1 /*
2 * "RTT as Real Time Clock" driver for AT91SAM9 SoC family
3 *
4 * (C) 2007 Michel Benoit
5 *
6 * Based on rtc-at91rm9200.c by Rick Bronson
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
12 */
13
14 #include <linux/module.h>
15 #include <linux/kernel.h>
16 #include <linux/platform_device.h>
17 #include <linux/time.h>
18 #include <linux/rtc.h>
19 #include <linux/interrupt.h>
20 #include <linux/ioctl.h>
21
22 #include <asm/mach/time.h>
23 #include <asm/arch/board.h>
24 #include <asm/arch/at91_rtt.h>
25
26
27 /*
28 * This driver uses two configurable hardware resources that live in the
29 * AT91SAM9 backup power domain (intended to be powered at all times)
30 * to implement the Real Time Clock interfaces
31 *
32 * - A "Real-time Timer" (RTT) counts up in seconds from a base time.
33 * We can't assign the counter value (CRTV) ... but we can reset it.
34 *
35 * - One of the "General Purpose Backup Registers" (GPBRs) holds the
36 * base time, normally an offset from the beginning of the POSIX
37 * epoch (1970-Jan-1 00:00:00 UTC). Some systems also include the
38 * local timezone's offset.
39 *
40 * The RTC's value is the RTT counter plus that offset. The RTC's alarm
41 * is likewise a base (ALMV) plus that offset.
42 *
43 * Not all RTTs will be used as RTCs; some systems have multiple RTTs to
44 * choose from, or a "real" RTC module. All systems have multiple GPBR
45 * registers available, likewise usable for more than "RTC" support.
46 */
47
48 /*
49 * We store ALARM_DISABLED in ALMV to record that no alarm is set.
50 * It's also the reset value for that field.
51 */
52 #define ALARM_DISABLED ((u32)~0)
53
54
55 struct sam9_rtc {
56 void __iomem *rtt;
57 struct rtc_device *rtcdev;
58 u32 imr;
59 };
60
61 #define rtt_readl(rtc, field) \
62 __raw_readl((rtc)->rtt + AT91_RTT_ ## field)
63 #define rtt_writel(rtc, field, val) \
64 __raw_writel((val), (rtc)->rtt + AT91_RTT_ ## field)
65
66 #define gpbr_readl(rtc) \
67 at91_sys_read(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR)
68 #define gpbr_writel(rtc, val) \
69 at91_sys_write(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR, (val))
70
71 /*
72 * Read current time and date in RTC
73 */
74 static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
75 {
76 struct sam9_rtc *rtc = dev_get_drvdata(dev);
77 u32 secs, secs2;
78 u32 offset;
79
80 /* read current time offset */
81 offset = gpbr_readl(rtc);
82 if (offset == 0)
83 return -EILSEQ;
84
85 /* reread the counter to help sync the two clock domains */
86 secs = rtt_readl(rtc, VR);
87 secs2 = rtt_readl(rtc, VR);
88 if (secs != secs2)
89 secs = rtt_readl(rtc, VR);
90
91 rtc_time_to_tm(offset + secs, tm);
92
93 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readtime",
94 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
95 tm->tm_hour, tm->tm_min, tm->tm_sec);
96
97 return 0;
98 }
99
100 /*
101 * Set current time and date in RTC
102 */
103 static int at91_rtc_settime(struct device *dev, struct rtc_time *tm)
104 {
105 struct sam9_rtc *rtc = dev_get_drvdata(dev);
106 int err;
107 u32 offset, alarm, mr;
108 unsigned long secs;
109
110 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "settime",
111 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
112 tm->tm_hour, tm->tm_min, tm->tm_sec);
113
114 err = rtc_tm_to_time(tm, &secs);
115 if (err != 0)
116 return err;
117
118 mr = rtt_readl(rtc, MR);
119
120 /* disable interrupts */
121 rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
122
123 /* read current time offset */
124 offset = gpbr_readl(rtc);
125
126 /* store the new base time in a battery backup register */
127 secs += 1;
128 gpbr_writel(rtc, secs);
129
130 /* adjust the alarm time for the new base */
131 alarm = rtt_readl(rtc, AR);
132 if (alarm != ALARM_DISABLED) {
