In order to give userspace GPIOs sane names I use devicetree aliases which application code can access from /proc/device-tree/aliases. Each GPIO has an alias with a sensible name and the string I assign to it supplies the GPIO pin number and any other relevant info such as whether it's an input or an output and whether it's active high or active low.
This technique can also be used to tell application the base pin numbers for MIO/EMIO if you wish. -----Original Message----- From: Mike Looijmans [mailto:mike.looijm...@topic.nl] Sent: 28 February 2017 11:07 To: meta-xilinx@yoctoproject.org Subject: Re: [meta-xilinx] gpio export from device tree 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 TOPIC Products Materiaalweg 4, NL-5681 RJ Best Postbus 440, NL-5680 AK Best Telefoon: +31 (0) 499 33 69 79 E-mail: mike.looijm...@topicproducts.com Website: www.topicproducts.com Please consider the environment before printing this e-mail -- _______________________________________________ meta-xilinx mailing list meta-xilinx@yoctoproject.org https://lists.yoctoproject.org/listinfo/meta-xilinx
