2 * "RTT as Real Time Clock" driver for AT91SAM9 SoC family
4 * (C) 2007 Michel Benoit
6 * Based on rtc-at91rm9200.c by Rick Bronson
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.
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>
24 #include <mach/at91_rtt.h>
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
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.
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.
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.
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.
50 * We store ALARM_DISABLED in ALMV to record that no alarm is set.
51 * It's also the reset value for that field.
53 #define ALARM_DISABLED ((u32)~0)
58 struct rtc_device
*rtcdev
;
64 #define rtt_readl(rtc, field) \
65 __raw_readl((rtc)->rtt + AT91_RTT_ ## field)
66 #define rtt_writel(rtc, field, val) \
67 __raw_writel((val), (rtc)->rtt + AT91_RTT_ ## field)
69 #define gpbr_readl(rtc) \
70 __raw_readl((rtc)->gpbr)
71 #define gpbr_writel(rtc, val) \
72 __raw_writel((val), (rtc)->gpbr)
75 * Read current time and date in RTC
77 static int at91_rtc_readtime(struct device
*dev
, struct rtc_time
*tm
)
79 struct sam9_rtc
*rtc
= dev_get_drvdata(dev
);
83 /* read current time offset */
84 offset
= gpbr_readl(rtc
);
88 /* reread the counter to help sync the two clock domains */
89 secs
= rtt_readl(rtc
, VR
);
90 secs2
= rtt_readl(rtc
, VR
);
92 secs
= rtt_readl(rtc
, VR
);
94 rtc_time_to_tm(offset
+ secs
, tm
);
96 dev_dbg(dev
, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readtime",
97 1900 + tm
->tm_year
, tm
->tm_mon
, tm
->tm_mday
,
98 tm
->tm_hour
, tm
->tm_min
, tm
->tm_sec
);
104 * Set current time and date in RTC
106 static int at91_rtc_settime(struct device
*dev
, struct rtc_time
*tm
)
108 struct sam9_rtc
*rtc
= dev_get_drvdata(dev
);
110 u32 offset
, alarm
, mr
;
113 dev_dbg(dev
, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "settime",
114 1900 + tm
->tm_year
, tm
->tm_mon
, tm
->tm_mday
,
115 tm
->tm_hour
, tm
->tm_min
, tm
->tm_sec
);
117 err
= rtc_tm_to_time(tm
, &secs
);
121 mr
= rtt_readl(rtc
, MR
);
123 /* disable interrupts */
124 rtt_writel(rtc
, MR
, mr
& ~(AT91_RTT_ALMIEN
| AT91_RTT_RTTINCIEN
));
126 /* read current time offset */
127 offset
= gpbr_readl(rtc
);
129 /* store the new base time in a battery backup register */
131 gpbr_writel(rtc
, secs
);
133 /* adjust the alarm time for the new base */
134 alarm
= rtt_readl(rtc
, AR
);
135 if (alarm
!= ALARM_DISABLED
) {
137 /* time jumped backwards, increase time until alarm */
138 alarm
+= (offset
- secs
);
139 } else if ((alarm
+ offset
) > secs
) {
140 /* time jumped forwards, decrease time until alarm */
141 alarm
-= (secs
- offset
);
143 /* time jumped past the alarm, disable alarm */
144 alarm
= ALARM_DISABLED
;
145 mr
&= ~AT91_RTT_ALMIEN
;
147 rtt_writel(rtc
, AR
, alarm
);
150 /* reset the timer, and re-enable interrupts */
151 rtt_writel(rtc
, MR
, mr
| AT91_RTT_RTTRST
);
156 static int at91_rtc_readalarm(struct device
*dev
, struct rtc_wkalrm
*alrm
)
158 struct sam9_rtc
*rtc
= dev_get_drvdata(dev
);
159 struct rtc_time
*tm
= &alrm
->time
;
160 u32 alarm
= rtt_readl(rtc
, AR
);
163 offset
= gpbr_readl(rtc
);
167 memset(alrm
, 0, sizeof(*alrm
));
168 if (alarm
!= ALARM_DISABLED
&& offset
!= 0) {
169 rtc_time_to_tm(offset
+ alarm
, tm
);
171 dev_dbg(dev
, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readalarm",
172 1900 + tm
