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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 | #include <linux/slab.h> |
22 | |
23 | #include <mach/board.h> |
24 | #include <mach/at91_rtt.h> |
25 | #include <mach/cpu.h> |
26 | |
27 | |
28 | /* |
29 | * This driver uses two configurable hardware resources that live in the |
30 | * AT91SAM9 backup power domain (intended to be powered at all times) |
31 | * to implement the Real Time Clock interfaces |
32 | * |
33 | * - A "Real-time Timer" (RTT) counts up in seconds from a base time. |
34 | * We can't assign the counter value (CRTV) ... but we can reset it. |
35 | * |
36 | * - One of the "General Purpose Backup Registers" (GPBRs) holds the |
37 | * base time, normally an offset from the beginning of the POSIX |
38 | * epoch (1970-Jan-1 00:00:00 UTC). Some systems also include the |
39 | * local timezone's offset. |
40 | * |
41 | * The RTC's value is the RTT counter plus that offset. The RTC's alarm |
42 | * is likewise a base (ALMV) plus that offset. |
43 | * |
44 | * Not all RTTs will be used as RTCs; some systems have multiple RTTs to |
45 | * choose from, or a "real" RTC module. All systems have multiple GPBR |
46 | * registers available, likewise usable for more than "RTC" support. |
47 | */ |
48 | |
49 | /* |
50 | * We store ALARM_DISABLED in ALMV to record that no alarm is set. |
51 | * It's also the reset value for that field. |
52 | */ |
53 | #define ALARM_DISABLED ((u32)~0) |
54 | |
55 | |
56 | struct sam9_rtc { |
57 | void __iomem *rtt; |
58 | struct rtc_device *rtcdev; |
59 | u32 imr; |
60 | }; |
61 | |
62 | #define rtt_readl(rtc, field) \ |
63 | __raw_readl((rtc)->rtt + AT91_RTT_ ## field) |
64 | #define rtt_writel(rtc, field, val) \ |
65 | __raw_writel((val), (rtc)->rtt + AT91_RTT_ ## field) |
66 | |
67 | #define gpbr_readl(rtc) \ |
68 | at91_sys_read(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR) |
69 | #define gpbr_writel(rtc, val) \ |
70 | at91_sys_write(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR, (val)) |
71 | |
72 | /* |
73 | * Read current time and date in RTC |
74 | */ |
75 | static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm) |
76 | { |
77 | struct sam9_rtc *rtc = dev_get_drvdata(dev); |
78 | u32 secs, secs2; |
79 | u32 offset; |
80 | |
81 | /* read current time offset */ |
82 | offset = gpbr_readl(rtc); |
83 | if (offset == 0) |
84 | return -EILSEQ; |
85 | |
86 | /* reread the counter to help sync the two clock domains */ |
87 | secs = rtt_readl(rtc, VR); |
88 | secs2 = rtt_readl(rtc, VR); |
89 | if (secs != secs2) |
90 | secs = rtt_readl(rtc, VR); |
91 | |
92 | rtc_time_to_tm(offset + secs, tm); |
93 | |
94 | dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readtime", |
95 | 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, |
96 | tm->tm_hour, tm->tm_min, tm->tm_sec); |
97 | |
98 | return 0; |
99 | } |
100 | |
101 | /* |
102 | * Set current time and date in RTC |
103 | */ |
104 | static int at91_rtc_settime(struct device *dev, struct rtc_time *tm) |
105 | { |
106 | struct sam9_rtc *rtc = dev_get_drvdata(dev); |
107 | int err; |
108 | u32 offset, alarm, mr; |
109 | unsigned long secs; |
110 | |
111 | dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "settime", |
