tools: usb: usbip: Add simple script to show how to setup vUDC

Add some simple script which creates a USB gadget using ConfigFS
and then exports it using vUDC.

This may be useful for people who just started playing with
USB/IP and vUDC as it shows exact steps how to setup all stuff.
Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Acked-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tools/usb/usbip/vudc/vudc_server_example.sh

+#!/bin/bash
+
+################################################################################
+# This is free and unencumbered software released into the public domain.
+#
+# Anyone is free to copy, modify, publish, use, compile, sell, or
+# distribute this software, either in source code form or as a compiled
+# binary, for any purpose, commercial or non-commercial, and by any
+# means.
+#
+# In jurisdictions that recognize copyright laws, the author or authors
+# of this software dedicate any and all copyright interest in the
+# software to the public domain. We make this dedication for the benefit
+# of the public at large and to the detriment of our heirs and
+# successors. We intend this dedication to be an overt act of
+# relinquishment in perpetuity of all present and future rights to this
+# software under copyright law.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+# IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+# OTHER DEALINGS IN THE SOFTWARE.
+#
+# For more information, please refer to <http://unlicense.org/>
+################################################################################
+
+################################################################################
+# This is a sample script which shows how to use vUDC with ConfigFS gadgets
+################################################################################
+
+# Stop script on error
+set -e
+
+################################################################################
+# Create your USB gadget
+# You may use bare ConfigFS interface (as below)
+# or libusbgx or gt toool
+# Instead of ConfigFS gadgets you may use any of legacy gadgets.
+################################################################################
+CONFIGFS_MOUNT_POINT="/sys/kernel/config"
+GADGET_NAME="g1"
+ID_VENDOR="0x1d6b"
+ID_PRODUCT="0x0104"
+
+cd ${CONFIGFS_MOUNT_POINT}/usb_gadget
+# Create a new USB gadget
+mkdir ${GADGET_NAME}
+cd ${GADGET_NAME}
+
+# This gadget contains one function - ACM (serial port over USB)
+FUNC_DIR="functions/acm.ser0"
+mkdir ${FUNC_DIR}
+
+# Just one configuration
+mkdir configs/c.1
+ln -s ${FUNC_DIR} configs/c.1
+
+# Set our gadget identity
+echo ${ID_VENDOR} > idVendor
+echo ${ID_PRODUCT} > idProduct
+
+################################################################################
+# Load vudc-module if vudc is not available
+# You may change value of num param to get more than one vUDC instance
+################################################################################
+[[ -d /sys/class/udc/usbip-vudc.0 ]] || modprobe usbip-vudc num=1
+
+################################################################################
+# Bind gadget to our vUDC
+# By default we bind to first one but you may change this if you would like
+# to use more than one instance
+################################################################################
+echo "usbip-vudc.0" > UDC
+
+################################################################################
+# Let's now run our usbip daemon in a USB device mode
+################################################################################
+usbipd --device &
+
+################################################################################
+# Now your USB gadget is available using USB/IP protocol.
+# To prepare your client, you should ensure that usbip-vhci module is inside
+# your kernel. If it's not then you can load it:
+#
+# $ modprobe usbip-vhci
+#
+# To check availability of your gadget you may try to list devices exported
+# on a remote server:
+#
+# $ modprobe usbip-vhci
+# $ usbip list -r $SERVER_IP
+# Exportable USB devices
+# ======================
+# usbipd: info: request 0x8005(6): complete
+#  - 127.0.0.1
+# usbip-vudc.0: Linux Foundation : unknown product (1d6b:0104)
+#            : /sys/devices/platform/usbip-vudc.0
+#            : (Defined at Interface level) (00/00/00)
+#
+# To attach this device to your client you may use:
+#
+# $ usbip attach -r $SERVER_IP -d usbip-vudc.0
+#
+################################################################################