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rtc-at91rm9200: avoid spurious irqs 

This fixes kernel http://bugzilla.kernel.org/show_bug.cgi?id=11112 (bogus
RTC update IRQs reported) for rtc-at91rm9200 by scrubbing old IRQ status
before enabling IRQs.

It also removes nonfunctional periodic IRQ support from this driver;
only update IRQs are reported, or provided by the hardware.

I suspect some other RTCs probably have versions of #11112; it's easy to
overlook, since most non-RTC drivers don't care about spurious IRQs:
they're not reported to userspace.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Report-by: W Unruh <unruh@physics.ubc.ca>
Cc: Andrew Victor <avictor.za@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Brownell 2008-07-23 21:30:46 -07:00 committed by Linus Torvalds
parent 773be7ee97
commit 449321b39f
1 changed files with 6 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
drivers/rtc/rtc-at91rm9200.c
View File

@ -171,8 +171,10 @@ static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
| BIN2BCD(tm.tm_mday) << 24
| AT91_RTC_DATEEN | AT91_RTC_MTHEN);
if (alrm->enabled)
if (alrm->enabled) {
at91_sys_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
at91_sys_write(AT91_RTC_IER, AT91_RTC_ALARM);
}
pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __func__,
at91_alarm_year, tm.tm_mon, tm.tm_mday, tm.tm_hour,
@ -191,28 +193,22 @@ static int at91_rtc_ioctl(struct device *dev, unsigned int cmd,
pr_debug("%s(): cmd=%08x, arg=%08lx.\n", __func__, cmd, arg);
/* important: scrub old status before enabling IRQs */
switch (cmd) {
case RTC_AIE_OFF: /* alarm off */
at91_sys_write(AT91_RTC_IDR, AT91_RTC_ALARM);
break;
case RTC_AIE_ON: /* alarm on */
at91_sys_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
at91_sys_write(AT91_RTC_IER, AT91_RTC_ALARM);
break;
case RTC_UIE_OFF: /* update off */
case RTC_PIE_OFF: /* periodic off */
at91_sys_write(AT91_RTC_IDR, AT91_RTC_SECEV);
break;
case RTC_UIE_ON: /* update on */
case RTC_PIE_ON: /* periodic on */
at91_sys_write(AT91_RTC_SCCR, AT91_RTC_SECEV);
at91_sys_write(AT91_RTC_IER, AT91_RTC_SECEV);
break;
case RTC_IRQP_READ: /* read periodic alarm frequency */
ret = put_user(AT91_RTC_FREQ, (unsigned long *) arg);
break;
case RTC_IRQP_SET: /* set periodic alarm frequency */
if (arg != AT91_RTC_FREQ)
ret = -EINVAL;
break;
default:
ret = -ENOIOCTLCMD;
break;