guess: Add device-tree feature

This feature scans the device tree [1] for compatible nodes and
determines which kernel modules are required for the current hardware.
It is intended to be used in embedded linux environments where device
trees are used to describe hardware.

[1] https://www.devicetree.org/specifications/

Signed-off-by: Alexey Gladkov <[email protected]>

Author: legionus

guess/device-tree/README.md

@@ -0,0 +1,13 @@
+# Guess module: device tree
+
+This feature scans the device tree [1] for compatible nodes and determines which
+kernel modules are required for the current hardware. It is intended to be used
+in embedded linux environments where device trees are used to describe hardware.
+
+You can disable this feature by adding to the `/etc/initrd.mk`:
+```
+DISABLE_GUESS += device-tree
+```
+
+[1] https://www.devicetree.org/specifications/
+[2] https://github.com/devicetree-org/devicetree-specification

guess/device-tree/action

@@ -0,0 +1,29 @@
+#!/bin/bash -eu
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+. guess-functions
+
+$TRACE_SOURCE "Processing ..."
+
+# Check Device Tree and Open Firmware support.
+[ -d "$SYSFS_PATH"/firmware/devicetree ] ||
+	exit 0
+
+# Do the search in reverse order. Searching for modalias files will show us
+# nodes that have kernel modules (uevents are much more than a node with
+# modalias), among them we look for those that have OF_NAME in uevent (mandatory
+# for open firemware) and for these nodes we look for real kernel modules.
+#
+# shellcheck disable=SC2016
+find "$SYSFS_PATH"/devices/ -type f -name modalias -printf '%h/uevent\0' |
+	xargs -r0 grep -l '^OF_NAME=' 2>/dev/null |
+	sed -e 's,/uevent$,/modalias,' |
+	xargs -r sed -e '${ s/$/\n/ }' |
+	depinfo ${KERNEL:+-k "$KERNEL"} --no-prefix --input=- 2>/dev/null |
+	sort -u |
+	sed -r -n -e 's,^.*/lib/modules/[^/]+/,,p' |
+	filter_device_tree_modules |
+while read -r mod; do
+	mod="${mod##*/}"
+	guess_optional_module "${mod%.ko}"
+done

guess/device-tree/rules.mk

@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+PHONY += guess-device-tree
+
+guess-device-tree:
+	$V echo "Processing $@ ..."
+	@ GUESS_SUFFIX=add:$@ \
+	    $(DETECTDIR)/device-tree/action
+
+guess: guess-device-tree

guess/loaded-modules/action

@@ -37,20 +37,7 @@ list_builtin_modules()
 	list_loaded_modules
 	list_builtin_modules
 } |
-	grep -E \
-		-e '^kernel/drivers/bus/' \
-		-e '^kernel/drivers/clk/' \
-		-e '^kernel/drivers/dma/' \
-		-e '^kernel/drivers/i2c/' \
-		-e '^kernel/drivers/mfd/' \
-		-e '^kernel/drivers/mmc/' \
-		-e '^kernel/drivers/nvmem/' \
-		-e '^kernel/drivers/phy/' \
-		-e '^kernel/drivers/power/supply/' \
-		-e '^kernel/drivers/regulator/' \
-		-e '^kernel/drivers/reset/' \
-		-e '^kernel/drivers/soc/' \
-		-e '^kernel/drivers/usb/phy/' |
+	filter_device_tree_modules |
 while read -r mod; do
 	mod="${mod##*/}"
 	guess_optional_module "${mod%.ko}"

tools/guess-functions

@@ -189,4 +189,23 @@ is_active_feature()
 	return 1
 }
 
+filter_device_tree_modules()
+{
+	grep -E \
+		-e '^kernel/drivers/bus/' \
+		-e '^kernel/drivers/clk/' \
+		-e '^kernel/drivers/dma/' \
+		-e '^kernel/drivers/i2c/' \
+		-e '^kernel/drivers/mfd/' \
+		-e '^kernel/drivers/mmc/' \
+		-e '^kernel/drivers/nvmem/' \
+		-e '^kernel/drivers/phy/' \
+		-e '^kernel/drivers/power/supply/' \
+		-e '^kernel/drivers/regulator/' \
+		-e '^kernel/drivers/reset/' \
+		-e '^kernel/drivers/soc/' \
+		-e '^kernel/drivers/usb/phy/' \
+	#
+}
+
 fi #__included_make_initrd_guess_functions