download/u-boot: Support reading tree and revision from board.cfg

Boards may want to specify a board-specific U-Boot revision. At the very
least, pseudo-boards for u-boot-libre releases will need to specify their
U-Boot versions somehow.

Copy the existing mechanism from download/coreboot for specifying
build info with board.cfg files. Specify the commit hash for the
'v2021.07' pseudo-board, and 'master' as the default.

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>

4 files changed, 58 insertions, 4 deletions

diff --git a/resources/scripts/download/u-boot b/resources/scripts/download/u-boot
index 7bd8e86d..ecd35adc 100755
--- a/resources/scripts/download/u-boot
+++ b/resources/scripts/download/u-boot
@@ -44,12 +44,62 @@ list_supported_boards() {
 downloadfor() {
 	board="${1}"
 
-	ubtree="u-boot/${board}"
-	uboot_revision="v2021.07"
+	# The loop will always exit, but this while loop is crafted
+	# such that a tree referencing a tree that references another tree is possible
+	# (and so on)
+	while true; do
+		ubrevision="undefined"
+		ubtree="undefined"
+
+		if [ ! -f "resources/u-boot/${board}/board.cfg" ]; then
+			printf "ERROR: %s: board.cfg does not exist for '%s'\n" \
+				"download/u-boot" "${board}"
+			return 1
+		fi
+
+		if [ -f "resources/u-boot/${board}/seen" ]; then
+			printf "ERROR: %s: logical loop; '%s' board.cfg refers to another tree, which ultimately refers back to '%s'.\n" \
+				"download/u-boot" "${board}" "${board}"
+			return 1
+		fi
+
+		# This is to override $ubrevision and $ubtree
+		source "resources/u-boot/${board}/board.cfg" || touch build_error
+		if [ -f build_error ]; then
+			printf "ERROR: %s: problem sourcing %s/board.cfg\n" \
+				"download/u-boot" "${board}"
+			return 1
+		fi
+		touch "resources/u-boot/${board}/seen"
+
+		if [ "${board}" != "${ubtree}" ]; then
+			board="${ubtree}"
+		else
+			if [ "${ubtree}" = "undefined" ]; then
+				printf "ERROR: %s: tree name undefined for '%s\n'" \
+					"download/u-boot" "${board}"
+				return 1
+			fi
+
+			if [ "${ubrevision}" = "undefined" ]; then
+				printf "ERROR: %s: commit ID undefined for '%s'\n" \
+					"download/u-boot" "${board}"
+				return 1
+			fi
+			break
+		fi
+	done
+
+	rm -f resources/u-boot/*/seen
+
+	ubtree="u-boot/${ubtree}"
 	if [ -d "${ubtree}" ]; then
 	    printf \
 		"REMARK: '%s' directory already exists. Skipping setup.\n" \
 		"${ubtree}"
+		if [ "${ubtree}" != "u-boot/${board}" ]; then
+			printf "(for board: '${board}')\n"
+		fi
 		return 0
 	fi
 
@@ -98,12 +148,12 @@ downloadfor() {
 		return 1
 	fi
 
-	git -C "${ubtree}" reset --hard ${uboot_revision} || \
+	git -C "${ubtree}" reset --hard ${ubrevision} || \
 	    touch build_error
 	if [ -f build_error ]; then
 	    printf \
 		"ERROR: %s: Unable to reset to commit ID/tag '%s' for board '%s' on tree '%s'\n" \
-		"download/u-boot" "${uboot_revision}" "${1}" "${ubtree}"
+		"download/u-boot" "${ubrevision}" "${board}" "${ubtree}"
 		return 1
 	fi
 }
diff --git a/resources/u-boot/default/board.cfg b/resources/u-boot/default/board.cfg
new file mode 100644
index 00000000..b821b351
--- /dev/null
+++ b/resources/u-boot/default/board.cfg
@@ -0,0 +1,2 @@
+ubtree="default"
+ubrevision="master"
diff --git a/resources/u-boot/v2021.07/.gitkeep b/resources/u-boot/v2021.07/.gitkeep
deleted file mode 100644
index e69de29b..00000000
--- a/resources/u-boot/v2021.07/.gitkeep
+++ /dev/null
diff --git a/resources/u-boot/v2021.07/board.cfg b/resources/u-boot/v2021.07/board.cfg
new file mode 100644
index 00000000..4bddc10c
--- /dev/null
+++ b/resources/u-boot/v2021.07/board.cfg
@@ -0,0 +1,2 @@
+ubtree="v2021.07"
+ubrevision="840658b093976390e9537724f802281c9c8439f5" # v2021.07