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 inline void
rtc_write_alarm(uint8_t val,enum ds1511reg reg)108 rtc_write_alarm(uint8_t val, enum ds1511reg reg)
109 {
110 rtc_write((val | 0x80), reg);
111 }
112
113 static noinline uint8_t
rtc_read(enum ds1511reg reg)114 rtc_read(enum ds1511reg reg)
115 {
116 return readb(ds1511_base + (reg * reg_spacing));
117 }
118
119 static inline void
rtc_disable_update(void)120 rtc_disable_update(void)
121 {
122 rtc_write((rtc_read(RTC_CMD) & ~RTC_TE), RTC_CMD);
123 }
124
125 static void
rtc_enable_update(void)126 rtc_enable_update(void)
127 {
128 rtc_write((rtc_read(RTC_CMD) | RTC_TE), RTC_CMD);
129 }
130
131 /*
132 * #define DS1511_WDOG_RESET_SUPPORT
133 *
134 * Uncomment this if you want to use these routines in
135 * some platform code.
136 */
137 #ifdef DS1511_WDOG_RESET_SUPPORT
138 /*
139 * just enough code to set the watchdog timer so that it
140 * will reboot the system
141 */
142 void
ds1511_wdog_set(unsigned long deciseconds)143 ds1511_wdog_set(unsigned long deciseconds)
144 {
145 /*
146 * the wdog timer can take 99.99 seconds
147 */
148 deciseconds %= 10000;
149 /*
150 * set the wdog values in the wdog registers
151 */
152 rtc_write(bin2bcd(deciseconds % 100), DS1511_WD_MSEC);
153 rtc_write(bin2bcd(deciseconds / 100), DS1511_WD_SEC);
154 /*
155 * set wdog enable and wdog 'steering' bit to issue a reset
156 */
157 rtc_write(rtc_read(RTC_CMD) | DS1511_WDE | DS1511_WDS, RTC_CMD);
158 }
159
160 void
ds1511_wdog_disable(void)161 ds1511_wdog_disable(void)
162 {
163 /*
164 * clear wdog enable and wdog 'steering' bits
165 */
166 rtc_write(rtc_read(RTC_CMD) & ~(DS1511_WDE | DS1511_WDS), RTC_CMD);
167 /*
168 * clear the wdog counter
169 */
170 rtc_write(0, DS1511_WD_MSEC);
171 rtc_write(0, DS1511_WD_SEC);
172 }
173 #endif
174
175 /*
176 * set the rtc chip's idea of the time.
177 * stupidly, some callers call with year unmolested;
178 * and some call with year = year - 1900. thanks.
179 */
ds1511_rtc_set_time(struct device * dev,struct rtc_time * rtc_tm)180 static int ds1511_rtc_set_time(struct device *dev, struct rtc_time *rtc_tm)
181 {
182 u8 mon, day, dow, hrs, min, sec, yrs, cen;
183 unsigned long flags;
184
185 /*
186 * won't have to change this for a while
187 */
188 if (rtc_tm->tm_year < 1900)
189 rtc_tm->tm_year += 1900;
190
191 if (rtc_tm->tm_year < 1970)
192 return -EINVAL;
193
194 yrs = rtc_tm->tm_year % 100;
195 cen = rtc_tm->tm_year / 100;
196 mon = rtc_tm->tm_mon + 1; /* tm_mon starts at zero */
197 day = rtc_tm->tm_mday;
198 dow = rtc_tm->tm_wday & 0x7; /* automatic BCD */
199 hrs = rtc_tm->tm_hour;
200 min = rtc_tm->tm_min;
201 sec = rtc_tm->tm_sec;
202
203 if ((mon > 12) || (day == 0))
204 return -EINVAL;
205
206 if (day > rtc_month_days(rtc_tm->tm_mon, rtc_tm->tm_year))
207 return -EINVAL;
208
209 if ((hrs >= 24) || (min >= 60) || (sec >= 60))
210 return -EINVAL;
211
212 /*
213 * each register is a different number of valid bits
214 */
215 sec = bin2bcd(sec) & 0x7f;
216 min = bin2bcd(min) & 0x7f;
217 hrs = bin2bcd(hrs) & 0x3f;
218 day = bin2bcd(day) & 0x3f;
219 mon = bin2bcd(mon) & 0x1f;
220 yrs = bin2bcd(yrs) & 0xff;
221 cen = bin2bcd(cen) & 0xff;
222
223 spin_lock_irqsave(&ds1511_lock, flags);
224 rtc_disable_update();
225 rtc_write(cen, RTC_CENTURY);
226 rtc_write(yrs, RTC_YEAR);
227 rtc_write((rtc_read(RTC_MON) & 0xe0) | mon, RTC_MON);
228 rtc_write(day, RTC_DOM);
229 rtc_write(hrs, RTC_HOUR);
230 rtc_write(min, RTC_MIN);
231 rtc_write(sec, RTC_SEC);
232 rtc_write(dow, RTC_DOW);
233 rtc_enable_update();
234 spin_unlock_irqrestore(&ds1511_lock, flags);
235
236 return 0;
237 }
238
ds1511_rtc_read_time(struct device * dev,struct rtc_time * rtc_tm)239 static int ds1511_rtc_read_time(struct device *dev, struct rtc_time *rtc_tm)
240 {
241 unsigned int century;
242 unsigned long flags;
243
244 spin_lock_irqsave(&ds1511_lock, flags);
245 rtc_disable_update();
246
247 rtc_tm->tm_sec = rtc_read(RTC_SEC) & 0x7f;
