at91_poweroff_get_wakeup_mode can return a negative error code and should
therefore not return an enum type. Similar, its result should not be
assigned to an enum type. Otherwise, the returned value is never negative,
resulting in a compiler warning and a missed error condition, which in turn
results in writing bad values into a chip register.

Also fix other compiler warnings which can be easily avoided.

drivers/power/reset/at91-poweroff.c:74:24:
	warning: type qualifiers ignored on function return type
drivers/power/reset/at91-poweroff.c:74:24:
	warning: no previous prototype for 'at91_poweroff_get_wakeup_mode'
drivers/power/reset/at91-poweroff.c:83:16:
	warning: comparison between signed and unsigned integer expressions
drivers/power/reset/at91-poweroff.c:97:2:
	warning: comparison of unsigned expression < 0 is always false

Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Acked-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: NSebastian Reichel <sre@kernel.org>

The wakeup status is read from Shutdown Status Register and not the
SHDW_CR which is the one at address 0.
Signed-off-by: NNicolas Ferre <nicolas.ferre@atmel.com>

Add a driver to handle the shutdown of the Atmel SoCs. This code used to be
(and still is) in arch/arm/mach-at91. We didn't remove it yet so that we can
convert all the boards to using this driver, before removing it entirely in a
separate patch.
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: NNicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>