usb/cdc-ncm: add embassy-net Device implementation.

6 files changed, 54 insertions, 371 deletions

diff --git a/examples/nrf/Cargo.toml b/examples/nrf/Cargo.toml
index 8b95ac3a6..a980a505c 100644
--- a/examples/nrf/Cargo.toml
+++ b/examples/nrf/Cargo.toml
@@ -16,7 +16,7 @@ embassy-executor = { version = "0.1.0", path = "../../embassy-executor", feature
 embassy-time = { version = "0.1.0", path = "../../embassy-time", features = ["defmt", "defmt-timestamp-uptime"] }
 embassy-nrf = { version = "0.1.0", path = "../../embassy-nrf", features = ["defmt", "nrf52840", "time-driver-rtc1", "gpiote", "unstable-pac"] }
 embassy-net = { version = "0.1.0", path = "../../embassy-net", features = ["defmt", "tcp", "dhcpv4", "medium-ethernet", "pool-16"], optional = true }
-embassy-usb = { version = "0.1.0", path = "../../embassy-usb", features = ["defmt"], optional = true }
+embassy-usb = { version = "0.1.0", path = "../../embassy-usb", features = ["defmt", "embassy-net"], optional = true }
 embedded-io = "0.4.0"
 embassy-lora = { version = "0.1.0", path = "../../embassy-lora", features = ["sx126x", "time", "defmt"], optional = true }
 
diff --git a/examples/nrf/src/bin/usb_ethernet.rs b/examples/nrf/src/bin/usb_ethernet.rs
index de93a2b45..e5f704524 100644
--- a/examples/nrf/src/bin/usb_ethernet.rs
+++ b/examples/nrf/src/bin/usb_ethernet.rs
@@ -3,19 +3,16 @@
 #![feature(type_alias_impl_trait)]
 
 use core::mem;
-use core::sync::atomic::{AtomicBool, Ordering};
-use core::task::Waker;
 
 use defmt::*;
 use embassy_executor::Spawner;
 use embassy_net::tcp::TcpSocket;
-use embassy_net::{PacketBox, PacketBoxExt, PacketBuf, Stack, StackResources};
+use embassy_net::{Stack, StackResources};
 use embassy_nrf::rng::Rng;
 use embassy_nrf::usb::{Driver, PowerUsb};
 use embassy_nrf::{interrupt, pac, peripherals};
-use embassy_sync::blocking_mutex::raw::ThreadModeRawMutex;
-use embassy_sync::channel::Channel;
-use embassy_usb::class::cdc_ncm::{CdcNcmClass, Receiver, Sender, State};
+use embassy_usb::class::cdc_ncm::embassy_net::{Device, Runner, State as NetState};
+use embassy_usb::class::cdc_ncm::{CdcNcmClass, State};
 use embassy_usb::{Builder, Config, UsbDevice};
 use embedded_io::asynch::Write;
 use static_cell::StaticCell;
@@ -27,56 +24,25 @@ macro_rules! singleton {
     ($val:expr) => {{
         type T = impl Sized;
         static STATIC_CELL: StaticCell<T> = StaticCell::new();
-        STATIC_CELL.init_with(move || $val)
+        let (x,) = STATIC_CELL.init(($val,));
+        x
     }};
 }
 
+const MTU: usize = 1514;
+
 #[embassy_executor::task]
 async fn usb_task(mut device: UsbDevice<'static, MyDriver>) -> ! {
     device.run().await
 }
 
 #[embassy_executor::task]
-async fn usb_ncm_rx_task(mut class: Receiver<'static, MyDriver>) {
-    loop {
-        warn!("WAITING for connection");
-        LINK_UP.store(false, Ordering::Relaxed);
-
-        class.wait_connection().await.unwrap();
-
-        warn!("Connected");
-        LINK_UP.store(true, Ordering::Relaxed);
-
-        loop {
-            let mut p = unwrap!(PacketBox::new(embassy_net::Packet::new()));
-            let n = match class.read_packet(&mut p[..]).await {
-                Ok(n) => n,
-                Err(e) => {
-                    warn!("error reading packet: {:?}", e);
-                    break;
-                }
-            };
-
-            let buf = p.slice(0..n);
-            if RX_CHANNEL.try_send(buf).is_err() {
-                warn!("Failed pushing rx'd packet to channel.");
-            }
-        }
-    }
-}
-
-#[embassy_executor::task]
-async fn usb_ncm_tx_task(mut class: Sender<'static, MyDriver>) {
-    loop {
-        let pkt = TX_CHANNEL.recv().await;
-        if let Err(e) = class.write_packet(&pkt[..]).await {
-            warn!("Failed to TX packet: {:?}", e);
-        }
-    }
+async fn usb_ncm_task(class: Runner<'static, MyDriver, MTU>) -> ! {
+    class.run().await
 }
 
