ARM: mvebu: add cpuidle support for Armada 370

ARM: mvebu: add cpuidle support for Armada 370

This commit introduces the cpuidle support for Armada 370. The main
difference compared to the already supported Armada XP is that the
Armada 370 has an issue caused by "a slow exit process from the deep
idle state due to heavy L1/L2 cache cleanup operations performed by
the BootROM software" (cf errata GL-BootROM-10).

To work around this issue, we replace the restart code of the BootROM
by some custom code located in an internal SRAM. For this purpose, we
use the common function mvebu_boot_addr_wa() introduced in the commit
"ARM: mvebu: Add a common function for the boot address work around".

The message in case of failure to suspend the system was switched from
the warn level to the debug level. Indeed due to the "slow exit
process from the deep idle state" in Armada 370, this situation
happens quite often. Using the debug level avoids spamming the kernel
logs, but still allows to enable it if needed.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1406120453-29291-15-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>