rtc: rtc-isl12057: add isil,irq2-can-wakeup-machine property for in-tree users

Current in-tree users of ISL12057 RTC chip (NETGEAR ReadyNAS 102, 104 and
2120) do not have the IRQ#2 pin of the chip (associated w/ the Alarm1
mechanism) connected to their SoC, but to a PMIC (TPS65251 FWIW).  This
specific hardware configuration allows the NAS to wake up when the alarms
rings.

Recently introduced alarm support for ISL12057 relies on the provision of
an "interrupts" property in system .dts file, which previous three users
will never get.  For that reason, alarm support on those devices is not
function.  To support this use case, this patch adds a new DT property for
ISL12057 (isil,irq2-can-wakeup-machine) to indicate that the chip is
capable of waking up the device using its IRQ#2 pin (even though it does
not have its IRQ#2 pin connected directly to the SoC).

This specific configuration was tested on a ReadyNAS 102 by setting an
alarm, powering off the device and see it reboot as expected when the
alarm rang w/:

  # echo `date '+%s' -d '+ 1 minutes'` > /sys/class/rtc/rtc0/wakealarm
  # shutdown -h now

As a side note, the ISL12057 remains in the list of trivial devices,
because the property is not per se required by the device to work but can
help handle system w/ specific requirements.  In exchange, the new feature
is described in details in a specific documentation file.

Signed-off-by: Arnaud Ebalard <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Alessandro Zummo <[email protected]>
Cc: Peter Huewe <[email protected]>
Cc: Linus Walleij <[email protected]>
Cc: Thierry Reding <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Darshana Padmadas <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Pawel Moll <[email protected]>
Cc: Stephen Warren <[email protected]>
Cc: Ian Campbell <[email protected]>
Cc: Grant Likely <[email protected]>
Cc: Rob Landley <[email protected]>
Cc: Jason Cooper <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Kumar Gala <[email protected]>
Cc: Uwe Kleine-König <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions