DMA Space C interface.
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long | l4re_dma_space_map (l4re_dma_space_t dma, l4re_ds_t src, l4_addr_t offset, l4_size_t *size, unsigned long attrs, enum l4re_dma_space_direction dir, l4re_dma_space_dma_addr_t *dma_addr) L4_NOTHROW |
| Map the given part of this data space into the DMA address space. More...
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long | l4re_dma_space_unmap (l4re_dma_space_t dma, l4re_dma_space_dma_addr_t dma_addr, l4_size_t size, unsigned long attrs, enum l4re_dma_space_direction dir) L4_NOTHROW |
| Unmap the given part of this data space from the DMA address space. More...
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long | l4re_dma_space_associate (l4re_dma_space_t dma, l4_cap_idx_t dma_task, unsigned long attr) L4_NOTHROW |
| Associate a DMA task for a device to this Dma_space. More...
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long | l4re_dma_space_disassociate (l4re_dma_space_t dma) |
| Disassociate the DMA task from this Dma_space. More...
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DMA Space C interface.
◆ l4re_dma_space_t
DMA space capability type.
DMA Address Space. A Dma_space represents the DMA address space of a device. Whenever a device needs direct access to parts of an L4Re::Dataspace, that part of the data space must be mapped to the DMA address space that is assigned to that device. After the DMA accesses to the memory are finished the memory must be unmapped from the device's DMA address space.
Mapping to a DMA address space, using map(), makes the given parts of the data space visible to the associated device at the returned DMA address. As long as the memory is mapped into a DMA space it is 'pinned' and cannot be subject to dynamic memory management such as swapping. Additionally, map() is responsible for the necessary syncing operations before the DMA.
unmap() is the reverse operation to map() and unmaps the given data-space part for the DMA address space. unmap() is responsible for the necessary sync operations after the DMA.
Definition at line 59 of file dma_space.h.
◆ l4re_dma_space_associate()
Associate a DMA task for a device to this Dma_space.
- Parameters
-
- Precondition
- requires capability rights: {RW}
- Parameters
-
[in] | dma_task | The DMA task used for the device that shall be associated with this DMA space. The dma_task might be an invalid capability when #Phys_space is set in attr , in this case the CPUs physical memory is used as DMA address space. |
[in] | attr | Attributes for this DMA space. See #Space_attrib. |
◆ l4re_dma_space_disassociate()
Disassociate the DMA task from this Dma_space.
- Parameters
-
- Precondition
- requires capability rights: {RW}
◆ l4re_dma_space_map()
Map the given part of this data space into the DMA address space.
- Parameters
-
- Precondition
- requires capability rights: {R}
- Parameters
-
[in] | src | Source data space (that describes the memory). Caller needs write rights to the data space. |
[in] | offset | The offset (bytes) within src . |
[in,out] | size | The size (bytes) of the of the region to be mapped to for DMA, after successful mapping the size returned is the size mapped for DMA as single block, this size might be smaller than the original input size, in this case the caller might call map() again with a new offset and the remaining size. |
[in] | attrs | The attributes used for this DMA mapping (a combination of Dma_space::Attribute values). |
[in] | dir | The direction of the DMA transfer issued with this mapping. The same value must later be passed to unmap(). |
[out] | dma_addr | The DMA address to use for DMA with the associated device. |
- Returns
- 0 in the case of success, a negative error code otherwise.
◆ l4re_dma_space_unmap()
Unmap the given part of this data space from the DMA address space.
- Parameters
-
- Precondition
- requires capability rights: {R}
- Parameters
-
dma_addr | The DMA address (returned by Dma_space::map()). |
size | The size (bytes) of the memory region to unmap. |
attrs | The attributes for the unmap (currently none). |
dir | The direction of the finished DMA operation. |