133 if (offset > secs) {
134 /* time jumped backwards, increase time until alarm */
135 alarm += (offset - secs);
136 } else if ((alarm + offset) > secs) {
137 /* time jumped forwards, decrease time until alarm */
138 alarm -= (secs - offset);
139 } else {
140 /* time jumped past the alarm, disable alarm */
141 alarm = ALARM_DISABLED;
142 mr &= ~AT91_RTT_ALMIEN;
143 }
144 rtt_writel(rtc, AR, alarm);
145 }
146
147 /* reset the timer, and re-enable interrupts */
148 rtt_writel(rtc, MR, mr | AT91_RTT_RTTRST);
149
150 return 0;
151 }
152
153 static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
154 {
155 struct sam9_rtc *rtc = dev_get_drvdata(dev);
156 struct rtc_time *tm = &alrm->time;
157 u32 alarm = rtt_readl(rtc, AR);
158 u32 offset;
159
160 offset = gpbr_readl(rtc);
161 if (offset == 0)
162 return -EILSEQ;
163
164 memset(alrm, 0, sizeof(alrm));
165 if (alarm != ALARM_DISABLED && offset != 0) {
166 rtc_time_to_tm(offset + alarm, tm);
167
168 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readalarm",
169 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
170 tm->tm_hour, tm->tm_min, tm->tm_sec);
171
172 if (rtt_readl(rtc, MR) & AT91_RTT_ALMIEN)
173 alrm->enabled = 1;
174 }
175
176 return 0;
177 }
178
179 static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
180 {
181 struct sam9_rtc *rtc = dev_get_drvdata(dev);
182 struct rtc_time *tm = &alrm->time;
183 unsigned long secs;
184 u32 offset;
185 u32 mr;
186 int err;
187
188 err = rtc_tm_to_time(tm, &secs);
189 if (err != 0)
190 return err;
191
192 offset = gpbr_readl(rtc);
193 if (offset == 0) {
194 /* time is not set */
195 return -EILSEQ;
196 }
197 mr = rtt_readl(rtc, MR);
198 rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
199
200 /* alarm in the past? finish and leave disabled */
201 if (secs <= offset) {
202 rtt_writel(rtc, AR, ALARM_DISABLED);
203 return 0;
204 }
205
206 /* else set alarm and maybe enable it */
207 rtt_writel(rtc, AR, secs - offset);
208 if (alrm->enabled)
209 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
210
211 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "setalarm",
212 tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour,
213 tm->tm_min, tm->tm_sec);
214
215 return 0;
216 }
217
218 /*
219 * Handle commands from user-space
220 */
221 static int at91_rtc_ioctl(struct device *dev, unsigned int cmd,
222 unsigned long arg)
223 {
224 struct sam9_rtc *rtc = dev_get_drvdata(dev);
225 int ret = 0;
226 u32 mr = rtt_readl(rtc, MR);
227
228 dev_dbg(dev, "ioctl: cmd=%08x, arg=%08lx, mr %08x\n", cmd, arg, mr);
229
230 switch (cmd) {
231 case RTC_AIE_OFF: /* alarm off */
232 rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
233 break;
234 case RTC_AIE_ON: /* alarm on */
235 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
236 break;
237 case RTC_UIE_OFF: /* update off */
238 rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
239 break;
240 case RTC_UIE_ON: /* update on */
241 rtt_writel(rtc, MR, mr | AT91_RTT_RTTINCIEN);
242 break;
243 default:
244 ret = -ENOIOCTLCMD;
245 break;
246 }
247
248 return ret;
249 }
250
251 /*
252 * Provide additional RTC information in /proc/driver/rtc
253 */
254 static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
255 {
256 struct sam9_rtc *rtc = dev_get_drvdata(dev);
257 u32 mr = mr = rtt_readl(rtc, MR);
258
259 seq_printf(seq, "update_IRQ\t: %s\n",
260 (mr & AT91_RTT_RTTINCIEN) ? "yes" : "no");
261 return 0;
262 }
263
264 /*
265 * IRQ handler for the RTC
266 */
267 static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc)
268 {
269 struct sam9_rtc *rtc = _rtc;
270 u32 sr, mr;
271 unsigned long events = 0;
272
273 /* Shared interrupt may be for another device. Note: reading
274 * SR clears it, so we must only read it in this irq handler!
