gpio/omap: free irq domain in probe() failure paths

Currently the IRQ domain is not freed once allocated, in the case where
omap_gpio_probe() fails. Therefore, ensure we free the domain if the
probe does fail. Furthermore, the local variable "ret" is not needed
and so remove this.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
gpio/omap: remove extra context restores in *_runtime_resume()

68942edb09f69b6e09522d1d346665eb3aadde49 (gpio/omap: fix wakeups
on level-triggered GPIOs) already restores the fallingdetect and
risingdetect contexts in *_runtime_resume(). These registers were
modified in *_runtime_suspend() to include even those configured
as level-triggered since only edge-triggered gpios can generate
wakeup events. Therefore, the old context restores of the same
registers present later in the code is not needed any more.
Remove them.

Signed-off-by: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Signed-off-by: Jon Hunter <jon-hunter@ti.com>
gpio/omap: optimise interrupt service routine

The OMAP GPIO interrupt service routine is checking each bit in the
GPIO interrupt status register to see which bits are set. It is not
efficient to check every bit especially if only a few bits are set.
Therefore, instead of checking every bit use the __ffs() function,
which returns the location of the first set bit, to find all the set
bits.

This optimisation was suggested-by and developed in collaboration
with Felipe Balbi.

Cc: Felipe Balbi <balbi@ti.com>

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
gpio/omap: force restore if context loss is not detectable

When booting with device-tree the function pointer for detecting context
loss is not populated. Ideally, the pm_runtime framework should be
enhanced to allow a means for reporting context/state loss and we could
avoid populating such function pointers altogether. In the interim until
a generic non-device specific solution is in place, force a restore of
the gpio bank when enabling the gpio controller.

Adds a new device-tree property for the OMAP GPIO controller to indicate
if the GPIO controller is located in a power-domain that never loses
power and hence will always maintain its logic state.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
ARM: dts: OMAP2+: Identify GPIO banks that are always powered

Add the "ti,gpio-always-on" property to the appropriate GPIO banks to
indicate which banks are always powered and will never lose logic state.

Cc: Benoit Cousson <b-cousson@ti.com>
Signed-off-by: Jon Hunter <jon-hunter@ti.com>