Add FrameBuffer configuration

nucleus/src/platform/rpi3/fb.rs

@@ -0,0 +1,107 @@
+use {
+    super::{
+        mailbox::{channel, read, write, MailboxOps, RegisterBlock, Result},
+        BcmHost,
+    },
+    core::ops::Deref,
+};
+
+/// FrameBuffer channel supported structure - use with mailbox::channel::FrameBuffer
+/// Must have the same alignment as the mailbox buffers.
+#[repr(C)]
+#[repr(align(16))]
+pub struct FrameBuffer {
+    pub width: u32,
+    pub height: u32,
+    pub vwidth: u32,
+    pub vheight: u32,
+    pub pitch: u32,
+    pub depth: u32,
+    pub x_offset: u32,
+    pub y_offset: u32,
+    pub pointer: u32,
+    pub size: u32,
+    // Must be after HW-dictated fields to not break structure alignment.
+    base_addr: usize,
+}
+
+// @todo rewrite in terms of using the Mailbox
+
+/// Deref to RegisterBlock
+///
+/// Allows writing
+/// ```
+/// self.STATUS.read()
+/// ```
+/// instead of something along the lines of
+/// ```
+/// unsafe { (*FrameBuffer::ptr()).STATUS.read() }
+/// ```
+impl Deref for FrameBuffer {
+    type Target = RegisterBlock; // mailbox RegisterBlock reused here
+
+    fn deref(&self) -> &Self::Target {
+        unsafe { &*self.ptr() }
+    }
+}
+
+impl core::fmt::Debug for FrameBuffer {
+    fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
+        write!(
+            f,
+            "\n\n\n#### FrameBuffer({}x{}, {}x{}, d{}, --{}--, +{}x{}, {}@{:x})\n\n\n",
+            self.width,
+            self.height,
+            self.vwidth,
+            self.vheight,
+            self.depth,
+            self.pitch,
+            self.x_offset,
+            self.y_offset,
+            self.size,
+            self.pointer,
+        )
+    }
+}
+
+impl FrameBuffer {
+    pub fn new(reg_base: usize, width: u32, height: u32, depth: u32) -> FrameBuffer {
+        FrameBuffer {
+            width,
+            height,
+            vwidth: width,
+            vheight: height,
+            pitch: 0,
+            depth,
+            x_offset: 0,
+            y_offset: 0,
+            pointer: 0, // could be 4096 for the alignment?
+            size: 0,
+
+            base_addr: reg_base,
+        }
+    }
+}
+
+impl MailboxOps for FrameBuffer {
+    /// Returns a pointer to the register block
+    fn ptr(&self) -> *const RegisterBlock {
+        self.base_addr as *const _
+    }
+
+    /// https://github.com/raspberrypi/firmware/wiki/Accessing-mailboxes says:
+    /// **With the exception of the property tags mailbox channel,**
+    /// when passing memory addresses as the data part of a mailbox message,
+    /// the addresses should be **bus addresses as seen from the VC.**
+    fn write(&self, _channel: u32) -> Result<()> {
+        write(
+            self,
+            BcmHost::phys2bus(&self as *const _ as usize) as *const _,
+            channel::FrameBuffer,
+        )
+    }
+
+    fn read(&self, _channel: u32) -> Result<()> {
+        read(self, 0, channel::FrameBuffer)
+    }
+}

nucleus/src/platform/rpi3/mailbox.rs

@@ -125,6 +125,9 @@ pub mod channel {
     // Count = 7,
     pub const PropertyTagsArmToVc: u32 = 8;
     pub const PropertyTagsVcToArm: u32 = 9;
+    /// Channel number is ignored. Use for implementations of MailboxOps that use hardcoded
+    /// channel number.
+    pub const Ignored: u32 = !0;
 }
 
 // Single code indicating request
@@ -236,7 +239,7 @@ pub mod alpha_mode {
     pub const IGNORED: u32 = 2;
 }
 
-fn write(regs: &RegisterBlock, buf: *const u32, channel: u32) -> Result<()> {
+pub fn write(regs: &RegisterBlock, buf: *const u32, channel: u32) -> Result<()> {
     let mut count: u32 = 0;
     let buf_ptr: u32 = buf as u32;
 
@@ -265,7 +268,7 @@ fn write(regs: &RegisterBlock, buf: *const u32, channel: u32) -> Result<()> {
     Ok(())
 }
 
-fn read(regs: &RegisterBlock, expected: u32, channel: u32) -> Result<()> {
+pub fn read(regs: &RegisterBlock, expected: u32, channel: u32) -> Result<()> {
     loop {
         let mut count: u32 = 0;
         while regs.STATUS.is_set(STATUS::EMPTY) {

nucleus/src/platform/rpi3/mod.rs

@@ -5,6 +5,7 @@
 
 #![allow(dead_code)]
 
+pub mod fb;
 pub mod mailbox;
 
 /// See BCM2835-ARM-Peripherals.pdf