Difference between revisions of "How to create USB Ethernet gadget for Jetson through configfs"
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| − | + | ==Initial requirements== | |
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'''1)''' First, verify that your kernel has support for configfs | '''1)''' First, verify that your kernel has support for configfs | ||
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sudo systemctl stop nv-l4t-usb-device-mode.service | sudo systemctl stop nv-l4t-usb-device-mode.service | ||
</pre> | </pre> | ||
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| + | ==Create and set up the gadget== | ||
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===Create the gadget=== | ===Create the gadget=== | ||
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</pre> | </pre> | ||
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| + | ===Create the configurations=== | ||
'''7)''' Each gadget consists of a number of configurations. You need to create a directory for each configuration. | '''7)''' Each gadget consists of a number of configurations. You need to create a directory for each configuration. | ||
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mkdir -p "configs/$CFG" | mkdir -p "configs/$CFG" | ||
</pre> | </pre> | ||
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| + | ===Create the functions=== | ||
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| − | '''12)''' Create | + | '''12)''' Create english string for configuration. |
<pre style="background:#d6e4f1"> | <pre style="background:#d6e4f1"> | ||
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</pre> | </pre> | ||
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| + | ===Create network bridge and enable the gadget=== | ||
'''13)''' Create and configure the network bridge. Set the device to "down" initially, the interface will be set to "up" in response to cable presence. | '''13)''' Create and configure the network bridge. Set the device to "down" initially, the interface will be set to "up" in response to cable presence. | ||
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| − | + | ==Bash script to create and enable the gadget== | |
'''1)''' Check the Initial requirements to create the gadget, then create a file for the bash script. | '''1)''' Check the Initial requirements to create the gadget, then create a file for the bash script. | ||
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</pre> | </pre> | ||
| − | ''' | + | '''2)''' Copy the following into ecm_usb_start.sh file. |
<pre style="background:#d6e4f1"> | <pre style="background:#d6e4f1"> | ||
Revision as of 12:03, 9 July 2021
Contents
Introduction
This wiki will guide you through the creation of an USB ethernet gadget using the ECM protocol. For this gadget a Jetson Nano Developer Kit with Jetpack 4.4 was used. The following steps are based NVIDIA's services scripts located at
/opt/nvidia/l4t-usb-device-mode/
and kernel documentation that you can find on the following links
https://www.kernel.org/doc/html/v5.8/usb/gadget_configfs.html#creating-the-configurations
https://www.kernel.org/doc/Documentation/ABI/testing/
Initial requirements
1) First, verify that your kernel has support for configfs
fgrep configfs /proc/filesystems
with the expected output being:
nodev configfs
2) You also need to disable the current devices that NVIDIA creates on start.
sudo systemctl stop nv-l4t-usb-device-mode.service
Create and set up the gadget
Create the gadget
1) Set CONFIGFS_HOME as the mount point for configfs.
CONFIGFS_HOME=/sys/kernel/config
2) Setup some device information.
GADGET_NAME="l4t" VID="0x0955" PID="0x7020" SERIAL="no-serial" MANUF="RR" PRODUCT="RR gadget"
3) For each gadget to be created its corresponding directory must be created.
mkdir -p "$CONFIGFS_HOME/usb_gadget/$GADGET_NAME" cd "$CONFIGFS_HOME/usb_gadget/$GADGET_NAME"
4) Each gadget needs to have its vendor id and product id specified.
echo "$VID" > idVendor echo "$PID" > idProduct
5) A gadget needs serial number, manufacturer and product strings. You need to create a strings subdirectory for each language to store them.
mkdir strings/0x409
6) Then the strings can be specified.
echo "$SERIAL" > strings/0x409/serialnumber echo "$MANUF" > strings/0x409/manufacturer echo "$PRODUCT" > strings/0x409/product
Create the configurations
7) Each gadget consists of a number of configurations. You need to create a directory for each configuration.
