core: generic_boot: Add add_dt_overlay_fragment()

This patch adds a dt routine add_dt_overlay_fragment(). This purpose of
which is to encapsulate the dynamic FDT node entries OPTEE provides inside
of a

fragment@0 {
        target-path = "/";
        __overlay__ {
                /* OPTEE nodes go here */
        };
};

A subsequent set of patches will wrapper up existing dynamic OPTEE nodes

- /firmware/optee
- /psci
- /reserved/memory
      optee@0xaddress

Once done it will be possible for a DTB in memory to be populated
with OPTEE fragments and for a subsequent bootloader to merge the OPTEE
populated overlay into a DTB loaded by a later stage.

if CFG_EXTERNAL_DTB_OVERLAY is not defined then this code has no effect.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/mk/config.mk b/mk/config.mk
index 80a653ef..c2e14e64 100644
--- a/mk/config.mk
+++ b/mk/config.mk
@@ -275,6 +275,16 @@ CFG_DT ?= n
 # editing of the supplied DTB.
 CFG_DTB_MAX_SIZE ?= 0x10000
 
+# Device Tree Overlay support.
+# This define enables support for an OP-TEE provided DTB overlay.
+# One of two modes is supported in this case:
+# 1. Append OP-TEE nodes to an existing DTB overlay located at CFG_DT_ADDR or
+#    passed in arg2
+# 2. Generate a new DTB overlay at CFG_DT_ADDR
+# A subsequent boot stage must then merge the generated overlay DTB into a main
+# DTB using the standard fdt_overlay_apply() method.
+CFG_EXTERNAL_DTB_OVERLAY ?= n
+
 # Enable core self tests and related pseudo TAs
 CFG_TEE_CORE_EMBED_INTERNAL_TESTS ?= y