fdt: Add support for embedded device tree (CONFIG_OF_EMBED)
This new option allows U-Boot to embed a binary device tree into its image
to allow run-time control of peripherals. This device tree is for U-Boot's
own use and is not necessarily the same one as is passed to the kernel.
The device tree compiler output should be placed in the $(obj)
rooted tree. Since $(OBJCOPY) insists on adding the path to the
generated symbol names, to ensure consistency it should be
invoked from the directory where the .dtb file is located and
given the input file name without the path.
This commit contains my entry for the ugliest Makefile / shell interaction
competition.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/README b/README
index d618957..094869c 100644
--- a/README
+++ b/README
@@ -824,8 +824,15 @@
experimental and only available on a few boards. The device
tree is available in the global data as gd->fdt_blob.
- U-Boot needs to get its device tree from somewhere. This will
- be enabled in a future patch.
+ U-Boot needs to get its device tree from somewhere. At present
+ the only way is to embed it in the image with CONFIG_OF_EMBED.
+
+ CONFIG_OF_EMBED
+ If this variable is defined, U-Boot will embed a device tree
+ binary in its image. This device tree file should be in the
+ board directory and called <soc>-<board>.dts. The binary file
+ is then picked up in board_init_f() and made available through
+ the global data structure as gd->blob.
- Watchdog:
CONFIG_WATCHDOG