We have configured GPIO using the following statements on IMX53 based custom board. In sysfs we could see "active_low" and "value" files under gpio folder.
gpio_request(TEST,"test");
gpio_direction_output(TEST,0);
gpio_export(TEST,0);
We couldn't able to set value in value file, if we set the value in "active_low" then it is reflecting on "value" file.
Hi Ravi,
You could take a look at the following links, where GPIO configuration information is provided:
Basic GPIO usage from Linux on UDOO NEO board
Access GPIO from Linux user space | FalsinSoft
Hope this will be useful for you.
Best regards!
/Carlos
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Hello Carlos!CarlosCasillas
I was able to successfully follow the "Simple GPIO Example - quandry" guide and control an GPIO output but now I would like to setup and configure it from the device tree, which I started to learn recently.
In other words, I would like to boot up the board and already have my GPIO listed under /sys/class/gpio/<my_gpio> like other devices that use GPIO in the device tree and have it setup as low by default.
I am using an IMX6Q SABRED SD. I have seen many examples but I get stuck with IMX6 because I don't seems to find a "fsl,imx6q-gpio" or similar and I wouldn't know what to populate in the register field.
References I have been using:
Pin settings app note:
http://cache.freescale.com/files/32bit/doc/app_note/AN5078.pdf
Device tree app note:
http://www.nxp.com/assets/documents/data/en/application-notes/AN5125.pdf
More on device tree:
Linux docs:
Documentation/devicetree/bindings/gpio/gpio.txt
-Andrey-