Merge #839

839: Misc LoRaWAN improvements r=lulf a=timokroeger

Trying too get `embassy-lora` running on a [LoRa-E5 Dev Board](https://wiki.seeedstudio.com/LoRa_E5_Dev_Board/).
I can see the join message arriving in the The Things Network console but the device does not receive the accept message yet.
Opening this PR anyway because I think there are some nice things to decouple the lora crate from the nucleo board.

`@lulf` Could you test if this PR breaks your LoRa setup? Marking as draft for the time being.

Co-authored-by: Timo Kröger <timokroeger93@gmail.com>
Co-authored-by: Ulf Lilleengen <lulf@redhat.com>

embassy-stm32/src/spi/mod.rs

@@ -179,6 +179,19 @@ impl<'d, T: Instance, Tx, Rx> Spi<'d, T, Tx, Rx> {
         )
     }
 
+    /// Useful for on chip peripherals like SUBGHZ which are hardwired.
+    /// The bus can optionally be exposed externally with `Spi::new()` still.
+    #[allow(dead_code)]
+    pub(crate) fn new_internal(
+        peri: impl Peripheral<P = T> + 'd,
+        txdma: impl Peripheral<P = Tx> + 'd,
+        rxdma: impl Peripheral<P = Rx> + 'd,
+        freq: Hertz,
+        config: Config,
+    ) -> Self {
+        Self::new_inner(peri, None, None, None, txdma, rxdma, freq, config)
+    }
+
     fn new_inner(
         peri: impl Peripheral<P = T> + 'd,
         sck: Option<PeripheralRef<'d, AnyPin>>,