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>

1 files changed, 9 insertions, 0 deletions

diff --git a/payloads/libpayload/arch/armv7/coreboot.c b/payloads/libpayload/arch/armv7/coreboot.c
index d1f03453a2..e16c354d6b 100644
--- a/payloads/libpayload/arch/armv7/coreboot.c
+++ b/payloads/libpayload/arch/armv7/coreboot.c
@@ -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;