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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 d142ccdcd9)
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
commit b8fad3d029
8 changed files with 142 additions and 42 deletions
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6
src/include/boot/coreboot_tables.h
View file

@ -218,6 +218,7 @@ struct lb_gpios {
#define LB_TAG_VDAT 0x0015
#define LB_TAG_VBNV 0x0019
#define LB_TAB_VBOOT_HANDOFF 0x0020
#define LB_TAB_DMA 0x0022
struct lb_range {
uint32_t tag;
uint32_t size;
@ -332,4 +333,9 @@ void uart_fill_lb(void *data);
void lb_add_serial(struct lb_serial *serial, void *data);
void lb_add_console(uint16_t consoletype, void *data);
/* Define this in mainboard.c to add board-specific table entries. */
void lb_board(struct lb_header *header);
struct lb_record *lb_new_record(struct lb_header *header);
#endif /* COREBOOT_TABLES_H */