CFG="c.1" CFG_STR="ECM" mkdir -p "configs/$CFG"
Create the functions
8) Create a directory for your gadget's functions.
FUNC_NAME="ecm" INSTANCE_NAME="usb0" FUNC="functions/$FUNC_NAME.$INSTANCE_NAME" mkdir -p "$FUNC"
FUNC_NAME corresponds to one of allowed function names and INSTANCE_NAME is an arbitrary string allowed in a filesystem.
9) Each function provides its specific set of attributes. For an ECM gadget, MAC Adresses are needed.
mac_ecm_h="7a:68:46:2f:bd:aa" mac_ecm_d="7a:68:46:2f:bd:ab"
10) Add the attributes.
echo "$mac_ecm_h" > "$FUNC/host_addr" echo "$mac_ecm_d" > "$FUNC/dev_addr"
11) Link functions with their configurations.
ln -sf "$FUNC" "configs/$CFG"
12) Create english string for configuration.
mkdir -p "configs/$CFG/strings/0x409" echo "$CFG_STR" > "configs/$CFG/strings/0x409/configuration"
Create network bridge and enable the gadget
13) Create and configure the network bridge. Set the device to "down" initially, the interface will be set to "up" in response to cable presence.
/sbin/brctl addbr l4tbr0 /sbin/ifconfig l4tbr0 down
14) In order to enable the gadget it must be bound to a UDC (USB Device Controller).
UDC_DEV=`ls /sys/class/udc` echo "$UDC_DEV" > UDC
15) Ethernet devices require additional configuration. This assigns the Ethernet device to an Ethernet bridge, and assigns the static IP to that bridge.
/sbin/brctl addif l4tbr0 "$(cat $FUNC/ifname)" /sbin/ifconfig "$(cat $FUNC/ifname)" up
Bash script to create and enable the gadget
1) Check the Initial requirements to create the gadget, then create a file for the bash script.
touch ecm_usb_start.sh
2) Copy the following into ecm_usb_start.sh file.
#!/bin/bash set -e CONFIGFS_HOME=/sys/kernel/config GADGET_NAME="l4t" VID="0x0955" PID="0x7020" SERIAL="no-serial" MANUF="RR" PRODUCT="RR gadget" mkdir -p "$CONFIGFS_HOME/usb_gadget/$GADGET_NAME" cd "$CONFIGFS_HOME/usb_gadget/$GADGET_NAME" echo "$VID" > idVendor echo "$PID" > idProduct mkdir -p strings/0x409 echo "$SERIAL" > strings/0x409/serialnumber echo "$MANUF" > strings/0x409/manufacturer echo "$PRODUCT" > strings/0x409/product CFG="c.1" CFG_STR="ECM" mkdir -p "configs/$CFG" FUNC_NAME="ecm" INSTANCE_NAME="usb0" FUNC="functions/$FUNC_NAME.$INSTANCE_NAME" mkdir -p "$FUNC" mac_ecm_h="7a:68:46:2f:bd:aa" mac_ecm_d="7a:68:46:2f:bd:ab" echo "$mac_ecm_h" > "$FUNC/host_addr" echo "$mac_ecm_d" > "$FUNC/dev_addr" ln -sf "$FUNC" "configs/$CFG" mkdir -p "configs/$CFG/strings/0x409" echo "$CFG_STR" > "configs/$CFG/strings/0x409/configuration" /sbin/brctl addbr l4tbr0 /sbin/ifconfig l4tbr0 down UDC_DEV=`ls /sys/class/udc` echo "$UDC_DEV" > UDC /sbin/brctl addif l4tbr0 "$(cat $FUNC/ifname)" /sbin/ifconfig "$(cat $FUNC/ifname)" up exit 0
3) Enable execution permissions.
chmod u+x ecm_usb_start.sh
4) Run the script.
sudo ./ecm_usb_start.sh
