feature: WebUSB capability implementation

This adds the WebUSB implementation as per
https://wicg.github.io/webusb/, using one in-endpoint and one
out-endpoint as well as an example for the RP2040 to illustrate this
capability.

1 files changed, 137 insertions, 0 deletions

diff --git a/examples/rp/src/bin/usb_webusb.rs b/examples/rp/src/bin/usb_webusb.rs
new file mode 100644
index 000000000..09f2c1cfd
--- /dev/null
+++ b/examples/rp/src/bin/usb_webusb.rs
@@ -0,0 +1,137 @@
+//! This example shows how to use USB (Universal Serial Bus) in the RP2040 chip.
+//!
+//! This creates a WebUSB capable device that echoes data back to the host.
+//!
+//! To test this in the browser (ideally host this on localhost:8080, to test the landing page
+//! feature):
+//! ```js
+//! (async () => {
+//!     const device = await navigator.usb.requestDevice({ filters: [{ vendorId: 0xf569 }] });
+//!     await device.open();
+//!     await device.claimInterface(1);
+//!     device.transferIn(1, 64).then(data => console.log(data));
+//!     await device.transferOut(1, new Uint8Array([1,2,3]));
+//! })();
+//! ```
+
+#![no_std]
+#![no_main]
+
+use defmt::info;
+use embassy_executor::Spawner;
+use embassy_futures::join::join;
+use embassy_rp::bind_interrupts;
+use embassy_rp::peripherals::USB;
+use embassy_rp::usb::{Driver as UsbDriver, InterruptHandler};
+use embassy_usb::class::web_usb::{Config as WebUsbConfig, State, Url, WebUsb};
+use embassy_usb::driver::{Driver, Endpoint, EndpointIn, EndpointOut};
+use embassy_usb::{Builder, Config};
+use {defmt_rtt as _, panic_probe as _};
+
+bind_interrupts!(struct Irqs {
+    USBCTRL_IRQ => InterruptHandler<USB>;
+});
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_rp::init(Default::default());
+
+    // Create the driver, from the HAL.
+    let driver = UsbDriver::new(p.USB, Irqs);
+
+    // Create embassy-usb Config
+    let mut config = Config::new(0xf569, 0x0001);
+    config.manufacturer = Some("Embassy");
+    config.product = Some("WebUSB example");
+    config.serial_number = Some("12345678");
+    config.max_power = 100;
+    config.max_packet_size_0 = 64;
+
+    // Required for windows compatibility.
+    // https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/kconfig/CONFIG_CDC_ACM_IAD.html#help
+    config.device_class = 0xff;
+    config.device_sub_class = 0x00;
+    config.device_protocol = 0x00;
+
+    // Create embassy-usb DeviceBuilder using the driver and config.
+    // It needs some buffers for building the descriptors.
+    let mut config_descriptor = [0; 256];
+    let mut bos_descriptor = [0; 256];
+    let mut control_buf = [0; 64];
+
+    let webusb_config = WebUsbConfig {
+        max_packet_size: 64,
+        vendor_code: 1,
+        // If defined, shows a landing page which the device manufacturer would like the user to visit in order to control their device. Suggest the user to navigate to this URL when the device is connected.
+        landing_url: Some(Url::new("http://localhost:8080")),
+    };
+
+    let mut state = State::new();
+
+    let mut builder = Builder::new(
+        driver,
+        config,
+        &mut config_descriptor,
+        &mut bos_descriptor,
+        &mut [], // no msos descriptors
+        &mut control_buf,
+    );
+
+    // Create classes on the builder (WebUSB just needs some setup, but doesn't return anything)
+    WebUsb::configure(&mut builder, &mut state, &webusb_config);
+    // Create some USB bulk endpoints for testing.
+    let mut endpoints = WebEndpoints::new(&mut builder, &webusb_config);
+
+    // Build the builder.
+    let mut usb = builder.build();
+
+    // Run the USB device.
+    let usb_fut = usb.run();
+
+    // Do some WebUSB transfers.
+    let webusb_fut = async {
+        loop {
+            endpoints.wait_connected().await;
+            info!("Connected");
+            endpoints.echo().await;
+        }
+    };
+
+    // Run everything concurrently.
+    // If we had made everything `'static` above instead, we could do this using separate tasks instead.
+    join(usb_fut, webusb_fut).await;
+}
+
+struct WebEndpoints<'d, D: Driver<'d>> {
+    write_ep: D::EndpointIn,
+    read_ep: D::EndpointOut,
+}
+
+impl<'d, D: Driver<'d>> WebEndpoints<'d, D> {
+    fn new(builder: &mut Builder<'d, D>, config: &'d WebUsbConfig<'d>) -> Self {
+        let mut func = builder.function(0xff, 0x00, 0x00);
+        let mut iface = func.interface();
+        let mut alt = iface.alt_setting(0xff, 0x00, 0x00, None);
+
+        let write_ep = alt.endpoint_bulk_in(config.max_packet_size);
+        let read_ep = alt.endpoint_bulk_out(config.max_packet_size);
+
+        WebEndpoints { write_ep, read_ep }
+    }
+
+    // Wait until the device's endpoints are enabled.
+    async fn wait_connected(&mut self) {
+        self.read_ep.wait_enabled().await
+    }
+
+    // Echo data back to the host.
+    async fn echo(&mut self) {
+        let mut buf = [0; 64];
+        loop {
+            let n = self.read_ep.read(&mut buf).await.unwrap();
+            let data = &buf[..n];
+            info!("Data read: {:x}", data);
+            self.write_ep.write(data).await.unwrap();
+        }
+    }
+}