#!/bin/sh
###############################################################################
# Determines the Open Firmware path based on the linux device name
#
# Joseph Jezak <josejx@gentoo.org> Copyright (C) 2010
# Rewrite of OFPath for newer kernels/scsi configurations
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
#
###############################################################################

### Set this to 1 to turn on debugging messages
DEBUG=0

### Find the device tree
if [ ! -e /proc/device-tree ]; then
	echo 1>&2 "ofpath: Cannot find the device tree!"
	exit 1
fi
DEV_TREE="/proc/device-tree"

### Check if sys is mounted
if ! (grep -q '.* .* sysfs ' /proc/mounts 2> /dev/null) ; then
	echo 1>&2 "ofpath: sysfs must be mounted for ofpath to support this system"
        exit 1
fi

### Get the sysfs mount point
SYS="$(m=`grep '.* .* sysfs ' /proc/mounts | head -n 1` ; echo `d=${m#* };echo ${d%% *}`)"
if [ -z "$SYS" -o ! -d "$SYS" ] ; then
	echo 1>&2 "ofpath: Unable to determine sysfs mountpoint"
	exit 1
fi


### Get the device from the user
### We dereference links to support devices like /dev/cdrom1
DEVICE=$1
if [ -z "$DEVICE" ]; then
	echo 1>&2 "ofpath: No device specified!"
	exit 1
fi
DEVICE=$(readlink -f "$DEVICE")
DEVICE=$(basename $DEVICE)
if [ -z "$DEVICE" ] || [ ! -e "/dev/$DEVICE" ]; then
	echo 1>&2 "ofpath: Invalid device: /dev/$DEVICE"
	exit 1
fi
[ "$DEBUG" = 1 ] && echo "Device is: $DEVICE"

### Get the partition if we have it
case ${DEVICE} in
	sd*) PARTITION="${DEVICE#sd?}" ;;
	### No partition for sr/sg devices
	sr*|sg*) PARTITION="${DEVICE#sr?}" ;;
	hd*) PARTITION="${DEVICE#hd?}" ;;
	*) echo "Unknown device string."; exit 1;;
esac
if [ ! -z "$PARTITION" ] && [ "$DEBUG" = 1 ]; then
	echo "Partition: $PARTITION"
fi

### Get the disk device name
DISK_NAME="${DEVICE%%${PARTITION}}"
[ "$DEBUG" = 1 ] && echo "Disk Name: $DISK_NAME"

### Find the devspec for the controller
DEVPATH=$(cd -P "$SYS/block/${DISK_NAME}/device" && pwd)
if [ -z "$DEVPATH" ]; then
	echo "Unable to determine device path!"
	exit 1
fi
[ "$DEBUG" = 1 ] && echo "Devpath is: $DEVPATH"

### Get the OF Path of the controller
case ${DISK_NAME} in
	sd*|sg*|sr*) CONTROLLER_PATH=$(cat ${DEVPATH}/../../../devspec) ;;
	hd*) CONTROLLER_PATH=$(cat ${DEVPATH}/../../devspec) ;;
	*) CONTROLLER_PATH="" ;;
esac
if [ -z "$CONTROLLER_PATH" ]; then
	echo "Unable to determine controller path!"
	exit 1
fi
[ "$DEBUG" = 1 ] && echo "Controller Path is: $CONTROLLER_PATH"

### Generate the disk number and partition info
case ${DISK_NAME} in
	sd*|sg*|sr*)
		DISK_NO="$(cd ${DEVPATH}/../; pwd)";
		DISK_NO="${DISK_NO##*:}";
		;;
	hd*)
		DISK_NO="$(cd ${DEVPATH}/../; pwd)";
		DISK_NO="${DISK_NO##*ide}";
		;;
	*) echo "Unsupported disk type!"; exit 1 ;;
esac
DISK_NO="disk@${DISK_NO}:"
[ "$DEBUG" = 1 ] && echo "Disk Number: ${DISK_NO}"

### We need to get the controller port path (if it has one)
if [ ! -d "$DEV_TREE/$CONTROLLER_PATH/disk" ] && [ ! -d "$DEV_TREE/$CONTROLLER_PATH/$DISK_NO" ]; then
	### FIXME I don't know if every scsi device uses the host nomenclature
	case ${DISK_NAME} in 
		sd*|sg*|sr*)
			PORT="$(cd ${DEVPATH}/../../; pwd)";
			PORT="${PORT##*host}";
			CTL_PORT="${CONTROLLER_PATH##*/}";
			CTL_PORT="${CTL_PORT%%-root*}";
			PORT="$CTL_PORT@$PORT"
			[ "$DEBUG" = 1 ] && echo "Port: $PORT"
			;;
		*) echo "Unsupported disk type!"; exit 1 ;;
	esac
fi

### Add the partition information if required
if [ ! -z $PARTITION ]; then
	DISK_NO="$DISK_NO$PARTITION"
fi

### Build the OF Path
if [ -z "$PORT" ]; then
	OFPATH="$CONTROLLER_PATH/$DISK_NO"
else
	OFPATH="$CONTROLLER_PATH/${PORT}/$DISK_NO"
fi

### Print out the ofpath
echo $OFPATH