Root/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
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
56struct sam9_rtc {
57    void __iomem *rtt;
58    struct rtc_device *rtcdev;
59    u32 imr;
60    void __iomem *gpbr;
61    int irq;
62};
63
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)
68
69#define gpbr_readl(rtc) \
70    __raw_readl((rtc)->gpbr)
71#define gpbr_writel(rtc, val) \
72    __raw_writel((val), (rtc)->gpbr)
73
74/*
75 * Read current time and date in RTC
76 */
77static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
78{
79    struct sam9_rtc *rtc = dev_get_drvdata(dev);
80    u32 secs, secs2;
81    u32 offset;
82
83    /* read current time offset */
84    offset = gpbr_readl(rtc);
85    if (offset == 0)
86        return -EILSEQ;
87
88    /* reread the counter to help sync the two clock domains */
89    secs = rtt_readl(rtc, VR);
90    secs2 = rtt_readl(rtc, VR);
91    if (secs != secs2)
92        secs = rtt_readl(rtc, VR);
93
94    rtc_time_to_tm(offset + secs, tm);
95
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);
99
100    return 0;
101}
102
103/*
104 * Set current time and date in RTC
105 */
106static int at91_rtc_settime(struct device *dev, struct rtc_time *tm)
107{
108    struct sam9_rtc *rtc = dev_get_drvdata(dev);
109    int err;
110    u32 offset, alarm, mr;
111    unsigned long secs;
112
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);
116
117    err = rtc_tm_to_time(tm, &secs);
118    if (err != 0)
119        return err;
120
121    mr = rtt_readl(rtc, MR);
122
123    /* disable interrupts */
124    rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
125
126    /* read current time offset */
127    offset = gpbr_readl(rtc);
128
129    /* store the new base time in a battery backup register */
130    secs += 1;
131    gpbr_writel(rtc, secs);
132
133    /* adjust the alarm time for the new base */
134    alarm = rtt_readl(rtc, AR);
135    if (alarm != ALARM_DISABLED) {
136        if (offset > secs) {
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);
142        } else {
143            /* time jumped past the alarm, disable alarm */
144            alarm = ALARM_DISABLED;
145            mr &= ~AT91_RTT_ALMIEN;
146        }
147        rtt_writel(rtc, AR, alarm);
148    }
149
150    /* reset the timer, and re-enable interrupts */
151    rtt_writel(rtc, MR, mr | AT91_RTT_RTTRST);
152
153    return 0;
154}
155
156static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
157{
158    struct sam9_rtc *rtc = dev_get_drvdata(dev);
159    struct rtc_time *tm = &alrm->time;
160    u32 alarm = rtt_readl(rtc, AR);
161    u32 offset;
162
163    offset = gpbr_readl(rtc);
164    if (offset == 0)
165        return -EILSEQ;
166
167    memset(alrm, 0, sizeof(*alrm));
168    if (alarm != ALARM_DISABLED && offset != 0) {
169        rtc_time_to_tm(offset + alarm, tm);
170
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);
174
175        if (rtt_readl(rtc, MR) & AT91_RTT_ALMIEN)
176            alrm->enabled = 1;
177    }
178
179    return 0;
180}
181
182static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
183{
184    struct sam9_rtc *rtc = dev_get_drvdata(dev);
185    struct rtc_time *tm = &alrm->time;
186    unsigned long secs;
187    u32 offset;
188    u32 mr;
189    int err;
190
191    err = rtc_tm_to_time(tm, &secs);
192    if (err != 0)
193        return err;
194
195    offset = gpbr_readl(rtc);
196    if (offset == 0) {
197        /* time is not set */
198        return -EILSEQ;
199    }
200    mr = rtt_readl(rtc, MR);
201    rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
202
203    /* alarm in the past? finish and leave disabled */
204    if (secs <= offset) {
205        rtt_writel(rtc, AR, ALARM_DISABLED);
206        return 0;
207    }
208
209    /* else set alarm and maybe enable it */
210    rtt_writel(rtc, AR, secs - offset);
211    if (alrm->enabled)
212        rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
213
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);
217
218    return 0;
219}
220
221static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
222{
223    struct sam9_rtc *rtc = dev_get_drvdata(dev);
224    u32 mr = rtt_readl(rtc, MR);
225
226    dev_dbg(dev, "alarm_irq_enable: enabled=%08x, mr %08x\n", enabled, mr);
227    if (enabled)
228        rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
229    else
230        rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
231    return 0;
232}
233
234/*
235 * Provide additional RTC information in /proc/driver/rtc
236 */
237static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
238{
239    struct sam9_rtc *rtc = dev_get_drvdata(dev);
240    u32 mr = mr = rtt_readl(rtc, MR);
241
242    seq_printf(seq, "update_IRQ\t: %s\n",
243            (mr & AT91_RTT_RTTINCIEN) ? "yes" : "no");
244    return 0;
245}
246
247/*
248 * IRQ handler for the RTC
249 */
250static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc)
251{
252    struct sam9_rtc *rtc = _rtc;
253    u32 sr, mr;
254    unsigned long events = 0;
255
256    /* Shared interrupt may be for another device. Note: reading
257     * SR clears it, so we must only read it in this irq handler!
