76 lines
2 KiB
Nix
76 lines
2 KiB
Nix
{ config, lib, ... }:
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let
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cfg = config.hardware.raspberry-pi."4";
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optionalProperty = name: value: lib.optionalString (value != null) "${name} = <${builtins.toString value}>;";
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simple-overlay = { target, status, frequency }: {
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name = "${target}-${status}-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 = <&${target}>;
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__overlay__ {
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status = "${status}";
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${optionalProperty "clock-frequency" frequency}
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};
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};
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};
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'';
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};
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in
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{
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options.hardware.raspberry-pi."4" = {
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i2c0 = {
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enable = lib.mkEnableOption ''
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Turn on the VideoCore I2C bus (maps to /dev/i2c-22) and enable access from the i2c group.
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After a reboot, i2c-tools (e.g. i2cdetect -F 22) should work for root or any user in i2c.
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'';
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frequency = lib.mkOption {
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type = lib.types.nullOr lib.types.int;
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default = null;
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description = ''
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interface clock-frequency
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'';
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};
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};
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i2c1 = {
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enable = lib.mkEnableOption ''
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Turn on the ARM I2C bus (/dev/i2c-1 on GPIO pins 3 and 5) and enable access from the i2c group.
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After a reboot, i2c-tools (e.g. i2cdetect -F 1) should work for root or any user in i2c.
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'';
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frequency = lib.mkOption {
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type = lib.types.nullOr lib.types.int;
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default = null;
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description = ''
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interface clock-frequency
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'';
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};
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};
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};
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config.hardware = lib.mkMerge [
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(lib.mkIf cfg.i2c0.enable {
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i2c.enable = lib.mkDefault true;
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deviceTree = {
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overlays = [ (simple-overlay {
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target = "i2c0if";
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status = "okay";
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inherit (cfg.i2c0) frequency;
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}) ];
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};
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})
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(lib.mkIf cfg.i2c1.enable {
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i2c.enable = lib.mkDefault true;
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deviceTree = {
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overlays = [ (simple-overlay {
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target = "i2c1";
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status = "okay";
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inherit (cfg.i2c1) frequency;
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}) ];
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};
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})
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];
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}
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