Version:  2.0.40 2.2.26 2.4.37 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2

Linux/drivers/rtc/rtc-at91sam9.c

  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 #include <linux/platform_data/atmel.h>
 23 #include <linux/io.h>
 24 #include <linux/mfd/syscon.h>
 25 #include <linux/regmap.h>
 26 #include <linux/suspend.h>
 27 #include <linux/clk.h>
 28 
 29 /*
 30  * This driver uses two configurable hardware resources that live in the
 31  * AT91SAM9 backup power domain (intended to be powered at all times)
 32  * to implement the Real Time Clock interfaces
 33  *
 34  *  - A "Real-time Timer" (RTT) counts up in seconds from a base time.
 35  *    We can't assign the counter value (CRTV) ... but we can reset it.
 36  *
 37  *  - One of the "General Purpose Backup Registers" (GPBRs) holds the
 38  *    base time, normally an offset from the beginning of the POSIX
 39  *    epoch (1970-Jan-1 00:00:00 UTC).  Some systems also include the
 40  *    local timezone's offset.
 41  *
 42  * The RTC's value is the RTT counter plus that offset.  The RTC's alarm
 43  * is likewise a base (ALMV) plus that offset.
 44  *
 45  * Not all RTTs will be used as RTCs; some systems have multiple RTTs to
 46  * choose from, or a "real" RTC module.  All systems have multiple GPBR
 47  * registers available, likewise usable for more than "RTC" support.
 48  */
 49 
 50 #define AT91_RTT_MR             0x00                    /* Real-time Mode Register */
 51 #define AT91_RTT_RTPRES         (0xffff << 0)           /* Real-time Timer Prescaler Value */
 52 #define AT91_RTT_ALMIEN         (1 << 16)               /* Alarm Interrupt Enable */
 53 #define AT91_RTT_RTTINCIEN      (1 << 17)               /* Real Time Timer Increment Interrupt Enable */
 54 #define AT91_RTT_RTTRST         (1 << 18)               /* Real Time Timer Restart */
 55 
 56 #define AT91_RTT_AR             0x04                    /* Real-time Alarm Register */
 57 #define AT91_RTT_ALMV           (0xffffffff)            /* Alarm Value */
 58 
 59 #define AT91_RTT_VR             0x08                    /* Real-time Value Register */
 60 #define AT91_RTT_CRTV           (0xffffffff)            /* Current Real-time Value */
 61 
 62 #define AT91_RTT_SR             0x0c                    /* Real-time Status Register */
 63 #define AT91_RTT_ALMS           (1 << 0)                /* Real-time Alarm Status */
 64 #define AT91_RTT_RTTINC         (1 << 1)                /* Real-time Timer Increment */
 65 
 66 /*
 67  * We store ALARM_DISABLED in ALMV to record that no alarm is set.
 68  * It's also the reset value for that field.
 69  */
 70 #define ALARM_DISABLED  ((u32)~0)
 71 
 72 
 73 struct sam9_rtc {
 74         void __iomem            *rtt;
 75         struct rtc_device       *rtcdev;
 76         u32                     imr;
 77         struct regmap           *gpbr;
 78         unsigned int            gpbr_offset;
 79         int                     irq;
 80         struct clk              *sclk;
 81         bool                    suspended;
 82         unsigned long           events;
 83         spinlock_t              lock;
 84 };
 85 
 86 #define rtt_readl(rtc, field) \
 87         readl((rtc)->rtt + AT91_RTT_ ## field)
 88 #define rtt_writel(rtc, field, val) \
 89         writel((val), (rtc)->rtt + AT91_RTT_ ## field)
 90 
 91 static inline unsigned int gpbr_readl(struct sam9_rtc *rtc)
 92 {
 93         unsigned int val;
 94 
 95         regmap_read(rtc->gpbr, rtc->gpbr_offset, &val);
 96 
 97         return val;
 98 }
 99 
100 static inline void gpbr_writel(struct sam9_rtc *rtc, unsigned int val)
101 {
102         regmap_write(rtc->gpbr, rtc->gpbr_offset, val);
103 }
104 
105 /*
106  * Read current time and date in RTC
107  */
108 static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
109 {
110         struct sam9_rtc *rtc = dev_get_drvdata(dev);
111         u32 secs, secs2;
112         u32 offset;
113 
114         /* read current time offset */
115         offset = gpbr_readl(rtc);
116         if (offset == 0)
117                 return -EILSEQ;
118 
119         /* reread the counter to help sync the two clock domains */
120         secs = rtt_readl(rtc, VR);
121         secs2 = rtt_readl(rtc, VR);
122         if (secs != secs2)
123                 secs = rtt_readl(rtc, VR);
124 
125         rtc_time_to_tm(offset + secs, tm);
126 
127         dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readtime",
128                 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
