Add the basic framework of /dev/fb0

Co-authored-by: Wei Zhang <ruoyuan.zw@antgroup.com>

kernel/comps/framebuffer/src/console.rs

@@ -8,7 +8,7 @@ use aster_console::{
     AnyConsoleDevice, ConsoleCallback, ConsoleSetFontError,
 };
 use ostd::{
-    mm::VmReader,
+    mm::{HasSize, VmReader},
     sync::{LocalIrqDisabled, SpinLock},
 };
 use spin::Once;
@@ -108,7 +108,7 @@ impl FramebufferConsole {
             font: BitmapFont::new_basic8x8(),
             is_output_enabled: true,
 
-            bytes: alloc::vec![0u8; framebuffer.size()],
+            bytes: alloc::vec![0u8; framebuffer.io_mem().size()],
             backend: framebuffer,
         };
 
@@ -195,7 +195,7 @@ impl ConsoleState {
     fn shift_lines_up(&mut self) {
         let offset = self.backend.calc_offset(0, self.font.height()).as_usize();
         self.bytes.copy_within(offset.., 0);
-        self.bytes[self.backend.size() - offset..].fill(0);
+        self.bytes[self.backend.io_mem().size() - offset..].fill(0);
 
         if self.is_output_enabled {
             self.backend.write_bytes_at(0, &self.bytes).unwrap();

kernel/comps/framebuffer/src/framebuffer.rs

@@ -84,11 +84,6 @@ pub(crate) fn init() {
 }
 
 impl FrameBuffer {
-    /// Returns the size of the framebuffer in bytes.
-    pub fn size(&self) -> usize {
-        self.io_mem.size()
-    }
-
     /// Returns the width of the framebuffer in pixels.
     pub fn width(&self) -> usize {
         self.width
@@ -99,6 +94,11 @@ impl FrameBuffer {
         self.height
     }
 
+    /// Returns a reference to the `IoMem` instance of the framebuffer.
+    pub fn io_mem(&self) -> &IoMem {
+        &self.io_mem
+    }
+
     /// Returns the pixel format of the framebuffer.
     pub fn pixel_format(&self) -> PixelFormat {
         self.pixel_format
@@ -129,7 +129,7 @@ impl FrameBuffer {
 
     /// Clears the framebuffer with default color (black).
     pub fn clear(&self) {
-        let frame = alloc::vec![0u8; self.size()];
+        let frame = alloc::vec![0u8; self.io_mem().size()];
         self.write_bytes_at(0, &frame).unwrap();
     }
 }

kernel/src/device/fb.rs

@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use alloc::sync::Arc;
+
+use aster_framebuffer::{ColorMapEntry, FrameBuffer, PixelFormat, FRAMEBUFFER, MAX_CMAP_SIZE};
+use device_id::{DeviceId, MajorId, MinorId};
+use ostd::{
+    mm::{io_util::HasVmReaderWriter, HasPaddr, HasSize},
+    Pod,
+};
+
+use super::char::{self, CharDevice, DevtmpfsName};
+use crate::{
+    current_userspace,
+    events::IoEvents,
+    fs::{
+        file_handle::Mappable,
+        inode_handle::FileIo,
+        utils::{InodeIo, IoctlCmd, StatusFlags},
+    },
+    prelude::*,
+    process::signal::{PollHandle, Pollable},
+};
+
+#[derive(Debug)]
+struct Fb;
+
+#[derive(Debug)]
+struct FbHandle {
+    framebuffer: Arc<FrameBuffer>,
+}
+
+impl Pollable for FbHandle {
+    fn poll(&self, mask: IoEvents, _poller: Option<&mut PollHandle>) -> IoEvents {
+        let events = IoEvents::IN | IoEvents::OUT;
+        events & mask
+    }
+}
+
+impl InodeIo for FbHandle {
+    fn read_at(
+        &self,
+        offset: usize,
+        writer: &mut VmWriter,
+        _status_flags: StatusFlags,
+    ) -> Result<usize> {
+    }
+
+    fn write_at(
+        &self,
+        offset: usize,
+        reader: &mut VmReader,
+        _status_flags: StatusFlags,
+    ) -> Result<usize> {
+    }
+}
+
+impl FileIo for FbHandle {
+    fn check_seekable(&self) -> Result<()> {
+        Ok(())
+    }
+
+    fn is_offset_aware(&self) -> bool {
+        true
+    }
+
+    fn mappable(&self) -> Result<Mappable> {
+        let iomem = self.framebuffer.io_mem();
+        Ok(Mappable::IoMem(iomem.clone()))
+    }
+
+    fn ioctl(&self, cmd: IoctlCmd, arg: usize) -> Result<i32> {
+        match cmd {
+            _ => {
+                log::debug!(
+                    "the ioctl command {:?} is not supported by framebuffer devices",
+                    cmd
+                );
+                return_errno_with_message!(
+                    Errno::ENOTTY,
+                    "the ioctl command is not supported by framebuffer devices"
+                )
+            }
+        }
+    }
+}

kernel/src/fs/file_handle.rs

@@ -156,6 +156,5 @@ pub enum Mappable {
     /// An inode object.
     Inode(Arc<dyn Inode>),
     /// An MMIO region.
-    #[expect(dead_code)]
     IoMem(IoMem),
 }

kernel/src/fs/utils/ioctl.rs

@@ -58,4 +58,18 @@ pub enum IoctlCmd {
     KDSKBMODE = 0x4B45,
     /// Get tdx report using TDCALL
     TDXGETREPORT = 0xc4405401,
+    /// Get variable screen information (resolution, color depth, etc.)
+    GETVSCREENINFO = 0x4600,
+    /// Set variable screen information
+    PUTVSCREENINFO = 0x4601,
+    /// Get fixed screen information (memory layout, line length, etc.)
+    GETFSCREENINFO = 0x4602,
+    /// Get framebuffer color map
+    GETCMAP = 0x4604,
+    /// Set framebuffer color map
+    PUTCMAP = 0x4605,
+    /// Pan display to show different part of virtual screen
+    PANDISPLAY = 0x4606,
+    /// Blank or unblank the framebuffer display
+    FBIOBLANK = 0x4611,
 }