tree c588c40d2f69226b0fd050771f35d422bbd814c3
parent 8e6583f1b5d1f5f129b873f1428b7e414263d847
author Uwe Kleine-König <uwe@kleine-koenig.org> 1467473290 +0200
committer Alexandre Belloni <alexandre.belloni@free-electrons.com> 1468272154 +0200

rtc: s35390a: improve irq handling

On some QNAP NAS devices the rtc can wake the machine. Several people
noticed that once the machine was woken this way it fails to shut down.
That's because the driver fails to acknowledge the interrupt and so it
keeps active and restarts the machine immediatly after shutdown. See
https://bugs.debian.org/794266 for a bug report.

Doing this correctly requires to interpret the INT2 flag of the first read
of the STATUS1 register because this bit is cleared by read.

Note this is not maximally robust though because a pending irq isn't
detected when the STATUS1 register was already read (and so INT2 is not
set) but the irq was not disabled. But that is a hardware imposed problem
that cannot easily be fixed by software.

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>