275 */
276 mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
277 sr = rtt_readl(rtc, SR) & (mr >> 16);
278 if (!sr)
279 return IRQ_NONE;
280
281 /* alarm status */
282 if (sr & AT91_RTT_ALMS)
283 events |= (RTC_AF | RTC_IRQF);
284
285 /* timer update/increment */
286 if (sr & AT91_RTT_RTTINC)
287 events |= (RTC_UF | RTC_IRQF);
288
289 rtc_update_irq(rtc->rtcdev, 1, events);
290
291 pr_debug("%s: num=%ld, events=0x%02lx\n", __FUNCTION__,
292 events >> 8, events & 0x000000FF);
293
294 return IRQ_HANDLED;
295 }
296
297 static const struct rtc_class_ops at91_rtc_ops = {
298 .ioctl = at91_rtc_ioctl,
299 .read_time = at91_rtc_readtime,
300 .set_time = at91_rtc_settime,
301 .read_alarm = at91_rtc_readalarm,
302 .set_alarm = at91_rtc_setalarm,
303 .proc = at91_rtc_proc,
304 };
305
306 /*
307 * Initialize and install RTC driver
308 */
309 static int __init at91_rtc_probe(struct platform_device *pdev)
310 {
311 struct resource *r;
312 struct sam9_rtc *rtc;
313 int ret;
314 u32 mr;
315
316 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
317 if (!r)
318 return -ENODEV;
319
320 rtc = kzalloc(sizeof *rtc, GFP_KERNEL);
321 if (!rtc)
322 return -ENOMEM;
323
324 /* platform setup code should have handled this; sigh */
325 if (!device_can_wakeup(&pdev->dev))
326 device_init_wakeup(&pdev->dev, 1);
327
328 platform_set_drvdata(pdev, rtc);
329 rtc->rtt = (void __force __iomem *) (AT91_VA_BASE_SYS - AT91_BASE_SYS);
330 rtc->rtt += r->start;
331
332 mr = rtt_readl(rtc, MR);
333
334 /* unless RTT is counting at 1 Hz, re-initialize it */
335 if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) {
336 mr = AT91_RTT_RTTRST | (AT91_SLOW_CLOCK & AT91_RTT_RTPRES);
337 gpbr_writel(rtc, 0);
338 }
339
340 /* disable all interrupts (same as on shutdown path) */
341 mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
342 rtt_writel(rtc, MR, mr);
343
344 rtc->rtcdev = rtc_device_register(pdev->name, &pdev->dev,
345 &at91_rtc_ops, THIS_MODULE);
346 if (IS_ERR(rtc->rtcdev)) {
347 ret = PTR_ERR(rtc->rtcdev);
348 goto fail;
349 }
350
351 /* register irq handler after we know what name we'll use */
352 ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt,
353 IRQF_DISABLED | IRQF_SHARED,
354 rtc->rtcdev->dev.bus_id, rtc);
355 if (ret) {
356 dev_dbg(&pdev->dev, "can't share IRQ %d?\n", AT91_ID_SYS);
357 rtc_device_unregister(rtc->rtcdev);
358 goto fail;
359 }
360
361 /* NOTE: sam9260 rev A silicon has a ROM bug which resets the
362 * RTT on at least some reboots. If you have that chip, you must
363 * initialize the time from some external source like a GPS, wall
364 * clock, discrete RTC, etc
365 */
366
367 if (gpbr_readl(rtc) == 0)
368 dev_warn(&pdev->dev, "%s: SET TIME!\n",
369 rtc->rtcdev->dev.bus_id);
370
371 return 0;
372
373 fail:
374 platform_set_drvdata(pdev, NULL);
375 kfree(rtc);
376 return ret;
377 }
378
379 /*
380 * Disable and remove the RTC driver
381 */
382 static int __exit at91_rtc_remove(struct platform_device *pdev)
383 {
384 struct sam9_rtc *rtc = platform_get_drvdata(pdev);
385 u32 mr = rtt_readl(rtc, MR);
386
387 /* disable all interrupts */
388 rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
389 free_irq(AT91_ID_SYS, rtc);
390
391 rtc_device_unregister(rtc->rtcdev);
392
393 platform_set_drvdata(pdev, NULL);
394 kfree(rtc);
395 return 0;
396 }
397
398 static void at91_rtc_shutdown(struct platform_device *pdev)
399 {
400 struct sam9_rtc *rtc = platform_get_drvdata(pdev);
401 u32 mr = rtt_readl(rtc, MR);
402
403 rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
404 rtt_writel(rtc, MR, mr & ~rtc->imr);
405 }
406
407 #ifdef CONFIG_PM
408
409 /* AT91SAM9 RTC Power management control */
410
411 static int at91_rtc_suspend(struct platform_device *pdev,
412 pm_message_t state)
413 {
414 struct sam9_rtc *rtc = platform_get_drvdata(pdev);
415 u32 mr = rtt_readl(rtc, MR);
416
417 /*
418 * This IRQ is shared with DBGU and other hardware which isn't
419 * necessarily a wakeup event source.
