4 files changed, 296 insertions, 0 deletions
diff --git a/src/screen/drm/card.zig b/src/screen/drm/card.zig
new file mode 100644
index 0000000..67f81f3
--- /dev/null
+++ b/src/screen/drm/card.zig
@@ -0,0 +1,45 @@
+const std = @import("std");
+const os = std.os.linux;
+
+const cerror = @import("../cerror.zig");
+
+const Resources = @import("resources.zig").Resources;
+const Connector = @import("connector.zig").Connector;
+
+
+pub const Card = struct {
+    const Self = @This();
+
+    file: std.fs.File,
+    allocator: std.mem.Allocator,
+
+    pub fn open(name: []const u8, allocator: std.mem.Allocator) !Self {
+        var dri_dir = try std.fs.openDirAbsolute("/dev/dri", .{});
+        defer dri_dir.close();
+
+        return .{
+            .file = try dri_dir.openFile(name, .{
+                .mode = .read_write,
+                .lock_nonblocking = true,
+            }),
+            .allocator = allocator,
+        };
+    }
+
+    pub fn close(self: *Card) void {
+        self.file.close();
+    }
+
+    pub fn is_kms(self: *Card) !bool {
+        const raw_info = Resources.raw_without_ids(self);
+        return raw_info.count_crtcs > 0 and raw_info.count_connectors > 0 and raw_info.count_encoders > 0;
+    }
+
+    pub fn resources(self: *Card) !Resources {
+        return Resources.init(self);
+    }
+
+    pub fn connector(self: *Card, id: u32) !Connector {
+        return Connector.init(self, id);
+    }
+};
diff --git a/src/screen/drm/connector.zig b/src/screen/drm/connector.zig
new file mode 100644
index 0000000..9d7f9ad
--- /dev/null
+++ b/src/screen/drm/connector.zig
@@ -0,0 +1,156 @@
+const std = @import("std");
+const os = std.os.linux;
+const Drm = @import("request.zig").Drm;
+const Card = @import("card.zig").Card;
+
+const RawConnector = extern struct {
+    encoder_ids: ?*u32,
+    modes: ?*ModeInfo,
+    prop_ids: ?*u32,
+    prop_value_ids: ?*u64,
+    count_modes: u32,
+    count_props: u32,
+    count_encoders: u32,
+    encoder_id: u32,
+    connector_id: u32,
+    connector_type: u32,
+    connector_type_id: u32,
+    connection: Connection,
+    mm_width: u32,
+    mm_height: u32,
+    subpixel: u32,
+    pad: u32,
+};
+
+const Connection = enum(u32) {
+    undefined_state = 0,
+    connected = 1,
+    disconnected = 2,
+    unknown = 3,
+};
+
+const ModeInfo = extern struct {
+    const Self = @This();
+    const Flags = packed struct(u32) {
+        phsync: bool,
+        nhsync: bool,
+        pvsync: bool,
+        nvsync: bool,
+        interlace: bool,
+        dblscan: bool,
+        csync: bool,
+        pcsync: bool,
+        ncsync: bool,
+        hskew: bool,
+        bcast: bool,
+        pixmux: bool,
+        dblclk: bool,
+        clkdiv2: bool,
+        _padding: u18,
+    };
+
+    clock: u32,
+    hdisplay: u16,
+    hsync_start: u16,
+    hsync_end: u16,
+    htotal: u16,
+    hskew: u16,
+    vdisplay: u16,
+    vsync_start: u16,
+    vsync_end: u16,
+    vtotal: u16,
+    vscan: u16,
+
+    vrefresh: u32,
+
+    flags: Flags,
+    type: u32,
+    name: [32]u8,
+
+    pub fn frame_rate(self: *const Self) f32 {
+        var rate = (@as(u64, @intCast(self.clock)) * 1000000 / self.htotal + self.vtotal / 2) / self.vtotal;
+
+        if (self.flags.interlace) {
+            rate *= 2;
+        }
+
+        if (self.flags.dblscan) {
+            rate /= 2;
+        }
+
+        if (self.vscan > 1) {
+            rate /= self.vscan;
+        }
+
+        return @as(f32, @floatFromInt(rate)) / 1000.0;
+    }
+};
+
+pub const Connector = struct {
+    const Self = @This();
+
+    card: *Card,
+
+    encoder_ids: []u32,
+    modes: []ModeInfo,
+    prop_ids: []u32,
+    prop_value_ids: []u64,
+    encoder_id: u32,
+    connector_id: u32,
+    connector_type: u32,
+    connector_type_id: u32,
+    connection: Connection,
+    mm_width: u32,
+    mm_height: u32,
+    subpixel: u32,
+    pad: u32,
+
+    pub fn raw_without_ids(card: *Card, id: u32) !RawConnector {
+        var result = std.mem.zeroInit(RawConnector, .{ .connector_id = id });
+        try Drm.get_connector.request(card.file.handle, RawConnector, &result);
+        return result;
+    }
+
+    // NOTE: This function does not take in account
+    //       that there might be some hot-plugging going
+    //       on. This might have to change in the future.