 #[embassy_executor::task]
-async fn net_task(stack: &'static Stack<Device>) -> ! {
+async fn net_task(stack: &'static Stack<Device<'static, MTU>>) -> ! {
     stack.run().await
 }
 
@@ -108,55 +74,32 @@ async fn main(spawner: Spawner) {
     config.device_sub_class = 0x02;
     config.device_protocol = 0x01;
 
-    struct Resources {
-        device_descriptor: [u8; 256],
-        config_descriptor: [u8; 256],
-        bos_descriptor: [u8; 256],
-        control_buf: [u8; 128],
-        serial_state: State<'static>,
-    }
-    let res: &mut Resources = singleton!(Resources {
-        device_descriptor: [0; 256],
-        config_descriptor: [0; 256],
-        bos_descriptor: [0; 256],
-        control_buf: [0; 128],
-        serial_state: State::new(),
-    });
-
     // Create embassy-usb DeviceBuilder using the driver and config.
     let mut builder = Builder::new(
         driver,
         config,
-        &mut res.device_descriptor,
-        &mut res.config_descriptor,
-        &mut res.bos_descriptor,
-        &mut res.control_buf,
+        &mut singleton!([0; 256])[..],
+        &mut singleton!([0; 256])[..],
+        &mut singleton!([0; 256])[..],
+        &mut singleton!([0; 128])[..],
         None,
     );
 
-    // WARNINGS for Android ethernet tethering:
-    // - On Pixel 4a, it refused to work on Android 11, worked on Android 12.
-    // - if the host's MAC address has the "locally-administered" bit set (bit 1 of first byte),
-    //   it doesn't work! The "Ethernet tethering" option in settings doesn't get enabled.
-    //   This is due to regex spaghetti: https://android.googlesource.com/platform/frameworks/base/+/refs/tags/android-mainline-12.0.0_r84/core/res/res/values/config.xml#417
-    //   and this nonsense in the linux kernel: https://github.com/torvalds/linux/blob/c00c5e1d157bec0ef0b0b59aa5482eb8dc7e8e49/drivers/net/usb/usbnet.c#L1751-L1757
-
     // Our MAC addr.
     let our_mac_addr = [0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC];
     // Host's MAC addr. This is the MAC the host "thinks" its USB-to-ethernet adapter has.
     let host_mac_addr = [0x88, 0x88, 0x88, 0x88, 0x88, 0x88];
 
     // Create classes on the builder.
-    let class = CdcNcmClass::new(&mut builder, &mut res.serial_state, host_mac_addr, 64);
+    let class = CdcNcmClass::new(&mut builder, singleton!(State::new()), host_mac_addr, 64);
 
     // Build the builder.
     let usb = builder.build();
 
     unwrap!(spawner.spawn(usb_task(usb)));
 
-    let (tx, rx) = class.split();
-    unwrap!(spawner.spawn(usb_ncm_rx_task(rx)));
-    unwrap!(spawner.spawn(usb_ncm_tx_task(tx)));
+    let (runner, device) = class.into_embassy_net_device::<MTU, 4, 4>(singleton!(NetState::new()), our_mac_addr);
+    unwrap!(spawner.spawn(usb_ncm_task(runner)));
 
     let config = embassy_net::ConfigStrategy::Dhcp;
     //let config = embassy_net::ConfigStrategy::Static(embassy_net::Config {
@@ -172,7 +115,6 @@ async fn main(spawner: Spawner) {
     let seed = u64::from_le_bytes(seed);
 
