LayerscapeのトピックRe: How to use GPIO on LS1021A

How to use GPIO on LS1021A

maumontadrien — Mon, 12 Mar 2018 08:37:07 GMT

Hello, I will use GPIO 3_13 and 3_14 LS1021A but the documentation does not explain anything about it.
Could someone give me the steps to follow for that?
- Kernel configuration
- RCW modification ...  
ps: I use the rocko branch of yocto and the meta-freescale.

Re: How to use GPIO on LS1021A

Pavel — Tue, 13 Mar 2018 09:15:01 GMT

NXP SDK supports sysfs possibility for GPIO using.

Look at the following pages:

https://www.kernel.org/doc/Documentation/gpio/sysfs.txt

http://falsinsoft.blogspot.ru/2012/11/access-gpio-from-linux-user-space.html

https://wiki.openwrt.org/doc/hardware/port.gpio

http://linux-sunxi.org/GPIO

The sysfs driver has been tested and is working. It has been accepted into the mainline kernel.

The SysFs interface is a very simple way to access the GPIO from user space and has the advantage of requiring very little setup.

Have a great day,
Pavel Chubakov

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Re: How to use GPIO on LS1021A

maumontadrien — Tue, 13 Mar 2018 10:18:09 GMT

Thank you for your help. I have added the sysfs gpio support and the GPIO driver on my kernel configuration.

I detect the 4 gpiochip. I can set the device direction to "out". But when I want set the gpio value, the output voltage doesn't change. I test with differents GPIO (GPIO3_13, GPIO3_14, GPIO1_15).

Re: How to use GPIO on LS1021A

maumontadrien — Mon, 19 Mar 2018 11:04:38 GMT

Should I change the RCW file to activate the GPIO control ?

Re: How to use GPIO on LS1021A

Pavel — Wed, 21 Mar 2018 03:58:51 GMT

If LS1021a GPIO1_15 is used, the LS1021a RCW UART_BASE bits should be cleared.

If LS1021a GPIO3_13 and GPIO3_15 are used, the LS1021a RCW EC1 bits should be set to 001.

See the Table 4-14 of the LS1021a Reference Manual.

Have a great day,
Pavel Chubakov

Re: How to use GPIO on LS1021A

maumontadrien — Wed, 21 Mar 2018 08:16:36 GMT

I find the solution, the RCW is include in u-boot on yocto.

The binary on the folder "work/ls1021atwr-poky-linux-gnueabi/rcw/git-r0/git/ls1021atwr/SSR_PNS_30/rcw_1200_sdboot.bin" is not used by u-boot generation.

We should modified the binary "work/ls1021atwr-poky-linux-gnueabi/u-boot-qoriq/2017.09+fslgit-r0/git/board/freescale/ls1021atwr/ls102xa_rcw_sd_ifc.cfg". This is the only file used by yocto to generate the final u-boot.img.

Re: How to use GPIO on LS1021A

Axent — Sun, 26 Mar 2023 13:36:29 GMT

Do you solved this?

I have the same problem
https://community.nxp.com/t5/Layerscape/Cannot-set-GPIO-state-with-gpio-direction-output/m-p/1622054#M12090

Thanks