Split usb_report_descriptor into usb_hid_{item,usage}

This is cleaner IMO.

* usb_hid_item deals with parsing the report descriptor.
* usb_hid_usage has tables that define each usage.

usb_hid_usage/src/button.rs

@@ -0,0 +1,17 @@
+use core::num::NonZeroU16;
+
+pub const PAGE: u16 = 0x09;
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum Usage {
+    NoButton,
+    Button(NonZeroU16),
+}
+
+impl TryFrom<u16> for Usage {
+    type Error = super::UnknownUsage;
+
+    fn try_from(n: u16) -> Result<Self, Self::Error> {
+        Ok(NonZeroU16::new(n).map_or(Self::NoButton, Self::Button))
+    }
+}

usb_hid_usage/src/generic_desktop.rs

@@ -0,0 +1,52 @@
+usage! {
+    [0x01]
+    0x01 Pointer
+    0x02 Mouse
+
+    0x04 Joystick
+    0x05 Gamepad
+    0x06 Keyboard
+    0x07 Keypad
+    0x08 MultiAxisController
+    0x09 TabletPcSystemControls
+    0x0a WaterCoolingDevice
+    0x0b ComputerChassisDevice
+    0x0c WirelessRadioControls
+    0x0d PortableDeviceControl
+    0x0e SystemMultiAxisController
+    0x0f SpatialController
+    0x10 AssistiveControl
+    0x11 DeviceDock
+    0x12 DockableDevice
+    0x13 CallStateManagementControl
+
+    0x30 X
+    0x31 Y
+    0x32 Z
+    0x33 Rx
+    0x34 Ry
+    0x35 Rz
+    0x36 Slider
+    0x37 Dial
+    0x38 Wheel
+    0x39 HatSwitch
+    0x3a CountedBuffer
+    0x3b ByteCount
+    0x3c MotionWakeup
+    0x3d Start
+    0x3e Select
+
+    0x40 Vx
+    0x41 Vy
+    0x42 Vz
+    0x43 Vbrx
+    0x44 Vbry
+    0x45 Vbrz
+    0x46 Vno
+    0x47 FeatureNotification
+    0x48 ResolutionMultiplier
+    0x49 Qx
+    0x4a Qy
+    0x4b Qz
+    0x4c Qw
+}

usb_hid_usage/src/lib.rs

@@ -0,0 +1,63 @@
+//!
+//! ## References
+//!
+//! * <https://www.usb.org/sites/default/files/hut1_3_0.pdf>
+
+#![no_std]
+
+macro_rules! usage {
+    { [$page:literal] $($i:literal $v:ident)* } => {
+        pub const PAGE: u16 = $page;
+
+        #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+        #[non_exhaustive]
+        pub enum Usage {
+            $($v,)*
+        }
+
+        impl TryFrom<u16> for Usage {
+            type Error = super::UnknownUsage;
+
+            fn try_from(n: u16) -> Result<Self, Self::Error> {
+                Ok(match n {
+                    $($i => Self::$v,)*
+                    _ => return Err(super::UnknownUsage),
+                })
+            }
+        }
+    };
+}
+
+macro_rules! page {
+    { $($v:ident $m:ident)* } => {
+        $(pub mod $m;)*
+
+        #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+        #[non_exhaustive]
+        pub enum UsagePage {
+            $($v,)*
+        }
+
+        impl TryFrom<u16> for UsagePage {
+            type Error = UnknownPage;
+
+            fn try_from(n: u16) -> Result<Self, Self::Error> {
+                Ok(match n {
+                    $($m::PAGE => Self::$v,)*
+                    _ => return Err(UnknownPage),
+                })
+            }
+        }
+    };
+}
+
+page! {
+    GenericDesktop generic_desktop
+    Button button
+}
+
+#[derive(Debug)]
+pub struct UnknownUsage;
+
+#[derive(Debug)]
+pub struct UnknownPage;