Add DSI related traits and data structures.

src/dsi.rs

@@ -0,0 +1,50 @@
+pub trait DsiHostCtrlIo {
+    type Error;
+
+    fn write(&mut self, command: DsiWriteCommand) -> Result<(), Self::Error>;
+    fn read(&mut self, command: DsiReadCommand, buf: &mut [u8]) -> Result<(), Self::Error>;
+}
+
+#[repr(u8)]
+#[derive(Debug)]
+pub enum DsiReadCommand {
+    DcsShort { arg: u8 } = 0x06,
+
+    // xx x101 0-7 arguments
+    GenericShortP0 = 0x04,
+    GenericShortP1 { arg0: u8 } = 0x14,
+    GenericShortP2 { arg0: u8, arg1: u8 } = 0x24,
+}
+
+impl DsiReadCommand {
+    pub fn discriminant(&self) -> u8 {
+        // SAFETY: Because `Self` is marked `repr(u8)`, its layout is a `repr(C)` `union`
+        // between `repr(C)` structs, each of which has the `u8` discriminant as its first
+        // field, so we can read the discriminant without offsetting the pointer.
+        unsafe { *<*const _>::from(self).cast::<u8>() }
+    }
+}
+
+#[repr(u8)]
+#[derive(Debug)]
+pub enum DsiWriteCommand<'i> {
+    DcsShortP0 { arg: u8 } = 0x5,
+    DcsShortP1 { arg: u8, data: u8 } = 0x15,
+    DcsLongWrite { arg: u8, data: &'i [u8] } = 0x39,
+
+    GenericShortP0 = 0x03,
+    GenericShortP1 = 0x13,
+    GenericShortP2 = 0x23,
+    GenericLongWrite { arg: u8, data: &'i [u8] } = 0x29,
+
+    SetMaximumReturnPacketSize(u16) = 0x37,
+}
+
+impl<'i> DsiWriteCommand<'i> {
+    pub fn discriminant(&self) -> u8 {
+        // SAFETY: Because `Self` is marked `repr(u8)`, its layout is a `repr(C)` `union`
+        // between `repr(C)` structs, each of which has the `u8` discriminant as its first
+        // field, so we can read the discriminant without offsetting the pointer.
+        unsafe { *<*const _>::from(self).cast::<u8>() }
+    }
+}

src/lib.rs

@@ -35,6 +35,8 @@
 //! conditions.
 #![no_std]
 
+pub mod dsi;
+
 /// A word type for the display memory buffer
 pub trait PixelWord: Copy {}
 impl PixelWord for u8 {}