129                 tm->tm_hour, tm->tm_min, tm->tm_sec);
130 
131         return 0;
132 }
133 
134 /*
135  * Set current time and date in RTC
136  */
137 static int at91_rtc_settime(struct device *dev, struct rtc_time *tm)
138 {
139         struct sam9_rtc *rtc = dev_get_drvdata(dev);
140         int err;
141         u32 offset, alarm, mr;
142         unsigned long secs;
143 
144         dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "settime",
145                 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
146                 tm->tm_hour, tm->tm_min, tm->tm_sec);
147 
148         err = rtc_tm_to_time(tm, &secs);
149         if (err != 0)
150                 return err;
151 
152         mr = rtt_readl(rtc, MR);
153 
154         /* disable interrupts */
155         rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
156 
157         /* read current time offset */
158         offset = gpbr_readl(rtc);
159 
160         /* store the new base time in a battery backup register */
161         secs += 1;
162         gpbr_writel(rtc, secs);
163 
164         /* adjust the alarm time for the new base */
165         alarm = rtt_readl(rtc, AR);
166         if (alarm != ALARM_DISABLED) {
167                 if (offset > secs) {
168                         /* time jumped backwards, increase time until alarm */
169                         alarm += (offset - secs);
170                 } else if ((alarm + offset) > secs) {
171                         /* time jumped forwards, decrease time until alarm */
172                         alarm -= (secs - offset);
173                 } else {
174                         /* time jumped past the alarm, disable alarm */
175                         alarm = ALARM_DISABLED;
176                         mr &= ~AT91_RTT_ALMIEN;
177                 }
178                 rtt_writel(rtc, AR, alarm);
179         }
180 
181         /* reset the timer, and re-enable interrupts */
182         rtt_writel(rtc, MR, mr | AT91_RTT_RTTRST);
183 
184         return 0;
185 }
186 
187 static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
188 {
189         struct sam9_rtc *rtc = dev_get_drvdata(dev);
190         struct rtc_time *tm = &alrm->time;
191         u32 alarm = rtt_readl(rtc, AR);
192         u32 offset;
193 
194         offset = gpbr_readl(rtc);
195         if (offset == 0)
196                 return -EILSEQ;
197 
198         memset(alrm, 0, sizeof(*alrm));
199         if (alarm != ALARM_DISABLED && offset != 0) {
200                 rtc_time_to_tm(offset + alarm, tm);
201 
202                 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readalarm",
203                         1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
204                         tm->tm_hour, tm->tm_min, tm->tm_sec);
205 
206                 if (rtt_readl(rtc, MR) & AT91_RTT_ALMIEN)
207                         alrm->enabled = 1;
208         }
209 
210         return 0;
211 }
212 
213 static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
214 {
215         struct sam9_rtc *rtc = dev_get_drvdata(dev);
216         struct rtc_time *tm = &alrm->time;
217         unsigned long secs;
218         u32 offset;
219         u32 mr;
220         int err;
221 
222         err = rtc_tm_to_time(tm, &secs);
223         if (err != 0)
224                 return err;
225 
226         offset = gpbr_readl(rtc);
227         if (offset == 0) {
228                 /* time is not set */
229                 return -EILSEQ;
230         }
231         mr = rtt_readl(rtc, MR);
232         rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
233 
234         /* alarm in the past? finish and leave disabled */
235         if (secs <= offset) {
236                 rtt_writel(rtc, AR, ALARM_DISABLED);
237                 return 0;
238         }
239 
240         /* else set alarm and maybe enable it */
241         rtt_writel(rtc, AR, secs - offset);
242         if (alrm->enabled)
243                 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
244 
245         dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "setalarm",
246                 tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour,
247                 tm->tm_min, tm->tm_sec);
248 
249         return 0;
250 }
251 
252 static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
253 {
254         struct sam9_rtc *rtc = dev_get_drvdata(dev);
255         u32 mr = rtt_readl(rtc, MR);
256 
257         dev_dbg(dev, "alarm_irq_enable: enabled=%08x, mr %08x\n", enabled, mr);