     // Init network stack
-    let device = Device { mac_addr: our_mac_addr };
     let stack = &*singleton!(Stack::new(
         device,
         config,
@@ -225,50 +167,3 @@ async fn main(spawner: Spawner) {
         }
     }
 }
-
-static TX_CHANNEL: Channel<ThreadModeRawMutex, PacketBuf, 8> = Channel::new();
-static RX_CHANNEL: Channel<ThreadModeRawMutex, PacketBuf, 8> = Channel::new();
-static LINK_UP: AtomicBool = AtomicBool::new(false);
-
-struct Device {
-    mac_addr: [u8; 6],
-}
-
-impl embassy_net::Device for Device {
-    fn register_waker(&mut self, waker: &Waker) {
-        // loopy loopy wakey wakey
-        waker.wake_by_ref()
-    }
-
-    fn link_state(&mut self) -> embassy_net::LinkState {
-        match LINK_UP.load(Ordering::Relaxed) {
-            true => embassy_net::LinkState::Up,
-            false => embassy_net::LinkState::Down,
-        }
-    }
-
-    fn capabilities(&self) -> embassy_net::DeviceCapabilities {
-        let mut caps = embassy_net::DeviceCapabilities::default();
-        caps.max_transmission_unit = 1514; // 1500 IP + 14 ethernet header
-        caps.medium = embassy_net::Medium::Ethernet;
-        caps
-    }
-
-    fn is_transmit_ready(&mut self) -> bool {
-        true
-    }
-
-    fn transmit(&mut self, pkt: PacketBuf) {
-        if TX_CHANNEL.try_send(pkt).is_err() {
-            warn!("TX failed")
-        }
-    }
-
-    fn receive<'a>(&mut self) -> Option<PacketBuf> {
-        RX_CHANNEL.try_recv().ok()
-    }
-
-    fn ethernet_address(&self) -> [u8; 6] {
-        self.mac_addr
-    }
-}
diff --git a/examples/rp/Cargo.toml b/examples/rp/Cargo.toml
index dfbc26426..31a08cfb6 100644
--- a/examples/rp/Cargo.toml
+++ b/examples/rp/Cargo.toml
@@ -10,7 +10,7 @@ embassy-sync = { version = "0.1.0", path = "../../embassy-sync", features = ["de
 embassy-executor = { version = "0.1.0", path = "../../embassy-executor", features = ["defmt", "integrated-timers"] }
 embassy-time = { version = "0.1.0", path = "../../embassy-time", features = ["defmt", "defmt-timestamp-uptime"] }
 embassy-rp = { version = "0.1.0", path = "../../embassy-rp", features = ["defmt", "unstable-traits", "nightly", "unstable-pac", "time-driver", "pio", "critical-section-impl"] }
-embassy-usb = { version = "0.1.0", path = "../../embassy-usb", features = ["defmt"] }
+embassy-usb = { version = "0.1.0", path = "../../embassy-usb", features = ["defmt", "embassy-net"] }
 embassy-net = { version = "0.1.0", path = "../../embassy-net", features = ["defmt", "nightly", "tcp", "dhcpv4", "medium-ethernet", "pool-16"] }
 embassy-futures = { version = "0.1.0", path = "../../embassy-futures" }
 embassy-usb-logger = { version = "0.1.0", path = "../../embassy-usb-logger" }
diff --git a/examples/rp/src/bin/usb_ethernet.rs b/examples/rp/src/bin/usb_ethernet.rs
index 1057fe7fd..d0aec874a 100644
--- a/examples/rp/src/bin/usb_ethernet.rs
+++ b/examples/rp/src/bin/usb_ethernet.rs
@@ -2,18 +2,14 @@
 #![no_main]
 #![feature(type_alias_impl_trait)]
 
-use core::sync::atomic::{AtomicBool, Ordering};
-use core::task::Waker;
-
 use defmt::*;
 use embassy_executor::Spawner;
 use embassy_net::tcp::TcpSocket;
-use embassy_net::{PacketBox, PacketBoxExt, PacketBuf, Stack, StackResources};
+use embassy_net::{Stack, StackResources};
 use embassy_rp::usb::Driver;
 use embassy_rp::{interrupt, peripherals};
-use embassy_sync::blocking_mutex::raw::ThreadModeRawMutex;
-use embassy_sync::channel::Channel;
-use embassy_usb::class::cdc_ncm::{CdcNcmClass, Receiver, Sender, State};
+use embassy_usb::class::cdc_ncm::embassy_net::{Device, Runner, State as NetState};
+use embassy_usb::class::cdc_ncm::{CdcNcmClass, State};
 use embassy_usb::{Builder, Config, UsbDevice};
 use embedded_io::asynch::Write;
 use static_cell::StaticCell;
@@ -25,56 +21,25 @@ macro_rules! singleton {
     ($val:expr) => {{
         type T = impl Sized;
         static STATIC_CELL: StaticCell<T> = StaticCell::new();
-        STATIC_CELL.init_with(move || $val)
+        let (x,) = STATIC_CELL.init(($val,));
+        x
     }};
 }
 
