arm: libpayload: Add cache coherent DMA memory definition and management
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>
diff --git a/src/lib/coreboot_table.c b/src/lib/coreboot_table.c
index f0ae6c5..9f9c453 100644
--- a/src/lib/coreboot_table.c
+++ b/src/lib/coreboot_table.c
@@ -77,7 +77,7 @@
return rec;
}
-static struct lb_record *lb_new_record(struct lb_header *header)
+struct lb_record *lb_new_record(struct lb_header *header)
{
struct lb_record *rec;
rec = lb_last_record(header);
@@ -298,6 +298,8 @@
}
+void __attribute__((weak)) lb_board(struct lb_header *header) { /* NOOP */ }
+
static struct lb_forward *lb_forward(struct lb_header *header, struct lb_header *next_header)
{
struct lb_record *rec;
@@ -425,6 +427,9 @@
#endif
add_cbmem_pointers(head);
+ /* Add board-specific table entries, if any. */
+ lb_board(head);
+
/* Remember where my valid memory ranges are */
return lb_table_fini(head);
}