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arm: libpayload: Add cache coherent DMA memory definition and management

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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>
This commit is contained in:
Julius Werner
2013-08-27 15:48:32 -07:00
committed by Isaac Christensen
parent 4498f6a6e5
commit b8fad3d029
8 changed files with 142 additions and 42 deletions
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9
payloads/libpayload/arch/armv7/coreboot.c
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@@ -108,6 +108,12 @@ static void cb_parse_vdat(unsigned char *ptr, struct sysinfo_t *info)
}
#endif
static void cb_parse_dma(unsigned char *ptr)
{
struct cb_range *dma = (struct cb_range *)ptr;
init_dma_memory(phys_to_virt(dma->range_start), dma->range_size);
}
static void cb_parse_tstamp(unsigned char *ptr, struct sysinfo_t *info)
{
struct cb_cbmem_tab *const cbmem = (struct cb_cbmem_tab *)ptr;
@@ -262,6 +268,9 @@ static int cb_parse_header(void *addr, int len, struct sysinfo_t *info)
cb_parse_vbnv(ptr, info);
break;
#endif
case CB_TAG_DMA:
cb_parse_dma(ptr);
break;
case CB_TAG_TIMESTAMPS:
cb_parse_tstamp(ptr, info);
break;