Add USB stack and simple HID implementation

This patch adds the usb-device and stm32f103xx-usb crates that provide a
USB stack.  It introduces the HidClass struct, a basic implementation of
the Human Interface Device (HID) USB class.  Devices with that class are
recognized as HID devices with the specified vendor and product ID, but
do not provide the endpoints required for interaction.

1 files changed, 88 insertions, 0 deletions

diff --git a/src/hid.rs b/src/hid.rs
new file mode 100644
index 0000000..4f1d506
--- /dev/null
+++ b/src/hid.rs
@@ -0,0 +1,88 @@
+// Copyright 2019 Robin Krahl <robin.krahl@ireas.org>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+use core::marker::PhantomData;
+
+use usb_device::bus::{InterfaceNumber, StringIndex, UsbBus, UsbBusAllocator};
+use usb_device::class::{ControlIn, ControlOut, UsbClass};
+use usb_device::descriptor::DescriptorWriter;
+use usb_device::endpoint::EndpointAddress;
+use usb_device::Result;
+
+const INTERFACE_CLASS_HID: u8 = 0x03;
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+#[repr(u8)]
+pub enum Subclass {
+    None = 0x00,
+    BootInterface = 0x01,
+}
+
+impl From<Subclass> for u8 {
+    fn from(subclass: Subclass) -> u8 {
+        subclass as u8
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+#[repr(u8)]
+pub enum Protocol {
+    None = 0x00,
+    Keyboard = 0x01,
+    Mouse = 0x02,
+}
+
+impl From<Protocol> for u8 {
+    fn from(protocol: Protocol) -> u8 {
+        protocol as u8
+    }
+}
+
+pub struct HidClass<'a, B: UsbBus> {
+    interface: InterfaceNumber,
+    subclass: Subclass,
+    protocol: Protocol,
+    marker: PhantomData<&'a B>,
+}
+
+impl<B: UsbBus> HidClass<'_, B> {
+    pub fn new(
+        alloc: &UsbBusAllocator<B>,
+        subclass: Subclass,
+        protocol: Protocol,
+    ) -> HidClass<'_, B> {
+        HidClass {
+            interface: alloc.interface(),
+            subclass,
+            protocol,
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<B: UsbBus> UsbClass<B> for HidClass<'_, B> {
+    fn poll(&mut self) {}
+
+    fn reset(&mut self) {}
+
+    fn get_configuration_descriptors(&self, writer: &mut DescriptorWriter) -> Result<()> {
+        writer.interface(
+            self.interface,
+            INTERFACE_CLASS_HID,
+            self.subclass.into(),
+            self.protocol.into(),
+        )
+    }
+
+    fn get_string(&self, _index: StringIndex, _lang_id: u16) -> Option<&str> {
+        None
+    }
+
+    fn endpoint_in_complete(&mut self, _addr: EndpointAddress) {}
+
+    fn endpoint_out(&mut self, _addr: EndpointAddress) {}
+
+    fn control_in(&mut self, _xfer: ControlIn<B>) {}
+
+    fn control_out(&mut self, _xfer: ControlOut<B>) {}
+}