blob: 2133f37906f2928f8d3ccacf0fc7bcd77aa7d3ce [file] [log] [blame]
David Brownell4cdf8542008-02-06 01:38:59 -08001/*
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
Russell Kinga09e64f2008-08-05 16:14:15 +010022#include <mach/board.h>
23#include <mach/at91_rtt.h>
David Brownell4cdf8542008-02-06 01:38:59 -080024
25
26/*
27 * This driver uses two configurable hardware resources that live in the
28 * AT91SAM9 backup power domain (intended to be powered at all times)
29 * to implement the Real Time Clock interfaces
30 *
31 * - A "Real-time Timer" (RTT) counts up in seconds from a base time.
32 * We can't assign the counter value (CRTV) ... but we can reset it.
33 *
34 * - One of the "General Purpose Backup Registers" (GPBRs) holds the
35 * base time, normally an offset from the beginning of the POSIX
36 * epoch (1970-Jan-1 00:00:00 UTC). Some systems also include the
37 * local timezone's offset.
38 *
39 * The RTC's value is the RTT counter plus that offset. The RTC's alarm
40 * is likewise a base (ALMV) plus that offset.
41 *
42 * Not all RTTs will be used as RTCs; some systems have multiple RTTs to
43 * choose from, or a "real" RTC module. All systems have multiple GPBR
44 * registers available, likewise usable for more than "RTC" support.
45 */
46
47/*
48 * We store ALARM_DISABLED in ALMV to record that no alarm is set.
49 * It's also the reset value for that field.
50 */
51#define ALARM_DISABLED ((u32)~0)
52
53
54struct sam9_rtc {
55 void __iomem *rtt;
56 struct rtc_device *rtcdev;
57 u32 imr;
58};
59
60#define rtt_readl(rtc, field) \
61 __raw_readl((rtc)->rtt + AT91_RTT_ ## field)
62#define rtt_writel(rtc, field, val) \
63 __raw_writel((val), (rtc)->rtt + AT91_RTT_ ## field)
64
65#define gpbr_readl(rtc) \
66 at91_sys_read(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR)
67#define gpbr_writel(rtc, val) \
68 at91_sys_write(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR, (val))
69
70/*
71 * Read current time and date in RTC
72 */
73static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
74{
75 struct sam9_rtc *rtc = dev_get_drvdata(dev);
76 u32 secs, secs2;
77 u32 offset;
78
79 /* read current time offset */
80 offset = gpbr_readl(rtc);
81 if (offset == 0)
82 return -EILSEQ;
83
84 /* reread the counter to help sync the two clock domains */
85 secs = rtt_readl(rtc, VR);
86 secs2 = rtt_readl(rtc, VR);
87 if (secs != secs2)
88 secs = rtt_readl(rtc, VR);
89
90 rtc_time_to_tm(offset + secs, tm);
91
92 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readtime",
93 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
94 tm->tm_hour, tm->tm_min, tm->tm_sec);
95
96 return 0;
97}
98
99/*
100 * Set current time and date in RTC
101 */
102static int at91_rtc_settime(struct device *dev, struct rtc_time *tm)
103{
104 struct sam9_rtc *rtc = dev_get_drvdata(dev);
105 int err;
106 u32 offset, alarm, mr;
107 unsigned long secs;
108
109 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "settime",
110 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
111 tm->tm_hour, tm->tm_min, tm->tm_sec);
112
113 err = rtc_tm_to_time(tm, &secs);
114 if (err != 0)
115 return err;
116
117 mr = rtt_readl(rtc, MR);
118
119 /* disable interrupts */
120 rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
121
122 /* read current time offset */
123 offset = gpbr_readl(rtc);
124
125 /* store the new base time in a battery backup register */
126 secs += 1;
127 gpbr_writel(rtc, secs);
128
129 /* adjust the alarm time for the new base */
130 alarm = rtt_readl(rtc, AR);
131 if (alarm != ALARM_DISABLED) {
132 if (offset > secs) {
133 /* time jumped backwards, increase time until alarm */