->tm_year
, tm
->tm_mon
, tm
->tm_mday
,
173 tm
->tm_hour
, tm
->tm_min
, tm
->tm_sec
);
175 if (rtt_readl(rtc
, MR
) & AT91_RTT_ALMIEN
)
182 static int at91_rtc_setalarm(struct device
*dev
, struct rtc_wkalrm
*alrm
)
184 struct sam9_rtc
*rtc
= dev_get_drvdata(dev
);
185 struct rtc_time
*tm
= &alrm
->time
;
191 err
= rtc_tm_to_time(tm
, &secs
);
195 offset
= gpbr_readl(rtc
);
197 /* time is not set */
200 mr
= rtt_readl(rtc
, MR
);
201 rtt_writel(rtc
, MR
, mr
& ~AT91_RTT_ALMIEN
);
203 /* alarm in the past? finish and leave disabled */
204 if (secs
<= offset
) {
205 rtt_writel(rtc
, AR
, ALARM_DISABLED
);
209 /* else set alarm and maybe enable it */
210 rtt_writel(rtc
, AR
, secs
- offset
);
212 rtt_writel(rtc
, MR
, mr
| AT91_RTT_ALMIEN
);
214 dev_dbg(dev
, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "setalarm",
215 tm
->tm_year
, tm
->tm_mon
, tm
->tm_mday
, tm
->tm_hour
,
216 tm
->tm_min
, tm
->tm_sec
);
221 static int at91_rtc_alarm_irq_enable(struct device
*dev
, unsigned int enabled
)
223 struct sam9_rtc
*rtc
= dev_get_drvdata(dev
);
224 u32 mr
= rtt_readl(rtc
, MR
);
226 dev_dbg(dev
, "alarm_irq_enable: enabled=%08x, mr %08x\n", enabled
, mr
);
228 rtt_writel(rtc
, MR
, mr
| AT91_RTT_ALMIEN
);
230 rtt_writel(rtc
, MR
, mr
& ~AT91_RTT_ALMIEN
);
235 * Provide additional RTC information in /proc/driver/rtc
237 static int at91_rtc_proc(struct device
*dev
, struct seq_file
*seq
)
239 struct sam9_rtc
*rtc
= dev_get_drvdata(dev
);
240 u32 mr
= mr
= rtt_readl(rtc
, MR
);
242 seq_printf(seq
, "update_IRQ\t: %s\n",
243 (mr
& AT91_RTT_RTTINCIEN
) ? "yes" : "no");
248 * IRQ handler for the RTC
250 static irqreturn_t
at91_rtc_interrupt(int irq
, void *_rtc
)
252 struct sam9_rtc
*rtc
= _rtc
;
254 unsigned long events
= 0;
256 /* Shared interrupt may be for another device. Note: reading
257 * SR clears it, so we must only read it in this irq handler!
259 mr
= rtt_readl(rtc
, MR
) & (AT91_RTT_ALMIEN
| AT91_RTT_RTTINCIEN
);
260 sr
= rtt_readl(rtc
, SR
) & (mr
>> 16);
265 if (sr
& AT91_RTT_ALMS
)
266 events
|= (RTC_AF
| RTC_IRQF
);
268 /* timer update/increment */
269 if (sr
& AT91_RTT_RTTINC
)
270 events
|= (RTC_UF
| RTC_IRQF
);
272 rtc_update_irq(rtc
->rtcdev
, 1, events
);
274 pr_debug("%s: num=%ld, events=0x%02lx\n", __func__
,
275 events
>> 8, events
& 0x000000FF);
280 static const struct rtc_class_ops at91_rtc_ops
= {
281 .read_time
= at91_rtc_readtime
,
282 .set_time
= at91_rtc_settime
,
283 .read_alarm
= at91_rtc_readalarm
,
284 .set_alarm
= at91_rtc_setalarm
,
285 .proc
= at91_rtc_proc
,
286 .alarm_irq_enable
= at91_rtc_alarm_irq_enable
,
290 * Initialize and install RTC driver
292 static int at91_rtc_probe(struct platform_device
*pdev
)
294 struct resource
*r
, *r_gpbr
;
295 struct sam9_rtc
*rtc
;
299 r
= platform_get_resource(pdev
, IORESOURCE_MEM
, 0);
300 r_gpbr
= platform_get_resource(pdev
, IORESOURCE_MEM
, 1);
302 dev_err(&pdev
->dev
, "need 2 ressources\n");
306 irq
= platform_get_irq(pdev
, 0);
308 dev_err(&pdev
->dev
, "failed to get interrupt resource\n");
312 rtc
= kzalloc(sizeof *rtc
, GFP_KERNEL
);
318 /* platform setup code should have handled this; sigh */
319 if (!device_can_wakeup(&pdev
->dev
))
320 device_init_wakeup(&pdev
->dev
, 1);
322 platform_set_drvdata(pdev
, rtc
);
323 rtc
->rtt
= ioremap(r
->start
, resource_size(r
));
325 dev_err(&pdev
->dev
, "failed to map registers, aborting.\n");
330 rtc
->gpbr
= ioremap(r_gpbr
