Struct FramebufferCharDevice 

pub struct FramebufferCharDevice {
    fb_resource: Arc<FramebufferResource>,
    mappings: RwLock<BTreeMap<usize, MockMapping>>,
}

Framebuffer character device implementation

This device provides character-based access to framebuffer memory. It acts as a bridge between user-space programs and the graphics hardware through the GraphicsManager.

Note: This device is stateless and does not maintain position information. Position management is handled by the FileObject layer for proper POSIX semantics.

Fields

fb_resource: Arc<FramebufferResource>

The framebuffer resource this device represents

mappings: RwLock<BTreeMap<usize, MockMapping>>

Track mappings for testing purposes

Implementations

impl FramebufferCharDevice

pub fn new(fb_resource: Arc<FramebufferResource>) -> Self

Create a new framebuffer character device

Arguments

• fb_resource - The framebuffer resource to access

Returns

A new FramebufferCharDevice instance

pub fn get_framebuffer_name(&self) -> &str

Get the framebuffer name this device represents

impl FramebufferCharDevice

fn current_var_info(&self) -> FbVarScreenInfo

Build a FbVarScreenInfo reflecting the current framebuffer configuration

fn handle_get_vscreeninfo(&self, arg: usize) -> Result<i32, &'static str>

Handle FBIOGET_VSCREENINFO control command

fn handle_get_fscreeninfo(&self, arg: usize) -> Result<i32, &'static str>

Handle FBIOGET_FSCREENINFO control command

fn handle_flush(&self, _arg: usize) -> Result<i32, &'static str>

Handle FBIO_FLUSH control command

This command forces any pending framebuffer changes to be displayed. For memory-mapped framebuffers, this typically involves ensuring CPU caches are flushed and any display controller updates are triggered.

fn trigger_display_update(&self) -> Result<(), &'static str>

Trigger display controller update

Some display controllers require explicit commands to update the display from framebuffer contents. This method handles such updates.

fn handle_put_vscreeninfo(&self, arg: usize) -> Result<i32, &'static str>

Handle FBIOPUT_VSCREENINFO control command

Trait Implementations

impl CharDevice for FramebufferCharDevice

fn read_byte(&self) -> Option<u8>

Read a single byte from the framebuffer

This method is not supported in the new position-per-file-handle architecture. Use read_at() through a DevFileObject instead for proper position management.

Returns

Always returns None to indicate unsupported operation

fn write_byte(&self, _byte: u8) -> Result<(), &'static str>

Write a single byte to the framebuffer

This method is not supported in the new position-per-file-handle architecture. Use write_at() through a DevFileObject instead for proper position management.

Arguments

• _byte - The byte to write (ignored)

Returns

Always returns an error to indicate unsupported operation

fn can_read(&self) -> bool

Check if the device is ready for reading

Returns

True if framebuffer is valid

fn can_write(&self) -> bool

Check if the device is ready for writing

Returns

True if framebuffer is valid

fn read_at( &self, position: u64, buffer: &mut [u8], ) -> Result<usize, &'static str>

Read data from a specific position in the framebuffer

Arguments

• position - Byte offset to read from
• buffer - Buffer to read data into

Returns

Result containing the number of bytes read or an error

fn write_at(&self, position: u64, buffer: &[u8]) -> Result<usize, &'static str>

Write data to a specific position in the framebuffer

Arguments

• position - Byte offset to write to
• buffer - Buffer containing data to write

Returns

Result containing the number of bytes written or an error

fn read(&self, buffer: &mut [u8]) -> usize

Read multiple bytes from the device

fn write(&self, buffer: &[u8]) -> Result<usize, &'static str>

Write multiple bytes to the device

fn can_seek(&self) -> bool

Check if this device supports seek operations

impl ControlOps for FramebufferCharDevice

fn control(&self, command: u32, arg: usize) -> Result<i32, &'static str>

Perform a control operation

fn supported_control_commands(&self) -> Vec<(u32, &'static str)>

Get a list of supported control commands

impl Device for FramebufferCharDevice

fn device_type(&self) -> DeviceType

fn name(&self) -> &'static str

fn as_any(&self) -> &dyn Any

fn as_any_mut(&mut self) -> &mut dyn Any

fn as_char_device(&self) -> Option<&dyn CharDevice>

Cast to CharDevice if this device is a character device

fn capabilities(&self) -> &'static [DeviceCapability]

Optional capabilities exposed by this device (default: none)

fn as_event_capable(&self) -> Option<&dyn EventCapableDevice>

Cast to EventCapableDevice if this device can emit events

fn as_block_device(&self) -> Option<&dyn BlockDevice>

Cast to BlockDevice if this device is a block device

fn as_graphics_device(&self) -> Option<&dyn GraphicsDevice>

Cast to GraphicsDevice if this device is a graphics device

fn as_network_device(&self) -> Option<&dyn NetworkDevice>

Cast to NetworkDevice if this device is a network device

fn into_block_device(self: Arc<Self>) -> Option<Arc<dyn BlockDevice>>

Cast Arc to Arc if this device is a block device This allows direct ownership of the block device for efficient I/O operations

fn into_char_device(self: Arc<Self>) -> Option<Arc<dyn CharDevice>>

Cast Arc to Arc if this device is a character device This allows direct ownership of the char device for efficient I/O operations

fn into_graphics_device(self: Arc<Self>) -> Option<Arc<dyn GraphicsDevice>>

Cast Arc to Arc if this device is a graphics device This allows direct ownership of the graphics device for efficient operations

fn into_network_device(self: Arc<Self>) -> Option<Arc<dyn NetworkDevice>>

Cast Arc to Arc if this device is a network device This allows direct ownership of the network device for efficient operations

impl MemoryMappingOps for FramebufferCharDevice

fn get_mapping_info( &self, offset: usize, length: usize, ) -> Result<(usize, usize, bool), &'static str>

Get mapping information for a region of the object

fn on_mapped(&self, vaddr: usize, _paddr: usize, length: usize, _offset: usize)

Notification that a mapping has been created

fn on_unmapped(&self, vaddr: usize, _length: usize)

Notification that a mapping has been removed

fn supports_mmap(&self) -> bool

Check if memory mapping is supported

fn get_mapping_info_with( &self, offset: usize, length: usize, _is_shared: bool, ) -> Result<(usize, usize, bool), &'static str>

Get mapping information with sharing intent.

fn mmap_owner_name(&self) -> String

Diagnostic helper: return a short owner name for logging

fn resolve_fault( &self, access: &AccessKind, map: &VirtualMemoryMap, ) -> Result<ResolveFaultResult, ResolveFaultError>

impl Selectable for FramebufferCharDevice

fn wait_until_ready( &self, _interest: ReadyInterest, _trapframe: &mut Trapframe, _timeout_ticks: Option<u64>, ) -> SelectWaitOutcome

Block the current task using the provided trapframe until the interest becomes ready or the optional timeout (in ticks) expires.

fn current_ready(&self, interest: ReadyInterest) -> ReadySet

Return current readiness for the given interest set.

fn set_nonblocking(&self, _enabled: bool)

Enable or disable non-blocking I/O semantics on this object.

fn is_nonblocking(&self) -> bool

Query whether non-blocking I/O semantics are enabled on this object.