Add HidDevice trait for device-specific information

The HID USB class needs device-specific information – currently, the
subclass and the protocol of the device, but also the report descriptors
and request handlers once we support these functions.  Therefore, this
patch introduces the HidDevice trait that provides this data.  It also
adds a Nitrokey struct that implements this trait for the Nitrokey Pro
device.

3 files changed, 37 insertions, 16 deletions

diff --git a/src/device.rs b/src/device.rs
index ea732e6..31f4293 100644
--- a/src/device.rs
+++ b/src/device.rs
@@ -4,9 +4,29 @@
 use usb_device::bus::{UsbBus, UsbBusAllocator};
 use usb_device::device::{UsbDevice, UsbDeviceBuilder, UsbVidPid};
 
+use crate::hid::{HidDevice, Protocol, Subclass};
+
 const VID_CLAY_LOGIC: u16 = 0x20a0;
 const PID_NITROKEY_PRO: u16 = 0x4108;
 
+pub struct Nitrokey {}
+
+impl Nitrokey {
+    pub fn new() -> Self {
+        Nitrokey {}
+    }
+}
+
+impl HidDevice for Nitrokey {
+    fn subclass(&self) -> Subclass {
+        Subclass::BootInterface
+    }
+
+    fn protocol(&self) -> Protocol {
+        Protocol::Keyboard
+    }
+}
+
 pub fn create_usb_device<B: UsbBus>(alloc: &UsbBusAllocator<B>) -> UsbDevice<'_, B> {
     UsbDeviceBuilder::new(alloc, UsbVidPid(VID_CLAY_LOGIC, PID_NITROKEY_PRO))
         .manufacturer("Nitrokey/ntw")
diff --git a/src/hid.rs b/src/hid.rs
index 9de68d6..0bb8a11 100644
--- a/src/hid.rs
+++ b/src/hid.rs
@@ -26,31 +26,31 @@ enum_u8! {
     }
 }
 
-pub struct HidClass<'a, B: UsbBus> {
+pub trait HidDevice {
+    fn subclass(&self) -> Subclass;
+
+    fn protocol(&self) -> Protocol;
+}
+
+pub struct HidClass<'a, B: UsbBus, D: HidDevice> {
+    device: D,
     interface: InterfaceNumber,
     endpoint_interrupt_in: EndpointIn<'a, B>,
     expect_interrupt_in_complete: bool,
-    subclass: Subclass,
-    protocol: Protocol,
 }
 
-impl<B: UsbBus> HidClass<'_, B> {
-    pub fn new(
-        alloc: &UsbBusAllocator<B>,
-        subclass: Subclass,
-        protocol: Protocol,
-    ) -> HidClass<'_, B> {
+impl<B: UsbBus, D: HidDevice> HidClass<'_, B, D> {
+    pub fn new(device: D, alloc: &UsbBusAllocator<B>) -> HidClass<'_, B, D> {
         HidClass {
+            device,
             interface: alloc.interface(),
             endpoint_interrupt_in: alloc.interrupt(8, 10),
             expect_interrupt_in_complete: false,
-            subclass,
-            protocol,
         }
     }
 }
 
-impl<B: UsbBus> UsbClass<B> for HidClass<'_, B> {
+impl<B: UsbBus, D: HidDevice> UsbClass<B> for HidClass<'_, B, D> {
     fn poll(&mut self) {}
 
     fn reset(&mut self) {
@@ -61,8 +61,8 @@ impl<B: UsbBus> UsbClass<B> for HidClass<'_, B> {
         writer.interface(
             self.interface,
             INTERFACE_CLASS_HID,
-            self.subclass.into(),
-            self.protocol.into(),
+            self.device.subclass().into(),
+            self.device.protocol().into(),
         )?;
         writer.endpoint(&self.endpoint_interrupt_in)?;
 
diff --git a/src/main.rs b/src/main.rs
index 3857967..e10f4d2 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -17,7 +17,8 @@ use hal::prelude::*;
 use stm32f103xx_usb::UsbBus;
 use usb_device::class::UsbClass;
 
-use crate::hid::{HidClass, Protocol, Subclass};
+use crate::device::Nitrokey;
+use crate::hid::HidClass;
 
 #[entry]
 fn main() -> ! {
@@ -38,7 +39,7 @@ fn main() -> ! {
     let mut gpioa = p.GPIOA.split(&mut rcc.apb2);
 
     let usb_bus = UsbBus::usb_with_reset(p.USB, &mut rcc.apb1, &clocks, &mut gpioa.crh, gpioa.pa12);
-    let mut usb_class = HidClass::new(&usb_bus, Subclass::BootInterface, Protocol::Keyboard);
+    let mut usb_class = HidClass::new(Nitrokey::new(), &usb_bus);
     let mut usb_dev = device::create_usb_device(&usb_bus);
     usb_dev.force_reset().expect("USB reset failed");