uarta.dts - uart a on pin 8 and 10 with flow control on pin 16 and 18
There are a lot more functionality not exposed in which you have to write your own overlay. These serve as simple references for you to get started with. You can reference Raspberry Pi’s overlays here. Decompile them with the dtc command and switch the compatibles, targets, buses, GPIOs, and interrupt. Most hardware will work but certain hardware features like I2S will not have matching pin positions due to differences in pinmux.
Yes, Raspberry Pi depend on the bootloader to read config.txt. Our bootloader does not read it at all. We are exploring creating a service to do it but that’s still in the conceptual stage at this point.
I have a PCF8523 RTC that I’ve previously used on Raspberry Pis. To use it on the aml-s905x-cc, should I be able to just change line 23 in i2c-ao-ds3231.dts to compatible = "nxp,pcf8523", build, install, and merge?
Unfortunately, in the kernel you provide, you don’t include the module for this particular RTC. Would you consider adding it to the kernel config you are using? It’s part of the mainline device tree, so it should just require enabling it as a module (and looking at the kernel config in /boot, it lists it as an option-it’s line 7378 in the current 6.0.19 kernel).
I get the gpio description in a kernel module with gpiod_get and export it via gpiod_export + gpiod_export_link. Which all seems fine, except the exported sysfs artifacts do not have the ‘edge’ file which from the Linux docs indicates that the gpio doesn’t support interrupts…
Following up on @Matthew_Splett’s question, what is the recommended way to enable interrupts on GPIO pins? I am not familiar at all with Device Tree Overlays, and I would not know how to start writing one.