coreboot: introduce boot_device

The boot_device is a region_device that represents the
device from which coreboot retrieves and boots its stages.
The existing cbfs implementations use the boot_device as
the intermediary for accessing the CBFS region. Also,
there's currently only support for a read-only view of
the boot_device. i.e. one cannot write to the boot_device
using this view. However, a writable boot_device could
be added in the future.

Change-Id: Ic0da796ab161b8025c90631be3423ba6473ad31c
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/10216
Tested-by: build bot (Jenkins)
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/lib/Makefile.inc

@@ -31,6 +31,7 @@ bootblock-y += memchr.c
 bootblock-y += memcmp.c
 bootblock-y += mem_pool.c
 bootblock-y += region.c
+bootblock-y += boot_device.c
 
 verstage-y += prog_ops.c
 verstage-y += delay.c
@@ -40,6 +41,7 @@ verstage-y += halt.c
 verstage-y += memcmp.c
 verstage-$(CONFIG_COLLECT_TIMESTAMPS) += timestamp.c
 verstage-y += region.c
+verstage-y += boot_device.c
 verstage-$(CONFIG_CONSOLE_CBMEM) += cbmem_console.c
 verstage-$(CONFIG_COMMON_CBFS_SPI_WRAPPER) += cbfs_spi.c
 
@@ -141,7 +143,11 @@ ramstage-y += mem_pool.c
 
 romstage-y += region.c
 ramstage-y += region.c
+romstage-y += boot_device.c
+ramstage-y += boot_device.c
 
+smm-y += region.c
+smm-y += boot_device.c
 smm-y += cbfs.c cbfs_core.c memcmp.c
 smm-$(CONFIG_COMPILER_GCC) += gcc.c