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dmaengine: sprd: Support DMA link-list mode

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The Spreadtrum DMA can support the link-list transaction mode, which means
DMA controller can do transaction one by one automatically once we linked
these transaction by link-list register.

Signed-off-by: Eric Long <eric.long@spreadtrum.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Eric Long 2018-08-28 19:09:07 +08:00 • committed by Vinod Koul
parent 5b394b2ddf
commit 4ac6954647
2 changed files with 143 additions and 7 deletions
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69
include/linux/dma/sprd-dma.h
View file

@ -58,4 +58,73 @@ enum sprd_dma_int_type {
SPRD_DMA_CFGERR_INT,
};
/*
* struct sprd_dma_linklist - DMA link-list address structure
* @virt_addr: link-list virtual address to configure link-list node
* @phy_addr: link-list physical address to link DMA transfer
*
* The Spreadtrum DMA controller supports the link-list mode, that means slaves
* can supply several groups configurations (each configuration represents one
* DMA transfer) saved in memory, and DMA controller will link these groups
* configurations by writing the physical address of each configuration into the
* link-list register.
*
* Just as shown below, the link-list pointer register will be pointed to the
* physical address of 'configuration 1', and the 'configuration 1' link-list
* pointer will be pointed to 'configuration 2', and so on.
* Once trigger the DMA transfer, the DMA controller will load 'configuration
* 1' to its registers automatically, after 'configuration 1' transaction is
* done, DMA controller will load 'configuration 2' automatically, until all
* DMA transactions are done.
*
* Note: The last link-list pointer should point to the physical address
* of 'configuration 1', which can avoid DMA controller loads incorrect
* configuration when the last configuration transaction is done.
*
* DMA controller linklist memory
* ====================== -----------------------
*| | | configuration 1 |<---
*| DMA controller | ------->| | |
*| | | | | |
*| | | | | |
*| | | | | |
*| linklist pointer reg |---- ----| linklist pointer | |
* ====================== | ----------------------- |
* | |
* | ----------------------- |
* | | configuration 2 | |
* --->| | |
* | | |
* | | |
* | | |
* ----| linklist pointer | |
* | ----------------------- |
* | |
* | ----------------------- |
* | | configuration 3 | |
* --->| | |
* | | |
* | . | |
* . |
* . |
* . |
* | . |
* | ----------------------- |
* | | configuration n | |
* --->| | |
* | | |
* | | |
* | | |
* | linklist pointer |----
* -----------------------
*
* To support the link-list mode, DMA slaves should allocate one segment memory
* from always-on IRAM or dma coherent memory to store these groups of DMA
* configuration, and pass the virtual and physical address to DMA controller.
*/
struct sprd_dma_linklist {
unsigned long virt_addr;
phys_addr_t phy_addr;
};
#endif