rt_dma_map_ops Struct Reference

#include <dma.h>

Data Fields
void *(*	alloc )(struct rt_device *dev, rt_size_t size, rt_ubase_t *dma_handle, rt_ubase_t flags)
void(*	free )(struct rt_device *dev, rt_size_t size, void *cpu_addr, rt_ubase_t dma_handle, rt_ubase_t flags)
rt_err_t(*	sync_out_data )(struct rt_device *dev, void *data, rt_size_t size, rt_ubase_t *dma_handle, rt_ubase_t flags)
rt_err_t(*	sync_in_data )(struct rt_device *dev, void *out_data, rt_size_t size, rt_ubase_t dma_handle, rt_ubase_t flags)

Detailed Description

DMA memory mapping operations vtable.

Abstracts device-specific DMA memory management: allocation, freeing, and cache synchronization for coherent and non-coherent devices. Devices may override these via dev->dma_ops or the device tree.

Field Documentation

alloc

void*(* rt_dma_map_ops::alloc) (struct rt_device *dev, rt_size_t size, rt_ubase_t *dma_handle, rt_ubase_t flags)

Allocate a DMA buffer (optional, may fall back to default)

Parameters

[in]	dev	DMA-capable device
[in]	size	Requested size in bytes
[out]	dma_handle	Physical DMA address
[in]	flags	Allocation flags (RT_DMA_F_*)

Returns

Kernel virtual address, or RT_NULL on failure

free

void(* rt_dma_map_ops::free) (struct rt_device *dev, rt_size_t size, void *cpu_addr, rt_ubase_t dma_handle, rt_ubase_t flags)

Free a DMA buffer (optional)

Parameters

[in]	dev	DMA-capable device
[in]	size	Buffer size in bytes
[in]	cpu_addr	Kernel virtual address
[in]	dma_handle	Physical DMA address
[in]	flags	Allocation flags

sync_out_data

rt_err_t(* rt_dma_map_ops::sync_out_data) (struct rt_device *dev, void *data, rt_size_t size, rt_ubase_t *dma_handle, rt_ubase_t flags)

Synchronize data for DMA output (CPU → device)

Performs any necessary cache flush and returns the DMA bus address.

Parameters

[in]	dev	DMA-capable device
[in]	data	Virtual address of data buffer
[in]	size	Buffer size in bytes
[out]	dma_handle	DMA bus address (may be NULL)
[in]	flags	Sync flags

Returns

RT_EOK on success

sync_in_data

rt_err_t(* rt_dma_map_ops::sync_in_data) (struct rt_device *dev, void *out_data, rt_size_t size, rt_ubase_t dma_handle, rt_ubase_t flags)

Synchronize data for DMA input (device → CPU)

Performs any necessary cache invalidation.

Parameters

[in]	dev	DMA-capable device
[in]	out_data	Virtual address of data buffer
[in]	size	Buffer size in bytes
[in]	dma_handle	DMA bus address
[in]	flags	Sync flags

Returns

RT_EOK on success