boards/kakute-f7-mini-v3: add MPU6000 SPI route

boards/kakute-f7-mini-v3/src/routes.rs

@@ -0,0 +1,72 @@
+//! Static electrical routes selected by the Kakute F7 Mini V3.
+//!
+//! The board describes which controller and pins are connected. Protocol
+//! framing and controller state remain in their respective reusable crates.
+
+use kaptan_spi::{SpiCompletion, SpiDevice};
+use kaptan_stm32f7::stm32f722::{Spi1, Spi1Error};
+use stm32f7::stm32f722;
+
+/// Chip-select-scoped SPI1/PB2 route wired to the MPU6000.
+pub struct KakuteMpu6000SpiRoute {
+    spi: Spi1,
+    chip_select: stm32f722::GPIOB,
+}
+
+impl KakuteMpu6000SpiRoute {
+    /// Configures board-selected PB2 chip select and combines it with SPI1.
+    pub(crate) fn new(rcc: &stm32f722::RCC, spi: Spi1, chip_select: stm32f722::GPIOB) -> Self {
+        rcc.ahb1enr().modify(|_, write| write.gpioben().set_bit());
+        chip_select
+            .moder()
+            .modify(|_, write| write.moder2().output());
+        chip_select
+            .otyper()
+            .modify(|_, write| write.ot2().push_pull());
+        chip_select
+            .ospeedr()
+            .modify(|_, write| write.ospeedr2().low_speed());
+        chip_select
+            .pupdr()
+            .modify(|_, write| write.pupdr2().floating());
+        chip_select.bsrr().write(|write| write.bs2().set_bit());
+
+        Self { spi, chip_select }
+    }
+
+    fn select(&self) {
+        self.chip_select.bsrr().write(|write| write.br2().set_bit());
+    }
+
+    fn deselect(&self) {
+        self.chip_select.bsrr().write(|write| write.bs2().set_bit());
+    }
+}
+
+impl SpiDevice for KakuteMpu6000SpiRoute {
+    type StartError = Spi1Error;
+
+    fn start_transfer(
+        &mut self,
+        transmit: &[u8],
+        receive: &mut [u8],
+    ) -> Result<(), Self::StartError> {
+        self.select();
+        if let Err(error) = self.spi.start_transfer(transmit, receive) {
+            self.deselect();
+            return Err(error);
+        }
+
+        Ok(())
+    }
+
+    fn complete_transfer(&mut self, completion: SpiCompletion) {
+        self.spi.complete_transfer(completion);
+        if matches!(
+            completion,
+            SpiCompletion::Complete | SpiCompletion::TransferFault
+        ) {
+            self.deselect();
+        }
+    }
+}