usb: add `add_class` to builder, so that `FooBarClass::new(&mut builder)` can set up everything.

2 files changed, 91 insertions, 127 deletions

diff --git a/examples/nrf/src/bin/usb/cdc_acm.rs b/examples/nrf/src/bin/usb/cdc_acm.rs
index 5e4abfea2..92cc16eb4 100644
--- a/examples/nrf/src/bin/usb/cdc_acm.rs
+++ b/examples/nrf/src/bin/usb/cdc_acm.rs
@@ -1,5 +1,8 @@
-use core::mem;
+use core::cell::{Cell, UnsafeCell};
+use core::mem::{self, MaybeUninit};
+use core::sync::atomic::{AtomicBool, Ordering};
 use defmt::info;
+use embassy::blocking_mutex::CriticalSectionMutex;
 use embassy_usb::class::{ControlInRequestStatus, RequestStatus, UsbClass};
 use embassy_usb::control::{self, Request};
 use embassy_usb::driver::{Endpoint, EndpointIn, EndpointOut, ReadError, WriteError};
@@ -25,6 +28,18 @@ const REQ_SET_LINE_CODING: u8 = 0x20;
 const REQ_GET_LINE_CODING: u8 = 0x21;
 const REQ_SET_CONTROL_LINE_STATE: u8 = 0x22;
 
+pub struct State {
+    control: MaybeUninit<Control>,
+}
+
+impl State {
+    pub fn new() -> Self {
+        Self {
+            control: MaybeUninit::uninit(),
+        }
+    }
+}
+
 /// Packet level implementation of a CDC-ACM serial port.
 ///
 /// This class can be used directly and it has the least overhead due to directly reading and
@@ -45,21 +60,32 @@ pub struct CdcAcmClass<'d, D: Driver<'d>> {
     pub data_if: InterfaceNumber,
     pub read_ep: D::EndpointOut,
     pub write_ep: D::EndpointIn,
-    pub control: CdcAcmControl,
+    control: &'d ControlShared,
+}
+
+struct Control {
+    comm_if: InterfaceNumber,
+    shared: UnsafeCell<ControlShared>,
 }
 
-pub struct CdcAcmControl {
-    pub comm_if: InterfaceNumber,
-    pub line_coding: LineCoding,
-    pub dtr: bool,
-    pub rts: bool,
+/// Shared data between Control and CdcAcmClass
+struct ControlShared {
+    line_coding: CriticalSectionMutex<Cell<LineCoding>>,
+    dtr: AtomicBool,
+    rts: AtomicBool,
 }
 
-impl UsbClass for CdcAcmControl {
+impl Control {
+    fn shared(&mut self) -> &ControlShared {
+        unsafe { &*(self.shared.get() as *const _) }
+    }
+}
+impl UsbClass for Control {
     fn reset(&mut self) {
-        self.line_coding = LineCoding::default();
-        self.dtr = false;
-        self.rts = false;
+        let shared = self.shared();
+        shared.line_coding.lock(|x| x.set(LineCoding::default()));
+        shared.dtr.store(false, Ordering::Relaxed);
+        shared.rts.store(false, Ordering::Relaxed);
     }
 
     fn control_out(&mut self, req: control::Request, data: &[u8]) -> RequestStatus {
@@ -77,18 +103,25 @@ impl UsbClass for CdcAcmControl {
                 RequestStatus::Accepted
             }
             REQ_SET_LINE_CODING if data.len() >= 7 => {
-                self.line_coding.data_rate = u32::from_le_bytes(data[0..4].try_into().unwrap());
-                self.line_coding.stop_bits = data[4].into();
-                self.line_coding.parity_type = data[5].into();
-                self.line_coding.data_bits = data[6];
-                info!("Set line coding to: {:?}", self.line_coding);
+                let coding = LineCoding {
+                    data_rate: u32::from_le_bytes(data[0..4].try_into().unwrap()),
+                    stop_bits: data[4].into(),
+                    parity_type: data[5].into(),
+                    data_bits: data[6],
+                };
+                self.shared().line_coding.lock(|x| x.set(coding));
+                info!("Set line coding to: {:?}", coding);
 
                 RequestStatus::Accepted
             }
             REQ_SET_CONTROL_LINE_STATE => {
-                self.dtr = (req.value & 0x0001) != 0;
-                self.rts = (req.value & 0x0002) != 0;
-                info!("Set dtr {}, rts {}", self.dtr, self.rts);
+                let dtr = (req.value & 0x0001) != 0;
+                let rts = (req.value & 0x0002) != 0;
+
+                let shared = self.shared();
+                shared.dtr.store(dtr, Ordering::Relaxed);
+                shared.rts.store(rts, Ordering::Relaxed);
+                info!("Set dtr {}, rts {}", dtr, rts);
 
