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
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| .. | ||
| armv7/arch | ||
| arpa | ||
| pci | ||
| storage | ||
| sys | ||
| usb | ||
| x86/arch | ||
| assert.h | ||
| cbfs.h | ||
| cbfs_core.h | ||
| cbfs_ram.h | ||
| coreboot_tables.h | ||
| ctype.h | ||
| endian.h | ||
| errno.h | ||
| getopt.h | ||
| inttypes.h | ||
| ipchksum.h | ||
| kconfig.h | ||
| keycodes.h | ||
| lar.h | ||
| libpayload.h | ||
| limits.h | ||
| lzma.h | ||
| malloc.h | ||
| multiboot_tables.h | ||
| panel.h | ||
| pci.h | ||
| stdarg.h | ||
| stddef.h | ||
| stdint.h | ||
| stdio.h | ||
| stdlib.h | ||
| string.h | ||
| strings.h | ||
| sysinfo.h | ||
| term.h | ||
| unistd.h | ||
| video_console.h | ||