134 alarm += (offset - secs);
135 } else if ((alarm + offset) > secs) {
136 /* time jumped forwards, decrease time until alarm */
137 alarm -= (secs - offset);
138 } else {
139 /* time jumped past the alarm, disable alarm */
140 alarm = ALARM_DISABLED;
141 mr &= ~AT91_RTT_ALMIEN;
142 }
143 rtt_writel(rtc, AR, alarm);
144 }
145
146 /* reset the timer, and re-enable interrupts */
147 rtt_writel(rtc, MR, mr | AT91_RTT_RTTRST);
148
149 return 0;
150}
151
152static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
153{
154 struct sam9_rtc *rtc = dev_get_drvdata(dev);
155 struct rtc_time *tm = &alrm->time;
156 u32 alarm = rtt_readl(rtc, AR);
157 u32 offset;
158
159 offset = gpbr_readl(rtc);
160 if (offset == 0)
161 return -EILSEQ;
162
163 memset(alrm, 0, sizeof(alrm));
164 if (alarm != ALARM_DISABLED && offset != 0) {
165 rtc_time_to_tm(offset + alarm, tm);
166
167 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readalarm",
168 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
169 tm->tm_hour, tm->tm_min, tm->tm_sec);
170
171 if (rtt_readl(rtc, MR) & AT91_RTT_ALMIEN)
172 alrm->enabled = 1;
173 }
174
175 return 0;
176}
177
178static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
179{
180 struct sam9_rtc *rtc = dev_get_drvdata(dev);
181 struct rtc_time *tm = &alrm->time;
182 unsigned long secs;
183 u32 offset;
184 u32 mr;
185 int err;
186
187 err = rtc_tm_to_time(tm, &secs);
188 if (err != 0)
189 return err;
190
191 offset = gpbr_readl(rtc);
192 if (offset == 0) {
193 /* time is not set */
194 return -EILSEQ;
195 }
196 mr = rtt_readl(rtc, MR);
197 rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
198
199 /* alarm in the past? finish and leave disabled */
200 if (secs <= offset) {
201 rtt_writel(rtc, AR, ALARM_DISABLED);
202 return 0;
203 }
204
205 /* else set alarm and maybe enable it */
206 rtt_writel(rtc, AR, secs - offset);
207 if (alrm->enabled)
208 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
209
210 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "setalarm",
211 tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour,
212 tm->tm_min, tm->tm_sec);
213
214 return 0;
215}
216
217/*
218 * Handle commands from user-space
219 */
220static int at91_rtc_ioctl(struct device *dev, unsigned int cmd,
221 unsigned long arg)
222{
223 struct sam9_rtc *rtc = dev_get_drvdata(dev);
224 int ret = 0;
225 u32 mr = rtt_readl(rtc, MR);
226
227 dev_dbg(dev, "ioctl: cmd=%08x, arg=%08lx, mr %08x\n", cmd, arg, mr);
228
229 switch (cmd) {
230 case RTC_AIE_OFF: /* alarm off */
231 rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
232 break;
233 case RTC_AIE_ON: /* alarm on */
234 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
235 break;
236 case RTC_UIE_OFF: /* update off */
237 rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
238 break;
239 case RTC_UIE_ON: /* update on */
240 rtt_writel(rtc, MR, mr | AT91_RTT_RTTINCIEN);
241 break;
242 default:
243 ret = -ENOIOCTLCMD;
244 break;
245 }
246
247 return ret;
248}
249
250/*
251 * Provide additional RTC information in /proc/driver/rtc
252 */
253static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
254{
255 struct sam9_rtc *rtc = dev_get_drvdata(dev);
256 u32 mr = mr = rtt_readl(rtc, MR);
257
258 seq_printf(seq, "update_IRQ\t: %s\n",
259 (mr & AT91_RTT_RTTINCIEN) ? "yes" : "no");
260 return 0;
261}
262
263/*
264 * IRQ handler for the RTC
265 */
266static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc)
267{
268 struct sam9_rtc *rtc = _rtc;
269 u32 sr, mr;
270 unsigned long events = 0;
271
272 /* Shared interrupt may be for another device. Note: reading
273 * SR clears it, so we must only read it in this irq handler!
