Please advise me on device tree syntax (dts file and/or dtsi file syntax) to enable by default a PIN INPUT PULLUP setting for GPIO lines on AM33XX SoC TI chip? Even enabling the pull ups on all GPIO pins in a particular bank would be fine.
I have NOT seen any syntax/documentation in the device tree bindings about this: https://git.yoctoproject.org/cgit/cgit.cgi/linux-yocto-4.4/tree/Documentation/devicetree/bindings?h=standard/beaglebone
From am33xx.dtsi file Device Tree Source for AM33XX SoC:
gpio0: gpio@44e07000 {
compatible = "ti,omap4-gpio";
ti,hwmods = "gpio1";
gpio-controller;
#gpio-cells = <2>;
interrupt-controller;
#interrupt-cells = <2>;
reg = <0x44e07000 0x1000>;
interrupts = <96>;
};
The following are files I can change:
From my platform common.dtsi file (overlay on top of am33xx in my kernel source) linux-yocto_4.4/arch/arm/boot/dts/am335x-_common.dtsi
#enabling this uio line and it will be assigned to an GPIO line
uio13: uio_pdrv_genirq@13 {
compatible = "uio,pdrv_genirq";
status = "disabled";
};
#turn on all GPIO lines in bank 0
&gpio0 {
ti,gpio-always-on;
};
From my platform dts file (overlay on top of am33xx in my kernel source and using common.dtsi file)
linux-yocto_4.4/arch/arm/boot/dts/am335x-.dts
&uio13 {
irq-gpio = <20>; /* GPIO 20 in bank 0 */
irq-trigger = <0x3>; /* trigger rising|falling */
status = "okay";
};