mailbox/omap: move the OMAP mailbox framework to drivers

The mailbox hardware (in OMAP) uses a queued mailbox interrupt
mechanism that provides a communication channel between processors
through a set of registers and their associated interrupt signals
by sending and receiving messages.

The OMAP mailbox framework/driver code is moved to be under
drivers/mailbox, in preparation for adapting to a common mailbox
driver framework. This allows the build for OMAP mailbox to be
enabled (it was disabled during the multi-platform support).

As part of the migration from plat and mach code:
- Kconfig symbols have been renamed to build OMAP1 or OMAP2+ drivers.
- mailbox.h under plat-omap/plat/include has been split into a public
  and private header files. The public header has only the API related
  functions and types.
- The module name mailbox.ko from plat-omap is changed to
  omap-mailbox.ko
- The module name mailbox_mach.ko from mach-omapX is changed as
    mailbox_omap1.ko for OMAP1
    mailbox_omap2.ko for OMAP2+

Cc: Tony Lindgren <tony@atomide.com>
[gregkh@linuxfoundation.org: ack for staging part]
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Omar Ramirez Luna <omar.ramirez@copitl.com>
Signed-off-by: Suman Anna <s-anna@ti.com>

drivers/mailbox/Kconfig

@@ -16,4 +16,38 @@ config PL320_MBOX
 	  Management Engine, primarily for cpufreq. Say Y here if you want
 	  to use the PL320 IPCM support.
 
+config OMAP_MBOX
+	tristate
+	help
+	  This option is selected by any OMAP architecture specific mailbox
+	  driver such as CONFIG_OMAP1_MBOX or CONFIG_OMAP2PLUS_MBOX. This
+	  enables the common OMAP mailbox framework code.
+
+config OMAP1_MBOX
+	tristate "OMAP1 Mailbox framework support"
+	depends on ARCH_OMAP1
+	select OMAP_MBOX
+	help
+	  Mailbox implementation for OMAP chips with hardware for
+	  interprocessor communication involving DSP in OMAP1. Say Y here
+	  if you want to use OMAP1 Mailbox framework support.
+
+config OMAP2PLUS_MBOX
+	tristate "OMAP2+ Mailbox framework support"
+	depends on ARCH_OMAP2PLUS
+	select OMAP_MBOX
+	help
+	  Mailbox implementation for OMAP family chips with hardware for
+	  interprocessor communication involving DSP, IVA1.0 and IVA2 in
+	  OMAP2/3; or IPU, IVA HD and DSP in OMAP4/5. Say Y here if you
+	  want to use OMAP2+ Mailbox framework support.
+
+config OMAP_MBOX_KFIFO_SIZE
+	int "Mailbox kfifo default buffer size (bytes)"
+	depends on OMAP2PLUS_MBOX || OMAP1_MBOX
+	default 256
+	help
+	  Specify the default size of mailbox's kfifo buffers (bytes).
+	  This can also be changed at runtime (via the mbox_kfifo_size
+	  module parameter).
 endif