zdev: Integrate firmware auto-configuration with initramfs-tools

Add initramfs-tools scripts that apply firmware-provided I/O
configuration data as auto-configuration during boot. This way, all I/O
devices configured by DPM are automatically brought online without
further user interaction.

This mechanism is active by default. It can be deactivated by specifying
the following parameter on the kernel command line:

  rd.zdev=no-auto

Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zdev/initramfs/hooks/zdev

@@ -0,0 +1,39 @@
+#!/bin/sh
+#
+# Copyright IBM Corp. 2016, 2017
+#
+# s390-tools is free software; you can redistribute it and/or modify
+# it under the terms of the MIT license. See LICENSE for details.
+#
+# hooks/zdev
+#   This hook script adds files required to apply firmware-provided I/O
+#   configuration data during boot.
+#
+
+PREREQ=""
+
+prereqs()
+{
+	echo "$PREREQ"
+}
+
+case $1 in
+	prereqs)
+	prereqs
+	exit 0
+	;;
+esac
+
+. /usr/share/initramfs-tools/hook-functions
+
+# Add modules for all device types supported by chzdev (required for
+# auto-configuration)
+zdev_modules="lcs qeth qeth_l2 qeth_l3 dasd_mod dasd_eckd_mod dasd_fba_mod dasd_diag_mod zfcp"
+
+for x in $zdev_modules ; do
+	manual_add_modules ${x}
+done
+
+copy_exec /sbin/chzdev
+copy_exec /sbin/lszdev
+copy_exec /sbin/vmcp