#!/bin/bash

# USB Gadget for Corelis CEC hardware

set -e

g=/sys/kernel/config/usb_gadget/g1
kernel_config=/sys/kernel/config
device="musb-hdrc.0.auto"

cec_usb_up() {
    modprobe libcomposite
	if [ ! -d ${g} ]; then
	  mount -t configfs none ${kernel_config}
	fi
    usb_ver="0x0200" # USB 2.0
    dev_class="2" # Communications
    vid="0x0B1E" # EWA
    pid="0x9010" # NetUSB II
    mfg="Corelis, Inc." # 
    prod="NetUSB II" # 
    # Read bluetooth mac address from eeprom - this is what LEGO firmware uses for serial
    serial="$(grep Serial /proc/cpuinfo | sed 's/Serial\s*: 0000\(\w*\)/\1/')"
    attr="0xC0" # Self powered
    pwr="1" # 2mA
    cfg1="RNDIS"
    cfg2="CDC"
    # add colons for MAC address format
    mac="$(echo ${serial} | sed 's/\(\w\w\)/:\1/g' | cut -b 2-)"
    # Change the first number for each MAC address - the second digit of 2 indicates
    # that these are "locally assigned (b2=1), unicast (b1=0)" addresses. This is
    # so that they don't conflict with any existing vendors. Care should be taken
    # not to change these two bits.
    dev_mac1="22$(echo ${mac} | cut -b 3-)"
    host_mac1="32$(echo ${mac} | cut -b 3-)"
    dev_mac2="02$(echo ${mac} | cut -b 3-)"
    host_mac2="12$(echo ${mac} | cut -b 3-)"
    ms_vendor_code="0xcd" # Microsoft
    ms_qw_sign="MSFT100" # also Microsoft (if you couldn't tell)
    ms_compat_id="RNDIS" # matches Windows RNDIS Drivers
    ms_subcompat_id="5162001" # matches Windows RNDIS 6.0 Driver

#    tmpdir=$(mktemp -d)
#    mount /dev/mmcblk0p1 $tmpdir
#    if [ -f $tmpdir/cecdev.txt ]; then
#        cdc_only=$(grep -i "^cdc_only=\(true\|yes\|1\)" $tmpdir/cecdev.txt | cut -b 10-)
#    fi
#    umount $tmpdir

    if [ -d ${g} ]; then
        if [ "$(cat ${g}/UDC)" != "" ]; then
            echo "Gadget is already up."
            exit 1
        fi
        echo "Cleaning up old directory..."
        cec_usb_down
    fi
    echo "Setting up gadget..."

    # Create a new gadget

    mkdir ${g}
    echo "${usb_ver}" > ${g}/bcdUSB
    echo "${dev_class}" > ${g}/bDeviceClass
    echo "${vid}" > ${g}/idVendor
    echo "${pid}" > ${g}/idProduct
    mkdir ${g}/strings/0x409
    echo "${mfg}" > ${g}/strings/0x409/manufacturer
    echo "${prod}" > ${g}/strings/0x409/product
    echo "${serial}" > ${g}/strings/0x409/serialnumber

    # Create 2 configurations. The first will be RNDIS, which is required by
    # Windows to be first. The second will be CDC. Linux and Mac are smart
    # enough to ignore RNDIS and load the CDC configuration.

    # There is a bug in OS X 10.11 that makes Mac no longer smart enough to
    # use the second configuration. So we've added the cdc_only check to
    # work around this.

    if [ -z $cdc_only ]; then

        # config 1 is for RNDIS

        mkdir ${g}/configs/c.1
        echo "${attr}" > ${g}/configs/c.1/bmAttributes
        echo "${pwr}" > ${g}/configs/c.1/MaxPower
        mkdir ${g}/configs/c.1/strings/0x409
        echo "${cfg1}" > ${g}/configs/c.1/strings/0x409/configuration

        # On Windows 7 and later, the RNDIS 5.1 driver would be used by default,
        # but it does not work very well. The RNDIS 6.0 driver works better. In
        # order to get this driver to load automatically, we have to use a
        # Microsoft-specific extension of USB.

        echo "1" > ${g}/os_desc/use
        echo "${ms_vendor_code}" > ${g}/os_desc/b_vendor_code
        echo "${ms_qw_sign}" > ${g}/os_desc/qw_sign

        # Create the RNDIS function, including the Microsoft-specific bits

        mkdir ${g}/functions/rndis.usb0
        echo "${dev_mac1}" > ${g}/functions/rndis.usb0/dev_addr
        echo "${host_mac1}" > ${g}/functions/rndis.usb0/host_addr
        echo "${ms_compat_id}" > ${g}/functions/rndis.usb0/os_desc/interface.0/compatible_id
        echo "${ms_subcompat_id}" > ${g}/functions/rndis.usb0/os_desc/interface.0/sub_compatible_id
    fi

    # config 2 is for CDC

    mkdir ${g}/configs/c.2
    echo "${attr}" > ${g}/configs/c.2/bmAttributes
    echo "${pwr}" > ${g}/configs/c.2/MaxPower
    mkdir ${g}/configs/c.2/strings/0x409
    echo "${cfg2}" > ${g}/configs/c.2/strings/0x409/configuration

    # Create the CDC function

    mkdir ${g}/functions/ecm.usb0
    echo "${dev_mac2}" > ${g}/functions/ecm.usb0/dev_addr
    echo "${host_mac2}" > ${g}/functions/ecm.usb0/host_addr

    # Link everything up and bind the USB device

    if [ -z $cdc_only ]; then
        ln -s ${g}/functions/rndis.usb0 ${g}/configs/c.1
        ln -s ${g}/configs/c.1 ${g}/os_desc
    fi
    ln -s ${g}/functions/ecm.usb0 ${g}/configs/c.2
    echo "${device}" > ${g}/UDC

    # bring up network interface
    ifup usb0
    sleep 1
    udhcpd /etc/udhcpd.conf

    echo "Done."
}

cec_usb_down() {
    if [ ! -d ${g} ]; then
        echo "Gadget is already down."
        exit 1
    fi
    echo "Taking down gadget..."
    
    # deconfigure so it will work next time
    ifdown usb0

    # Have to unlink and remove directories in reverse order.
    # Checks allow to finish takedown after error.

    if [ "$(cat ${g}/UDC)" != "" ]; then
        echo "" > ${g}/UDC
    fi
    rm -f ${g}/os_desc/c.1
    rm -f ${g}/configs/c.2/ecm.usb0
    rm -f ${g}/configs/c.1/rndis.usb0
    [ -d ${g}/functions/ecm.usb0 ] && rmdir ${g}/functions/ecm.usb0
    [ -d ${g}/functions/rndis.usb0 ] && rmdir ${g}/functions/rndis.usb0
    [ -d ${g}/configs/c.2/strings/0x409 ] && rmdir ${g}/configs/c.2/strings/0x409
    [ -d ${g}/configs/c.2 ] && rmdir ${g}/configs/c.2
    [ -d ${g}/configs/c.1/strings/0x409 ] && rmdir ${g}/configs/c.1/strings/0x409
    [ -d ${g}/configs/c.1 ] && rmdir ${g}/configs/c.1
    [ -d ${g}/strings/0x409 ] && rmdir ${g}/strings/0x409
    rmdir ${g}
	
    umount ${kernel_config}
	
    echo "Done."
}

case $@ in

up)
    cec_usb_up
    ;;
down)
    cec_usb_down
    ;;
*)
    echo "Usage: usb_ether.sh up|down"
    exit 1
    ;;
esac