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  1. 05 2月, 2014 2 次提交
    • M
      spi: Make core DMA mapping functions generate scatterlists · 6ad45a27
      由 Mark Brown 提交于 
      We cannot unconditionally use dma_map_single() to map data for use with
SPI since transfers may exceed a page and virtual addresses may not be
provided with physically contiguous pages. Further, addresses allocated
using vmalloc() need to be mapped differently to other addresses.

Currently only the MXS driver handles all this, a few drivers do handle
the possibility that buffers may not be physically contiguous which is
the main potential problem but many don't even do that. Factoring this
out into the core will make it easier for drivers to do a good job so if
the driver is using the core DMA code then generate a scatterlist
instead of mapping to a single address so do that.

This code is mainly based on a combination of the existing code in the MXS
and PXA2xx drivers. In future we should be able to extend it to allow the
core to concatenate adjacent transfers if they are compatible, improving
performance.

Currently for simplicity clients are not allowed to use the scatterlist
when they do DMA mapping, in the future the existing single address
mappings will be replaced with use of the scatterlist most likely as
part of pre-verifying transfers.

This change makes it mandatory to use scatterlists when using the core DMA
mapping so update the s3c64xx driver to do this when used with dmaengine.
Doing so makes the code more ugly but it is expected that the old s3c-dma
code can be removed very soon.
Signed-off-by: NMark Brown <broonie@linaro.org>
      6ad45a27
    • M
      spi: Provide core support for full duplex devices · 3a2eba9b
      由 Mark Brown 提交于 
      It is fairly common for SPI devices to require that one or both transfer
directions is always active. Currently drivers open code this in various
ways with varying degrees of efficiency. Start factoring this out by
providing flags SPI_MASTER_MUST_TX and SPI_MASTER_MUST_RX. These will cause
the core to provide buffers for the requested direction if none are
specified in the underlying transfer.

Currently this is fairly inefficient since we actually allocate a data
buffer which may get large, support for mapping transfers using a
scatterlist will allow us to avoid this for DMA based transfers.
Signed-off-by: NMark Brown <broonie@linaro.org>
      3a2eba9b
  3. 04 2月, 2014 2 次提交
  5. 03 2月, 2014 1 次提交
    • M
      spi: Provide core support for DMA mapping transfers · 99adef31
      由 Mark Brown 提交于 
      The process of DMA mapping buffers for SPI transfers does not vary between
devices so in order to save duplication of code in drivers this can be
factored out into the core, allowing it to be integrated with the work that
is being done on factoring out the common elements from the data path
including more sharing of dmaengine code.

In order to use this masters need to provide a can_dma() operation and while
the hardware is prepared they should ensure that DMA channels are provided
in tx_dma and rx_dma. The core will then ensure that the buffers are mapped
for DMA prior to calling transfer_one_message().

Currently the cleanup on error is not complete, this needs to be improved.
Signed-off-by: NMark Brown <broonie@linaro.org>
      99adef31
  7. 22 1月, 2014 2 次提交
  9. 17 1月, 2014 3 次提交
  11. 16 1月, 2014 1 次提交
  13. 14 1月, 2014 4 次提交
  15. 13 1月, 2014 13 次提交
  17. 10 1月, 2014 4 次提交
  19. 09 1月, 2014 3 次提交
  21. 08 1月, 2014 3 次提交
  23. 07 1月, 2014 2 次提交