Add InputProp comments

services/comps/virtio/src/device/input/device.rs

@@ -12,13 +12,23 @@ use super::{
 };
 
 bitflags! {
+    /// The properties of input device.
+    ///
+    /// Ref: Linux input-event-codes.h
     pub struct InputProp : u8{
+        /// Needs a pointer
         const POINTER           = 1 << 0;
+        /// Direct input devices
         const DIRECT            = 1 << 1;
+        /// Has button(s) under pad
         const BUTTONPAD         = 1 << 2;
+        /// Touch rectangle only
         const SEMI_MT           = 1 << 3;
+        /// Softbuttons at top of pad
         const TOPBUTTONPAD      = 1 << 4;
+        /// Is a pointing stick
         const POINTING_STICK    = 1 << 5;
+        /// Has accelerometer
         const ACCELEROMETER     = 1 << 6;
     }
 }