+const MTU: usize = 1514;
+
 #[embassy_executor::task]
 async fn usb_task(mut device: UsbDevice<'static, MyDriver>) -> ! {
     device.run().await
 }
 
 #[embassy_executor::task]
-async fn usb_ncm_rx_task(mut class: Receiver<'static, MyDriver>) {
-    loop {
-        warn!("WAITING for connection");
-        LINK_UP.store(false, Ordering::Relaxed);
-
-        class.wait_connection().await.unwrap();
-
-        warn!("Connected");
-        LINK_UP.store(true, Ordering::Relaxed);
-
-        loop {
-            let mut p = unwrap!(PacketBox::new(embassy_net::Packet::new()));
-            let n = match class.read_packet(&mut p[..]).await {
-                Ok(n) => n,
-                Err(e) => {
-                    warn!("error reading packet: {:?}", e);
-                    break;
-                }
-            };
-
-            let buf = p.slice(0..n);
-            if RX_CHANNEL.try_send(buf).is_err() {
-                warn!("Failed pushing rx'd packet to channel.");
-            }
-        }
-    }
-}
-
-#[embassy_executor::task]
-async fn usb_ncm_tx_task(mut class: Sender<'static, MyDriver>) {
-    loop {
-        let pkt = TX_CHANNEL.recv().await;
-        if let Err(e) = class.write_packet(&pkt[..]).await {
-            warn!("Failed to TX packet: {:?}", e);
-        }
-    }
+async fn usb_ncm_task(class: Runner<'static, MyDriver, MTU>) -> ! {
+    class.run().await
 }
 
 #[embassy_executor::task]
-async fn net_task(stack: &'static Stack<Device>) -> ! {
+async fn net_task(stack: &'static Stack<Device<'static, MTU>>) -> ! {
     stack.run().await
 }
 
@@ -100,55 +65,32 @@ async fn main(spawner: Spawner) {
     config.device_sub_class = 0x02;
     config.device_protocol = 0x01;
 
-    struct Resources {
-        device_descriptor: [u8; 256],
-        config_descriptor: [u8; 256],
-        bos_descriptor: [u8; 256],
-        control_buf: [u8; 128],
-        serial_state: State<'static>,
-    }
-    let res: &mut Resources = singleton!(Resources {
-        device_descriptor: [0; 256],
-        config_descriptor: [0; 256],
-        bos_descriptor: [0; 256],
-        control_buf: [0; 128],
-        serial_state: State::new(),
-    });
-
     // Create embassy-usb DeviceBuilder using the driver and config.
     let mut builder = Builder::new(
         driver,
         config,
-        &mut res.device_descriptor,
-        &mut res.config_descriptor,
-        &mut res.bos_descriptor,
-        &mut res.control_buf,
+        &mut singleton!([0; 256])[..],
+        &mut singleton!([0; 256])[..],
+        &mut singleton!([0; 256])[..],
+        &mut singleton!([0; 128])[..],
         None,
     );
 
-    // WARNINGS for Android ethernet tethering:
-    // - On Pixel 4a, it refused to work on Android 11, worked on Android 12.
-    // - if the host's MAC address has the "locally-administered" bit set (bit 1 of first byte),
-    //   it doesn't work! The "Ethernet tethering" option in settings doesn't get enabled.
-    //   This is due to regex spaghetti: https://android.googlesource.com/platform/frameworks/base/+/refs/tags/android-mainline-12.0.0_r84/core/res/res/values/config.xml#417
-    //   and this nonsense in the linux kernel: https://github.com/torvalds/linux/blob/c00c5e1d157bec0ef0b0b59aa5482eb8dc7e8e49/drivers/net/usb/usbnet.c#L1751-L1757
-
     // Our MAC addr.
     let our_mac_addr = [0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC];
     // Host's MAC addr. This is the MAC the host "thinks" its USB-to-ethernet adapter has.
     let host_mac_addr = [0x88, 0x88, 0x88, 0x88, 0x88, 0x88];
 
