spi: implement setting bit order

esp-hal/src/spi/master.rs

@@ -64,6 +64,7 @@ use super::{
     HalfDuplexMode,
     IsFullDuplex,
     IsHalfDuplex,
+    SpiBitOrder,
     SpiDataMode,
     SpiMode,
 };
@@ -481,6 +482,14 @@ where
         self
     }
 
+    /// Set the bit order for the SPI instance.
+    ///
+    /// The default is MSB first for both read and write.
+    pub fn with_bit_order(mut self, read_order: SpiBitOrder, write_order: SpiBitOrder) -> Self {
+        self.spi.set_bit_order(read_order, write_order);
+        self
+    }
+
     /// Setup pins for this SPI instance.
     ///
     /// All pins are optional. Pass [crate::gpio::NO_PIN] if you don't need the
@@ -718,6 +727,14 @@ where
     pub fn change_bus_frequency(&mut self, frequency: HertzU32, clocks: &Clocks) {
         self.spi.ch_bus_freq(frequency, clocks);
     }
+
+    /// Set the bit order for the SPI instance.
+    ///
+    /// The default is MSB first for both read and write.
+    pub fn with_bit_order(mut self, read_order: SpiBitOrder, write_order: SpiBitOrder) -> Self {
+        self.spi.set_bit_order(read_order, write_order);
+        self
+    }
 }
 
 impl<T, M> HalfDuplexReadWrite for Spi<'_, T, M>
@@ -2630,6 +2647,43 @@ pub trait Instance: crate::private::Sealed {
         });
     }
 
+    #[cfg(not(any(esp32, esp32s2)))]
+    fn set_bit_order(&mut self, read_order: SpiBitOrder, write_order: SpiBitOrder) {
+        let reg_block = self.register_block();
+
+        let read_value = match read_order {
+            SpiBitOrder::MSBFirst => 0,
+            SpiBitOrder::LSBFirst => 1,
+        };
+        let write_value = match write_order {
+            SpiBitOrder::MSBFirst => 0,
+            SpiBitOrder::LSBFirst => 1,
+        };
+        reg_block.ctrl().modify(|_, w| unsafe {
+            w.rd_bit_order().bits(read_value);
+            w.wr_bit_order().bits(write_value);
+            w
+        });
+    }
+    #[cfg(any(esp32, esp32s2))]
+    fn set_bit_order(&mut self, read_order: SpiBitOrder, write_order: SpiBitOrder) {
+        let reg_block = self.register_block();
+
+        let read_value = match read_order {
+            SpiBitOrder::MSBFirst => false,
+            SpiBitOrder::LSBFirst => true,
+        };
+        let write_value = match write_order {
+            SpiBitOrder::MSBFirst => false,
+            SpiBitOrder::LSBFirst => true,
+        };
+        reg_block.ctrl().modify(|_, w| unsafe {
+            w.rd_bit_order().bit(read_value);
+            w.wr_bit_order().bit(write_value);
+            w
+        });
+    }
+
     fn read_byte(&mut self) -> nb::Result<u8, Error> {
         if self.busy() {
             return Err(nb::Error::WouldBlock);

esp-hal/src/spi/mod.rs

@@ -44,6 +44,14 @@ pub enum SpiMode {
     Mode3,
 }
 
+/// SPI Bit Order
+#[derive(Debug, Clone, Copy, PartialEq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum SpiBitOrder {
+    MSBFirst,
+    LSBFirst,
+}
+
 pub trait DuplexMode {}
 pub trait IsFullDuplex: DuplexMode {}
 pub trait IsHalfDuplex: DuplexMode {}