Merge branch 'main' into main

1 files changed, 62 insertions, 0 deletions

diff --git a/embassy-net-esp-hosted/src/iface.rs b/embassy-net-esp-hosted/src/iface.rs
new file mode 100644
index 000000000..1f57851e0
--- /dev/null
+++ b/embassy-net-esp-hosted/src/iface.rs
@@ -0,0 +1,62 @@
+use embassy_time::Timer;
+use embedded_hal::digital::InputPin;
+use embedded_hal_async::digital::Wait;
+use embedded_hal_async::spi::SpiDevice;
+
+/// Physical interface trait for communicating with the ESP chip.
+pub trait Interface {
+    /// Wait for the HANDSHAKE signal indicating the ESP is ready for a new transaction.
+    async fn wait_for_handshake(&mut self);
+
+    /// Wait for the READY signal indicating the ESP has data to send.
+    async fn wait_for_ready(&mut self);
+
+    /// Perform a SPI transfer, exchanging data with the ESP chip.
+    async fn transfer(&mut self, rx: &mut [u8], tx: &[u8]);
+}
+
+/// Standard SPI interface.
+///
+/// This interface is what's implemented in the upstream `esp-hosted-fg` firmware. It uses:
+/// - An `SpiDevice` for SPI communication (CS is handled by the device)
+/// - A handshake pin that signals when the ESP is ready for a new transaction
+/// - A ready pin that indicates when the ESP has data to send
+pub struct SpiInterface<SPI, IN> {
+    spi: SPI,
+    handshake: IN,
+    ready: IN,
+}
+
+impl<SPI, IN> SpiInterface<SPI, IN>
+where
+    SPI: SpiDevice,
+    IN: InputPin + Wait,
+{
+    /// Create a new SpiInterface.
+    pub fn new(spi: SPI, handshake: IN, ready: IN) -> Self {
+        Self { spi, handshake, ready }
+    }
+}
+
+impl<SPI, IN> Interface for SpiInterface<SPI, IN>
+where
+    SPI: SpiDevice,
+    IN: InputPin + Wait,
+{
+    async fn wait_for_handshake(&mut self) {
+        self.handshake.wait_for_high().await.unwrap();
+    }
+
+    async fn wait_for_ready(&mut self) {
+        self.ready.wait_for_high().await.unwrap();
+    }
+
+    async fn transfer(&mut self, rx: &mut [u8], tx: &[u8]) {
+        self.spi.transfer(rx, tx).await.unwrap();
+
+        // The esp-hosted firmware deasserts the HANDSHAKE pin a few us AFTER ending the SPI transfer
+        // If we check it again too fast, we'll see it's high from the previous transfer, and if we send it
+        // data it will get lost.
+        Timer::after_micros(100).await;
+    }
+}