112 | 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, |
113 | tm->tm_hour, tm->tm_min, tm->tm_sec); |
114 | |
115 | err = rtc_tm_to_time(tm, &secs); |
116 | if (err != 0) |
117 | return err; |
118 | |
119 | mr = rtt_readl(rtc, MR); |
120 | |
121 | /* disable interrupts */ |
122 | rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN)); |
123 | |
124 | /* read current time offset */ |
125 | offset = gpbr_readl(rtc); |
126 | |
127 | /* store the new base time in a battery backup register */ |
128 | secs += 1; |
129 | gpbr_writel(rtc, secs); |
130 | |
131 | /* adjust the alarm time for the new base */ |
132 | alarm = rtt_readl(rtc, AR); |
133 | if (alarm != ALARM_DISABLED) { |
134 | if (offset > secs) { |
135 | /* time jumped backwards, increase time until alarm */ |
136 | alarm += (offset - secs); |
137 | } else if ((alarm + offset) > secs) { |
138 | /* time jumped forwards, decrease time until alarm */ |
139 | alarm -= (secs - offset); |
140 | } else { |
141 | /* time jumped past the alarm, disable alarm */ |
142 | alarm = ALARM_DISABLED; |
143 | mr &= ~AT91_RTT_ALMIEN; |
144 | } |
145 | rtt_writel(rtc, AR, alarm); |
146 | } |
147 | |
148 | /* reset the timer, and re-enable interrupts */ |
149 | rtt_writel(rtc, MR, mr | AT91_RTT_RTTRST); |
150 | |
151 | return 0; |
152 | } |
153 | |
154 | static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm) |
155 | { |
156 | struct sam9_rtc *rtc = dev_get_drvdata(dev); |
157 | struct rtc_time *tm = &alrm->time; |
158 | u32 alarm = rtt_readl(rtc, AR); |
159 | u32 offset; |
160 | |
161 | offset = gpbr_readl(rtc); |
162 | if (offset == 0) |
163 | return -EILSEQ; |
164 | |
165 | memset(alrm, 0, sizeof(*alrm)); |
166 | if (alarm != ALARM_DISABLED && offset != 0) { |
167 | rtc_time_to_tm(offset + alarm, tm); |
168 | |
169 | dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readalarm", |
170 | 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday, |
171 | tm->tm_hour, tm->tm_min, tm->tm_sec); |
172 | |
173 | if (rtt_readl(rtc, MR) & AT91_RTT_ALMIEN) |
174 | alrm->enabled = 1; |
175 | } |
176 | |
177 | return 0; |
178 | } |
179 | |
180 | static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm) |
181 | { |
182 | struct sam9_rtc *rtc = dev_get_drvdata(dev); |
183 | struct rtc_time *tm = &alrm->time; |
184 | unsigned long secs; |
185 | u32 offset; |
186 | u32 mr; |
187 | int err; |
188 | |
189 | err = rtc_tm_to_time(tm, &secs); |
190 | if (err != 0) |
191 | return err; |
192 | |
193 | offset = gpbr_readl(rtc); |
194 | if (offset == 0) { |
195 | /* time is not set */ |
196 | return -EILSEQ; |
197 | } |
198 | mr = rtt_readl(rtc, MR); |
199 | rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN); |
200 | |
201 | /* alarm in the past? finish and leave disabled */ |
202 | if (secs <= offset) { |
203 | rtt_writel(rtc, AR, ALARM_DISABLED); |
204 | return 0; |
205 | } |
206 | |
207 | /* else set alarm and maybe enable it */ |
208 | rtt_writel(rtc, AR, secs - offset); |
209 | if (alrm->enabled) |
210 | rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN); |
211 | |
212 | dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "setalarm", |
213 | tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, |
214 | tm->tm_min, tm->tm_sec); |
215 | |
216 | return 0; |
