Linux/TMDXEVM3358: DMTimer control from userspace

Anuj Chaudhary

Part Number: TMDXEVM3358

Tool/software: Linux

Hi,

I have am335x GP EVM with ti-processor-sdk-linux-am335x-evm-04.02.00.09 SDK ported. I want to use DMTimer from userspace. I found dmtimer api in Linux/arch/arm/plat-omap/dmtimer.c and Linux/arch/arm/plat-omap/include/plat/dmtimer.h . When I tried to use any of dmtimer.c API from my code composure 7.0 application, its not compiling and gives dependency errors like *.h header file not found. I have included above two paths (Linux/arch/arm/plat-omap/ and Linux/arch/arm/plat-omap/include/plat/) in CCS but it keeps giving new header file dependencies. Please tell me how to compile dmtimer. from CCS.

over 6 years ago

0 Rex Chang over 6 years ago

TI__Guru 50170 points

Hi, Anuj,

The dmtimer.c is kernel space API, not be used in user space. If you need a timer in user space, you will need to ioctl into your kernel driver to use it, or check the url on how to implement timer in user space, stackoverflow.com/.../how-to-implement-highly-accurate-timers-in-linux-userspace

Rex

0 Anuj Chaudhary over 6 years ago in reply to Rex Chang

Prodigy 140 points

Thanks for reply. How to use it in my application from kernel space. Plz guide

0 Rex Chang over 6 years ago in reply to Anuj Chaudhary

TI__Guru 50170 points

Hi, Anuj,

You will need to write a kernel driver to take your user space call. From your kernel driver, it calls the dmtimer API. Please search how to write a linux driver. There are more detailed info on internet than I can put in the forum. Besides, user space application is not in our support scope.

Rex

0 Anuj Chaudhary over 6 years ago in reply to Rex Chang

Prodigy 140 points

Ok thanks

0 Anuj Chaudhary over 6 years ago in reply to Anuj Chaudhary

Prodigy 140 points

Hi,
I am trying to access DMTimer 1ms registers using devmem2 from user space. I am able to read registers like TCRR and can see that it is upcounting and running in auto reload mode. But when i try to write to register (TCLR) to stop timer, linux prompt hangs and doesn't return. What is this issue?

0 Anuj Chaudhary over 6 years ago in reply to Anuj Chaudhary

Prodigy 140 points

Problem is solved. Had to enable timer from CM_PER register.

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Linux/TMDXEVM3358: DMTimer control from userspace