rtc_write(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
301 	       0x80 : bin2bcd(pdata->alrm_hour) & 0x3f,
302 	       RTC_ALARM_HOUR);
303 	rtc_write(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
304 	       0x80 : bin2bcd(pdata->alrm_min) & 0x7f,
305 	       RTC_ALARM_MIN);
306 	rtc_write(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
307 	       0x80 : bin2bcd(pdata->alrm_sec) & 0x7f,
308 	       RTC_ALARM_SEC);
309 	rtc_write(rtc_read(RTC_CMD) | (pdata->irqen ? RTC_TIE : 0), RTC_CMD);
310 	rtc_read(RTC_CMD1);	/* clear interrupts */
311 	spin_unlock_irqrestore(&pdata->lock, flags);
312 }
313 
314 static int
ds1511_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alrm)315 ds1511_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
316 {
317 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
318 
319 	if (pdata->irq <= 0)
320 		return -EINVAL;
321 
322 	pdata->alrm_mday = alrm->time.tm_mday;
323 	pdata->alrm_hour = alrm->time.tm_hour;
324 	pdata->alrm_min = alrm->time.tm_min;
325 	pdata->alrm_sec = alrm->time.tm_sec;
326 	if (alrm->enabled)
327 		pdata->irqen |= RTC_AF;
328 
329 	ds1511_rtc_update_alarm(pdata);
330 	return 0;
331 }
332 
333 static int
ds1511_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alrm)334 ds1511_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
335 {
336 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
337 
338 	if (pdata->irq <= 0)
339 		return -EINVAL;
340 
341 	alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
342 	alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
343 	alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
344 	alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
345 	alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
346 	return 0;
347 }
348 
349 static irqreturn_t
ds1511_interrupt(int irq,void * dev_id)350 ds1511_interrupt(int irq, void *dev_id)
351 {
352 	struct platform_device *pdev = dev_id;
353 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
354 	unsigned long events = 0;
355 
356 	spin_lock(&pdata->lock);
357 	/*
358 	 * read and clear interrupt
359 	 */
360 	if (rtc_read(RTC_CMD1) & DS1511_IRQF) {
361 		events = RTC_IRQF;
362 		if (rtc_read(RTC_ALARM_SEC) & 0x80)
363 			events |= RTC_UF;
364 		else
365 			events |= RTC_AF;
366 		rtc_update_irq(pdata->rtc, 1, events);
367 	}
368 	spin_unlock(&pdata->lock);
369 	return events ? IRQ_HANDLED : IRQ_NONE;
370 }
371 
ds1511_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)372 static int ds1511_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
373 {
374 	struct rtc_plat_data *pdata = dev_get_drvdata(dev);
375 
376 	if (pdata->irq <= 0)
377 		return -EINVAL;
378 	if (enabled)
379 		pdata->irqen |= RTC_AF;
380 	else
381 		pdata->irqen &= ~RTC_AF;
382 	ds1511_rtc_update_alarm(pdata);
383 	return 0;
384 }
385 
386 static const struct rtc_class_ops ds1511_rtc_ops = {
387 	.read_time		= ds1511_rtc_read_time,
388 	.set_time		= ds1511_rtc_set_time,
389 	.read_alarm		= ds1511_rtc_read_alarm,
390 	.set_alarm		= ds1511_rtc_set_alarm,
391 	.alarm_irq_enable	= ds1511_rtc_alarm_irq_enable,
392 };
393 
ds1511_nvram_read(void * priv,unsigned int pos,void * buf,size_t size)394 static int ds1511_nvram_read(void *priv, unsigned int pos, void *buf,
