Struct CoherentHandle 

pub struct CoherentHandle { /* private fields */ }

An opaque DMA allocation without a kernel virtual mapping.

Unlike Coherent, a CoherentHandle does not provide CPU access to the allocated memory. The allocation is always performed with DMA_ATTR_NO_KERNEL_MAPPING, meaning no kernel virtual mapping is created for the buffer. The value returned by the C API as the CPU address is an opaque handle used only to free the allocation.

This is useful for buffers that are only ever accessed by hardware.

Invariants

• cpu_handle holds the opaque handle returned by dma_alloc_attrs with DMA_ATTR_NO_KERNEL_MAPPING set, and is only valid for passing back to dma_free_attrs.
• dma_handle is the corresponding bus address for device DMA.
• size is the allocation size in bytes as passed to dma_alloc_attrs.
• dma_attrs contains the attributes used for the allocation, always including DMA_ATTR_NO_KERNEL_MAPPING.

Implementations

impl CoherentHandle

pub fn alloc_with_attrs( dev: &Device<Bound>, size: usize, gfp_flags: Flags, dma_attrs: Attrs, ) -> Result<Self>

Allocates size bytes of coherent DMA memory without creating a kernel virtual mapping.

Additional DMA attributes may be passed via dma_attrs; DMA_ATTR_NO_KERNEL_MAPPING is always set implicitly.

Returns EINVAL if size is zero, ENOMEM if the allocation fails.

pub fn alloc(dev: &Device<Bound>, size: usize, gfp_flags: Flags) -> Result<Self>

Allocates size bytes of coherent DMA memory without creating a kernel virtual mapping.

pub fn dma_handle(&self) -> DmaAddress

Returns the DMA handle for this allocation.

This address can be programmed into device hardware for DMA access.

pub fn size(&self) -> usize

Returns the size in bytes of this allocation.

Trait Implementations

impl Drop for CoherentHandle

fn drop(&mut self)

Executes the destructor for this type.

impl Send for CoherentHandle

impl Sync for CoherentHandle