#!/bin/sh
#===============================================================================
#
#  accelerometer_calibrate
#
#  Copyright (C) 2012-2013 by Digi International Inc.
#  All rights reserved.
#
#  This program is free software; you can redistribute it and/or modify it
#  under the terms of the GNU General Public License version 2 as published by
#  the Free Software Foundation.
#
#  !Description: calibrate CCIMX5X accelerometer
#
#  The calibration details for this particular accelerometer (MMA7455L) are in
#  Freescale's Application Note AN3745.
#
#===============================================================================

DEL_PLATFORM="$(cat /sys/kernel/machine/name)"

## Per-platform accelerometer data
# <platform> <driver_name> <i2c_address> <invert X-Y axis>
while read _pl _name _i2c _invertXY; do
	eval "${_pl}_name=\"${_name}\""
	eval "${_pl}_i2c=\"${_i2c}\""
	eval "${_pl}_invertXY=\"${_invertXY}\""
done<<-_EOF_
        ccimx51         mma7455l        1-001d  y
        ccimx53         mma7455l        2-001d
_EOF_

eval SYSFS_I2C_PATH="/sys/bus/i2c/drivers/\${${DEL_PLATFORM}_name}/\${${DEL_PLATFORM}_i2c}"
eval INVERTXY="\${${DEL_PLATFORM}_invertXY}"

SYS_ACCEL_MODE="${SYSFS_I2C_PATH}/mode"
SYS_ACCEL_MEASURE="${SYSFS_I2C_PATH}/measure"
SYS_ACCEL_GSELECT="${SYSFS_I2C_PATH}/gSelect"
SYS_ACCEL_CALIBRATION="${SYSFS_I2C_PATH}/calibration"

CALIBRATION_CFG="/etc/accel_calibration"

get_average_samples() {
	local NUM_SAMPLES="20"
	local x_total="0"
	local y_total="0"
	local z_total="0"
	local _x
	local _y
	local _z
	read _x _y _z < "${SYS_ACCEL_MEASURE}"
	for i in $(seq ${NUM_SAMPLES}); do
		x_total="$(( x_total + _x ))"
		y_total="$(( y_total + _y ))"
		z_total="$(( z_total + _z ))"
		read _x _y _z < "${SYS_ACCEL_MEASURE}"
	done
	X="$(( x_total / ${NUM_SAMPLES} ))"
	Y="$(( y_total / ${NUM_SAMPLES} ))"
	Z="$(( z_total / ${NUM_SAMPLES} ))"
	if [ -n "${INVERTXY}" ]; then
		X="$(( (-1) * X ))"
		Y="$(( (-1) * Y ))"
	fi
}

onexit() {
	local exit_status=${1:-$?}
	echo Exiting $0 with $exit_status
	exit $exit_status
}

trap onexit SIGHUP SIGINT SIGQUIT SIGTERM


if [ -f "${SYS_ACCEL_MODE}" -a -f "${SYS_ACCEL_MEASURE}" \
	-a -f "${SYS_ACCEL_GSELECT}" -a -f "${SYS_ACCEL_CALIBRATION}" ]; then
	: # Accelerometer exists: continue
else
	printf "\n[ERROR]Accelerometer not present\n"
	exit 1
fi

cat <<_EOF_
************************************
*      MMA7455L Accelerometer      *
*        Calibration Script        *
************************************

Please put the module in a flat surface before continuing...

_EOF_

while [ "${gSelect}" != "2" -a "${gSelect}" != "4" -a "${gSelect}" != "8" ]; do
	read -p "Enter g sensitivity (2, 4 or 8): " gSelect
done

echo -n "Measurement" > "${SYS_ACCEL_MODE}"
echo -n "${gSelect}" > "${SYS_ACCEL_GSELECT}"

Z_CALIBRATED="-$((128 / gSelect))"

get_average_samples
read X_offset Y_offset Z_offset < "${SYS_ACCEL_CALIBRATION}"
while [ "${X}" != "0" -o "${Y}" != "0" -o "${Z}" != "${Z_CALIBRATED}" ]; do
	[ "${X}" != "0" ] && X_offset="$((X_offset + (0 - X) * 2))"
	[ "${Y}" != "0" ] && Y_offset="$((Y_offset + (0 - Y) * 2))"
	[ "${Z}" != "${Z_CALIBRATED}" ] && Z_offset="$((Z_offset + (Z_CALIBRATED - Z) * 2))"
	echo -n ${X_offset} ${Y_offset} ${Z_offset} > "${SYS_ACCEL_CALIBRATION}"
	get_average_samples
done

printf "\nDone!. Saving calibration config: ${CALIBRATION_CFG}\n\n"

printf "%s %s %s %s\n" ${gSelect} ${X_offset} ${Y_offset} ${Z_offset} > ${CALIBRATION_CFG}