395 			     size_t size)
396 {
397 	int i;
398 
399 	rtc_write(pos, DS1511_RAMADDR_LSB);
400 	for (i = 0; i < size; i++)
401 		*(char *)buf++ = rtc_read(DS1511_RAMDATA);
402 
403 	return 0;
404 }
405 
ds1511_nvram_write(void * priv,unsigned int pos,void * buf,size_t size)406 static int ds1511_nvram_write(void *priv, unsigned int pos, void *buf,
407 			      size_t size)
408 {
409 	int i;
410 
411 	rtc_write(pos, DS1511_RAMADDR_LSB);
412 	for (i = 0; i < size; i++)
413 		rtc_write(*(char *)buf++, DS1511_RAMDATA);
414 
415 	return 0;
416 }
417 
ds1511_rtc_probe(struct platform_device * pdev)418 static int ds1511_rtc_probe(struct platform_device *pdev)
419 {
420 	struct resource *res;
421 	struct rtc_plat_data *pdata;
422 	int ret = 0;
423 	struct nvmem_config ds1511_nvmem_cfg = {
424 		.name = "ds1511_nvram",
425 		.word_size = 1,
426 		.stride = 1,
427 		.size = DS1511_RAM_MAX,
428 		.reg_read = ds1511_nvram_read,
429 		.reg_write = ds1511_nvram_write,
430 		.priv = &pdev->dev,
431 	};
432 
433 	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
434 	if (!pdata)
435 		return -ENOMEM;
436 
437 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
438 	ds1511_base = devm_ioremap_resource(&pdev->dev, res);
439 	if (IS_ERR(ds1511_base))
440 		return PTR_ERR(ds1511_base);
441 	pdata->ioaddr = ds1511_base;
442 	pdata->irq = platform_get_irq(pdev, 0);
443 
444 	/*
445 	 * turn on the clock and the crystal, etc.
446 	 */
447 	rtc_write(DS1511_BME, RTC_CMD);
448 	rtc_write(0, RTC_CMD1);
449 	/*
450 	 * clear the wdog counter
451 	 */
452 	rtc_write(0, DS1511_WD_MSEC);
453 	rtc_write(0, DS1511_WD_SEC);
454 	/*
455 	 * start the clock
456 	 */
457 	rtc_enable_update();
458 
459 	/*
460 	 * check for a dying bat-tree
461 	 */
462 	if (rtc_read(RTC_CMD1) & DS1511_BLF1)
463 		dev_warn(&pdev->dev, "voltage-low detected.\n");
464 
465 	spin_lock_init(&pdata->lock);
466 	platform_set_drvdata(pdev, pdata);
467 
468 	pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
469 	if (IS_ERR(pdata->rtc))
470 		return PTR_ERR(pdata->rtc);
471 
472 	pdata->rtc->ops = &ds1511_rtc_ops;
473 
474 	pdata->rtc->nvram_old_abi = true;
475 
476 	ret = rtc_register_device(pdata->rtc);
477 	if (ret)
478 		return ret;
479 
480 	rtc_nvmem_register(pdata->rtc, &ds1511_nvmem_cfg);
481 
482 	/*
483 	 * if the platform has an interrupt in mind for this device,
484 	 * then by all means, set it
485 	 */
486 	if (pdata->irq > 0) {
487 		rtc_read(RTC_CMD1);
488 		if (devm_request_irq(&pdev->dev, pdata->irq, ds1511_interrupt,
489 			IRQF_SHARED, pdev->name, pdev) < 0) {
490 
491 			dev_warn(&pdev->dev, "interrupt not available.\n");
492 			pdata->irq = 0;
493 		}
494 	}
495 
496 	return 0;
497 }
498 
499 /* work with hotplug and coldplug */
500 MODULE_ALIAS("platform:ds1511");
501 
502 static struct platform_driver ds1511_rtc_driver = {
503 	.probe		= ds1511_rtc_probe,
504 	.driver		= {
505 		.name	= "ds1511",
506 	},
507 };
508 
509 module_platform_driver(ds1511_rtc_driver);
510 
511 MODULE_AUTHOR("Andrew Sharp <andy.sharp@lsi.com>");
512 MODULE_DESCRIPTION("Dallas DS1511 RTC driver");
513 MODULE_LICENSE("GPL");
514