Created Wednesday 11 January 2017
Many good links concerning interracting with GPIOs were found along the way...
GPIO Description & Software Interfaces:
https://www.kernel.org/doc/Documentation/gpio/gpio.txt
GPIO Sysfs Interface for Userspace:
https://www.kernel.org/doc/Documentation/gpio/sysfs.txt
Viewing GPIO Configuration using debugfs:
http://elinux.org/GPIO
GPIO Interfaces
There are two different ways to obtain and use GPIOs:
- Descriptor-based
Optional: CONFIG_GPIOLIB - may be required for some GPIO hardware such as NXP PCA8574/PCA8575
Support for CONFIG_GPIO_SYSFS was added in Linux kernel 2.6.27 (2008 time frame)
- Legacy integer-based
Additional documentation & examples:
http://www.emcraft.com/stm32f429discovery/controlling-gpio-from-linux-user-space
https://blackfin.uclinux.org/doku.php?id=linux-kernel:drivers:gpio-sysfs
http://falsinsoft.blogspot.com/2012/11/access-gpio-from-linux-user-space.html
https://lwn.net/Articles/532714/
https://www.kernel.org/doc/Documentation/gpio/sysfs.txt
http://elinux.org/GPIO#Configure_the_kernel_for_GPIO_support_in_sysfs
http://www.wiki.xilinx.com/Linux+GPIO+Driver
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/gpio/gpio.txt
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/gpio/sysfs.txt
https://lwn.net/Articles/574055/
https://www.kernel.org/doc/Documentation/gpio/driver.txt
For shell script (bash) example - bottom of page:
https://developer.ridgerun.com/wiki/index.php/How_to_use_GPIO_signals
GPIO usage from a Kernel developer's perspective:
https://lwn.net/Articles/532717/