258     */
259    mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
260    sr = rtt_readl(rtc, SR) & (mr >> 16);
261    if (!sr)
262        return IRQ_NONE;
263
264    /* alarm status */
265    if (sr & AT91_RTT_ALMS)
266        events |= (RTC_AF | RTC_IRQF);
267
268    /* timer update/increment */
269    if (sr & AT91_RTT_RTTINC)
270        events |= (RTC_UF | RTC_IRQF);
271
272    rtc_update_irq(rtc->rtcdev, 1, events);
273
274    pr_debug("%s: num=%ld, events=0x%02lx\n", __func__,
275        events >> 8, events & 0x000000FF);
276
277    return IRQ_HANDLED;
278}
279
280static 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,
287};
288
289/*
290 * Initialize and install RTC driver
291 */
292static int __devinit at91_rtc_probe(struct platform_device *pdev)
293{
294    struct resource *r, *r_gpbr;
295    struct sam9_rtc *rtc;
296    int ret, irq;
297    u32 mr;
298
299    r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
300    r_gpbr = platform_get_resource(pdev, IORESOURCE_MEM, 1);
301    if (!r || !r_gpbr) {
302        dev_err(&pdev->dev, "need 2 ressources\n");
303        return -ENODEV;
304    }
305
306    irq = platform_get_irq(pdev, 0);
307    if (irq < 0) {
308        dev_err(&pdev->dev, "failed to get interrupt resource\n");
309        return irq;
310    }
311
312    rtc = kzalloc(sizeof *rtc, GFP_KERNEL);
313    if (!rtc)
314        return -ENOMEM;
315
316    rtc->irq = irq;
317
318    /* platform setup code should have handled this; sigh */
319    if (!device_can_wakeup(&pdev->dev))
320        device_init_wakeup(&pdev->dev, 1);
321
322    platform_set_drvdata(pdev, rtc);
323    rtc->rtt = ioremap(r->start, resource_size(r));
324    if (!rtc->rtt) {
325        dev_err(&pdev->dev, "failed to map registers, aborting.\n");
326        ret = -ENOMEM;
327        goto fail;
328    }
329
330    rtc->gpbr = ioremap(r_gpbr->start, resource_size(r_gpbr));
331    if (!rtc->gpbr) {
332        dev_err(&pdev->dev, "failed to map gpbr registers, aborting.\n");
333        ret = -ENOMEM;
334        goto fail_gpbr;
335    }
336
337    mr = rtt_readl(rtc, MR);
338
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);
342        gpbr_writel(rtc, 0);
343    }
344
345    /* disable all interrupts (same as on shutdown path) */
346    mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
347    rtt_writel(rtc, MR, mr);
348
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);
353        goto fail_register;
354    }
355
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);
359    if (ret) {
360        dev_dbg(&pdev->dev, "can't share IRQ %d?\n", rtc->irq);
361        rtc_device_unregister(rtc->rtcdev);
362        goto fail_register;
363    }
364
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
369     */
370
371    if (gpbr_readl(rtc) == 0)
372        dev_warn(&pdev->dev, "%s: SET TIME!\n",
373                dev_name(&rtc->rtcdev->dev));
374
375    return 0;
376
377fail_register:
378    iounmap(rtc->gpbr);
379fail_gpbr:
380    iounmap(rtc->rtt);
381fail:
382    platform_set_drvdata(pdev, NULL);
383    kfree(rtc);
384    return ret;
385}
386
387/*
388 * Disable and remove the RTC driver
389 */
390static int __devexit at91_rtc_remove(struct platform_device *pdev)
391{
392    struct sam9_rtc *rtc = platform_get_drvdata(pdev);
393    u32 mr = rtt_readl(rtc, MR);
394
395    /* disable all interrupts */
396    rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
397    free_irq(rtc->irq, rtc);
398
399    rtc_device_unregister(rtc->rtcdev);
400
401    iounmap(rtc->gpbr);
402    iounmap(rtc->rtt);
403    platform_set_drvdata(pdev, NULL);
404    kfree(rtc);
405    return 0;
406}
407
408static void at91_rtc_shutdown(struct platform_device *pdev)
409{
410    struct sam9_rtc *rtc = platform_get_drvdata(pdev);
411    u32 mr = rtt_readl(rtc, MR);
412
413    rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
414    rtt_writel(rtc, MR, mr & ~rtc->imr);
415}
416
417#ifdef CONFIG_PM
418
419/* AT91SAM9 RTC Power management control */
420
421static int at91_rtc_suspend(struct platform_device *pdev,
422                    pm_message_t state)
423{
424    struct sam9_rtc *rtc = platform_get_drvdata(pdev);
425    u32 mr = rtt_readl(rtc, MR);
426
427    /*
428     * This IRQ is shared with DBGU and other hardware which isn't
429     * necessarily a wakeup event source.
430     */
431    rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
432    if (rtc->imr) {
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);
438        } else
439            rtt_writel(rtc, MR, mr & ~rtc->imr);
440    }
441
442    return 0;
443}
444
445static int at91_rtc_resume(struct platform_device *pdev)
446{
447    struct sam9_rtc *rtc = platform_get_drvdata(pdev);
448    u32 mr;
449
450    if (rtc->imr) {
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);
455    }
456
457    return 0;
458}
459#else
460#define at91_rtc_suspend NULL
461#define at91_rtc_resume NULL
462#endif
463
464static struct platform_driver at91_rtc_driver = {
465    .probe = at91_rtc_probe,
466    .remove = __devexit_p(at91_rtc_remove),
467    .shutdown = at91_rtc_shutdown,
468    .suspend = at91_rtc_suspend,
469    .resume = at91_rtc_resume,
470    .driver = {
471        .name = "rtc-at91sam9",
472        .owner = THIS_MODULE,
473    },
474};
475
476static int __init at91_rtc_init(void)
477{
478    return platform_driver_register(&at91_rtc_driver);
479}
480module_init(at91_rtc_init);
481
482static void __exit at91_rtc_exit(void)
483{
484    platform_driver_unregister(&at91_rtc_driver);
485}
486module_exit(at91_rtc_exit);
487
488
489MODULE_AUTHOR("Michel Benoit");
490MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x");
491MODULE_LICENSE("GPL");
492

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