#!/bin/sh

# Script which detect automaticaly the alsa-states file to put
# in place in fuonction of board on which the script are executed.
#
# This script are use with systemd-generators
# see man for more information or
# https://www.freedesktop.org/software/systemd/man/systemd.generator.html
#
# How to debug:
# mkdir /tmp/normal-dir /tmp/early-dir /tmp/late-dir
# SYSTEMD_LOG_LEVEL=debug /lib/systemd/system-generators/system-generator-alsa-states \
#        /tmp/normal-dir /tmp/early-dir /tmp/late-dir
# find /tmp/normal-dir /tmp/early-dir /tmp/late-dir
#
#
function debug_print() {
    if `echo $SYSTEMD_LOG_LEVEL |grep -q debug` ;
    then
        echo "[DEBUG] $@"
    fi
}

#
# Main
#
if [ ! -d /proc/device-tree/ ];
then
    debug_print "Proc Device tree are not available, Could not detect on which board we are"
    exit 1
fi
if [ -e /var/lib/alsa/asound.state ];
then
    LINE=`cat /var/lib/alsa/asound.state | wc -l`
    if [ $LINE -lt 3 ];
    then
        # dummy alsa-state file contains only one comment
        debug_print "remove previous dummy alsa-state file"
        rm /var/lib/alsa/asound.state
    else
        debug_print "alsa-state file already configured"
        exit 0
    fi
fi
# get the name file available for alsa-states
ALSA_STATE_FILES=`ls -1 /var/lib/alsa/asound-*`

for f in $ALSA_STATE_FILES;
do
    #extract name of board
    board=`echo $f | sed -e "s|/var/lib/alsa/asound-\(.*\).state|\1|"`
    #search on device tree compatible entry if the board are present
    if `grep -q $board /proc/device-tree/compatible` ;
    then
        # device tree compatible entry match with board name
        # configure alsa-state
        if test -x /usr/sbin/alsactl
        then
            debug_print "active alsactl with $f"
            #/usr/sbin/alsactl -f $f restore
            cp $f /var/lib/alsa/asound.state
            break;
        fi
    fi
done
exit 0