                 RequestStatus::Accepted
             }
@@ -112,11 +145,12 @@ impl UsbClass for CdcAcmControl {
             // REQ_GET_ENCAPSULATED_COMMAND is not really supported - it will be rejected below.
             REQ_GET_LINE_CODING if req.length == 7 => {
                 info!("Sending line coding");
+                let coding = self.shared().line_coding.lock(|x| x.get());
                 let mut data = [0; 7];
-                data[0..4].copy_from_slice(&self.line_coding.data_rate.to_le_bytes());
-                data[4] = self.line_coding.stop_bits as u8;
-                data[5] = self.line_coding.parity_type as u8;
-                data[6] = self.line_coding.data_bits;
+                data[0..4].copy_from_slice(&coding.data_rate.to_le_bytes());
+                data[4] = coding.stop_bits as u8;
+                data[5] = coding.parity_type as u8;
+                data[6] = coding.data_bits;
                 control.accept(&data)
             }
             _ => control.reject(),
@@ -127,7 +161,11 @@ impl UsbClass for CdcAcmControl {
 impl<'d, D: Driver<'d>> CdcAcmClass<'d, D> {
     /// Creates a new CdcAcmClass with the provided UsbBus and max_packet_size in bytes. For
     /// full-speed devices, max_packet_size has to be one of 8, 16, 32 or 64.
-    pub fn new(builder: &mut UsbDeviceBuilder<'d, D>, max_packet_size: u16) -> Self {
+    pub fn new(
+        builder: &mut UsbDeviceBuilder<'d, D>,
+        state: &'d mut State,
+        max_packet_size: u16,
+    ) -> Self {
         let comm_if = builder.alloc_interface();
         let comm_ep = builder.alloc_interrupt_endpoint_in(8, 255);
         let data_if = builder.alloc_interface();
@@ -207,22 +245,29 @@ impl<'d, D: Driver<'d>> CdcAcmClass<'d, D> {
         builder.config_descriptor.endpoint(write_ep.info()).unwrap();
         builder.config_descriptor.endpoint(read_ep.info()).unwrap();
 
+        let control = state.control.write(Control {
+            comm_if,
+            shared: UnsafeCell::new(ControlShared {
+                dtr: AtomicBool::new(false),
+                rts: AtomicBool::new(false),
+                line_coding: CriticalSectionMutex::new(Cell::new(LineCoding {
+                    stop_bits: StopBits::One,
+                    data_bits: 8,
+                    parity_type: ParityType::None,
+                    data_rate: 8_000,
+                })),
+            }),
+        });
+
+        let control_shared = unsafe { &*(control.shared.get() as *const _) };
+        builder.add_class(control);
+
         CdcAcmClass {
             comm_ep,
             data_if,
             read_ep,
             write_ep,
-            control: CdcAcmControl {
-                comm_if,
-                dtr: false,
-                rts: false,
-                line_coding: LineCoding {
-                    stop_bits: StopBits::One,
-                    data_bits: 8,
-                    parity_type: ParityType::None,
-                    data_rate: 8_000,
-                },
-            },
+            control: control_shared,
         }
     }
 
@@ -234,18 +279,18 @@ impl<'d, D: Driver<'d>> CdcAcmClass<'d, D> {
 
     /// Gets the current line coding. The line coding contains information that's mainly relevant
     /// for USB to UART serial port emulators, and can be ignored if not relevant.
-    pub fn line_coding(&self) -> &LineCoding {
-        &self.control.line_coding
+    pub fn line_coding(&self) -> LineCoding {
+        self.control.line_coding.lock(|x| x.get())
     }
 
     /// Gets the DTR (data terminal ready) state
     pub fn dtr(&self) -> bool {
-        self.control.dtr
+        self.control.dtr.load(Ordering::Relaxed)
     }
 
     /// Gets the RTS (request to send) state
     pub fn rts(&self) -> bool {
-        self.control.rts
+        self.control.rts.load(Ordering::Relaxed)
     }
 
     /// Writes a single packet into the IN endpoint.
@@ -264,88 +309,6 @@ impl<'d, D: Driver<'d>> CdcAcmClass<'d, D> {
     }
 }
 
