[DistroKit] [PATCH 03/14] rauc-udev: add a compatibility layer for mapping partitions

[Roland Hieber <rhi@pengutronix.de>]

When we add RAUC support for different platforms later, we need a way to
specify their respective root partitions in RAUC's system.conf; however,
the names of the actual partitions can differ on different hardware
platforms. Add a short udev rule that can add symlinks to the actual
partitions based on the device tree compatible. This way we can refer to
the partitions in system.conf using the symlinks on all boards that we
want to support.

This commit only adds a stub for now; we will add the code that creates
the actual symlinks for each hardware in later commits.

Signed-off-by: Roland Hieber <rhi@pengutronix.de>
---
 configs/ptxconfig                             |  5 ++-
 projectroot/usr/lib/udev/of_base_compatible   |  4 ++
 .../lib/udev/rules.d/90-rauc-partitions.rules | 15 ++++++++
 rules/rauc-udev.in                            | 10 +++++
 rules/rauc-udev.make                          | 37 +++++++++++++++++++
 5 files changed, 70 insertions(+), 1 deletion(-)
 create mode 100755 projectroot/usr/lib/udev/of_base_compatible
 create mode 100644 projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules
 create mode 100644 rules/rauc-udev.in
 create mode 100644 rules/rauc-udev.make

diff --git a/configs/ptxconfig b/configs/ptxconfig
index 170c12408553..9f4fc06d5138 100644
--- a/configs/ptxconfig
+++ b/configs/ptxconfig
@@ -3,6 +3,7 @@
 # PTXdist 2023.05.0
 #
 PTXCONF_DATAPARTITION=y
+PTXCONF_RAUC_UDEV=y
 
 #
 # ------------------------------------
@@ -700,7 +701,9 @@ PTXCONF_BUSYBOX_TEST=y
 # PTXCONF_BUSYBOX_TIMEOUT is not set
 PTXCONF_BUSYBOX_TOUCH=y
 PTXCONF_BUSYBOX_FEATURE_TOUCH_SUSV3=y
-# PTXCONF_BUSYBOX_TR is not set
+PTXCONF_BUSYBOX_TR=y
+PTXCONF_BUSYBOX_FEATURE_TR_CLASSES=y
+PTXCONF_BUSYBOX_FEATURE_TR_EQUIV=y
 PTXCONF_BUSYBOX_TRUE=y
 # PTXCONF_BUSYBOX_TRUNCATE is not set
 # PTXCONF_BUSYBOX_TSORT is not set
diff --git a/projectroot/usr/lib/udev/of_base_compatible b/projectroot/usr/lib/udev/of_base_compatible
new file mode 100755
index 000000000000..07c7f767ad90
--- /dev/null
+++ b/projectroot/usr/lib/udev/of_base_compatible
@@ -0,0 +1,4 @@
+#!/bin/sh
+# SPDX-License-Identifier: 0-BSD
+# SPDX-FileCopyrightText: 2021 Roland Hieber, Pengutronix <rhi@pengutronix.de>
+printf 'OF_BASE_COMPATIBLE="%s"\n' "$(tr '\0' ' ' < /sys/firmware/devicetree/base/compatible)"
diff --git a/projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules b/projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules
new file mode 100644
index 000000000000..c08f9b5633dc
--- /dev/null
+++ b/projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: 0-BSD
+# SPDX-FileCopyrightText: 2021 Roland Hieber, Pengutronix <rhi@pengutronix.de>
+
+ACTION=="remove", GOTO="rauc_partitions_end"
+SUBSYSTEM!="block", GOTO="rauc_partitions_end"
+
+IMPORT{program}="of_base_compatible"
+
+# Add symlinks named /dev/disk/by-usage/{data,rootfs0,rootfs1} pointing
+# to the correct partitions based on the device tree compatible
+
+# fallback for boards not yet supported by RAUC
+KERNEL=="mmcblk0p3", SYMLINK+="disk/by-usage/data"
+
+LABEL="rauc_partitions_end"
diff --git a/rules/rauc-udev.in b/rules/rauc-udev.in
new file mode 100644
index 000000000000..f960c537f58f
--- /dev/null
+++ b/rules/rauc-udev.in
@@ -0,0 +1,10 @@
+## SECTION=project_specific
+
+config RAUC_UDEV
+	tristate
+	prompt "rauc udev rules"
+	select BUSYBOX		if RUNTIME
+	select BUSYBOX_TR	if RUNTIME
+	select UDEV		if RUNTIME
+	help
+	  udev rules for cross-hardware-compatible partition symlinks
diff --git a/rules/rauc-udev.make b/rules/rauc-udev.make
new file mode 100644
index 000000000000..6a806fc43e34
--- /dev/null
+++ b/rules/rauc-udev.make
@@ -0,0 +1,37 @@
+# -*-makefile-*-
+#
+# Copyright (C) 2021 by Roland Hieber, Pengutronix <rhi@pengutronix.de>
+#
+# For further information about the PTXdist project and license conditions
+# see the README file.
+#
+
+#
+# We provide this package
+#
+PACKAGES-$(PTXCONF_RAUC_UDEV) += rauc-udev
+
+RAUC_UDEV_VERSION	:= 1
+RAUC_UDEV_LICENSE	:= 0-BSD
+
+# ----------------------------------------------------------------------------
+# Target-Install
+# ----------------------------------------------------------------------------
+
+$(STATEDIR)/rauc-udev.targetinstall:
+	@$(call targetinfo)
+
+	@$(call install_init, rauc-udev)
+	@$(call install_fixup,rauc-udev,PRIORITY,optional)
+	@$(call install_fixup,rauc-udev,SECTION,base)
+	@$(call install_fixup,rauc-udev,AUTHOR,"Roland Hieber, Pengutronix <rhi@pengutronix.de>")
+	@$(call install_fixup,rauc-udev,DESCRIPTION,missing)
+
+	@$(call install_alternative, rauc-udev, 0, 0, 0755, /usr/lib/udev/of_base_compatible)
+	@$(call install_alternative, rauc-udev, 0, 0, 0644, /usr/lib/udev/rules.d/90-rauc-partitions.rules)
+
+	@$(call install_finish,rauc-udev)
+
+	@$(call touch)
+
+# vim: syntax=make
-- 
2.39.2