[DistroKit] [PATCH 1/8] 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                             |  1 +
 projectroot/usr/lib/udev/of_base_compatible   |  4 ++
 .../lib/udev/rules.d/90-rauc-partitions.rules | 12 ++++++
 rules/rauc-udev.in                            |  8 ++++
 rules/rauc-udev.make                          | 37 +++++++++++++++++++
 5 files changed, 62 insertions(+)
 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 3c8c001aaf8e..a6a3f29afb53 100644
--- a/configs/ptxconfig
+++ b/configs/ptxconfig
@@ -3,6 +3,7 @@
 # PTXdist 2022.12.0
 #
 PTXCONF_DATAPARTITION=y
+PTXCONF_RAUC_UDEV=y
 
 #
 # ------------------------------------
diff --git a/projectroot/usr/lib/udev/of_base_compatible b/projectroot/usr/lib/udev/of_base_compatible
new file mode 100755
index 000000000000..6b59c9cc569d
--- /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' "$(xargs -0  printf "%s " < /sys/firmware/devicetree/base/compatible)"
diff --git a/projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules b/projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules
new file mode 100644
index 000000000000..0300e8b9daad
--- /dev/null
+++ b/projectroot/usr/lib/udev/rules.d/90-rauc-partitions.rules
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: 0-BSD
+# SPDX-FileCopyrightText: 2021 Roland Hieber, Pengutronix <rhi@pengutronix.de>
+
+ACTION=="remove", GOTO="rauc_partitions_end"
+SUBSYSTEM!="block", GOTO="rauc_partitions_end"
+
+IMPORT{program}="of_base_compatible"
+
+# Add symlinks named /dev/disk/by-usage/{data,rootfs0,rootfs1} pointing
+# to the correct partitions based on the device tree compatible
+
+LABEL="rauc_partitions_end"
diff --git a/rules/rauc-udev.in b/rules/rauc-udev.in
new file mode 100644
index 000000000000..4e90343ba2dc
--- /dev/null
+++ b/rules/rauc-udev.in
@@ -0,0 +1,8 @@
+## SECTION=project_specific
+
+config RAUC_UDEV
+	tristate
+	prompt "rauc udev rules"
+	select UDEV if RUNTIME
+	help
+	  udev rules for cross-hardware-compatible partition symlinks
diff --git a/rules/rauc-udev.make b/rules/rauc-udev.make
new file mode 100644
index 000000000000..6a806fc43e34
--- /dev/null
+++ b/rules/rauc-udev.make
@@ -0,0 +1,37 @@
+# -*-makefile-*-
+#
+# Copyright (C) 2021 by Roland Hieber, Pengutronix <rhi@pengutronix.de>
+#
+# For further information about the PTXdist project and license conditions
+# see the README file.
+#
+
+#
+# We provide this package
+#
+PACKAGES-$(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
-- 
2.30.2