can: Add error traits like rust-embedded#296

Author: timokroeger

src/can/blocking.rs

@@ -6,7 +6,7 @@ pub trait Can {
     type Frame: crate::can::Frame;
 
     /// Associated error type.
-    type Error;
+    type Error: crate::can::Error;
 
     /// Puts a frame in the transmit buffer. Blocks until space is available in
     /// the transmit buffer.

src/can/mod.rs

@@ -45,3 +45,71 @@ pub trait Frame: Sized {
     /// Returns the frame data (0..8 bytes in length).
     fn data(&self) -> &[u8];
 }
+
+/// CAN error
+pub trait Error: core::fmt::Debug {
+    /// Convert error to a generic CAN error kind
+    ///
+    /// By using this method, CAN errors freely defined by HAL implementations
+    /// can be converted to a set of generic serial errors upon which generic
+    /// code can act.
+    fn kind(&self) -> ErrorKind;
+}
+
+/// CAN error kind
+///
+/// This represents a common set of CAN operation errors. HAL implementations are
+/// free to define more specific or additional error types. However, by providing
+/// a mapping to these common CAN errors, generic code can still react to them.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
+#[non_exhaustive]
+pub enum ErrorKind {
+    /// The peripheral receive buffer was overrun.
+    Overrun,
+
+    // MAC sublayer errors
+    /// A bit error is detected at that bit time when the bit value that is
+    /// monitored differs from the bit value sent.
+    Bit,
+
+    /// A stuff error is detected at the bit time of the sixth consecutive
+    /// equal bit level in a frame field that shall be coded by the method
+    /// of bit stuffing.
+    Stuff,
+
+    /// Calculated CRC sequence does not equal the received one.
+    Crc,
+
+    /// A form error shall be detected when a fixed-form bit field contains
+    /// one or more illegal bits.
+    Form,
+
+    /// An ACK  error shall be detected by a transmitter whenever it does not
+    /// monitor a dominant bit during the ACK slot.
+    Ack,
+}
+
+impl Error for ErrorKind {
+    fn kind(&self) -> ErrorKind {
+        *self
+    }
+}
+
+impl core::fmt::Display for ErrorKind {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        match self {
+            Self::Overrun => write!(f, "The peripheral receive buffer was overrun"),
+            Self::Bit => write!(
+                f,
+                "Bit value that is monitored differs from the bit value sent"
+            ),
+            Self::Stuff => write!(f, "Sixth consecutive equal bits detected"),
+            Self::Crc => write!(f, "Calculated CRC sequence does not equal the received one"),
+            Self::Form => write!(
+                f,
+                "A fixed-form bit field contains one or more illegal bits"
+            ),
+            Self::Ack => write!(f, "Transmitted frame was not acknowledged"),
+        }
+    }
+}

src/can/nb.rs

@@ -6,7 +6,7 @@ pub trait Can {
     type Frame: crate::can::Frame;
 
     /// Associated error type.
-    type Error;
+    type Error: crate::can::Error;
 
     /// Puts a frame in the transmit buffer to be sent on the bus.
     ///