258         if (enabled)
259                 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
260         else
261                 rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
262         return 0;
263 }
264 
265 /*
266  * Provide additional RTC information in /proc/driver/rtc
267  */
268 static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
269 {
270         struct sam9_rtc *rtc = dev_get_drvdata(dev);
271         u32 mr = mr = rtt_readl(rtc, MR);
272 
273         seq_printf(seq, "update_IRQ\t: %s\n",
274                         (mr & AT91_RTT_RTTINCIEN) ? "yes" : "no");
275         return 0;
276 }
277 
278 static irqreturn_t at91_rtc_cache_events(struct sam9_rtc *rtc)
279 {
280         u32 sr, mr;
281 
282         /* Shared interrupt may be for another device.  Note: reading
283          * SR clears it, so we must only read it in this irq handler!
284          */
285         mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
286         sr = rtt_readl(rtc, SR) & (mr >> 16);
287         if (!sr)
288                 return IRQ_NONE;
289 
290         /* alarm status */
291         if (sr & AT91_RTT_ALMS)
292                 rtc->events |= (RTC_AF | RTC_IRQF);
293 
294         /* timer update/increment */
295         if (sr & AT91_RTT_RTTINC)
296                 rtc->events |= (RTC_UF | RTC_IRQF);
297 
298         return IRQ_HANDLED;
299 }
300 
301 static void at91_rtc_flush_events(struct sam9_rtc *rtc)
302 {
303         if (!rtc->events)
304                 return;
305 
306         rtc_update_irq(rtc->rtcdev, 1, rtc->events);
307         rtc->events = 0;
308 
309         pr_debug("%s: num=%ld, events=0x%02lx\n", __func__,
310                 rtc->events >> 8, rtc->events & 0x000000FF);
311 }
312 
313 /*
314  * IRQ handler for the RTC
315  */
316 static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc)
317 {
318         struct sam9_rtc *rtc = _rtc;
319         int ret;
320 
321         spin_lock(&rtc->lock);
322 
323         ret = at91_rtc_cache_events(rtc);
324 
325         /* We're called in suspended state */
326         if (rtc->suspended) {
327                 /* Mask irqs coming from this peripheral */
328                 rtt_writel(rtc, MR,
329                            rtt_readl(rtc, MR) &
330                            ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
331                 /* Trigger a system wakeup */
332                 pm_system_wakeup();
333         } else {
334                 at91_rtc_flush_events(rtc);
335         }
336 
337         spin_unlock(&rtc->lock);
338 
339         return ret;
340 }
341 
342 static const struct rtc_class_ops at91_rtc_ops = {
343         .read_time      = at91_rtc_readtime,
344         .set_time       = at91_rtc_settime,
345         .read_alarm     = at91_rtc_readalarm,
346         .set_alarm      = at91_rtc_setalarm,
347         .proc           = at91_rtc_proc,
348         .alarm_irq_enable = at91_rtc_alarm_irq_enable,
349 };
350 
351 static const struct regmap_config gpbr_regmap_config = {
352         .reg_bits = 32,
353         .val_bits = 32,
354         .reg_stride = 4,
355 };
356 
357 /*
358  * Initialize and install RTC driver
359  */
360 static int at91_rtc_probe(struct platform_device *pdev)
361 {
362         struct resource *r;
363         struct sam9_rtc *rtc;
364         int             ret, irq;
365         u32             mr;
366         unsigned int    sclk_rate;
367 
368         irq = platform_get_irq(pdev, 0);
369         if (irq < 0) {
370                 dev_err(&pdev->dev, "failed to get interrupt resource\n");
371                 return irq;
372         }
373 
374         rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
375         if (!rtc)
376                 return -ENOMEM;
377 
378         rtc->irq = irq;
379 
380         /* platform setup code should have handled this; sigh */
381         if (!device_can_wakeup(&pdev->dev))
382                 device_init_wakeup(&pdev->dev, 1);
383 
384         platform_set_drvdata(pdev, rtc);
385 
386         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
387         rtc->rtt = devm_ioremap_resource(&pdev->dev, r);
388         if (IS_ERR(rtc->rtt))
389                 return PTR_ERR(rtc->rtt);
390 
391         if (!pdev->dev.of_node) {
392                 /*
393                  * TODO: Remove this code chunk when removing non DT board
394                  * support. Remember to remove the gpbr_regmap_config
395                  * variable too.
