Reliable hostapd init script - example with brcmfmac driver in GB region - See http://skl.me/#wifi-access-point-in-debian

hostapd

#!/bin/sh

### BEGIN INIT INFO
# Provides:             hostapd
# Required-Start:       $remote_fs
# Required-Stop:        $remote_fs
# Should-Start:         $network
# Should-Stop:
# Default-Start:        2 3 4 5
# Default-Stop:         0 1 6
# Short-Description:    Advanced IEEE 802.11 management daemon
# Description:          Userspace IEEE 802.11 AP and IEEE 802.1X/WPA/WPA2/EAP
#                       Authenticator
### END INIT INFO

PATH=/sbin:/bin:/usr/sbin:/usr/bin
DAEMON_SBIN=/usr/sbin/hostapd
DAEMON_CONF=/etc/hostapd/hostapd.conf
NAME=hostapd
DESC="advanced IEEE 802.11 management"
PIDFILE=/var/run/hostapd.pid

[ -x "$DAEMON_SBIN" ] || exit 0
[ -n "$DAEMON_CONF" ] || exit 0

DAEMON_OPTS="-B -P $PIDFILE $DAEMON_OPTS $DAEMON_CONF"

. /lib/lsb/init-functions

case "$1" in
    start)
        log_daemon_msg "Starting $DESC" "$NAME"

        modprobe brcmfmac
	    sleep 2

        rfkill unblock wifi
        ip link set wlan0 up
        iw wlan0 set power_save off
	ifconfig wlan0 192.168.100.1

        start-stop-daemon --start --quiet --exec "$DAEMON_SBIN" \
            --pidfile "$PIDFILE" -- $DAEMON_OPTS >/dev/null
        log_end_msg "$?"
        ;;
    stop)
        log_daemon_msg "Stopping $DESC" "$NAME"
        start-stop-daemon --stop --quiet --exec "$DAEMON_SBIN" \
            --pidfile "$PIDFILE"

        ip link set wlan0 down
        modprobe -r brcmfmac
        log_end_msg "$?"
        ;;
    reload)
        log_daemon_msg "Reloading $DESC" "$NAME"
        start-stop-daemon --stop --signal HUP --exec "$DAEMON_SBIN" \
            --pidfile "$PIDFILE"
        log_end_msg "$?"
        ;;
    restart|force-reload)
        $0 stop
        sleep 2
        $0 start
        ;;
    status)
        start-stop-daemon -p "$PIDFILE" --status
        exit $?
        ;;
    *)
        N=/etc/init.d/$NAME
        echo "Usage: $N {start|stop|restart|force-reload|reload|status}" >&2
        exit 1
        ;;
esac

exit 0

hostapd.conf

ssid=
wpa_passphrase=
interface=wlan0
hw_mode=g
channel=6
country_code=GB
ieee80211d=1
ieee80211h=1
ieee80211n=1
wmm_enabled=1
wme_enabled=1
auth_algs=1
wpa=2
wpa_key_mgmt=WPA-PSK
rsn_pairwise=CCMP