refactor(arch): split the nrf arch into multiple submodule files

Split the `nrf` arch to make it more manageable when it keeps growing.

src/riot-rs-embassy/src/arch/nrf/hwrng.rs

@@ -0,0 +1,26 @@
+use crate::arch;
+
+embassy_nrf::bind_interrupts!(struct Irqs {
+    RNG => embassy_nrf::rng::InterruptHandler<embassy_nrf::peripherals::RNG>;
+});
+
+pub fn construct_rng(peripherals: &mut arch::OptionalPeripherals) {
+    cfg_if::cfg_if! {
+        // The union of all contexts that wind up in a construct_rng should be synchronized
+        // with laze-project.yml's hwrng module.
+        if #[cfg(any(context = "nrf51", context = "nrf52"))] {
+            let rng = embassy_nrf::rng::Rng::new(
+                peripherals
+                    .RNG
+                    // We don't even have to take it out, just use it to seed the RNG
+                    .as_mut()
+                    .expect("RNG has not been previously used"),
+                arch::hwrng::Irqs,
+            );
+
+            riot_rs_random::construct_rng(rng);
+        } else if #[cfg(context = "riot-rs")] {
+            compile_error!("hardware RNG is not supported on this architecture");
+        }
+    }
+}

src/riot-rs-embassy/src/arch/nrf/mod.rs

@@ -0,0 +1,36 @@
+#[cfg(feature = "hwrng")]
+pub mod hwrng;
+
+#[cfg(feature = "usb")]
+pub mod usb;
+
+pub(crate) use embassy_executor::InterruptExecutor as Executor;
+
+#[cfg(context = "nrf52")]
+pub use embassy_nrf::interrupt::SWI0_EGU0 as SWI;
+
+#[cfg(context = "nrf5340")]
+pub use embassy_nrf::interrupt::EGU0 as SWI;
+
+pub use embassy_nrf::{config::Config, interrupt, peripherals, OptionalPeripherals};
+
+#[cfg(context = "nrf52")]
+#[interrupt]
+unsafe fn SWI0_EGU0() {
+    // SAFETY:
+    // - called from ISR
+    // - not called before `start()`, as the interrupt is enabled by `start()`
+    //   itself
+    unsafe { crate::EXECUTOR.on_interrupt() }
+}
+
+#[cfg(context = "nrf5340")]
+#[interrupt]
+unsafe fn EGU0() {
+    unsafe { crate::EXECUTOR.on_interrupt() }
+}
+
+pub fn init(config: Config) -> OptionalPeripherals {
+    let peripherals = embassy_nrf::init(config);
+    OptionalPeripherals::from(peripherals)
+}

src/riot-rs-embassy/src/arch/nrf/usb.rs

@@ -0,0 +1,29 @@
+use embassy_nrf::{
+    bind_interrupts, peripherals,
+    usb::{
+        self,
+        vbus_detect::{self, HardwareVbusDetect},
+        Driver,
+    },
+};
+
+use crate::arch;
+
+#[cfg(context = "nrf52")]
+bind_interrupts!(struct Irqs {
+    USBD => usb::InterruptHandler<peripherals::USBD>;
+    POWER_CLOCK => vbus_detect::InterruptHandler;
+});
+
+#[cfg(context = "nrf5340")]
+bind_interrupts!(struct Irqs {
+    USBD => usb::InterruptHandler<peripherals::USBD>;
+    USBREGULATOR => vbus_detect::InterruptHandler;
+});
+
+pub type UsbDriver = Driver<'static, peripherals::USBD, HardwareVbusDetect>;
+
+pub fn driver(peripherals: &mut arch::OptionalPeripherals) -> UsbDriver {
+    let usbd = peripherals.USBD.take().unwrap();
+    Driver::new(usbd, Irqs, HardwareVbusDetect::new(Irqs))
+}

src/riot-rs-embassy/src/lib.rs

@@ -8,7 +8,7 @@ pub mod define_peripherals;
 
 cfg_if::cfg_if! {
     if #[cfg(context = "nrf")] {
-        #[path = "arch/nrf.rs"]
+        #[path = "arch/nrf/mod.rs"]
         pub mod arch;
     } else if #[cfg(context = "rp2040")] {
         #[path = "arch/rp2040.rs"]