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