[meta-xilinx] gpio export from device tree

[Mike Looijmans]

On 27-02-17 22:52, Jean-Francois Dagenais wrote:
...
> So my questions are:
> * which clause, if any, is proper in dts to export the GPIOs preferably with names (like /sys/class/gpio/my_gpio_name_here). Do I need to declare a new node which doesn’t bind to a diver for example…

There have been a number of proposals for this in the kernel, but 
they've all been rejected. The consensus seems to be that you should 
write a driver if you want to do this kind of thing in a portable way.

> * (this one may be quite available in the megabytes of documentation) how does the gpio numbers in the kernel map to MIOxx and EMIOxx numbers. If anyone could point at the right doc that would save me so much grief.

They map really weird yeah. Maybe it's on purpose to discourage using 
gpio from userspace...
Best solution I found was to open /sys/class/gpiochip*/name files and 
look for the zynq gpio controller, and then use that offset. On my 
current board the zynq GPIO starts at "906". With 54 MIO GPIO pins, the 
EMIO GPIO pins thus start at 960.


-- 
Mike Looijmans


Kind regards,

Mike Looijmans
System Expert

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