The controller has 3 mailbox channels, the last of which can be
used in Secure mode only.
+config IMX_MBOX
+ tristate "i.MX Mailbox"
+ depends on ARCH_MXC || COMPILE_TEST
+ help
+ Mailbox implementation for i.MX Messaging Unit (MU).
+
config PLATFORM_MHU
tristate "Platform MHU Mailbox"
depends on OF