     // Create classes on the builder.
-    let class = CdcNcmClass::new(&mut builder, &mut res.serial_state, host_mac_addr, 64);
+    let class = CdcNcmClass::new(&mut builder, singleton!(State::new()), host_mac_addr, 64);
 
     // Build the builder.
     let usb = builder.build();
 
     unwrap!(spawner.spawn(usb_task(usb)));
 
-    let (tx, rx) = class.split();
-    unwrap!(spawner.spawn(usb_ncm_rx_task(rx)));
-    unwrap!(spawner.spawn(usb_ncm_tx_task(tx)));
+    let (runner, device) = class.into_embassy_net_device::<MTU, 4, 4>(singleton!(NetState::new()), our_mac_addr);
+    unwrap!(spawner.spawn(usb_ncm_task(runner)));
 
     let config = embassy_net::ConfigStrategy::Dhcp;
     //let config = embassy_net::ConfigStrategy::Static(embassy_net::Config {
@@ -161,7 +103,6 @@ async fn main(spawner: Spawner) {
     let seed = 1234; // guaranteed random, chosen by a fair dice roll
 
     // Init network stack
-    let device = Device { mac_addr: our_mac_addr };
     let stack = &*singleton!(Stack::new(
         device,
         config,
@@ -214,50 +155,3 @@ async fn main(spawner: Spawner) {
         }
     }
 }
-
-static TX_CHANNEL: Channel<ThreadModeRawMutex, PacketBuf, 8> = Channel::new();
-static RX_CHANNEL: Channel<ThreadModeRawMutex, PacketBuf, 8> = Channel::new();
-static LINK_UP: AtomicBool = AtomicBool::new(false);
-
-struct Device {
-    mac_addr: [u8; 6],
-}
-
-impl embassy_net::Device for Device {
-    fn register_waker(&mut self, waker: &Waker) {
-        // loopy loopy wakey wakey
-        waker.wake_by_ref()
-    }
-
-    fn link_state(&mut self) -> embassy_net::LinkState {
-        match LINK_UP.load(Ordering::Relaxed) {
-            true => embassy_net::LinkState::Up,
-            false => embassy_net::LinkState::Down,
-        }
-    }
-
-    fn capabilities(&self) -> embassy_net::DeviceCapabilities {
-        let mut caps = embassy_net::DeviceCapabilities::default();
-        caps.max_transmission_unit = 1514; // 1500 IP + 14 ethernet header
-        caps.medium = embassy_net::Medium::Ethernet;
-        caps
-    }
-
-    fn is_transmit_ready(&mut self) -> bool {
-        true
-    }
-
-    fn transmit(&mut self, pkt: PacketBuf) {
-        if TX_CHANNEL.try_send(pkt).is_err() {
-            warn!("TX failed")
-        }
-    }
-
-    fn receive<'a>(&mut self) -> Option<PacketBuf> {
-        RX_CHANNEL.try_recv().ok()
-    }
-
-    fn ethernet_address(&self) -> [u8; 6] {
-        self.mac_addr
-    }
-}
diff --git a/examples/stm32l5/Cargo.toml b/examples/stm32l5/Cargo.toml
index 73ad50787..bb8515312 100644
--- a/examples/stm32l5/Cargo.toml
+++ b/examples/stm32l5/Cargo.toml
@@ -11,7 +11,7 @@ embassy-sync = { version = "0.1.0", path = "../../embassy-sync", features = ["de
 embassy-executor = { version = "0.1.0", path = "../../embassy-executor", features = ["defmt", "integrated-timers"] }
 embassy-time = { version = "0.1.0", path = "../../embassy-time", features = ["defmt", "defmt-timestamp-uptime", "tick-hz-32_768"] }
 embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["nightly", "defmt", "unstable-pac", "stm32l552ze", "time-driver-any", "exti", "unstable-traits", "memory-x"]  }
-embassy-usb = { version = "0.1.0", path = "../../embassy-usb", features = ["defmt"] }
+embassy-usb = { version = "0.1.0", path = "../../embassy-usb", features = ["defmt", "embassy-net"] }
 embassy-net = { version = "0.1.0", path = "../../embassy-net", features = ["defmt", "nightly", "tcp", "dhcpv4", "medium-ethernet", "pool-16"] }
 embassy-futures = { version = "0.1.0", path = "../../embassy-futures" }
 usbd-hid = "0.6.0"
diff --git a/examples/stm32l5/src/bin/usb_ethernet.rs b/examples/stm32l5/src/bin/usb_ethernet.rs
index 4f36d3f5a..b49329ea4 100644
--- a/examples/stm32l5/src/bin/usb_ethernet.rs
+++ b/examples/stm32l5/src/bin/usb_ethernet.rs
@@ -2,20 +2,16 @@
 #![no_main]
 #![feature(type_alias_impl_trait)]
 
