#!/bin/sh

CONFIGFS_HOME=/sys/kernel/config
VID=0xabcd
PID=0x1234
serial_number="myserial"
manufacturer="mymfg"
product="myproduct"
name="c"
number="1"
configuration=""
maxpower="120"

### UVC gadget function
CONFIG="configs/$name.$number"

# FUNCTION="<name>.<instance name>"
# where <name> corresponds to one of allowed function names and instance name is an arbitrary string allowed in a filesystem
FUNCTION="uvc.0"
STREAM_MAXPACKET="2048"

# where <udc name> is one of those found in /sys/class/udc/*
UDC_NAME="f8102800.usb"
# UDC_NAME="f80a1000.dwc3"

# load libcomposite module
modprobe libcomposite

### 1. Create a gadget ###
mount -t configfs none $CONFIGFS_HOME
mkdir -p $CONFIGFS_HOME/usb_gadget/g1

# cd to its configfs node
cd $CONFIGFS_HOME/usb_gadget/g1

# Each gadget needs to have its vendor id <VID> and product id <PID> specified:
# configure it (vid/pid can be anything if USB Class is used for driver compat)
echo $VID > idVendor
echo $PID > idProduct

# A gadget also needs its serial number, manufacturer and product strings
# In order to have a place to store them, a strings subdirectory must be createdfor each language
# Create English string
mkdir -p strings/0x409

# Then the strings can be specified(configure its serial/mfg/product):
echo $serial_number > strings/0x409/serialnumber
echo $manufacturer > strings/0x409/manufacturer
echo $product > strings/0x409/product

### 2. Creating the configurations ###
# Each gadget will consist of a number of configurations, their corresponding directories must be created:
# where <name> can be any string which is legal in a filesystem and the <number> is the configuration's number
mkdir -p configs/$name.$number

# Each configuration also needs its strings, so a subdirectory must be created for each language.
mkdir -p configs/$name.$number/strings/0x409

# Then the configuration string can be specified:
# echo $configuration > configs/c.1/strings/0x409/configuration
# Some attributes can also be set for a configuration, e.g.:
# echo $maxpower > configs/$name.$number/MaxPower

### 3. Creating the functions ###
# The gadget will provide some functions, for each function its corresponding directory must be created:
# Create UVC gadget function
mkdir -p functions/$FUNCTION

# Each function provides its specific set of attributes, with either read-only or read-write access.
# Where applicable they need to be written to as appropriate.

create_function() {
        # Example usage:
        # create_function <width> <height> <format> <name>

        WIDTH=$1
        HEIGHT=$2
        FORMAT=$3
        NAME=$4

        wdir=functions/$FUNCTION/streaming/$FORMAT/$NAME/${HEIGHT}p
        mkdir -p $wdir

        echo $WIDTH  > $wdir/wWidth
        echo $HEIGHT > $wdir/wHeight

        echo 29491200 > $wdir/dwMinBitRate
        echo 29491200 > $wdir/dwMaxBitRate

        echo $(( $WIDTH * $HEIGHT * 2 )) > $wdir/dwMaxVideoFrameBufferSize

        # dwFrameInterfal is in 100-ns units (fps = 1/(dwFrameInterval * 10000000))
        # 333333 -> 30 fps
        # 666666 -> 15 fps
        # 5000000 -> 2 fps
        cat <<EOF > $wdir/dwFrameInterval
333333
666666
5000000
EOF
}

# YUY2 resolution
create_function 640 360 uncompressed u
create_function 640 480 uncompressed u
create_function 1280 720 uncompressed u

# MJPEG resolution
create_function 640 360 mjpeg m
create_function 640 480 mjpeg m
create_function 1280 720 mjpeg m

# Create header
mkdir -p functions/$FUNCTION/streaming/header/h
cd functions/$FUNCTION/streaming/header/h
ln -s ../../uncompressed/u
ln -s ../../mjpeg/m
cd ../../class/fs
ln -s ../../header/h
cd ../../class/hs
ln -s ../../header/h
cd ../../class/ss
ln -s ../../header/h
cd ../../../control
mkdir -p header/h
ln -s header/h class/fs
ln -s header/h class/ss
cd ../../../

# Configure max packet size
echo $STREAM_MAXPACKET > functions/$FUNCTION/streaming_maxpacket

### 4. Associating the functions with theireirthe functions with theirheir eir  configurations
# At this moment a number of gadgets is created, each of which has a number of
# configurations specified and a number of functions available. What remains
# is specifying which function is available in which configuration (the same
# function can be used in multiple configurations). This is achieved with
# creating symbolic links:
# Assign configuration to function
ln -s functions/$FUNCTION configs/$name.$number

### 5. Enabling the gadget
# In order to enable the gadget it must be bound to a UDC (USB Device Controller).
# Bind USB Device Controller (UDC)
echo $UDC_NAME > UDC