396                  */
397                 void __iomem *gpbr;
398 
399                 r = platform_get_resource(pdev, IORESOURCE_MEM, 1);
400                 gpbr = devm_ioremap_resource(&pdev->dev, r);
401                 if (IS_ERR(gpbr))
402                         return PTR_ERR(gpbr);
403 
404                 rtc->gpbr = regmap_init_mmio(NULL, gpbr,
405                                              &gpbr_regmap_config);
406         } else {
407                 struct of_phandle_args args;
408 
409                 ret = of_parse_phandle_with_fixed_args(pdev->dev.of_node,
410                                                 "atmel,rtt-rtc-time-reg", 1, 0,
411                                                 &args);
412                 if (ret)
413                         return ret;
414 
415                 rtc->gpbr = syscon_node_to_regmap(args.np);
416                 rtc->gpbr_offset = args.args[0];
417         }
418 
419         if (IS_ERR(rtc->gpbr)) {
420                 dev_err(&pdev->dev, "failed to retrieve gpbr regmap, aborting.\n");
421                 return -ENOMEM;
422         }
423 
424         rtc->sclk = devm_clk_get(&pdev->dev, NULL);
425         if (IS_ERR(rtc->sclk))
426                 return PTR_ERR(rtc->sclk);
427 
428         sclk_rate = clk_get_rate(rtc->sclk);
429         if (!sclk_rate || sclk_rate > AT91_RTT_RTPRES) {
430                 dev_err(&pdev->dev, "Invalid slow clock rate\n");
431                 return -EINVAL;
432         }
433 
434         ret = clk_prepare_enable(rtc->sclk);
435         if (ret) {
436                 dev_err(&pdev->dev, "Could not enable slow clock\n");
437                 return ret;
438         }
439 
440         mr = rtt_readl(rtc, MR);
441 
442         /* unless RTT is counting at 1 Hz, re-initialize it */
443         if ((mr & AT91_RTT_RTPRES) != sclk_rate) {
444                 mr = AT91_RTT_RTTRST | (sclk_rate & AT91_RTT_RTPRES);
445                 gpbr_writel(rtc, 0);
446         }
447 
448         /* disable all interrupts (same as on shutdown path) */
449         mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
450         rtt_writel(rtc, MR, mr);
451 
452         rtc->rtcdev = devm_rtc_device_register(&pdev->dev, pdev->name,
453                                         &at91_rtc_ops, THIS_MODULE);
454         if (IS_ERR(rtc->rtcdev))
455                 return PTR_ERR(rtc->rtcdev);
456 
457         /* register irq handler after we know what name we'll use */
458         ret = devm_request_irq(&pdev->dev, rtc->irq, at91_rtc_interrupt,
459                                IRQF_SHARED | IRQF_COND_SUSPEND,
460                                dev_name(&rtc->rtcdev->dev), rtc);
461         if (ret) {
462                 dev_dbg(&pdev->dev, "can't share IRQ %d?\n", rtc->irq);
463                 return ret;
464         }
465 
466         /* NOTE:  sam9260 rev A silicon has a ROM bug which resets the
467          * RTT on at least some reboots.  If you have that chip, you must
468          * initialize the time from some external source like a GPS, wall
469          * clock, discrete RTC, etc
470          */
471 
472         if (gpbr_readl(rtc) == 0)
473                 dev_warn(&pdev->dev, "%s: SET TIME!\n",
474                                 dev_name(&rtc->rtcdev->dev));
475 
476         return 0;
477 }
478 
479 /*
480  * Disable and remove the RTC driver
481  */
482 static int at91_rtc_remove(struct platform_device *pdev)
483 {
484         struct sam9_rtc *rtc = platform_get_drvdata(pdev);
485         u32             mr = rtt_readl(rtc, MR);
