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>

4 files changed, 44 insertions, 1 deletions

diff --git a/src/include/boot/coreboot_tables.h b/src/include/boot/coreboot_tables.h
index 3c569a132d..db3c508285 100644
--- a/src/include/boot/coreboot_tables.h
+++ b/src/include/boot/coreboot_tables.h
@@ -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 */
diff --git a/src/lib/coreboot_table.c b/src/lib/coreboot_table.c
index f0ae6c5bc0..9f9c453a5b 100644
--- a/src/lib/coreboot_table.c
+++ b/src/lib/coreboot_table.c
@@ -77,7 +77,7 @@ static struct lb_record *lb_last_record(struct lb_header *header)
 	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 @@ static void lb_strings(struct lb_header *header)
 
 }
 
+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 @@ unsigned long write_coreboot_table(
 #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);
 }
diff --git a/src/mainboard/google/pit/mainboard.c b/src/mainboard/google/pit/mainboard.c
index 77c54a189f..467b9d04e9 100644
--- a/src/mainboard/google/pit/mainboard.c
+++ b/src/mainboard/google/pit/mainboard.c
@@ -45,6 +45,10 @@
 #define DRAM_START	(CONFIG_SYS_SDRAM_BASE >> 20)
 #define DRAM_SIZE	CONFIG_DRAM_SIZE_MB
 
+/* Arbitrary range of DMA memory for depthcharge's drivers */
+#define DMA_START	(0x77300000)
+#define DMA_SIZE	(0x00100000)
+
 static struct edid edid = {
 	.ha = 1366,
 	.va = 768,
@@ -452,6 +456,7 @@ static void mainboard_enable(device_t dev)
 
 	/* set up caching for the DRAM */
 	mmu_config_range(DRAM_START, DRAM_SIZE, DCACHE_WRITEBACK);
+	mmu_config_range(DMA_START >> 20, DMA_SIZE >> 20, DCACHE_OFF);
 	tlb_invalidate_all();
 
 	/* this is going to move, but we must have it now and we're
@@ -472,3 +477,14 @@ struct chip_operations mainboard_ops = {
 	.name	= "Samsung/Google ARM Chromebook",
 	.enable_dev = mainboard_enable,
 };
+
+void lb_board(struct lb_header *header)
+{
+	struct lb_range *dma;
+
+	dma = (struct lb_range *)lb_new_record(header);
+	dma->tag = LB_TAB_DMA;
+	dma->size = sizeof(*dma);
+	dma->range_start = (intptr_t)DMA_START;
+	dma->range_size = DMA_SIZE;
+}
diff --git a/src/mainboard/google/snow/mainboard.c b/src/mainboard/google/snow/mainboard.c
index d209a762fc..dfaf81d537 100644
--- a/src/mainboard/google/snow/mainboard.c
+++ b/src/mainboard/google/snow/mainboard.c
@@ -46,6 +46,10 @@
 #define DRAM_SIZE	CONFIG_DRAM_SIZE_MB
 #define DRAM_END	(DRAM_START + DRAM_SIZE)	/* plus one... */
 
+/* Arbitrary range of DMA memory for depthcharge's drivers */
+#define DMA_START	(0x77300000)
+#define DMA_SIZE	(0x00100000)
+
 static struct edid edid = {
 	.ha = 1366,
 	.va = 768,
@@ -320,6 +324,7 @@ static void mainboard_enable(device_t dev)
 	mmu_init();
 	mmu_config_range(0, DRAM_START, DCACHE_OFF);
 	mmu_config_range(DRAM_START, DRAM_SIZE, DCACHE_WRITEBACK);
+	mmu_config_range(DMA_START >> 20, DMA_SIZE >> 20, DCACHE_OFF);
 	mmu_config_range(DRAM_END, 4096 - DRAM_END, DCACHE_OFF);
 	dcache_invalidate_all();
 	dcache_mmu_enable();
@@ -342,3 +347,14 @@ struct chip_operations mainboard_ops = {
 	.name	= "Samsung/Google ARM Chromebook",
 	.enable_dev = mainboard_enable,
 };
+
+void lb_board(struct lb_header *header)
+{
+	struct lb_range *dma;
+
+	dma = (struct lb_range *)lb_new_record(header);
+	dma->tag = LB_TAB_DMA;
+	dma->size = sizeof(*dma);
+	dma->range_start = (intptr_t)DMA_START;
+	dma->range_size = DMA_SIZE;
+}