Add CMSIS-DAP driver

2 files changed, 102 insertions, 0 deletions

diff --git a/embassy-usb/src/class/cmsis_dap_v2.rs b/embassy-usb/src/class/cmsis_dap_v2.rs
new file mode 100644
index 000000000..41f6be5dd
--- /dev/null
+++ b/embassy-usb/src/class/cmsis_dap_v2.rs
@@ -0,0 +1,101 @@
+//! CMSIS-DAP V2 class implementation.
+
+use core::mem::MaybeUninit;
+
+use crate::driver::{Driver, Endpoint, EndpointError, EndpointIn, EndpointOut};
+use crate::types::StringIndex;
+use crate::{msos, Builder, Handler};
+
+/// State for the CMSIS-DAP v2 USB class.
+pub struct State {
+    control: MaybeUninit<Control>,
+}
+
+struct Control {
+    iface_string: StringIndex,
+}
+
+impl Handler for Control {
+    fn get_string(&mut self, index: StringIndex, _lang_id: u16) -> Option<&str> {
+        if index == self.iface_string {
+            Some("CMSIS-DAP v2 Interface")
+        } else {
+            warn!("unknown string index requested");
+            None
+        }
+    }
+}
+
+impl State {
+    /// Create a new `State`.
+    pub const fn new() -> Self {
+        Self {
+            control: MaybeUninit::uninit(),
+        }
+    }
+}
+
+/// USB device class for CMSIS-DAP v2 probes.
+pub struct CmsisDapV2Class<'d, D: Driver<'d>> {
+    read_ep: D::EndpointOut,
+    write_ep: D::EndpointIn,
+    max_packet_size: u16,
+}
+
+impl<'d, D: Driver<'d>> CmsisDapV2Class<'d, D> {
+    /// Creates a new CmsisDapV2Class with the provided UsbBus and `max_packet_size` in bytes. For
+    /// full-speed devices, `max_packet_size` has to be 64.
+    pub fn new(builder: &mut Builder<'d, D>, state: &'d mut State, max_packet_size: u16) -> Self {
+        // DAP - Custom Class 0
+        let iface_string = builder.string();
+        let mut function = builder.function(0xFF, 0, 0);
+        function.msos_feature(msos::CompatibleIdFeatureDescriptor::new("WINUSB", ""));
+        function.msos_feature(msos::RegistryPropertyFeatureDescriptor::new(
+            "DeviceInterfaceGUIDs",
+            // CMSIS-DAP standard GUID, from https://arm-software.github.io/CMSIS_5/DAP/html/group__DAP__ConfigUSB__gr.html
+            msos::PropertyData::RegMultiSz(&["{CDB3B5AD-293B-4663-AA36-1AAE46463776}"]),
+        ));
+        let mut interface = function.interface();
+        let mut alt = interface.alt_setting(0xFF, 0, 0, Some(iface_string));
+        let read_ep = alt.endpoint_bulk_out(max_packet_size);
+        let write_ep = alt.endpoint_bulk_in(max_packet_size);
+        drop(function);
+
+        builder.handler(state.control.write(Control { iface_string }));
+
+        CmsisDapV2Class {
+            read_ep,
+            write_ep,
+            max_packet_size,
+        }
+    }
+
+    /// Waits for the USB host to enable this interface
+    pub async fn wait_connection(&mut self) {
+        self.read_ep.wait_enabled().await;
+    }
+
+    /// Write data to the host.
+    pub async fn write_packet(&mut self, data: &[u8]) -> Result<(), EndpointError> {
+        for chunk in data.chunks(self.max_packet_size as usize) {
+            self.write_ep.write(chunk).await?;
+        }
+        if data.len() % self.max_packet_size as usize == 0 {
+            self.write_ep.write(&[]).await?;
+        }
+        Ok(())
+    }
+
+    /// Read data from the host.
+    pub async fn read_packet(&mut self, data: &mut [u8]) -> Result<usize, EndpointError> {
+        let mut n = 0;
+
+        loop {
+            let i = self.read_ep.read(&mut data[n..]).await?;
+            n += i;
+            if i < self.max_packet_size as usize {
+                return Ok(n);
+            }
+        }
+    }
+}
diff --git a/embassy-usb/src/class/mod.rs b/embassy-usb/src/class/mod.rs
index 4bd89eb66..c01707971 100644
--- a/embassy-usb/src/class/mod.rs
+++ b/embassy-usb/src/class/mod.rs
@@ -1,6 +1,7 @@
 //! Implementations of well-known USB classes.
 pub mod cdc_acm;
 pub mod cdc_ncm;
+pub mod cmsis_dap_v2;
 pub mod hid;
 pub mod midi;
 pub mod uac1;