Autorotate to tablet mode for Linux

#!/usr/bin/env bash
# tivasyk <[email protected]>
# License: GPU GPL v3

# Settings
# --------
# It's probably a good idea to verify these prior to first use of the script and
# modify if necessary.

# IIO devices path (Linux industrial I/O subsystem)
# One probably does not need to change this
# iio_devices_path - path to the iio devices buffer tree
# iio_devices_name - the file containing device name
iio_devices_path="/sys/bus/iio/devices/iio:device"
iio_devices_name="name"

# Accelerometer device path and sensor files
# accel_device_name - what we expect to find in the ../iio:deviceX/name file
# accel_device_path - will be populated by identify_device(), may be set to override
# accel_sensor_x - the channel file of the axis to check for screen rotation (x,y,z)
accel_device_name="accel_3d"
accel_device_path=""
accel_sensor_x="in_accel_x_raw"
accel_sensor_y="in_accel_y_raw"
accel_sensor_z="in_accel_z_raw"

# Current display that will be rotated. This will be populated automatically
# with the name of connected output (xrandr) by the script if left empty.
# Otherwise one can fill this in manually to omit automatical detection
xdisplay=""

# Input devices (touchpad and touchscreen)
# One probably needs to run xinput --list to verify the names of the input devices
# actually present and modify these variables accordingly. Leaving one of them blank
# will omit rotation for that device.
touchpad=''
touchscreen='SYNAPTICS Synaptics Touch Digitizer V04'

# Error codes
error_arguments=1   # Incorrect argument(s) either to the script or a function
error_device=2      # Accelerometer device path or folder structure not found?
error_sensor=3      # Accelerometer sensor channel file $accel_sensor not found?

# Functions
# ---------
show_help() {
    local NAME
    NAME=$(basename "$0")
    cat <<EOF
$NAME is a shell script that will check the IIO accelerometer sensor and turn to tablet or laptop mode: set the screen and touchscreen orientation according to rotation, launch onboard keyboard.

Usage: $NAME [--cont [<interval>]] [--help]

    -h, --help  Print this help and quit
    -c, --cont  Run continuously at specified interval (default 1s)

Example: $NAME --cont 2 &   # Run the script in the background at 2s intervals

NOTE: The script has only been tested on Acer Aspire R13 (R7-371T) transformer laptop.
EOF
}

identify_device() {
    # Will look for the device whose name is given as the only argument,
    # by comparing the devices names in /sys/bus/iio/devices/iio:deviceX/name
    # file and return the path to the device folder.
    # Relies on the devices_path variable set in the Setting section.
    # Process arguments:
    if [[ $# -eq 0 ]]; then
        # Incorrect arguments
        exit ${error_arguments}
    else
        local device_name="${1}"
    fi
    # Loop through all devices and check names:
    local device
    for device in "${iio_devices_path}"* ; do
        if [[ $(cat "${device}/${iio_devices_name}") == "${device_name}" ]]; then
            echo "${device}"
        fi
    done
}

read_accelerometer() {
    # The first argument is obligatory and should specify one axis
    # of the accelerometer device: -x, -y or -z
    # Also --raw will not try to decode the reading.
    # Process arguments:
    if [[ $# -eq 0 ]]; then
        # Incorrect arguments
        exit ${error_arguments}
    else
        while [[ "$*" != "" ]]; do
            local accel_sensor=${accel_sensor_x}
            case "$1" in
                # Check for --raw option
                "-r"|"--raw" ) local option_raw=1 ; shift ;;
                # Select accelerometer axis (-x is default)
                "-x" ) shift ;;
                "-y" ) accel_sensor=${accel_sensor_y} ; shift ;;
                "-z" ) accel_sensor=${accel_sensor_z} ; shift ;;
                # Ignore any other options
                * ) shift ;;
            esac
        done
    fi
    # Read the sensor:
    if [[ -f "${accel_device_path}/${accel_sensor}" ]]; then
        local reading ; reading=$(cat "${accel_device_path}/${accel_sensor}")
    else
        # No sensor file found?
        exit ${error_sensor}
    fi
    # Decode the reading
    # It's a 16-bit signed integer, but reads as a string
    # 1..1000 : positive angle (0-90°)
    # 65575..54576 : negative angle (0-90°)
    local max_reading=1000
    local max_positive=32767
    local max_integer=65535
    # Decode reading into degrees (unless option_raw in set)
    if [[ -z ${option_raw} ]]; then
        if [[ ${reading} -gt ${max_positive} ]]; then
            echo "$(((reading - max_integer) / (max_reading / 90)))"
        else
            echo "$((reading / (max_reading / 90)))"
        fi
    else
        echo "${reading}"
    fi
}