217 | } |
218 | |
219 | /* |
220 | * Handle commands from user-space |
221 | */ |
222 | static int at91_rtc_ioctl(struct device *dev, unsigned int cmd, |
223 | unsigned long arg) |
224 | { |
225 | struct sam9_rtc *rtc = dev_get_drvdata(dev); |
226 | int ret = 0; |
227 | u32 mr = rtt_readl(rtc, MR); |
228 | |
229 | dev_dbg(dev, "ioctl: cmd=%08x, arg=%08lx, mr %08x\n", cmd, arg, mr); |
230 | |
231 | switch (cmd) { |
232 | case RTC_AIE_OFF: /* alarm off */ |
233 | rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN); |
234 | break; |
235 | case RTC_AIE_ON: /* alarm on */ |
236 | rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN); |
237 | break; |
238 | case RTC_UIE_OFF: /* update off */ |
239 | rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN); |
240 | break; |
241 | case RTC_UIE_ON: /* update on */ |
242 | rtt_writel(rtc, MR, mr | AT91_RTT_RTTINCIEN); |
243 | break; |
244 | default: |
245 | ret = -ENOIOCTLCMD; |
246 | break; |
247 | } |
248 | |
249 | return ret; |
250 | } |
251 | |
252 | /* |
253 | * Provide additional RTC information in /proc/driver/rtc |
254 | */ |
255 | static int at91_rtc_proc(struct device *dev, struct seq_file *seq) |
256 | { |
257 | struct sam9_rtc *rtc = dev_get_drvdata(dev); |
258 | u32 mr = mr = rtt_readl(rtc, MR); |
259 | |
260 | seq_printf(seq, "update_IRQ\t: %s\n", |
261 | (mr & AT91_RTT_RTTINCIEN) ? "yes" : "no"); |
262 | return 0; |
263 | } |
264 | |
265 | /* |
266 | * IRQ handler for the RTC |
267 | */ |
268 | static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc) |
269 | { |
270 | struct sam9_rtc *rtc = _rtc; |
271 | u32 sr, mr; |
272 | unsigned long events = 0; |
273 | |
274 | /* Shared interrupt may be for another device. Note: reading |
275 | * SR clears it, so we must only read it in this irq handler! |
276 | */ |
277 | mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); |
278 | sr = rtt_readl(rtc, SR) & (mr >> 16); |
279 | if (!sr) |
280 | return IRQ_NONE; |
281 | |
282 | /* alarm status */ |
283 | if (sr & AT91_RTT_ALMS) |
284 | events |= (RTC_AF | RTC_IRQF); |
285 | |
286 | /* timer update/increment */ |
287 | if (sr & AT91_RTT_RTTINC) |
288 | events |= (RTC_UF | RTC_IRQF); |
289 | |
290 | rtc_update_irq(rtc->rtcdev, 1, events); |
291 | |
292 | pr_debug("%s: num=%ld, events=0x%02lx\n", __func__, |
293 | events >> 8, events & 0x000000FF); |
294 | |
295 | return IRQ_HANDLED; |
296 | } |
297 | |
298 | static const struct rtc_class_ops at91_rtc_ops = { |
299 | .ioctl = at91_rtc_ioctl, |
300 | .read_time = at91_rtc_readtime, |
301 | .set_time = at91_rtc_settime, |
302 | .read_alarm = at91_rtc_readalarm, |
303 | .set_alarm = at91_rtc_setalarm, |
304 | .proc = at91_rtc_proc, |
305 | }; |
306 | |
307 | /* |
308 | * Initialize and install RTC driver |
309 | */ |
310 | static int __init at91_rtc_probe(struct platform_device *pdev) |
311 | { |
312 | struct resource *r; |
313 | struct sam9_rtc *rtc; |
314 | int ret; |
315 | u32 mr; |
316 | |
317 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
318 | if (!r) |
319 | return -ENODEV; |
320 | |
321 | rtc = kzalloc(sizeof *rtc, GFP_KERNEL); |
322 | if (!rtc) |
323 | return -ENOMEM; |
324 | |
325 | /* platform setup code should have handled this; sigh */ |
326 | if (!device_can_wakeup(&pdev->dev)) |
