I'm working on a board based on the iMX6 and am trying to configure a number of GPIOs that are being used as chip enable and reset lines. Based on the research I've done, the way to handle this is via the gpio-reset driver in the device tree. Following the documentation I've come up with the below code which compiles but I'm not sure how to then control these reset lines from user space.
The first device tree driver I used was the gpio-leds which created an leds folder in sys/class with nodes to control the LED. However I don't see anything similar for reset. So I have 2 questions:
1) Is GPIO-RESET the correct binding to use for controlling reset lines, enable lines, etc.
2) Is there documentation on how to handle this and other bindings from user space, similar to how I'm controlling the GPIO-LED?
Kernel: Linux buildroot 4.1.15
/dts-v1/;
#include <dt-bindings/input/input.h>
#include <dt-bindings/gpio/gpio.h>
#include <dt-bindings/pinctrl/omap.h>
#include "imx6ul.dtsi"
/ {
model = "Freescale i.MX6 UltraLite 14x14 EVK Board";
compatible = "fsl,imx6ul-14x14-evk", "fsl,imx6ul";
memory {
reg = <0x80000000 0x20000000>;
};
/* Reset Line Configuration */
gpio_resets {
compatible = "linux,gpio-reset";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_gpioreset>;
gnss {
gpios = <&gpio1 4 0>;
asserted-state = <0>;
duration-ms = <100>;
auto;
};
};
...
};
&iomuxc {
pinctrl-names = "default";
imx6ul-evk {
pinctrl_gpioreset:
gpiorstgrp {
fsl,pins = <
MX6UL_PAD_GPIO1_IO04__GPIO1_IO04 0x000010B0 /* GNSS RESET_N */
>;
};
...
};