add register_bits_typed! macro

src/regs.rs

@@ -164,6 +164,34 @@ macro_rules! register_bits {
     );
 }
 
+/// Define a multi-bit field of a register, coerced to a certain type
+///
+/// Because read bits are just transmuted to the `$type`, its
+/// definition must be annotated with `#[repr($bit_type)]`!
+#[macro_export]
+macro_rules! register_bits_typed {
+    ($mod_name: ident, $name: ident, $bit_type: ty, $type: ty, $bit_begin: expr, $bit_end: expr) => (
+        impl $mod_name::Read {
+            pub fn $name(&self) -> $type {
+                use bit_field::BitField;
+
+                let bits = self.inner.get_bits($bit_begin..=$bit_end) as $bit_type;
+                unsafe { core::mem::transmute(bits) }
+            }
+        }
+
+        impl $mod_name::Write {
+            pub fn $name(mut self, value: $type) -> Self {
+                use bit_field::BitField;
+
+                let bits = (value as $bit_type).into();
+                self.inner.set_bits($bit_begin..=$bit_end, bits);
+                self
+            }
+        }
+    );
+}
+
 #[macro_export]
 macro_rules! register_at {
     ($name: ident, $addr: expr, $ctor: ident) => (

src/slcr.rs

@@ -1,8 +1,11 @@
 ///! Register definitions for System Level Control
 
 use volatile_register::{RO, WO, RW};
-use crate::{register, register_bit, register_bits, register_at, regs::RegisterW, regs::RegisterRW};
+use crate::{register, register_at,
+            register_bit, register_bits, register_bits_typed,
+            regs::RegisterW, regs::RegisterRW};
 
+#[repr(u8)]
 pub enum PllSource {
     IoPll  = 0b00,
     ArmPll = 0b10,
@@ -246,7 +249,7 @@ register!(uart_clk_ctrl, UartClkCtrl, RW, u32);
 register_bit!(uart_clk_ctrl, clkact0, 0);
 register_bit!(uart_clk_ctrl, clkact1, 1);
 register_bits!(uart_clk_ctrl, divisor, u8, 8, 13);
-register_bits!(uart_clk_ctrl, srcsel, u8, 4, 5);
+register_bits_typed!(uart_clk_ctrl, srcsel, u8, PllSource, 4, 5);
 register_at!(UartClkCtrl, 0xF8000154, new);
 impl UartClkCtrl {
     pub fn enable_uart0(&mut self) {
@@ -255,7 +258,7 @@ impl UartClkCtrl {
             // b. Select the IO PLL, slcr.UART_CLK_CTRL[SRCSEL] = 0.
             // c. Enable the UART 0 Reference clock, slcr.UART_CLK_CTRL [CLKACT0] = 1.
             w.divisor(0x14)
-             .srcsel(PllSource::IoPll as u8)
+             .srcsel(PllSource::IoPll)
              .clkact0(true)
         })
     }
@@ -266,7 +269,7 @@ impl UartClkCtrl {
             // b. Select the IO PLL, slcr.UART_CLK_CTRL[SRCSEL] = 0.
             // c. Enable the UART 1 Reference clock, slcr.UART_CLK_CTRL [CLKACT1] = 1.
             w.divisor(0x14)
-             .srcsel(PllSource::IoPll as u8)
+             .srcsel(PllSource::IoPll)
              .clkact1(true)
         })
     }

src/uart/mod.rs

@@ -65,11 +65,10 @@ impl Uart {
         // * 1 stop bit
         // * Normal channel mode
         // * No parity
-        let parity_mode = regs::ParityMode::None;
         self.regs.mode.write(
             regs::Mode::zeroed()
-                .par(parity_mode as u8)
-                .chmode(regs::ChannelMode::Normal as u8)
+                .par(regs::ParityMode::None)
+                .chmode(regs::ChannelMode::Normal)
         );
 
         // Configure the Baud Rate

src/uart/regs.rs

@@ -1,7 +1,8 @@
 use volatile_register::{RO, WO, RW};
 
-use crate::{register, register_bit, register_bits, register_at, regs::*};
+use crate::{register, register_bit, register_bits, register_bits_typed, register_at, regs::*};
 
+#[repr(u8)]
 pub enum ChannelMode {
     Normal         = 0b00,
     AutomaticEcho  = 0b01,
@@ -9,6 +10,7 @@ pub enum ChannelMode {
     RemoteLoopback = 0b11,
 }
 
+#[repr(u8)]
 pub enum ParityMode {
     EvenParity = 0b000,
     OddParity  = 0b001,
@@ -17,6 +19,7 @@ pub enum ParityMode {
     None       = 0b100,
 }
 
+#[repr(u8)]
 pub enum StopBits {
     One        = 0b00,
     OneAndHalf = 0b01,
@@ -60,11 +63,11 @@ register_bit!(control, stpbrk, 8);
 
 register!(mode, Mode, RW, u32);
 /// Channel mode: Defines the mode of operation of the UART.
-register_bits!(mode, chmode, u8, 8, 9);
+register_bits_typed!(mode, chmode, u8, ChannelMode, 8, 9);
 /// Number of stop bits
-register_bits!(mode, nbstop, u8, 6, 7);
+register_bits_typed!(mode, nbstop, u8, StopBits, 6, 7);
 /// Parity type select
-register_bits!(mode, par, u8, 3, 5);
+register_bits_typed!(mode, par, u8, ParityMode, 3, 5);
 /// Character length select
 register_bits!(mode, chrl, u8, 1, 2);
 /// Clock source select