impl embedded_hal::spi::FullDuplex<u8> for Spi<SPI0>

Author: longfangsong

src/spi.rs

@@ -1,47 +1,50 @@
 //! (TODO) Serial Peripheral Interface (SPI)
 
-use crate::pac::SPI0;
 use crate::clock::Clocks;
+use crate::pac::spi0::ctrlr0::TMOD_A as transfer_mode;
+use crate::pac::SPI0;
 use crate::sysctl::{self, APB0};
-pub use embedded_hal::spi::{Mode, Polarity, Phase};
 use core::convert::Infallible;
+pub use embedded_hal::spi::{Mode, Phase, Polarity};
 
-/// 
 pub struct Spi<SPI> {
-    spi: SPI
+    spi: SPI,
+    // Different with other MCUs like STM32 and Atmel
+    // k210 use fpioa to map a pin directly to SPI SS 0-3 instead of using an ordinary GPIO
+    // when transferring data, we'll set `pac::SPIX::ser` to (1 << cs_id) to select this device
+    cs_id: u8,
 }
 
 impl Spi<SPI0> {
     pub fn spi0(
-        spi: SPI0, 
-        mode: Mode, 
-        frame_format: FrameFormat, 
-        endian: Endian, 
-        clock: &Clocks, 
-        apb0: &mut APB0
+        spi: SPI0,
+        cs_id: u8, // todo: currently we presume SPI0_SS<cs_id> is already configured correctly, maybe we can do this for the user?
+        mode: Mode,
+        frame_format: FrameFormat,
+        endian: Endian,
+        clock: &Clocks,
+        apb0: &mut APB0,
     ) -> Self {
         let work_mode = hal_mode_to_pac(mode);
         let frame_format = frame_format_to_pac(frame_format);
-        let tmod = crate::pac::spi0::ctrlr0::TMOD_A::TRANS_RECV; // todo other modes
         let endian = endian as u32;
         let data_bit_length = 8; // todo more length
         let _ = clock; // todo
         unsafe {
             // no interrupts for now
-            spi.imr.write(|w| w.bits(0x00));
+            spi.imr.write(|w| w.bits(0x0));
             // no dma for now
-            spi.dmacr.write(|w| w.bits(0x00));
+            spi.dmacr.write(|w| w.bits(0x0));
             spi.dmatdlr.write(|w| w.bits(0x10));
-            spi.dmardlr.write(|w| w.bits(0x00));
+            spi.dmardlr.write(|w| w.bits(0x0));
             // no slave access for now
-            spi.ser.write(|w| w.bits(0x00));
-            spi.ssienr.write(|w| w.bits(0x00));
+            spi.ser.write(|w| w.bits(0x0));
+            spi.ssienr.write(|w| w.bits(0x0));
             // set control registers
             spi.ctrlr0.write(|w| {
+                // no need to set tmod here, which will (and needs to) be set on each send/recv
                 w.work_mode()
                     .variant(work_mode)
-                    .tmod()
-                    .variant(tmod)
                     .frame_format()
                     .variant(frame_format)
                     .data_length()
@@ -53,19 +56,27 @@ impl Spi<SPI0> {
         // enable APB0 bus
         apb0.enable();
         // enable peripheral via sysctl
-        sysctl::clk_en_peri().modify(|_r, w| 
-            w.spi0_clk_en().set_bit());
-        Spi { spi }
+        sysctl::clk_en_peri().modify(|_r, w| w.spi0_clk_en().set_bit());
+        Spi { spi, cs_id }
     }
 
     pub fn release(self) -> SPI0 {
         // power off
-        sysctl::clk_en_peri().modify(|_r, w| 
-            w.spi0_clk_en().clear_bit());
+        sysctl::clk_en_peri().modify(|_r, w| w.spi0_clk_en().clear_bit());
         self.spi
     }
+
+    /// for making our life easier to use the same SPI interface but with different chip selected
+    pub fn take_for_cs(self, cs_id: u8) -> Self {
+        Self {
+            spi: self.spi,
+            cs_id,
+        }
+    }
 }
 
+// todo: Shall we make FrameFormat a type parameter instead?
+// so FullDuplex<u8> can be implemented for Spi<SPI0, FrameFormat::Standard> only
 impl embedded_hal::spi::FullDuplex<u8> for Spi<SPI0> {
     /// An enumeration of SPI errors
     type Error = Infallible;
@@ -75,12 +86,52 @@ impl embedded_hal::spi::FullDuplex<u8> for Spi<SPI0> {
     /// **NOTE** A word must be sent to the slave before attempting to call this
     /// method.
     fn try_read(&mut self) -> nb::Result<u8, Self::Error> {
-        todo!()
+        self.spi
+            .ctrlr0
+            .modify(|_, w| w.tmod().variant(transfer_mode::RECV));
+        unsafe {
+            // C sdk said ctrlr1 = rx_len(1) / frame_width(1) - 1;
+            self.spi.ctrlr1.write(|w| w.bits(0x0));
+            // enable spi
+            self.spi.ssienr.write(|w| w.bits(0x1));
+            // select that chip
+            self.spi.ser.write(|w| w.bits(0x1 << self.cs_id));
+            // clear dr
+            self.spi.dr[0].write(|w| w.bits(0xffffffff));
+        }
+        let bytes_in_buffer = self.spi.rxflr.read().bits();
+        let result = if bytes_in_buffer == 0 {
+            Err(nb::Error::WouldBlock)
+        } else {
+            Ok(self.spi.dr[0].read().bits() as u8)
+        };
+        self.spi.ser.reset();
+        self.spi.ssienr.reset();
+        result
     }
 
     /// Sends a word to the slave
     fn try_send(&mut self, word: u8) -> nb::Result<(), Self::Error> {
-        todo!("{}", word)
+        self.spi
+            .ctrlr0
+            .modify(|_, w| w.tmod().variant(transfer_mode::TRANS));
+        unsafe {
+            self.spi.ssienr.write(|w| w.bits(0x0));
+            self.spi.ser.write(|w| w.bits(0x1 << self.cs_id));
+        }
+        const MAX_FIFO_SIZE: u32 = 32;
+        let empty_in_buffer = MAX_FIFO_SIZE - self.spi.txflr.read().bits();
+        let result = if empty_in_buffer == 0 {
+            Err(nb::Error::WouldBlock)
+        } else {
+            unsafe {
+                self.spi.dr[0].write(|w| w.bits(word as u32));
+            }
+            Ok(())
+        };
+        self.spi.ser.reset();
+        self.spi.ssienr.reset();
+        result
     }
 }
 
@@ -101,7 +152,7 @@ pub enum Endian {
 #[inline]
 fn hal_mode_to_pac(mode: Mode) -> crate::pac::spi0::ctrlr0::WORK_MODE_A {
     use crate::pac::spi0::ctrlr0::WORK_MODE_A;
-    use {Polarity::*, Phase::*};
+    use {Phase::*, Polarity::*};
     match (mode.polarity, mode.phase) {
         (IdleLow, CaptureOnFirstTransition) => WORK_MODE_A::MODE0,
         (IdleLow, CaptureOnSecondTransition) => WORK_MODE_A::MODE1,