248 rtc_tm->tm_min = rtc_read(RTC_MIN) & 0x7f;
249 rtc_tm->tm_hour = rtc_read(RTC_HOUR) & 0x3f;
250 rtc_tm->tm_mday = rtc_read(RTC_DOM) & 0x3f;
251 rtc_tm->tm_wday = rtc_read(RTC_DOW) & 0x7;
252 rtc_tm->tm_mon = rtc_read(RTC_MON) & 0x1f;
253 rtc_tm->tm_year = rtc_read(RTC_YEAR) & 0x7f;
254 century = rtc_read(RTC_CENTURY);
255
256 rtc_enable_update();
257 spin_unlock_irqrestore(&ds1511_lock, flags);
258
259 rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
260 rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
261 rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
262 rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
263 rtc_tm->tm_wday = bcd2bin(rtc_tm->tm_wday);
264 rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
265 rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
266 century = bcd2bin(century) * 100;
267
268 /*
269 * Account for differences between how the RTC uses the values
270 * and how they are defined in a struct rtc_time;
271 */
272 century += rtc_tm->tm_year;
273 rtc_tm->tm_year = century - 1900;
274
275 rtc_tm->tm_mon--;
276
277 return 0;
278 }
279
280 /*
281 * write the alarm register settings
282 *
283 * we only have the use to interrupt every second, otherwise
284 * known as the update interrupt, or the interrupt if the whole
285 * date/hours/mins/secs matches. the ds1511 has many more
286 * permutations, but the kernel doesn't.
287 */
288 static void
ds1511_rtc_update_alarm(struct rtc_plat_data * pdata)289 ds1511_rtc_update_alarm(struct rtc_plat_data *pdata)
290 {
291 unsigned long flags;
292
293 spin_lock_irqsave(&pdata->lock, flags);
294 rtc_write(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
295 0x80 : bin2bcd(pdata->alrm_mday) & 0x3f,
296 RTC_ALARM_DATE);
297 rtc_write(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
298 0x80 : bin2bcd(pdata->alrm_hour) & 0x3f,
299 RTC_ALARM_HOUR);
300 rtc_write(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
301 0x80 : bin2bcd(pdata->alrm_min) & 0x7f,
302 RTC_ALARM_MIN);
303 rtc_write(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
304 0x80 : bin2bcd(pdata->alrm_sec) & 0x7f,
305 RTC_ALARM_SEC);
306 rtc_write(rtc_read(RTC_CMD) | (pdata->irqen ? RTC_TIE : 0), RTC_CMD);
307 rtc_read(RTC_CMD1); /* clear interrupts */
308 spin_unlock_irqrestore(&pdata->lock, flags);
309 }
310
311 static int
ds1511_rtc_set_alarm(struct device * dev,struct rtc_wkalrm * alrm)312 ds1511_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
313 {
314 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
315
316 if (pdata->irq <= 0)
317 return -EINVAL;
318
319 pdata->alrm_mday = alrm->time.tm_mday;
320 pdata->alrm_hour = alrm->time.tm_hour;
321 pdata->alrm_min = alrm->time.tm_min;
322 pdata->alrm_sec = alrm->time.tm_sec;
323 if (alrm->enabled)
324 pdata->irqen |= RTC_AF;
325
326 ds1511_rtc_update_alarm(pdata);
327 return 0;
328 }
329
330 static int
ds1511_rtc_read_alarm(struct device * dev,struct rtc_wkalrm * alrm)331 ds1511_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
332 {
333 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
334
335 if (pdata->irq <= 0)
336 return -EINVAL;
337
338 alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
339 alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
340 alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
341 alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
342 alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
343 return 0;
344 }
345
346 static irqreturn_t
ds1511_interrupt(int irq,void * dev_id)347 ds1511_interrupt(int irq, void *dev_id)
348 {
349 struct platform_device *pdev = dev_id;
350 struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
351 unsigned long events = 0;
352
353 spin_lock(&pdata->lock);
354 /*
355 * read and clear interrupt
356 */
357 if (rtc_read(RTC_CMD1) & DS1511_IRQF) {
358 events = RTC_IRQF;
359 if (rtc_read(RTC_ALARM_SEC) & 0x80)
360 events |= RTC_UF;
361 else
362 events |= RTC_AF;