+    pub fn init(card: *Card, id: u32) !Self {
+        var raw = try Self.raw_without_ids(card, id);
+        const resources = .{
+            .encoder_ids = try card.allocator.alloc(u32, raw.count_encoders),
+            .modes = try card.allocator.alloc(ModeInfo, raw.count_modes),
+            .prop_ids = try card.allocator.alloc(u32, raw.count_props),
+            .prop_value_ids = try card.allocator.alloc(u64, raw.count_props),
+            .encoder_id = raw.encoder_id,
+            .connector_id = raw.connector_id,
+            .connector_type = raw.connector_type,
+            .connector_type_id = raw.connector_type_id,
+            .connection = raw.connection,
+            .mm_width = raw.mm_width,
+            .mm_height = raw.mm_height,
+            .subpixel = raw.subpixel,
+            .pad = raw.pad,
+            .card = card,
+        };
+
+        @memset(resources.encoder_ids, 0);
+        @memset(resources.modes, std.mem.zeroes(ModeInfo));
+        @memset(resources.prop_ids, 0);
+        @memset(resources.prop_value_ids, 0);
+
+        raw.encoder_ids = @ptrCast(resources.encoder_ids);
+        raw.modes = @ptrCast(resources.modes);
+        raw.prop_ids = @ptrCast(resources.prop_ids);
+        raw.prop_value_ids = @ptrCast(resources.prop_value_ids);
+
+        try Drm.get_connector.request(card.file.handle, RawConnector, &raw);
+
+        return resources;
+    }
+
+    pub fn deinit(self: *Self) void {
+        self.card.allocator.free(self.encoder_ids);
+        self.card.allocator.free(self.modes);
+        self.card.allocator.free(self.prop_ids);
+    }
+};
diff --git a/src/screen/drm/request.zig b/src/screen/drm/request.zig
new file mode 100644
index 0000000..bf9701c
--- /dev/null
+++ b/src/screen/drm/request.zig
@@ -0,0 +1,19 @@
+const std = @import("std");
+const os = std.os.linux;
+const cerror = @import("../cerror.zig");
+
+fn ioctl(fd: os.fd_t, request: u32, arg: usize) !void {
+    try cerror.from_usize(os.ioctl(fd, request, arg));
+}
+
+pub const Drm = enum(u8) {
+    const Self = @This();
+
+    get_resources = 0xA0,
+    get_connector = 0xA7,
+
+    pub fn request(self: Self, fd: os.fd_t, T: type, arg: *T) !void {
+        const id = os.IOCTL.IOWR('d', @intFromEnum(self), T);
+        try ioctl(fd, id, @intFromPtr(arg));
+    }
+};
diff --git a/src/screen/drm/resources.zig b/src/screen/drm/resources.zig
new file mode 100644
index 0000000..6128f37
--- /dev/null
+++ b/src/screen/drm/resources.zig
@@ -0,0 +1,76 @@
+const std = @import("std");
+const os = std.os.linux;
+const cerror = @import("../cerror.zig");
+const Card = @import("card.zig").Card;
+const Drm = @import("request.zig").Drm;
+
+const RawResources = extern struct {
+    fb_ids: ?*u32,
+    crtc_ids: ?*u32,
+    connector_ids: ?*u32,
+    encoder_ids: ?*u32,
+    count_fbs: u32,
+    count_crtcs: u32,
+    count_connectors: u32,
+    count_encoders: u32,
+    min_width: u32,
+    max_width: u32,
+    min_height: u32,
+    max_height: u32,
+};
+
+pub const Resources = struct {
+    const Self = @This();
+    const Range = struct { min: u32, max: u32 };
+
+    card: *Card,
+
+    fb_ids: []u32,
+    crtc_ids: []u32,
+    connector_ids: []u32,
+    encoder_ids: []u32,
+    width: Range,
+    height: Range,
+
+    pub fn raw_without_ids(card: *Card) !RawResources {
+        var result = std.mem.zeroes(RawResources);
+        try Drm.get_resources.request(card.file.handle, RawResources, &result);
+        return result;
+    }
+
+    // NOTE: This function does not take in account
+    //       that there might be some hot-plugging going
+    //       on. This might have to change in the future.
+    pub fn init(card: *Card) !Self {
+        var raw = try Self.raw_without_ids(card);
+        const resources = .{
+            .fb_ids = try card.allocator.alloc(u32, raw.count_fbs),
+            .crtc_ids = try card.allocator.alloc(u32, raw.count_crtcs),
+            .connector_ids = try card.allocator.alloc(u32, raw.count_connectors),
+            .encoder_ids = try card.allocator.alloc(u32, raw.count_encoders),
+            .width = .{ .min = raw.min_width, .max = raw.max_width },
+            .height = .{ .min = raw.min_height, .max = raw.max_height },
+            .card = card,
+        };
+
+        @memset(resources.fb_ids, 0);
+        @memset(resources.crtc_ids, 0);
+        @memset(resources.connector_ids, 0);
+        @memset(resources.encoder_ids, 0);
+
+        raw.fb_ids = @ptrCast(resources.fb_ids);
+        raw.crtc_ids = @ptrCast(resources.crtc_ids);
+        raw.connector_ids = @ptrCast(resources.connector_ids);
+        raw.encoder_ids = @ptrCast(resources.encoder_ids);
+        try Drm.get_resources.request(card.file.handle, RawResources, &raw);
+
+        return resources;
+    }
+
+    pub fn deinit(self: *Self) void {
+        self.card.allocator.free(self.fb_ids);
+        self.card.allocator.free(self.crtc_ids);
+        self.card.allocator.free(self.connector_ids);
+        self.card.allocator.free(self.encoder_ids);
+    }
+};