headphone-jack-monitor

#!/bin/bash
# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

# TODO(thutt): Convert to /bin/sh from bash
# TODO(thutt): Lookup board configs by config file installed
# by private overlay.
# TODO(thutt): This scripts makes an assumption that all Arm-based boards use
#       WM8903 and that the board will always have the same codec.
#
NAME=$(basename "${0}");
AMIXER=${AMIXER:-"/usr/bin/amixer"};
SLEEP_TIME=${SLEEP_TIME:-"0.5"}; # Seconds to sleep between GPIO checking.
HP_GPIO="185";                   # Headphone GPIO.
HP_GPIO_DIR="/sys/class/gpio/gpio${HP_GPIO}";
# This represents the board this image is targeted for.
BOARD="$(cat /etc/lsb-release | grep CHROMEOS_RELEASE_BOARD | cut -d'=' -f2)"
# This is the codec chip we are currently using.
CODEC="$(cat /proc/asound/pcm | head -n1 | cut -d':' -f2 | awk '{print $1}')"

declare active_low;           # inv: '0' or '1'.
declare machine_kind;         # inv: An element of 'machine_to_codec'.
declare codec;                # inv: ${machine_to_codec[${machine_kind}]}

function log ()
{
    msg=${1};
    logger "${NAME}: ${msg}.";
}

function failure ()
{
    msg=${1};
    log "Headphone jack cannot be monitored: ${msg}";
    false || exit;
}

function get_gpio_attribute ()
{
    attribute=${1};             # Pathname of GPIO attribute to read.
    shift;
    if [ -f "${attribute}" ] ; then
        cat "${attribute}";
        true && return;
    else
        echo "";
        false || return;
    fi;
}

function wm8903_set_output_headphones ()
{
    ${AMIXER} set 'Speaker' off  &>/dev/null
    ${AMIXER} set 'Int Spk' off    &>/dev/null
    ${AMIXER} set 'Headphone' on &>/dev/null
}

function wm8903_set_output_internal_speaker ()
{
    ${AMIXER} set 'Speaker' on    &>/dev/null
    ${AMIXER} set 'Int Spk' on    &>/dev/null
    ${AMIXER} set 'Headphone' off &>/dev/null
}

function wm8903_initialize ()
{
    # Without enabling DACL, Kaen has no speaker output.
    ${AMIXER} set 'Speaker'   100%              &>/dev/null
    ${AMIXER} set 'Headphone' 100%              &>/dev/null
    ${AMIXER} set 'Digital'   100%              &>/dev/null
    ${AMIXER} set "Left Speaker Mixer DACL"  on &>/dev/null
    ${AMIXER} set "Right Speaker Mixer DACL" on &>/dev/null
    ${AMIXER} set 'ADC Input' 'DMIC'            &>/dev/null
}

function initialize_codec ()
{
    # Board type is found in /etc/lsb-release:
    #    tegra2_seaboard
    # We need to support the audio config per board.
    local machine_kind=$BOARD
    # Codec type is found in /proc/asound/pcm
    # TODO(thutt): We should support more than one codec, and
    # support more than one codec per board. Current implementation
    # is a stopgap.
    codec=""
    if [ "$CODEC" = "WM8903" ]; then
      codec="wm8903"
    fi

    if [ -n "${codec}" ] ; then
        init_fn="${codec}_initialize";
        if declare -f ${init_fn} >/dev/null; then
            ${init_fn};
        else
            false;
        fi;
    else
        false;
    fi;
}

function multiplex ()
{
    local hp_gpio_dir=${1};
    local value_pathname="${hp_gpio_dir}/value";
    local -a value;

    value[1]="-";               # Force mismatch on first loop.
    while true ; do
        value[0]=${value[1]};
        value[1]="$(get_gpio_attribute "${value_pathname}")";
        if [ "${value[0]}" != "${value[1]}" ] ; then
            # Headphone Jack has changed state.
            case "${active_low}${value[1]}" in
                "00" ) ${codec}_set_output_headphones;       ;;
                "01" ) ${codec}_set_output_internal_speaker; ;;
                "10" ) ${codec}_set_output_internal_speaker; ;;
                "11" ) ${codec}_set_output_headphones;       ;;
                *    ) # Ignore invalid combos.
                    ;;
            esac;
        fi;
        sleep ${SLEEP_TIME};
    done;
}

function main ()
{
    local hp_gpio_dir=$(readlink --canonicalize "${HP_GPIO_DIR}");
    if [ ! -d "${hp_gpio_dir}" ] ; then
        failure "'${HP_GPIO_DIR}' does not exist";
    fi;

    active_low=$(get_gpio_attribute "${hp_gpio_dir}/active_low");
    if [ -z "${active_low}" ] ; then
        failure "Unable to determine active low or active high";
    fi;
    multiplex ${hp_gpio_dir}
}

if initialize_codec ; then
    main;
else
    log "Unknown machine / sound codec combo; headphone jack not managed."
fi;
true && exit;