-use core::sync::atomic::{AtomicBool, Ordering};
-use core::task::Waker;
-
 use defmt::*;
 use embassy_executor::Spawner;
 use embassy_net::tcp::TcpSocket;
-use embassy_net::{PacketBox, PacketBoxExt, PacketBuf, Stack, StackResources};
+use embassy_net::{Stack, StackResources};
 use embassy_stm32::rcc::*;
 use embassy_stm32::rng::Rng;
 use embassy_stm32::usb::Driver;
 use embassy_stm32::{interrupt, Config};
-use embassy_sync::blocking_mutex::raw::ThreadModeRawMutex;
-use embassy_sync::channel::Channel;
-use embassy_usb::class::cdc_ncm::{CdcNcmClass, Receiver, Sender, State};
+use embassy_usb::class::cdc_ncm::embassy_net::{Device, Runner, State as NetState};
+use embassy_usb::class::cdc_ncm::{CdcNcmClass, State};
 use embassy_usb::{Builder, UsbDevice};
 use embedded_io::asynch::Write;
 use rand_core::RngCore;
@@ -28,56 +24,25 @@ macro_rules! singleton {
     ($val:expr) => {{
         type T = impl Sized;
         static STATIC_CELL: StaticCell<T> = StaticCell::new();
-        STATIC_CELL.init_with(move || $val)
+        let (x,) = STATIC_CELL.init(($val,));
+        x
     }};
 }
 
+const MTU: usize = 1514;
+
 #[embassy_executor::task]
 async fn usb_task(mut device: UsbDevice<'static, MyDriver>) -> ! {
     device.run().await
 }
 
 #[embassy_executor::task]
-async fn usb_ncm_rx_task(mut class: Receiver<'static, MyDriver>) {
-    loop {
-        warn!("WAITING for connection");
-        LINK_UP.store(false, Ordering::Relaxed);
-
-        class.wait_connection().await.unwrap();
-
-        warn!("Connected");
-        LINK_UP.store(true, Ordering::Relaxed);
-
-        loop {
-            let mut p = unwrap!(PacketBox::new(embassy_net::Packet::new()));
-            let n = match class.read_packet(&mut p[..]).await {
-                Ok(n) => n,
-                Err(e) => {
-                    warn!("error reading packet: {:?}", e);
-                    break;
-                }
-            };
-
-            let buf = p.slice(0..n);
-            if RX_CHANNEL.try_send(buf).is_err() {
-                warn!("Failed pushing rx'd packet to channel.");
-            }
-        }
-    }
-}
-
-#[embassy_executor::task]
-async fn usb_ncm_tx_task(mut class: Sender<'static, MyDriver>) {
-    loop {
-        let pkt = TX_CHANNEL.recv().await;
-        if let Err(e) = class.write_packet(&pkt[..]).await {
-            warn!("Failed to TX packet: {:?}", e);
-        }
-    }
+async fn usb_ncm_task(class: Runner<'static, MyDriver, MTU>) -> ! {
+    class.run().await
 }
 
 #[embassy_executor::task]
-async fn net_task(stack: &'static Stack<Device>) -> ! {
+async fn net_task(stack: &'static Stack<Device<'static, MTU>>) -> ! {
     stack.run().await
 }
 
@@ -106,55 +71,32 @@ async fn main(spawner: Spawner) {
     config.device_sub_class = 0x02;
     config.device_protocol = 0x01;
 
-    struct Resources {
-        device_descriptor: [u8; 256],
-        config_descriptor: [u8; 256],
-        bos_descriptor: [u8; 256],
-        control_buf: [u8; 128],
-        serial_state: State<'static>,
-    }
-    let res: &mut Resources = singleton!(Resources {
-        device_descriptor: [0; 256],
-        config_descriptor: [0; 256],
-        bos_descriptor: [0; 256],
-        control_buf: [0; 128],
-        serial_state: State::new(),
-    });
-
     // Create embassy-usb DeviceBuilder using the driver and config.
     let mut builder = Builder::new(
         driver,
         config,
-        &mut res.device_descriptor,
-        &mut res.config_descriptor,
-        &mut res.bos_descriptor,
-        &mut res.control_buf,
+        &mut singleton!([0; 256])[..],
+        &mut singleton!([0; 256])[..],
+        &mut singleton!([0; 256])[..],
+        &mut singleton!([0; 128])[..],
         None,
     );
 
