mirror of https://gitee.com/openkylin/linux.git
1ec1e82f25
This patch adds support for the Freescale i.MX SDMA engine. The SDMA engine is a scatter/gather DMA engine which is implemented as a seperate coprocessor. SDMA needs its own firmware which is requested using the standard request_firmware mechanism. The firmware has different entry points for each peripheral type, so drivers have to pass the peripheral type to the DMA engine which in turn picks the correct firmware entry point from a table contained in the firmware image itself. The original Freescale code also supports support for transfering data to the internal SRAM which needs different entry points to the firmware. Support for this is currently not implemented. Also, support for the ASRC (asymmetric sample rate converter) is skipped. I took a very simple approach to implement dmaengine support. Only a single descriptor is statically assigned to a each channel. This means that transfers can't be queued up but only a single transfer is in progress. This simplifies implementation a lot and is sufficient for the usual device/memory transfers. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Reviewed-by: Linus Walleij <linus.ml.walleij@gmail.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> |
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