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What device file for touchscreen?

Posted: Thu Apr 26, 2007 2:39 pm
by mikrodidakt

What device file should I open to be able to use the driver ads7846 for the touchscreen?
Or is there a way to get the major and minor number that a driver is using have compiled the driver in to the kernel so it is not a module.

I am using the board AT91SAM9261ek


Posted: Fri Apr 27, 2007 7:30 am
by mwolfram

if using the input system in kernel 2.6.x the devices should appear in /dev/input/ starting from input0. If enabled there is a corresponding event0 etc entry too.


Posted: Fri Apr 27, 2007 8:56 am
by mikrodidakt
Thanks mike for your answer.

I don't have a device file input0 but I do have device files even0-event5
and then I have two device file ts0 and ts1.

I am not shore what you mean with input system I have configured the kernel so that the input device support and the touchscreen under that is configured.

Every driver have a minor and major number connected to them, right?
So if I am missing the device file and would like to create it what major and minor number should that device file have so that I can use the touchscreen driver ads7846? Is there a way to find out what major number a driver is using or could the driver be using a dynamic major number?


Posted: Fri Apr 27, 2007 10:03 am
by mwolfram
Have you checked where the ts0 and ts1 come from? And what else do you have enabled to get event0-5?

Having a working udev will do the job for you with creating the right device files. I don't have an ads7846 driver, so where did you get it? Is it part of the patches from maxim? Or have you written it yourself? If you want you can send it to me using my email address.


Posted: Fri May 04, 2007 2:25 pm
by nferre
The touchscreen is a ads7843 device. The ads7846 Linux driver has been modified to support ads7843. The code is at the moment in the Linux -mm tree.
Anyway, you will find it in the experimental at91 Linux patchset (applied on top of patches). They are located on this web site ( in the project section.

Note that it uses SPI and that SPI and SD/MMC cannot be used at the same time on at91sam9261ek.