nixos-hardware/raspberry-pi/4/i2c.nix
2022-12-31 11:57:44 +01:00

76 lines
2 KiB
Nix

{ config, lib, ... }:
let
cfg = config.hardware.raspberry-pi."4";
optionalProperty = name: value: lib.optionalString (value != null) "${name} = <${builtins.toString value}>;";
simple-overlay = { target, status, frequency }: {
name = "${target}-${status}-overlay";
dtsText = ''
/dts-v1/;
/plugin/;
/ {
compatible = "brcm,bcm2711";
fragment@0 {
target = <&${target}>;
__overlay__ {
status = "${status}";
${optionalProperty "clock-frequency" frequency}
};
};
};
'';
};
in
{
options.hardware.raspberry-pi."4" = {
i2c0 = {
enable = lib.mkEnableOption ''
Turn on the VideoCore I2C bus (maps to /dev/i2c-22) and enable access from the i2c group.
After a reboot, i2c-tools (e.g. i2cdetect -F 22) should work for root or any user in i2c.
'';
frequency = lib.mkOption {
type = lib.types.nullOr lib.types.int;
default = null;
description = ''
interface clock-frequency
'';
};
};
i2c1 = {
enable = lib.mkEnableOption ''
Turn on the ARM I2C bus (/dev/i2c-1 on GPIO pins 3 and 5) and enable access from the i2c group.
After a reboot, i2c-tools (e.g. i2cdetect -F 1) should work for root or any user in i2c.
'';
frequency = lib.mkOption {
type = lib.types.nullOr lib.types.int;
default = null;
description = ''
interface clock-frequency
'';
};
};
};
config.hardware = lib.mkMerge [
(lib.mkIf cfg.i2c0.enable {
i2c.enable = lib.mkDefault true;
deviceTree = {
overlays = [ (simple-overlay {
target = "i2c0if";
status = "okay";
inherit (cfg.i2c0) frequency;
}) ];
};
})
(lib.mkIf cfg.i2c1.enable {
i2c.enable = lib.mkDefault true;
deviceTree = {
overlays = [ (simple-overlay {
target = "i2c1";
status = "okay";
inherit (cfg.i2c1) frequency;
}) ];
};
})
];
}