363 rtc_update_irq(pdata->rtc, 1, events);
364 }
365 spin_unlock(&pdata->lock);
366 return events ? IRQ_HANDLED : IRQ_NONE;
367 }
368
ds1511_rtc_alarm_irq_enable(struct device * dev,unsigned int enabled)369 static int ds1511_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
370 {
371 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
372
373 if (pdata->irq <= 0)
374 return -EINVAL;
375 if (enabled)
376 pdata->irqen |= RTC_AF;
377 else
378 pdata->irqen &= ~RTC_AF;
379 ds1511_rtc_update_alarm(pdata);
380 return 0;
381 }
382
383 static const struct rtc_class_ops ds1511_rtc_ops = {
384 .read_time = ds1511_rtc_read_time,
385 .set_time = ds1511_rtc_set_time,
386 .read_alarm = ds1511_rtc_read_alarm,
387 .set_alarm = ds1511_rtc_set_alarm,
388 .alarm_irq_enable = ds1511_rtc_alarm_irq_enable,
389 };
390
ds1511_nvram_read(void * priv,unsigned int pos,void * buf,size_t size)391 static int ds1511_nvram_read(void *priv, unsigned int pos, void *buf,
392 size_t size)
393 {
394 int i;
395
396 rtc_write(pos, DS1511_RAMADDR_LSB);
397 for (i = 0; i < size; i++)
398 *(char *)buf++ = rtc_read(DS1511_RAMDATA);
399
400 return 0;
401 }
402
ds1511_nvram_write(void * priv,unsigned int pos,void * buf,size_t size)403 static int ds1511_nvram_write(void *priv, unsigned int pos, void *buf,
404 size_t size)
405 {
406 int i;
407
408 rtc_write(pos, DS1511_RAMADDR_LSB);
409 for (i = 0; i < size; i++)
410 rtc_write(*(char *)buf++, DS1511_RAMDATA);
411
412 return 0;
413 }
414
ds1511_rtc_probe(struct platform_device * pdev)415 static int ds1511_rtc_probe(struct platform_device *pdev)
416 {
417 struct resource *res;
418 struct rtc_plat_data *pdata;
419 int ret = 0;
420 struct nvmem_config ds1511_nvmem_cfg = {
421 .name = "ds1511_nvram",
422 .word_size = 1,
423 .stride = 1,
424 .size = DS1511_RAM_MAX,
425 .reg_read = ds1511_nvram_read,
426 .reg_write = ds1511_nvram_write,
427 .priv = &pdev->dev,
428 };
429
430 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
431 if (!pdata)
432 return -ENOMEM;
433
434 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
435 ds1511_base = devm_ioremap_resource(&pdev->dev, res);
436 if (IS_ERR(ds1511_base))
437 return PTR_ERR(ds1511_base);
438 pdata->ioaddr = ds1511_base;
439 pdata->irq = platform_get_irq(pdev, 0);
440
441 /*
442 * turn on the clock and the crystal, etc.
443 */
444 rtc_write(DS1511_BME, RTC_CMD);
445 rtc_write(0, RTC_CMD1);
446 /*
447 * clear the wdog counter
448 */
449 rtc_write(0, DS1511_WD_MSEC);
450 rtc_write(0, DS1511_WD_SEC);
451 /*
452 * start the clock
453 */
454 rtc_enable_update();
455
456 /*
457 * check for a dying bat-tree
458 */
459 if (rtc_read(RTC_CMD1) & DS1511_BLF1)
460 dev_warn(&pdev->dev, "voltage-low detected.\n");
461
462 spin_lock_init(&pdata->lock);
463 platform_set_drvdata(pdev, pdata);
464
465 pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
466 if (IS_ERR(pdata->rtc))
467 return PTR_ERR(pdata->rtc);
468
469 pdata->rtc->ops = &ds1511_rtc_ops;
470
471 pdata->rtc->nvram_old_abi = true;
472
473 ret = rtc_register_device(pdata->rtc);
474 if (ret)
475 return ret;
476
477 rtc_nvmem_register(pdata->rtc, &ds1511_nvmem_cfg);
478
479 /*
480 * if the platform has an interrupt in mind for this device,
481 * then by all means, set it
482 */
483 if (pdata->irq > 0) {
484 rtc_read(RTC_CMD1);
485 if (devm_request_irq(&pdev->dev, pdata->irq, ds1511_interrupt,
486 IRQF_SHARED, pdev->name, pdev) < 0) {
487
488 dev_warn(&pdev->dev, "interrupt not available.\n");
489 pdata->irq = 0;
490 }
491 }
492
493 return 0;
494 }
495
496 /* work with hotplug and coldplug */
497 MODULE_ALIAS("platform:ds1511");
498
499 static struct platform_driver ds1511_rtc_driver = {
500 .probe = ds1511_rtc_probe,
501 .driver = {
502 .name = "ds1511",
503 },
504 };
505
506 module_platform_driver(ds1511_rtc_driver);
507
508 MODULE_AUTHOR("Andrew Sharp <andy.sharp@lsi.com>");
509 MODULE_DESCRIPTION("Dallas DS1511 RTC driver");
510 MODULE_LICENSE("GPL");
511