#!/bin/sh

MODE="NOT_SET"
FILE="NOT_SET"
TYPE="NOT_SET"

usage()
{
	echo "eepflash: Writes or reads .eep binary image to/from HAT EEPROM on a Raspberry Pi"
	echo ""
	echo "./eepflash.sh"
	echo "	-h --help: display this help message"
	echo "	-r --read: read .eep from the eeprom"
	echo "	-w --write: write .eep to the eeprom"
	echo "	-f=file_name --file=file_name: binary .eep file to read to/from"
	echo "	-t=eeprom_type --type=eeprom_type: eeprom type to use"
	echo "		We support the following eeprom types:"
	echo "		-24c32"
	echo "		-24c64"
	echo "		-24c128"
	echo "		-24c256"
	echo "		-24c512"
	echo "		-24c1024"
	echo ""
}

if [ "$(id -u)" != "0" ]; then
   echo "This script must be run as root" 1>&2
   exit 1
fi
 
while [ "$1" != "" ]; do
    PARAM=`echo $1 | awk -F= '{print $1}'`
    VALUE=`echo $1 | awk -F= '{print $2}'`
	case $PARAM in
		-h | --help)
			usage
			exit
			;;
		-r | --read)
			MODE="read"
			;;
		-w | --write)
			MODE="write"
			;;
		-t | --type)
			if [ "$VALUE" = "24c32" ] || [ "$VALUE" = "24c64" ] || [ "$VALUE" = "24c128" ] ||
				[ "$VALUE" = "24c256" ] || [ "$VALUE" = "24c512" ] || [ "$VALUE" = "24c1024" ]; then
					TYPE=$VALUE
			else
				echo "ERROR: Unrecognised eeprom type. Try -h for help"
				exit 1
			fi
			;;
		-f | --file)
			FILE=$VALUE
			;;
		*)
			echo "ERROR: unknown parameter \"$PARAM\""
			usage
			exit 1
			;;
    esac
    shift
done
 
if [ "$MODE" = "NOT_SET" ]; then
	echo "You need to set mode (read or write). Try -h for help."
	exit 1
elif [ "$FILE"  = "NOT_SET" ]; then
	echo "You need to set binary .eep file to read to/from. Try -h for help."
	exit 1
elif [ "$TYPE" = "NOT_SET" ]; then
	echo "You need to set eeprom type. Try -h for help."
	exit 1
fi

echo "This will attempt to talk to an eeprom at i2c address 0x50. Make sure there is an eeprom at this address."
echo "This script comes with ABSOLUTELY no warranty. Continue only if you know what you are doing."

while true; do
	read -p "Do you wish to continue? (yes/no): " yn
	case $yn in
		yes | Yes ) break;;
		no | No ) exit;;
		* ) echo "Please type yes or no.";;
	esac
done

modprobe i2c_dev
dtoverlay i2c-gpio i2c_gpio_sda=0 i2c_gpio_scl=1
rc=$?
if [ $rc != 0 ]; then
	echo "Loading of i2c-gpio dtoverlay failed. Do an rpi-update (and maybe apt-get update; apt-get upgrade)."
	exit $rc
fi
modprobe at24
rc=$?
if [ $rc != 0 ]; then
	echo "Modprobe of at24 failed. Do an rpi-update."
	exit $rc
fi

if [ ! -d "/sys/class/i2c-adapter/i2c-3/3-0050" ]; then
	echo "$TYPE 0x50" > /sys/class/i2c-adapter/i2c-3/new_device
fi


if [ "$MODE" = "write" ]
 then
	echo "Writing..."
	dd if=$FILE of=/sys/class/i2c-adapter/i2c-3/3-0050/eeprom
	rc=$?
elif [ "$MODE" = "read" ]
 then
	echo "Reading..."
	dd if=/sys/class/i2c-adapter/i2c-3/3-0050/eeprom of=$FILE
	rc=$?
fi

if [ $rc != 0 ]; then
	echo "Error doing I/O operation."
	exit $rc
else
	echo "Done."
fi