Fake serial number of USB device

udevusb

I have a mobile phone connected to my PC via USB.

When viewing the device info using

sudo udevadm info --attribute-walk

the product and vendor id's show up fine, but there is no ATTR{serial}. An application I'm using (Android adb) needs the device to report a serial number to work properly.

Is there any way I can fake the serial number of the device, for example by using a udev rule?

Clarification: The question is not on how to get the serial number of the USB device, but on how to set the serial number.

I had an Android phone that does not report a serial number over USB, and the adb tool did not like this too much. So far there does not seem to be any simple solution for this. However, there days it is very easy to just buy a proper Android phone for development.

Best Answer

First, make sure that the device not reporting a serial number is really the problem. adb devices will list the serial number as all question marks if it doesn't have permission to access the corresponding device under /dev/bus/usb/. Also remember the adb starts up a server, you may need to kill that to get it to re-probe.

Assuming it really is a problem with the device, I quickly checked the adb source code. It appears register_device in core/adb/usb_linux.c reads the serial number straight from the device. core/adb/usb_libusb.c calls libusb_get_device_descriptor to do it, which (checking the libusb source code) grabs it from sysfs or directly from the device. So no udev trickery is going to help, unfortunately.

Your choices would seem to be:

figure out how to make adb work without a serial number. Possibly, patch adb (it is open source). This is a question more for Stack Overflow, I think.
patch to kernel usbfs driver to fake a response to adb's request. This sounds much harder than patching adb to me.
patch the kernel to allow faking the serial # in syfs, assuming adb is using libusb.
fix the broken hardware.

Related Solutions

Use a Linux directory as a USB-OTG device to an Android phone

The IOIO board interfaces to Android as an OTG device. You can even use the power to the IOIO board to charge the android phone. More info here: https://github.com/ytai/ioio/wiki

You could use the board's UART port to create an interface to the pc. I am currently using this board to spit out data from my app to a microcontroller and it works very well.

You will probably need to write some software to make it work at both ends but the hard work seems to have been done.

Python – How to make a udev rule using a “sibling” device’s serial number (for USB devices with no unique serials)

Well, this is not an answer to the question but brings me a solution. so here it is.

I fiddle quite a bit with Udev rules, could not get anything better than my Arduino persistently appear on /dev/arduino01 (will use /dev/arduino02, /dev/arduino03,... for other jigs)

My testing script is in Python, I just found out that there is a nice library called pyudev so I decided to have a look at this route.

After just few minutes, I ended up with

from pyudev import *
context = Context()
Arduino = Device.from_device_file(context, '/dev/arduino01') 
Hub = Arduino.find_parent("usb","usb_device").find_parent("usb") #first find_parent brings me up to the USB device Arduino, another find_parent brings me to the Hub

Fixture = Enumerator(context)
for dev in Fixture.match_parent(Hub).match_subsystem('tty'):
    if (dev.get('ID_VENDOR_ID')=="10c4" and dev.get('ID_MODEL_ID')=="ea60"): #I got those ID through udevadm.
        powermeter=dev
    if (dev.get('ID_VENDOR_ID')=="067b" and dev.get('ID_MODEL_ID')=="2303"): #I got those ID through udevadm.
        temprecorder=dev

print('Arduino in on ' + str(Arduino.device_node)) #prints : Arduino is on /dev/ttyACM0
print('Powermeter in on ' + str(powermeter.device_node)) #prints : Powermeter is on /dev/ttyUSB1
print('Thermometer in on ' + str(temprecorder.device_node)) #prints : Thermometer is on /dev/ttyUSB0

This gives me the USB ports of my 3 devices of the test jig, I can now feed it to my testing routine script.

The more savvy between us will then have seen that my temprecorder is through a pl2303 USB-serial and my powermeter through a CP2102 USB-serial.

Best Answer

Related Solutions

Use a Linux directory as a USB-OTG device to an Android phone

Python – How to make a udev rule using a “sibling” device’s serial number (for USB devices with no unique serials)

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