cp210x usb to serial converter linux driver

Silicon labs have a range of usb to serial converters called the cp210x series. With modern OEM computers moving away from installing serial ports these devices are becoming more and more useful. Now, cp210x actually refers to the chipset that is doing the conversion of USB to UART. So you can install these chips in your own designs to completely rid the dependence on serial cables. In windows Silicon Labs provide customizable drivers which means you can provide your own branding. For example, if I made a device with a cp2102 chip I could set it up so when someone plugged it into their computer it would read, “Dave’s awesome USB device”.

So I have been using the cp2102 evaluation kit from Silicon Labs. Basically because it is a robust and reliable method of USB-Serial conversion. An added benefit of these device is that they can support speeds higher than what is available with standard RS232 hardware. For example I can transfer data with a baud rate of 2Mbps.

I recently received a question about using cp210x from Silicon Labs with linux. So linux has basic support [2] for cp210x devices from a community made driver (as of 2.6.39). Silicon Labs have released new products in this product range, namely cp2105 for example, which the current linux driver doesn’t recognise.

For example:

usb 1-1.2: device v10c4 pea70 is not supported
usb 1-1.2: New USB device found, idVendor=10c4, idProduct=ea70
usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=5
usb 1-1.2: Product: CP2105 Dual USB to UART Bridge Controller
usb 1-1.2: Manufacturer: Silicon Labs
usb 1-1.2: SerialNumber: 0000BBA1

On the silicon labs website [1], they have released a new version of the driver. Unfortunately this doesn’t work out of the box and seems to be aimed towards Ret Hat users. So I am going to briefly go through how to build and install the new driver in Ubuntu. To make your life easier I have done the required modifications and have them here for download.

Drivers: cp201x.tar

This driver supports the following devices:
CP2101
CP2102
CP2103
CP2104
CP2105

./configure
make
make install

For example:

dave@ubuntu:~/cp210x_silabs/cp210x-3.1.0/cp210x$ ./configure
Kernel version  : 2.6.38-8-generic
Module extension        : .ko
KO File   : cp210x.ko
Kernel Dir  : /lib/modules/2.6.38-8-generic/build
Module File  : cp2101.ko
Module Dir  : /lib/modules/2.6.38-8-generic
Current Dir  : /home/dave/cp210x_silabs/cp210x-3.1.0/cp210x

dave@ubuntu:~/cp210x_silabs/cp210x-3.1.0/cp210x$ make
make -C /lib/modules/2.6.38-8-generic/build -I /home/dave/cp210x_silabs/cp210x-3.1.0/cp210x M=/home/dave/cp210x_silabs/cp210x-3.1.0/cp210x modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.38-8-generic'
  CC [M]  /home/dave/cp210x_silabs/cp210x-3.1.0/cp210x/cp210x.o
/home/dave/cp210x_silabs/cp210x-3.1.0/cp210x/cp210x.c:454:1: warning: "/*" within comment
/home/dave/cp210x_silabs/cp210x-3.1.0/cp210x/cp210x.c:723:1: warning: initialization from incompatible pointer type
/home/dave/cp210x_silabs/cp210x-3.1.0/cp210x/cp210x.c:724:1: warning: initialization from incompatible pointer type
/home/dave/cp210x_silabs/cp210x-3.1.0/cp210x/cp210x.c:728:1: warning: initialization from incompatible pointer type
  Building modules, stage 2.
  MODPOST 1 modules
  CC      /home/dave/cp210x_silabs/cp210x-3.1.0/cp210x/cp210x.mod.o
  LD [M]  /home/dave/cp210x_silabs/cp210x-3.1.0/cp210x/cp210x.ko
make[1]: Leaving directory `/usr/src/linux-headers-2.6.38-8-generic'

A couple of warnings in there, but we will ignore them for the time.

You can see from the output that it made the file: /home/dave/cp210x_silabs/cp210x-3.1.0/cp210x/cp210x.ko

You can do a “make install” but I didn’t want it to overwrite my existing driver:

Backed up my old driver

dave@ubuntu:~/cp210x_silabs/cp210x-3.1.0/cp210x$ sudo mv /lib/modules/2.6.38-8-generic/kernel/drivers/usb/serial/cp210x.ko cp210x.ko.ori

Then copied over the new one:

dave@ubuntu:~/cp210x_silabs/cp210x-3.1.0/cp210x$ sudo mv cp210x.ko /lib/modules/2.6.38-8-generic/kernel/drivers/usb/serial/cp210x.ko

I then did a depmod, then a modinfo.

dave@ubuntu:~/cp210x_silabs/cp210x-3.1.0/cp210x$ sudo depmod
dave@ubuntu:~/cp210x_silabs/cp210x-3.1.0/cp210x$ sudo modinfo cp210x
filename:       /lib/modules/2.6.38-8-generic/kernel/drivers/usb/serial/cp210x.ko
version:        v1.10.0
license:        GPL
description:    Silicon Labs CP210x USB Serial Adaptor Driver
author:         RMS
srcversion:     35585FF341190212CF9E53A
alias:          usb:v18EFpE00Fd*dc*dsc*dp*ic*isc*ip*
alias:          usb:v16D6p0001d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v166Ap0303d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v13ADp9999d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C5pEA61d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4pF004d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4pF003d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4pF002d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4pF001d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4pEA70d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4pEA61d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4pEA60d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p846Ed*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p83A8d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p8341d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p8293d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p826Bd*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p822Bd*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p8218d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p81E7d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p81E2d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p81C8d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p81ACd*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p81A6d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p819Fd*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p815Ed*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p814Bd*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p814Ad*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p813Dd*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p8115d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p80F6d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p80DDd*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p80CAd*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p807Ad*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p8066d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p8054d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p8053d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p803Bd*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10C4p800Ad*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10B5pAC70d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10ABp10C5d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v10A6pAA26d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v0FCFp1006d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v0FCFp1004d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v0FCFp1003d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v08E6p5501d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v0489pE000d*dc*dsc*dp*ic*isc*ip*
alias:          usb:v0471p066Ad*dc*dsc*dp*ic*isc*ip*
depends:        usbserial
vermagic:       2.6.38-8-generic SMP mod_unload modversions 686
parm:           debug:Enable verbose debugging messages (bool)

Update:
1. I have just noticed that make install doesn’t work for the driver I attached. Just copy it over like I did above, then do a depmod.
2. I think that the driver version hasn’t been incremented, as it still reads v1.10.0 after update. You could update the source if you want it to read correctly.

References
[1] http://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspx
[2] http://www.etheus.net/CP210x_Linux_Driver