486 
487         /* disable all interrupts */
488         rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
489 
490         if (!IS_ERR(rtc->sclk))
491                 clk_disable_unprepare(rtc->sclk);
492 
493         return 0;
494 }
495 
496 static void at91_rtc_shutdown(struct platform_device *pdev)
497 {
498         struct sam9_rtc *rtc = platform_get_drvdata(pdev);
499         u32             mr = rtt_readl(rtc, MR);
500 
501         rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
502         rtt_writel(rtc, MR, mr & ~rtc->imr);
503 }
504 
505 #ifdef CONFIG_PM_SLEEP
506 
507 /* AT91SAM9 RTC Power management control */
508 
509 static int at91_rtc_suspend(struct device *dev)
510 {
511         struct sam9_rtc *rtc = dev_get_drvdata(dev);
512         u32             mr = rtt_readl(rtc, MR);
513 
514         /*
515          * This IRQ is shared with DBGU and other hardware which isn't
516          * necessarily a wakeup event source.
517          */
518         rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
519         if (rtc->imr) {
520                 if (device_may_wakeup(dev) && (mr & AT91_RTT_ALMIEN)) {
521                         unsigned long flags;
522 
523                         enable_irq_wake(rtc->irq);
524                         spin_lock_irqsave(&rtc->lock, flags);
525                         rtc->suspended = true;
526                         spin_unlock_irqrestore(&rtc->lock, flags);
527                         /* don't let RTTINC cause wakeups */
528                         if (mr & AT91_RTT_RTTINCIEN)
529                                 rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
530                 } else
531                         rtt_writel(rtc, MR, mr & ~rtc->imr);
532         }
533 
534         return 0;
535 }
536 
537 static int at91_rtc_resume(struct device *dev)
538 {
539         struct sam9_rtc *rtc = dev_get_drvdata(dev);
540         u32             mr;
541 
542         if (rtc->imr) {
543                 unsigned long flags;
544 
545                 if (device_may_wakeup(dev))
546                         disable_irq_wake(rtc->irq);
547                 mr = rtt_readl(rtc, MR);
548                 rtt_writel(rtc, MR, mr | rtc->imr);
549 
550                 spin_lock_irqsave(&rtc->lock, flags);
551                 rtc->suspended = false;
552                 at91_rtc_cache_events(rtc);
553                 at91_rtc_flush_events(rtc);
554                 spin_unlock_irqrestore(&rtc->lock, flags);
555         }
556 
557         return 0;
558 }
559 #endif
560 
561 static SIMPLE_DEV_PM_OPS(at91_rtc_pm_ops, at91_rtc_suspend, at91_rtc_resume);
562 
563 #ifdef CONFIG_OF
564 static const struct of_device_id at91_rtc_dt_ids[] = {
565         { .compatible = "atmel,at91sam9260-rtt" },
566         { /* sentinel */ }
567 };
568 MODULE_DEVICE_TABLE(of, at91_rtc_dt_ids);
569 #endif
570 
571 static struct platform_driver at91_rtc_driver = {
572         .probe          = at91_rtc_probe,
573         .remove         = at91_rtc_remove,
574         .shutdown       = at91_rtc_shutdown,
575         .driver         = {
576                 .name   = "rtc-at91sam9",
577                 .pm     = &at91_rtc_pm_ops,
578                 .of_match_table = of_match_ptr(at91_rtc_dt_ids),
579         },
580 };
581 
582 module_platform_driver(at91_rtc_driver);
583 
584 MODULE_AUTHOR("Michel Benoit");
585 MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x");
586 MODULE_LICENSE("GPL");
587 

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