327 | device_init_wakeup(&pdev->dev, 1); |
328 | |
329 | platform_set_drvdata(pdev, rtc); |
330 | rtc->rtt = (void __force __iomem *) (AT91_VA_BASE_SYS - AT91_BASE_SYS); |
331 | rtc->rtt += r->start; |
332 | |
333 | mr = rtt_readl(rtc, MR); |
334 | |
335 | /* unless RTT is counting at 1 Hz, re-initialize it */ |
336 | if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) { |
337 | mr = AT91_RTT_RTTRST | (AT91_SLOW_CLOCK & AT91_RTT_RTPRES); |
338 | gpbr_writel(rtc, 0); |
339 | } |
340 | |
341 | /* disable all interrupts (same as on shutdown path) */ |
342 | mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); |
343 | rtt_writel(rtc, MR, mr); |
344 | |
345 | rtc->rtcdev = rtc_device_register(pdev->name, &pdev->dev, |
346 | &at91_rtc_ops, THIS_MODULE); |
347 | if (IS_ERR(rtc->rtcdev)) { |
348 | ret = PTR_ERR(rtc->rtcdev); |
349 | goto fail; |
350 | } |
351 | |
352 | /* register irq handler after we know what name we'll use */ |
353 | ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt, |
354 | IRQF_DISABLED | IRQF_SHARED, |
355 | dev_name(&rtc->rtcdev->dev), rtc); |
356 | if (ret) { |
357 | dev_dbg(&pdev->dev, "can't share IRQ %d?\n", AT91_ID_SYS); |
358 | rtc_device_unregister(rtc->rtcdev); |
359 | goto fail; |
360 | } |
361 | |
362 | /* NOTE: sam9260 rev A silicon has a ROM bug which resets the |
363 | * RTT on at least some reboots. If you have that chip, you must |
364 | * initialize the time from some external source like a GPS, wall |
365 | * clock, discrete RTC, etc |
366 | */ |
367 | |
368 | if (gpbr_readl(rtc) == 0) |
369 | dev_warn(&pdev->dev, "%s: SET TIME!\n", |
370 | dev_name(&rtc->rtcdev->dev)); |
371 | |
372 | return 0; |
373 | |
374 | fail: |
375 | platform_set_drvdata(pdev, NULL); |
376 | kfree(rtc); |
377 | return ret; |
378 | } |
379 | |
380 | /* |
381 | * Disable and remove the RTC driver |
382 | */ |
383 | static int __exit at91_rtc_remove(struct platform_device *pdev) |
384 | { |
385 | struct sam9_rtc *rtc = platform_get_drvdata(pdev); |
386 | u32 mr = rtt_readl(rtc, MR); |
387 | |
388 | /* disable all interrupts */ |
389 | rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN)); |
390 | free_irq(AT91_ID_SYS, rtc); |
391 | |
392 | rtc_device_unregister(rtc->rtcdev); |
393 | |
394 | platform_set_drvdata(pdev, NULL); |
395 | kfree(rtc); |
396 | return 0; |
397 | } |
398 | |
399 | static void at91_rtc_shutdown(struct platform_device *pdev) |
400 | { |
401 | struct sam9_rtc *rtc = platform_get_drvdata(pdev); |
402 | u32 mr = rtt_readl(rtc, MR); |
403 | |
404 | rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); |
405 | rtt_writel(rtc, MR, mr & ~rtc->imr); |
406 | } |
407 | |
408 | #ifdef CONFIG_PM |
409 | |
410 | /* AT91SAM9 RTC Power management control */ |
411 | |
412 | static int at91_rtc_suspend(struct platform_device *pdev, |
413 | pm_message_t state) |
414 | { |
415 | struct sam9_rtc *rtc = platform_get_drvdata(pdev); |
416 | u32 mr = rtt_readl(rtc, MR); |
417 | |
418 | /* |
419 | * This IRQ is shared with DBGU and other hardware which isn't |
420 | * necessarily a wakeup event source. |
421 | */ |
422 | rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN); |
423 | if (rtc->imr) { |
424 | if (device_may_wakeup(&pdev->dev) && (mr & AT91_RTT_ALMIEN)) { |
