Brightness (OpenBSD): add support

Requires root permission. Not tested

CMakeLists.txt

@@ -786,7 +786,7 @@ elseif(OpenBSD)
         src/detection/bluetoothradio/bluetoothradio_linux.c
         src/detection/board/board_nosupport.c
         src/detection/bootmgr/bootmgr_nosupport.c
-        src/detection/brightness/brightness_nosupport.c
+        src/detection/brightness/brightness_obsd.c
         src/detection/btrfs/btrfs_nosupport.c
         src/detection/chassis/chassis_nosupport.c
         src/detection/cpu/cpu_obsd.c

src/detection/brightness/brightness_obsd.c

@@ -0,0 +1,30 @@
+#include "brightness.h"
+#include "common/io/io.h"
+
+#include <dev/wscons/wsconsio.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+const char* ffDetectBrightness(FF_MAYBE_UNUSED FFBrightnessOptions* options, FFlist* result)
+{
+    FF_AUTO_CLOSE_FD int devfd = open("/dev/ttyC0", O_RDONLY);
+
+    if (devfd < 0) return "open(dev/ttyC0, O_RDONLY) failed";
+
+    struct wsdisplay_param param = {
+        .param = WSDISPLAYIO_PARAM_BRIGHTNESS,
+    };
+
+    if (ioctl(devfd, WSDISPLAYIO_GETPARAM, &param) < 0)
+        return "ioctl(WSDISPLAYIO_GETPARAM) failed";
+
+    FFBrightnessResult* brightness = (FFBrightnessResult*) ffListAdd(result);
+    ffStrbufInitStatic(&brightness->name, "wsdisplay");
+
+    brightness->max = param.max;
+    brightness->min = param.min;
+    brightness->current = param.curval;
+
+    return NULL;
+}