cbfs: Allow CBFS to be used in SPL

Add a new Kconfig option to enable CBFS in SPL. This can be useful when
the memory-init code is in CBFS.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

fs/Makefile

@@ -8,6 +8,7 @@ ifdef CONFIG_SPL_BUILD
 obj-$(CONFIG_FS_LOADER) += fs.o
 obj-$(CONFIG_SPL_FS_FAT) += fat/
 obj-$(CONFIG_SPL_FS_EXT4) += ext4/
+obj-$(CONFIG_SPL_FS_CBFS) += cbfs/
 else
 obj-y				+= fs.o
 

fs/cbfs/Kconfig

@@ -6,3 +6,15 @@ config FS_CBFS
 	  on systems that use coreboot as the first boot-loader and then load
 	  U-Boot to actually boot the Operating System. You can also enable
 	  CMD_CBFS to get command-line access.
+
+config SPL_FS_CBFS
+	bool "Enable CBFS (Coreboot Filesystem) in SPL"
+	help
+	  Define this to enable support for reading from a Coreboot
+	  filesystem. This is a ROM-based filesystem used for accessing files
+	  on systems that use coreboot as the first boot-loader and then load
+	  U-Boot to actually boot the Operating System.
+
+	  Note that most functions in the CBFS API do not work with SPL. Only
+	  those which accept a cbfs_priv * can be used, since BSS is not
+	  available.