274 */
275 mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
David Brownell9fedc9f2008-03-19 17:01:09 -0700276 sr = rtt_readl(rtc, SR) & (mr >> 16);
David Brownell4cdf8542008-02-06 01:38:59 -0800277 if (!sr)
278 return IRQ_NONE;
279
280 /* alarm status */
281 if (sr & AT91_RTT_ALMS)
282 events |= (RTC_AF | RTC_IRQF);
283
284 /* timer update/increment */
285 if (sr & AT91_RTT_RTTINC)
286 events |= (RTC_UF | RTC_IRQF);
287
288 rtc_update_irq(rtc->rtcdev, 1, events);
289
Harvey Harrison2a4e2b82008-04-28 02:12:00 -0700290 pr_debug("%s: num=%ld, events=0x%02lx\n", __func__,
David Brownell4cdf8542008-02-06 01:38:59 -0800291 events >> 8, events & 0x000000FF);
292
293 return IRQ_HANDLED;
294}
295
296static const struct rtc_class_ops at91_rtc_ops = {
297 .ioctl = at91_rtc_ioctl,
298 .read_time = at91_rtc_readtime,
299 .set_time = at91_rtc_settime,
300 .read_alarm = at91_rtc_readalarm,
301 .set_alarm = at91_rtc_setalarm,
302 .proc = at91_rtc_proc,
303};
304
305/*
306 * Initialize and install RTC driver
307 */
308static int __init at91_rtc_probe(struct platform_device *pdev)
309{
310 struct resource *r;
311 struct sam9_rtc *rtc;
312 int ret;
313 u32 mr;
314
315 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
316 if (!r)
317 return -ENODEV;
318
319 rtc = kzalloc(sizeof *rtc, GFP_KERNEL);
320 if (!rtc)
321 return -ENOMEM;
322
David Brownell9fedc9f2008-03-19 17:01:09 -0700323 /* platform setup code should have handled this; sigh */
324 if (!device_can_wakeup(&pdev->dev))
325 device_init_wakeup(&pdev->dev, 1);
326
David Brownell4cdf8542008-02-06 01:38:59 -0800327 platform_set_drvdata(pdev, rtc);
328 rtc->rtt = (void __force __iomem *) (AT91_VA_BASE_SYS - AT91_BASE_SYS);
329 rtc->rtt += r->start;
330
331 mr = rtt_readl(rtc, MR);
332
333 /* unless RTT is counting at 1 Hz, re-initialize it */
334 if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) {
335 mr = AT91_RTT_RTTRST | (AT91_SLOW_CLOCK & AT91_RTT_RTPRES);
336 gpbr_writel(rtc, 0);
337 }
338
339 /* disable all interrupts (same as on shutdown path) */
340 mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
341 rtt_writel(rtc, MR, mr);
342
343 rtc->rtcdev = rtc_device_register(pdev->name, &pdev->dev,
344 &at91_rtc_ops, THIS_MODULE);
345 if (IS_ERR(rtc->rtcdev)) {
346 ret = PTR_ERR(rtc->rtcdev);
347 goto fail;
348 }
349
350 /* register irq handler after we know what name we'll use */
351 ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt,
352 IRQF_DISABLED | IRQF_SHARED,
353 rtc->rtcdev->dev.bus_id, rtc);
354 if (ret) {
355 dev_dbg(&pdev->dev, "can't share IRQ %d?\n", AT91_ID_SYS);
356 rtc_device_unregister(rtc->rtcdev);
357 goto fail;
358 }
359
360 /* NOTE: sam9260 rev A silicon has a ROM bug which resets the
361 * RTT on at least some reboots. If you have that chip, you must
362 * initialize the time from some external source like a GPS, wall
363 * clock, discrete RTC, etc
364 */
365
366 if (gpbr_readl(rtc) == 0)
367 dev_warn(&pdev->dev, "%s: SET TIME!\n",
368 rtc->rtcdev->dev.bus_id);
369
370 return 0;
371
372fail:
373 platform_set_drvdata(pdev, NULL);
374 kfree(rtc);
375 return ret;
376}
377
378/*
379 * Disable and remove the RTC driver
380 */
381static int __exit at91_rtc_remove(struct platform_device *pdev)
382{
383 struct sam9_rtc *rtc = platform_get_drvdata(pdev);
384 u32 mr = rtt_readl(rtc, MR);
385
386 /* disable all interrupts */
387 rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
388 free_irq(AT91_ID_SYS, rtc);
389
390 rtc_device_unregister(rtc->rtcdev);
391
392 platform_set_drvdata(pdev, NULL);
393 kfree(rtc);
394 return 0;
395}
396
397static void at91_rtc_shutdown(struct platform_device *pdev)
398{
399 struct sam9_rtc *rtc = platform_get_drvdata(pdev);
400 u32 mr = rtt_readl(rtc, MR);
401
402 rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
403 rtt_writel(rtc, MR, mr & ~rtc->imr);
404}
405
406#ifdef CONFIG_PM
407
408/* AT91SAM9 RTC Power management control */
409
410static int at91_rtc_suspend(struct platform_device *pdev,
411 pm_message_t state)
412{
413 struct sam9_rtc *rtc = platform_get_drvdata(pdev);
414 u32 mr = rtt_readl(rtc, MR);
415
416 /*
417 * This IRQ is shared with DBGU and other hardware which isn't
418 * necessarily a wakeup event source.