-/*
-impl<B: UsbBus> UsbClass<B> for CdcAcmClass<'_, B> {
-    fn get_configuration_descriptors(&self, builder.config_descriptor: &mut Descriptorbuilder.config_descriptor) -> Result<()> {
-
-        Ok(())
-    }
-
-    fn reset(&mut self) {
-        self.line_coding = LineCoding::default();
-        self.dtr = false;
-        self.rts = false;
-    }
-
-    fn control_in(&mut self, xfer: ControlIn<B>) {
-        let req = xfer.request();
-
-        if !(req.request_type == control::RequestType::Class
-            && req.recipient == control::Recipient::Interface
-            && req.index == u8::from(self.comm_if) as u16)
-        {
-            return;
-        }
-
-        match req.request {
-            // REQ_GET_ENCAPSULATED_COMMAND is not really supported - it will be rejected below.
-            REQ_GET_LINE_CODING if req.length == 7 => {
-                xfer.accept(|data| {
-                    data[0..4].copy_from_slice(&self.line_coding.data_rate.to_le_bytes());
-                    data[4] = self.line_coding.stop_bits as u8;
-                    data[5] = self.line_coding.parity_type as u8;
-                    data[6] = self.line_coding.data_bits;
-
-                    Ok(7)
-                })
-                .ok();
-            }
-            _ => {
-                xfer.reject().ok();
-            }
-        }
-    }
-
-    fn control_out(&mut self, xfer: ControlOut<B>) {
-        let req = xfer.request();
-
-        if !(req.request_type == control::RequestType::Class
-            && req.recipient == control::Recipient::Interface
-            && req.index == u8::from(self.comm_if) as u16)
-        {
-            return;
-        }
-
-        match req.request {
-            REQ_SEND_ENCAPSULATED_COMMAND => {
-                // We don't actually support encapsulated commands but pretend we do for standards
-                // compatibility.
-                xfer.accept().ok();
-            }
-            REQ_SET_LINE_CODING if xfer.data().len() >= 7 => {
-                self.line_coding.data_rate =
-                    u32::from_le_bytes(xfer.data()[0..4].try_into().unwrap());
-                self.line_coding.stop_bits = xfer.data()[4].into();
-                self.line_coding.parity_type = xfer.data()[5].into();
-                self.line_coding.data_bits = xfer.data()[6];
-
-                xfer.accept().ok();
-            }
-            REQ_SET_CONTROL_LINE_STATE => {
-                self.dtr = (req.value & 0x0001) != 0;
-                self.rts = (req.value & 0x0002) != 0;
-
-                xfer.accept().ok();
-            }
-            _ => {
-                xfer.reject().ok();
-            }
-        };
-    }
-}
-
- */
-
 /// Number of stop bits for LineCoding
 #[derive(Copy, Clone, PartialEq, Eq, defmt::Format)]
 pub enum StopBits {
@@ -393,7 +356,7 @@ impl From<u8> for ParityType {
 ///
 /// This is provided by the host for specifying the standard UART parameters such as baud rate. Can
 /// be ignored if you don't plan to interface with a physical UART.
-#[derive(defmt::Format)]
+#[derive(Clone, Copy, defmt::Format)]
 pub struct LineCoding {
     stop_bits: StopBits,
     data_bits: u8,
diff --git a/examples/nrf/src/bin/usb/main.rs b/examples/nrf/src/bin/usb/main.rs
index 73ac3a21f..398dd07b6 100644
--- a/examples/nrf/src/bin/usb/main.rs
+++ b/examples/nrf/src/bin/usb/main.rs
@@ -16,12 +16,11 @@ use embassy_nrf::interrupt;
 use embassy_nrf::pac;
 use embassy_nrf::usb::Driver;
 use embassy_nrf::Peripherals;
-use embassy_usb::class::UsbClass;
 use embassy_usb::driver::{EndpointIn, EndpointOut};
 use embassy_usb::{Config, UsbDeviceBuilder};
 use futures::future::join3;
 
-use crate::cdc_acm::CdcAcmClass;
+use crate::cdc_acm::{CdcAcmClass, State};
 
 #[embassy::main]
 async fn main(_spawner: Spawner, p: Peripherals) {
@@ -48,6 +47,9 @@ async fn main(_spawner: Spawner, p: Peripherals) {
     let mut device_descriptor = [0; 256];
     let mut config_descriptor = [0; 256];
     let mut bos_descriptor = [0; 256];
+
+    let mut state = State::new();
+
     let mut builder = UsbDeviceBuilder::new(
         driver,
         config,
@@ -57,11 +59,10 @@ async fn main(_spawner: Spawner, p: Peripherals) {
     );
 
     // Create classes on the builder.
-    let mut class = CdcAcmClass::new(&mut builder, 64);
+    let mut class = CdcAcmClass::new(&mut builder, &mut state, 64);
 
     // Build the builder.
-    let mut classes: [&mut dyn UsbClass; 1] = [&mut class.control];
-    let mut usb = builder.build(&mut classes);
+    let mut usb = builder.build();
 
     // Run the USB device.
     let fut1 = usb.run();