-    // WARNINGS for Android ethernet tethering:
-    // - On Pixel 4a, it refused to work on Android 11, worked on Android 12.
-    // - if the host's MAC address has the "locally-administered" bit set (bit 1 of first byte),
-    //   it doesn't work! The "Ethernet tethering" option in settings doesn't get enabled.
-    //   This is due to regex spaghetti: https://android.googlesource.com/platform/frameworks/base/+/refs/tags/android-mainline-12.0.0_r84/core/res/res/values/config.xml#417
-    //   and this nonsense in the linux kernel: https://github.com/torvalds/linux/blob/c00c5e1d157bec0ef0b0b59aa5482eb8dc7e8e49/drivers/net/usb/usbnet.c#L1751-L1757
-
     // Our MAC addr.
     let our_mac_addr = [0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC];
     // Host's MAC addr. This is the MAC the host "thinks" its USB-to-ethernet adapter has.
     let host_mac_addr = [0x88, 0x88, 0x88, 0x88, 0x88, 0x88];
 
     // Create classes on the builder.
-    let class = CdcNcmClass::new(&mut builder, &mut res.serial_state, host_mac_addr, 64);
+    let class = CdcNcmClass::new(&mut builder, singleton!(State::new()), host_mac_addr, 64);
 
     // Build the builder.
     let usb = builder.build();
 
     unwrap!(spawner.spawn(usb_task(usb)));
 
-    let (tx, rx) = class.split();
-    unwrap!(spawner.spawn(usb_ncm_rx_task(rx)));
-    unwrap!(spawner.spawn(usb_ncm_tx_task(tx)));
+    let (runner, device) = class.into_embassy_net_device::<MTU, 4, 4>(singleton!(NetState::new()), our_mac_addr);
+    unwrap!(spawner.spawn(usb_ncm_task(runner)));
 
     let config = embassy_net::ConfigStrategy::Dhcp;
     //let config = embassy_net::ConfigStrategy::Static(embassy_net::Config {
@@ -168,7 +110,6 @@ async fn main(spawner: Spawner) {
     let seed = rng.next_u64();
 
     // Init network stack
-    let device = Device { mac_addr: our_mac_addr };
     let stack = &*singleton!(Stack::new(
         device,
         config,
@@ -221,50 +162,3 @@ async fn main(spawner: Spawner) {
         }
     }
 }
-
-static TX_CHANNEL: Channel<ThreadModeRawMutex, PacketBuf, 8> = Channel::new();
-static RX_CHANNEL: Channel<ThreadModeRawMutex, PacketBuf, 8> = Channel::new();
-static LINK_UP: AtomicBool = AtomicBool::new(false);
-
-struct Device {
-    mac_addr: [u8; 6],
-}
-
-impl embassy_net::Device for Device {
-    fn register_waker(&mut self, waker: &Waker) {
-        // loopy loopy wakey wakey
-        waker.wake_by_ref()
-    }
-
-    fn link_state(&mut self) -> embassy_net::LinkState {
-        match LINK_UP.load(Ordering::Relaxed) {
-            true => embassy_net::LinkState::Up,
-            false => embassy_net::LinkState::Down,
-        }
-    }
-
-    fn capabilities(&self) -> embassy_net::DeviceCapabilities {
-        let mut caps = embassy_net::DeviceCapabilities::default();
-        caps.max_transmission_unit = 1514; // 1500 IP + 14 ethernet header
-        caps.medium = embassy_net::Medium::Ethernet;
-        caps
-    }
-
-    fn is_transmit_ready(&mut self) -> bool {
-        true
-    }
-
-    fn transmit(&mut self, pkt: PacketBuf) {
-        if TX_CHANNEL.try_send(pkt).is_err() {
-            warn!("TX failed")
-        }
-    }
-
-    fn receive<'a>(&mut self) -> Option<PacketBuf> {
-        RX_CHANNEL.try_recv().ok()
-    }
-
-    fn ethernet_address(&self) -> [u8; 6] {
-        self.mac_addr
-    }
-}