419 */
420 rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
421 if (rtc->imr) {
422 if (device_may_wakeup(&pdev->dev) && (mr & AT91_RTT_ALMIEN)) {
423 enable_irq_wake(AT91_ID_SYS);
424 /* don't let RTTINC cause wakeups */
425 if (mr & AT91_RTT_RTTINCIEN)
426 rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
427 } else
428 rtt_writel(rtc, MR, mr & ~rtc->imr);
429 }
430
431 return 0;
432}
433
434static int at91_rtc_resume(struct platform_device *pdev)
435{
436 struct sam9_rtc *rtc = platform_get_drvdata(pdev);
437 u32 mr;
438
439 if (rtc->imr) {
440 if (device_may_wakeup(&pdev->dev))
441 disable_irq_wake(AT91_ID_SYS);
442 mr = rtt_readl(rtc, MR);
443 rtt_writel(rtc, MR, mr | rtc->imr);
444 }
445
446 return 0;
447}
448#else
449#define at91_rtc_suspend NULL
450#define at91_rtc_resume NULL
451#endif
452
453static struct platform_driver at91_rtc_driver = {
454 .driver.name = "rtc-at91sam9",
455 .driver.owner = THIS_MODULE,
456 .remove = __exit_p(at91_rtc_remove),
457 .shutdown = at91_rtc_shutdown,
458 .suspend = at91_rtc_suspend,
459 .resume = at91_rtc_resume,
460};
461
462/* Chips can have more than one RTT module, and they can be used for more
463 * than just RTCs. So we can't just register as "the" RTT driver.
464 *
465 * A normal approach in such cases is to create a library to allocate and
466 * free the modules. Here we just use bus_find_device() as like such a
467 * library, binding directly ... no runtime "library" footprint is needed.
468 */
469static int __init at91_rtc_match(struct device *dev, void *v)
470{
471 struct platform_device *pdev = to_platform_device(dev);
472 int ret;
473
474 /* continue searching if this isn't the RTT we need */
475 if (strcmp("at91_rtt", pdev->name) != 0
476 || pdev->id != CONFIG_RTC_DRV_AT91SAM9_RTT)
477 goto fail;
478
479 /* else we found it ... but fail unless we can bind to the RTC driver */
480 if (dev->driver) {
481 dev_dbg(dev, "busy, can't use as RTC!\n");
482 goto fail;
483 }
484 dev->driver = &at91_rtc_driver.driver;
485 if (device_attach(dev) == 0) {
486 dev_dbg(dev, "can't attach RTC!\n");
487 goto fail;
488 }
489 ret = at91_rtc_probe(pdev);
490 if (ret == 0)
491 return true;
492
493 dev_dbg(dev, "RTC probe err %d!\n", ret);
494fail:
495 return false;
496}
497
498static int __init at91_rtc_init(void)
499{
500 int status;
501 struct device *rtc;
502
503 status = platform_driver_register(&at91_rtc_driver);
504 if (status)
505 return status;
506 rtc = bus_find_device(&platform_bus_type, NULL,
507 NULL, at91_rtc_match);
508 if (!rtc)
509 platform_driver_unregister(&at91_rtc_driver);
510 return rtc ? 0 : -ENODEV;
511}
512module_init(at91_rtc_init);
513
514static void __exit at91_rtc_exit(void)
515{
516 platform_driver_unregister(&at91_rtc_driver);
517}
518module_exit(at91_rtc_exit);
519
520
521MODULE_AUTHOR("Michel Benoit");
522MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x");
523MODULE_LICENSE("GPL");