->start
, resource_size(r_gpbr
));
332 dev_err(&pdev
->dev
, "failed to map gpbr registers, aborting.\n");
337 mr
= rtt_readl(rtc
, MR
);
339 /* unless RTT is counting at 1 Hz, re-initialize it */
340 if ((mr
& AT91_RTT_RTPRES
) != AT91_SLOW_CLOCK
) {
341 mr
= AT91_RTT_RTTRST
| (AT91_SLOW_CLOCK
& AT91_RTT_RTPRES
);
345 /* disable all interrupts (same as on shutdown path) */
346 mr
&= ~(AT91_RTT_ALMIEN
| AT91_RTT_RTTINCIEN
);
347 rtt_writel(rtc
, MR
, mr
);
349 rtc
->rtcdev
= rtc_device_register(pdev
->name
, &pdev
->dev
,
350 &at91_rtc_ops
, THIS_MODULE
);
351 if (IS_ERR(rtc
->rtcdev
)) {
352 ret
= PTR_ERR(rtc
->rtcdev
);
356 /* register irq handler after we know what name we'll use */
357 ret
= request_irq(rtc
->irq
, at91_rtc_interrupt
, IRQF_SHARED
,
358 dev_name(&rtc
->rtcdev
->dev
), rtc
);
360 dev_dbg(&pdev
->dev
, "can't share IRQ %d?\n", rtc
->irq
);
361 rtc_device_unregister(rtc
->rtcdev
);
365 /* NOTE: sam9260 rev A silicon has a ROM bug which resets the
366 * RTT on at least some reboots. If you have that chip, you must
367 * initialize the time from some external source like a GPS, wall
368 * clock, discrete RTC, etc
371 if (gpbr_readl(rtc
) == 0)
372 dev_warn(&pdev
->dev
, "%s: SET TIME!\n",
373 dev_name(&rtc
->rtcdev
->dev
));
382 platform_set_drvdata(pdev
, NULL
);
388 * Disable and remove the RTC driver
390 static int at91_rtc_remove(struct platform_device
*pdev
)
392 struct sam9_rtc
*rtc
= platform_get_drvdata(pdev
);
393 u32 mr
= rtt_readl(rtc
, MR
);
395 /* disable all interrupts */
396 rtt_writel(rtc
, MR
, mr
& ~(AT91_RTT_ALMIEN
| AT91_RTT_RTTINCIEN
));
397 free_irq(rtc
->irq
, rtc
);
399 rtc_device_unregister(rtc
->rtcdev
);
403 platform_set_drvdata(pdev
, NULL
);
408 static void at91_rtc_shutdown(struct platform_device
*pdev
)
410 struct sam9_rtc
*rtc
= platform_get_drvdata(pdev
);
411 u32 mr
= rtt_readl(rtc
, MR
);
413 rtc
->imr
= mr
& (AT91_RTT_ALMIEN
| AT91_RTT_RTTINCIEN
);
414 rtt_writel(rtc
, MR
, mr
& ~rtc
->imr
);
419 /* AT91SAM9 RTC Power management control */
421 static int at91_rtc_suspend(struct platform_device
*pdev
,
424 struct sam9_rtc
*rtc
= platform_get_drvdata(pdev
);
425 u32 mr
= rtt_readl(rtc
, MR
);
428 * This IRQ is shared with DBGU and other hardware which isn't
429 * necessarily a wakeup event source.
431 rtc
->imr
= mr
& (AT91_RTT_ALMIEN
| AT91_RTT_RTTINCIEN
);
433 if (device_may_wakeup(&pdev
->dev
) && (mr
& AT91_RTT_ALMIEN
)) {
434 enable_irq_wake(rtc
->irq
);
435 /* don't let RTTINC cause wakeups */
436 if (mr
& AT91_RTT_RTTINCIEN
)
437 rtt_writel(rtc
, MR
, mr
& ~AT91_RTT_RTTINCIEN
);
439 rtt_writel(rtc
, MR
, mr
& ~rtc
->imr
);
445 static int at91_rtc_resume(struct platform_device
*pdev
)
447 struct sam9_rtc
*rtc
= platform_get_drvdata(pdev
);
451 if (device_may_wakeup(&pdev
->dev
))
452 disable_irq_wake(rtc
->irq
);
453 mr
= rtt_readl(rtc
, MR
);
454 rtt_writel(rtc
, MR
, mr
| rtc
->imr
);
460 #define at91_rtc_suspend NULL
461 #define at91_rtc_resume NULL
464 static struct platform_driver at91_rtc_driver
= {
465 .probe
= at91_rtc_probe
,
466 .remove
= at91_rtc_remove
,
467 .shutdown
= at91_rtc_shutdown
,
468 .suspend
= at91_rtc_suspend
,
469 .resume
= at91_rtc_resume
,
471 .name
= "rtc-at91sam9",
472 .owner
= THIS_MODULE
,
476 module_platform_driver(at91_rtc_driver
);
478 MODULE_AUTHOR("Michel Benoit");
479 MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x");
480 MODULE_LICENSE("GPL");