dts: renamed FIT_EMBED to MULTI_DTB_FIT and moved it to the dts Kconfig

CONFIG_FIT_EMBED might be confused with CONFIG_OF_EMBED, rename it
MULTI_DTB_FIT as it is able to get a DTB from a FIT image containing
multiple DTBs. Also move the option to the Kconfig dedicated to the DTS
options and create a README for this feature.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/doc/README.multi-dtb-fit b/doc/README.multi-dtb-fit
new file mode 100644
index 00000000000..0d4f068bbf3
--- /dev/null
+++ b/doc/README.multi-dtb-fit
@@ -0,0 +1,15 @@
+MULTI DTB FIT
+
+The purpose of this feature is to enable u-boot to select its DTB from a FIT
+appended at the end of the binary.
+
+Usually the DTB is selected by the SPL and passed down to U-Boot. But some
+platforms don't use the SPL. In this case MULTI_DTB_FIT can used to provide
+U-Boot with a choice of DTBs.
+The relevant DTBs are packed into a FIT (list provided by CONFIG__OF_LIST). The
+FIT is automatically generated at the end of the compilation and appended to
+u-boot.bin so that U-Boot can locate it and select the correct DTB from inside
+the FIT.
+The selection is done using board_fit_config_name_match() (same as what the SPL
+uses to select the DTB for U-Boot). The selection happens during fdtdec_setup()
+which is called during before relocation by board_init_f().