3 files changed, 39 insertions, 0 deletions

diff --git a/embassy-stm32/build.rs b/embassy-stm32/build.rs
index 1e11eb8dc..9dd94941c 100644
--- a/embassy-stm32/build.rs
+++ b/embassy-stm32/build.rs
@@ -170,6 +170,11 @@ fn main() {
                     }
                     singletons.push(p.name.to_string());
                 }
+
+                "eth" => {
+                    singletons.push(p.name.to_string());
+                    singletons.push("ETH_SMA".to_string());
+                }
                 //"dbgmcu" => {}
                 //"syscfg" => {}
                 //"dma" => {}
diff --git a/embassy-stm32/src/eth/mod.rs b/embassy-stm32/src/eth/mod.rs
index 10b3a0517..bef6a02b2 100644
--- a/embassy-stm32/src/eth/mod.rs
+++ b/embassy-stm32/src/eth/mod.rs
@@ -5,6 +5,7 @@
 #[cfg_attr(eth_v2, path = "v2/mod.rs")]
 mod _version;
 mod generic_phy;
+mod sma;
 
 use core::mem::MaybeUninit;
 use core::task::Context;
diff --git a/embassy-stm32/src/eth/sma/mod.rs b/embassy-stm32/src/eth/sma/mod.rs
new file mode 100644
index 000000000..106a6b2bd
--- /dev/null
+++ b/embassy-stm32/src/eth/sma/mod.rs
@@ -0,0 +1,33 @@
+//! Station Management Agent (also known as MDIO or SMI).
+
+#![macro_use]
+
+use embassy_hal_internal::PeripheralType;
+#[cfg(eth_v2)]
+pub(crate) use regs::{Macmdioar as AddressRegister, Macmdiodr as DataRegister};
+#[cfg(any(eth_v1a, eth_v1b, eth_v1c))]
+pub(crate) use regs::{Macmiiar as AddressRegister, Macmiidr as DataRegister};
+use stm32_metapac::common::{RW, Reg};
+use stm32_metapac::eth::regs;
+
+trait SealedInstance {
+    fn regs() -> (Reg<AddressRegister, RW>, Reg<DataRegister, RW>);
+}
+
+/// MDIO instance.
+#[allow(private_bounds)]
+pub trait Instance: SealedInstance + PeripheralType + Send + 'static {}
+
+impl SealedInstance for crate::peripherals::ETH_SMA {
+    fn regs() -> (Reg<AddressRegister, RW>, Reg<DataRegister, RW>) {
+        let mac = crate::pac::ETH.ethernet_mac();
+
+        #[cfg(any(eth_v1a, eth_v1b, eth_v1c))]
+        return (mac.macmiiar(), mac.macmiidr());
+
+        #[cfg(eth_v2)]
+        return (mac.macmdioar(), mac.macmdiodr());
+    }
+}
+
+impl Instance for crate::peripherals::ETH_SMA {}