Module dma 

Direct Memory Access (DMA).

This module provides DmaCoherent and DmaStream abstractions for managing DMA memory regions with different remapping, caching and synchronization requirements.

Usage in IRQs

Creating DMA objects (via alloc, alloc_uninit, or map constructors) requires IRQs to be enabled, to avoid deadlocks during cross-CPU TLB flushes. Note that it means DMA objects cannot be created from (hard) interrupt context.

Other operations on DMA objects may still be performed in any context, even with IRQs disabled. For example, it is valid to drop a DmaStream from an IRQ handler after the device has finished processing it.

Structs

DmaCoherent

A DMA memory object that can be accessed in a cache-coherent manner.

DmaStream

A DMA memory object with streaming access.

Enums

FromAndToDevice

Data flows both from and to the device.

FromDevice

Data flows from the device.

ToDevice

Data flows to the device.

Traits

DmaDirection

DmaDirection limits the data flow direction of DmaStream and prevents users from reading and writing to DmaStream unexpectedly.