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Which GPIO is which physical pin in linux?

Emil Ohlsson
Intellectual 410 points

Hi!

I'm working on porting the 2.6.37-patch version of the PSP kernel to a new board which is based on the TI816X EVM. The hardware is very similar, and I have linux up and running on the target platform. The processor is a TMS320C6A8168.

So right now I'm trying to blink three LEDs which are connected to GP1[0,1,2]. However I am a bit confused on exactly how to do this. I have tried to study the documentation, but I have a lot of loose ends, so excuse me if I sound a bit confused.

Some background:
I added muxing information in the arch/arm/mach-omap2/board-ti8168evm.c. So the pins should be set up correctly.

I have created a kernel module which exposes a GPIO via the SysFS interface.

However, I do not know which GPIO corresponds to which physical pin. Is there some table I could check out?

Do I need to export gpiochip1? If so, how do I do that?

It seems to me that the GPIO implementation is OMAP-specific, is there some documentation describing this implementation?

Any help is appreciated :)

Thanks,
Emil

  • 0
    TI__Expert 6655 points

    Hi Emil,

    Anil: Go through the GPIO driver user guide http://processors.wiki.ti.com/index.php/Sitara_GPIO_Driver_User_Guide

    Some background:
    I added muxing information in the arch/arm/mach-omap2/board-ti8168evm.c. So the pins should be set up correctly.

    Anil: Follow the user guide (Introduction)

    I have created a kernel module which exposes a GPIO via the SysFS interface.

    Anil: This is not required, all the GPIO lines are exported as Sysfs entries. Make sure that same GPIO's are not used by other drivers

    However, I do not know which GPIO corresponds to which physical pin. Is there some table I could check out?

    Anil: It's simple, BANK_NUMBER * 32 + 0 is the GPIO starting number.

    Eg: GP1_IO0 is 1*32+0 = 32 is the GPIO number for GPIO bank one IO number 0. 

    Regards

    AnilKumar

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