425 | enable_irq_wake(AT91_ID_SYS); |
426 | /* don't let RTTINC cause wakeups */ |
427 | if (mr & AT91_RTT_RTTINCIEN) |
428 | rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN); |
429 | } else |
430 | rtt_writel(rtc, MR, mr & ~rtc->imr); |
431 | } |
432 | |
433 | return 0; |
434 | } |
435 | |
436 | static int at91_rtc_resume(struct platform_device *pdev) |
437 | { |
438 | struct sam9_rtc *rtc = platform_get_drvdata(pdev); |
439 | u32 mr; |
440 | |
441 | if (rtc->imr) { |
442 | if (device_may_wakeup(&pdev->dev)) |
443 | disable_irq_wake(AT91_ID_SYS); |
444 | mr = rtt_readl(rtc, MR); |
445 | rtt_writel(rtc, MR, mr | rtc->imr); |
446 | } |
447 | |
448 | return 0; |
449 | } |
450 | #else |
451 | #define at91_rtc_suspend NULL |
452 | #define at91_rtc_resume NULL |
453 | #endif |
454 | |
455 | static struct platform_driver at91_rtc_driver = { |
456 | .driver.name = "rtc-at91sam9", |
457 | .driver.owner = THIS_MODULE, |
458 | .remove = __exit_p(at91_rtc_remove), |
459 | .shutdown = at91_rtc_shutdown, |
460 | .suspend = at91_rtc_suspend, |
461 | .resume = at91_rtc_resume, |
462 | }; |
463 | |
464 | /* Chips can have more than one RTT module, and they can be used for more |
465 | * than just RTCs. So we can't just register as "the" RTT driver. |
466 | * |
467 | * A normal approach in such cases is to create a library to allocate and |
468 | * free the modules. Here we just use bus_find_device() as like such a |
469 | * library, binding directly ... no runtime "library" footprint is needed. |
470 | */ |
471 | static int __init at91_rtc_match(struct device *dev, void *v) |
472 | { |
473 | struct platform_device *pdev = to_platform_device(dev); |
474 | int ret; |
475 | |
476 | /* continue searching if this isn't the RTT we need */ |
477 | if (strcmp("at91_rtt", pdev->name) != 0 |
478 | || pdev->id != CONFIG_RTC_DRV_AT91SAM9_RTT) |
479 | goto fail; |
480 | |
481 | /* else we found it ... but fail unless we can bind to the RTC driver */ |
482 | if (dev->driver) { |
483 | dev_dbg(dev, "busy, can't use as RTC!\n"); |
484 | goto fail; |
485 | } |
486 | dev->driver = &at91_rtc_driver.driver; |
487 | if (device_attach(dev) == 0) { |
488 | dev_dbg(dev, "can't attach RTC!\n"); |
489 | goto fail; |
490 | } |
491 | ret = at91_rtc_probe(pdev); |
492 | if (ret == 0) |
493 | return true; |
494 | |
495 | dev_dbg(dev, "RTC probe err %d!\n", ret); |
496 | fail: |
497 | return false; |
498 | } |
499 | |
500 | static int __init at91_rtc_init(void) |
501 | { |
502 | int status; |
503 | struct device *rtc; |
504 | |
505 | status = platform_driver_register(&at91_rtc_driver); |
506 | if (status) |
507 | return status; |
508 | rtc = bus_find_device(&platform_bus_type, NULL, |
509 | NULL, at91_rtc_match); |
510 | if (!rtc) |
511 | platform_driver_unregister(&at91_rtc_driver); |
512 | return rtc ? 0 : -ENODEV; |
513 | } |
514 | module_init(at91_rtc_init); |
515 | |
516 | static void __exit at91_rtc_exit(void) |
517 | { |
518 | platform_driver_unregister(&at91_rtc_driver); |
519 | } |
520 | module_exit(at91_rtc_exit); |
521 | |
522 | |
523 | MODULE_AUTHOR("Michel Benoit"); |
524 | MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x"); |
525 | MODULE_LICENSE("GPL"); |
526 |
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