rotate_screen() {
    # Will try to rotate the display and input devices, using:
    # xrandr to rotate the display picture;
    # xinput to rotate the touchpad and touchscreen (via Coordinate Transformation Matrix).
    # Relies on touchpad and touchscreen variables set in the Settings section.
    # Rotate the display:
    xrandr --output $1 --rotate $2
    # Rotate the input devices
    transform='Coordinate Transformation Matrix'
    case "$2" in
        normal)
        [ ! -z "$touchpad" ]    && xinput set-prop "$touchpad"    "$transform" 1 0 0 0 1 0 0 0 1
        [ ! -z "$touchscreen" ] && xinput set-prop "$touchscreen" "$transform" 1 0 0 0 1 0 0 0 1
        ;;
        inverted)
        [ ! -z "$touchpad" ]    && xinput set-prop "$touchpad"    "$transform" -1 0 1 0 -1 1 0 0 1
        [ ! -z "$touchscreen" ] && xinput set-prop "$touchscreen" "$transform" -1 0 1 0 -1 1 0 0 1
        ;;
        left)
        [ ! -z "$touchpad" ]    && xinput set-prop "$touchpad"    "$transform" 0 -1 1 1 0 0 0 0 1
        [ ! -z "$touchscreen" ] && xinput set-prop "$touchscreen" "$transform" 0 -1 1 1 0 0 0 0 1
        ;;
        right)
        [ ! -z "$touchpad" ]    && xinput set-prop "$touchpad"    "$transform" 0 1 0 -1 0 1 0 0 1
        [ ! -z "$touchscreen" ] && xinput set-prop "$touchscreen" "$transform" 0 1 0 -1 0 1 0 0 1
        ;;
    esac
}

main() {
    # Process arguments
    while [[ "$*" != "" ]]; do
        case "$1" in
            "-h"|"--help" )
                show_help
                exit 0
                ;;
            "-c"|"--cont" )
                # Check next argument for repeat interval
                option_cont=1
                shift
                if [[ ! -z "$1" && -z "${1//[0-9.]/}" ]]; then
                    option_cont="$1"
                    shift
                fi
                ;;
            * )
                ;;
        esac
    done
    # Identify the current display to be rotated
    if [[ "${xdisplay}" == "" ]]; then
        xdisplay=`xrandr --current | grep " connected" | sed -e 's/ .*//g'`
    fi
    # Identify the accelerometer device, unless the accel_device_path has been set manually
    if [[ "${accel_device_path}" == "" ]]; then
        accel_device_path=$(identify_device ${accel_device_name})
    fi
    # Run the test
    while true ; do
        # Get the screen rotation angle from the accelerometer sensor
        angle_x=$(read_accelerometer -x)
        angle_y=$(read_accelerometer -y)
        angle_z=$(read_accelerometer -z)
        # Check orientation
        if [[ ${angle_z//-/} -lt 80 && ${angle_x} -gt 20 ]]; then
            echo "Screen orientation: left (x=${angle_x}, y=${angle_y}, z=${angle_z})"
            rotate_screen ${xdisplay} left
        elif [[ ${angle_z//-/} -lt 80 && ${angle_x} -lt -20 ]]; then
            echo "Screen orientation: right (x=${angle_x}, y=${angle_y}, z=${angle_z})"
            rotate_screen ${xdisplay} right
        elif [[ ${angle_y//-/} -gt 20 && ${angle_x//-/} -lt 20 ]]; then
            echo "Screen orientation: normal (x=${angle_x}, y=${angle_y}, z=${angle_z})"
            rotate_screen ${xdisplay} normal
        else
            echo "Screen orientation: keep (x=${angle_x}, y=${angle_y}, z=${angle_z})"
        fi
        # Run continuously (option_cont)?
        if [[ "${option_cont}" == "" ]]; then
           exit 0
        else
        sleep ${option_cont}
        fi
     done
}

main "$@"