420 */
421 rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
422 if (rtc->imr) {
423 if (device_may_wakeup(&pdev->dev) && (mr & AT91_RTT_ALMIEN)) {
424 enable_irq_wake(AT91_ID_SYS);
425 /* don't let RTTINC cause wakeups */
426 if (mr & AT91_RTT_RTTINCIEN)
427 rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
428 } else
429 rtt_writel(rtc, MR, mr & ~rtc->imr);
430 }
431
432 return 0;
433 }
434
435 static int at91_rtc_resume(struct platform_device *pdev)
436 {
437 struct sam9_rtc *rtc = platform_get_drvdata(pdev);
438 u32 mr;
439
440 if (rtc->imr) {
441 if (device_may_wakeup(&pdev->dev))
442 disable_irq_wake(AT91_ID_SYS);
443 mr = rtt_readl(rtc, MR);
444 rtt_writel(rtc, MR, mr | rtc->imr);
445 }
446
447 return 0;
448 }
449 #else
450 #define at91_rtc_suspend NULL
451 #define at91_rtc_resume NULL
452 #endif
453
454 static struct platform_driver at91_rtc_driver = {
455 .driver.name = "rtc-at91sam9",
456 .driver.owner = THIS_MODULE,
457 .remove = __exit_p(at91_rtc_remove),
458 .shutdown = at91_rtc_shutdown,
459 .suspend = at91_rtc_suspend,
460 .resume = at91_rtc_resume,
461 };
462
463 /* Chips can have more than one RTT module, and they can be used for more
464 * than just RTCs. So we can't just register as "the" RTT driver.
465 *
466 * A normal approach in such cases is to create a library to allocate and
467 * free the modules. Here we just use bus_find_device() as like such a
468 * library, binding directly ... no runtime "library" footprint is needed.
469 */
470 static int __init at91_rtc_match(struct device *dev, void *v)
471 {
472 struct platform_device *pdev = to_platform_device(dev);
473 int ret;
474
475 /* continue searching if this isn't the RTT we need */
476 if (strcmp("at91_rtt", pdev->name) != 0
477 || pdev->id != CONFIG_RTC_DRV_AT91SAM9_RTT)
478 goto fail;
479
480 /* else we found it ... but fail unless we can bind to the RTC driver */
481 if (dev->driver) {
482 dev_dbg(dev, "busy, can't use as RTC!\n");
483 goto fail;
484 }
485 dev->driver = &at91_rtc_driver.driver;
486 if (device_attach(dev) == 0) {
487 dev_dbg(dev, "can't attach RTC!\n");
488 goto fail;
489 }
490 ret = at91_rtc_probe(pdev);
491 if (ret == 0)
492 return true;
493
494 dev_dbg(dev, "RTC probe err %d!\n", ret);
495 fail:
496 return false;
497 }
498
499 static int __init at91_rtc_init(void)
500 {
501 int status;
502 struct device *rtc;
503
504 status = platform_driver_register(&at91_rtc_driver);
505 if (status)
506 return status;
507 rtc = bus_find_device(&platform_bus_type, NULL,
508 NULL, at91_rtc_match);
509 if (!rtc)
510 platform_driver_unregister(&at91_rtc_driver);
511 return rtc ? 0 : -ENODEV;
512 }
513 module_init(at91_rtc_init);
514
515 static void __exit at91_rtc_exit(void)
516 {
517 platform_driver_unregister(&at91_rtc_driver);
518 }
519 module_exit(at91_rtc_exit);
520
521
522 MODULE_AUTHOR("Michel Benoit");
523 MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x");
524 MODULE_LICENSE("GPL");
525
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