pifacertc

#!/bin/sh

. /lib/lsb/init-functions


#set_revision_var() {
#    revision=$(grep "Revision" /proc/cpuinfo | sed -e "s/Revision\t: //")
#    RPI2_REVISION=$((16#a01041))
#    RPI3_REVISION=$((16#a02082))
#    if [ "$((16#$revision))" -ge "$RPI3_REVISION" ]; then
#        RPI_REVISION="3"
#    elif [ "$((16#$revision))" -ge "$RPI2_REVISION" ]; then
#        RPI_REVISION="2"
#    else
#        RPI_REVISION="1"
#    fi
#}


case "$1" in

start)
        #check if i2c-tools is installed
        dpkg -s i2c-tools > /dev/null 2>&1
        if [ $? -eq 1 ]; then
                log_failure_msg "The package `i2c-tools` is not installed"
                exit 1
        fi

	#find the valid i2c bus number
        i2cdetect -y 0 > /dev/null 2>&1
        if [ $? -eq 0 ]; then
                i2cbus=0  #i2c-0
        else
                i2cdetect -y 1 > /dev/null 2>&1
                if [ $? -eq 0 ]; then
                        i2cbus=1  #i2c-1
                else
                        log_failure_msg "Cannot communicate on I2C bus 0 or 1. Check that I2C is enabled in raspi-config"
                        exit 1
                fi
        fi
        log_success_msg "Found I2C bus i2c-$i2cbus"

	#make sure i2c-dev kernel module is loaded
        log_success_msg "Probing i2c-dev driver"
        modprobe i2c-dev
        if [ $? -ne 0 ]; then
                log_failure_msg "Probing i2c-dev driver failed, aborting"
                exit 1
        fi


        # Calibrate the RTC (default: 0x47). See datasheet for MCP7940N
        log_success_msg "Calibrating the RTC module"
        i2cset -y $i2cbus 0x6f 0x08 0x47
        if [ $? -ne 0 ]; then
                log_failure_msg "Calibrating the RTC module failed, aborting"
                exit 1
        fi

	#load the mcp7941x driver (will show up as rtc_ds1307 in lsmod)
	log_success_msg "Probing the mcp7941x driver"
	modprobe i2c:mcp7941x
	if [ $? -ne 0 ]; then
		log_failure_msg "Probing the mcp7941x driver failed, aborting"
		exit 1
	fi

	#instantiating the rtc device
	log_success_msg "Add the mcp7941x device in the sys filesystem"
	# https://www.kernel.org/doc/Documentation/i2c/instantiating-devices
	echo mcp7941x 0x6f > /sys/class/i2c-dev/i2c-$i2cbus/device/new_device
	if [ $? -ne 0 ]; then
		log_failure_msg "Adding the mcp7941x device failed, aborting"
		exit 1
	fi

	#pushing the RTC time in the system clock (assuming RTC is in UTC)
	log_success_msg "Synchronise the system clock to the hardware RTC"
	hwclock --hctosys -u
	if [ $? -ne 0 ]; then
		log_failure_msg "Something wrong happened while syncing the RTC to the sys clock!"
		exit 1
	fi
  ;;


stop)

        #check if i2c-tools is installed
        dpkg -s i2c-tools > /dev/null 2>&1
        if [ $? -eq 1 ]; then
                log_failure_msg "The package `i2c-tools` is not installed"
                exit 1
        fi

        i2cdetect -y 0 > /dev/null 2>&1
        if [ $? -eq 0 ]; then
                i2cbus=0  #i2c-0
        else
                i2cdetect -y 1 > /dev/null 2>&1
                if [ $? -eq 0 ]; then
                        i2cbus=1  #i2c-1
                else
                        log_failure_msg "Cannot communicate on I2C bus 0 or 1. Check that I2C is enabled in raspi-config"
                        exit 1
                fi
        fi
        log_success_msg "Found I2C bus i2c-$i2cbus"

        if [ -e /dev/rtc ]; then
		log_success_msg "Removing the mcp7941x device from the sys filesystem"
        	# https://www.kernel.org/doc/Documentation/i2c/instantiating-devices
        	echo 0x6f > /sys/class/i2c-dev/i2c-$i2cbus/device/delete_device
        	if [ $? -ne 0 ]; then
                	log_failure_msg "Removing the mcp7941x device failed"
        	fi
	else
		log_failure_msg "Finding device node /dev/rtc "
	fi

        log_success_msg "Unloading driver"
	rmmod rtc_ds1307
	if [ ! $? -eq 0 ]; then
        	log_failure_msg "Unloading the driver"
        fi
  ;;


restart)
  ;;


*)
    echo "Usage: \$0 [start][stop]" >&2
    exit 3
    ;;
esac

pifacertc.service

[Unit]
Description=PiFace RTC module init
Before=multi-user.target graphical.target
After=mountkernfs.service udev.service remote-fs.target raspi-config.service
Requires=udev.service remote-fs.target raspi-config.service

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/opt/PiFace/pifacertc start
ExecStop=/opt/PiFace/pifacertc stop

[Install]
WantedBy=multi-user.target graphical.target