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Commit 449321b3 authored by David Brownell's avatar David Brownell Committed by Linus Torvalds
Browse files

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: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Report-by: default avatarW Unruh <unruh@physics.ubc.ca>
Cc: Andrew Victor <avictor.za@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 773be7ee

drivers/rtc/rtc-at91rm9200.c

+6 −10
Original line number Diff line number Diff line
@@ -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;