b8fad3d029
This patch adds a mechanism to set aside a region of cache-coherent (i.e. usually uncached) virtual memory, which can be used to communicate with DMA devices without automatic cache snooping (common on ARM) without the need of explicit flush/invalidation instructions in the driver code. This works by setting aside said region in the (board-specific) page table setup, as exemplary done in this patch for the Snow and Pit boards. It uses a new mechanism for adding board-specific Coreboot table entries to describe this region in an entry with the LB_DMA tag. Libpayload's memory allocator is enhanced to be able to operate on distinct types/regions of memory. It provides dma_malloc() and dma_memalign() functions for use in drivers, which by default just operate on the same heap as their traditional counterparts. However, if the Coreboot table parsing code finds a CB_DMA section, further requests through the dma_xxx() functions will return memory from the region described therein instead. Change-Id: Ia9c249249e936bbc3eb76e7b4822af2230ffb186 Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/167155 (cherry picked from commit d142ccdcd902a9d6ab4d495fbe6cbe85c61a5f01) Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com> Reviewed-on: http://review.coreboot.org/6622 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org> |
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| Config.in | ||