nixos-hardware/raspberry-pi/4/dwc2.nix
2021-05-28 11:18:51 +02:00

78 lines
2.5 KiB
Nix

{ config, lib, pkgs, ... }:
let
cfg = config.hardware.raspberry-pi."4".dwc2;
in
{
options.hardware = {
raspberry-pi."4".dwc2 = {
enable = lib.mkEnableOption ''
Enable the UDC controller to support USB OTG gadget functions.
In order to verify that this works, connect the Raspberry Pi with
another computer via the USB C cable, and then do one of:
- `modprobe g_serial`
- `modprobe g_mass_storage file=/path/to/some/iso-file.iso`
On the Raspberry Pi, `dmesg` should then show success-indicating output
that is related to the dwc2 and g_serial/g_mass_storage modules.
On the other computer, a serial/mass-storage device should pop up in
the system logs.
For more information about what gadget functions exist along with handy
guides on how to test them, please refer to:
https://www.kernel.org/doc/Documentation/usb/gadget-testing.txt
'';
dr_mode = lib.mkOption {
type = lib.types.enum [ "host" "peripheral" "otg" ];
default = "otg";
description = ''
Dual role mode setting for the dwc2 USB controller driver.
'';
};
};
};
config = lib.mkIf cfg.enable {
# Configure for modesetting in the device tree
hardware.deviceTree = {
overlays = [
# this *should* be equivalent to (which doesn't work):
# https://github.com/raspberrypi/linux/blob/rpi-5.10.y/arch/arm/boot/dts/overlays/dwc2-overlay.dts
# but actually it's obtained using
# dtc -I dtb -O dts ${config.hardware.deviceTree.kernelPackage}/dtbs/overlays/dwc2.dtbo
# (changes: modified top-level "compatible" field)
# which is slightly different and works
{
name = "dwc2-overlay";
dtsText = ''
/dts-v1/;
/plugin/;
/ {
compatible = "brcm,bcm2711";
fragment@0 {
target = <&usb>;
#address-cells = <0x01>;
#size-cells = <0x01>;
__overlay__ {
compatible = "brcm,bcm2835-usb";
dr_mode = "${cfg.dr_mode}";
g-np-tx-fifo-size = <0x20>;
g-rx-fifo-size = <0x22e>;
g-tx-fifo-size = <0x200 0x200 0x200 0x200 0x200 0x100 0x100>;
status = "okay";
phandle = <0x01>;
};
};
};
'';
}
];
};
};
}