2 files changed, 40 insertions, 0 deletions
diff --git a/src/northbridge/intel/haswell/gma.c b/src/northbridge/intel/haswell/gma.c
index 057d65ad55..8be25e785f 100644
--- a/src/northbridge/intel/haswell/gma.c
+++ b/src/northbridge/intel/haswell/gma.c
@@ -127,6 +127,45 @@ u32 map_oprom_vendev(u32 vendev)
 	return new_vendev;
 }
 
+/* GTT is the Global Translation Table for the graphics pipeline.
+ * It is used to translate graphics addresses to physical
+ * memory addresses. As in the CPU, GTTs map 4K pages.
+ * The setgtt function adds a further bit of flexibility:
+ * it allows you to set a range (the first two parameters) to point
+ * to a physical address (third parameter);the physical address is
+ * incremented by a count (fourth parameter) for each GTT in the
+ * range.
+ * Why do it this way? For ultrafast startup,
+ * we can point all the GTT entries to point to one page,
+ * and set that page to 0s:
+ * memset(physbase, 0, 4096);
+ * setgtt(0, 4250, physbase, 0);
+ * this takes about 2 ms, and is a win because zeroing
+ * the page takes a up to 200 ms.
+ * This call sets the GTT to point to a linear range of pages
+ * starting at physbase.
+ */
+
+#define GTT_PTE_BASE (2 << 20)
+
+void
+set_translation_table(int start, int end, u64 base, int inc)
+{
+	int i;
+
+	for(i = start; i < end; i++){
+		u64 physical_address = base + i*inc;
+		/* swizzle the 32:39 bits to 4:11 */
+		u32 word = physical_address | ((physical_address >> 28) & 0xff0) | 1;
+		/* note: we've confirmed by checking
+		 * the values that mrc does no
+		 * useful setup before we run this.
+		 */
+		gtt_write(GTT_PTE_BASE + i * 4, word);
+		gtt_read(GTT_PTE_BASE + i * 4);
+	}
+}
+
 static struct resource *gtt_res = NULL;
 
 u32 gtt_read(u32 reg)
diff --git a/src/northbridge/intel/haswell/haswell.h b/src/northbridge/intel/haswell/haswell.h
index bcd22d1be6..55f6f284e4 100644
--- a/src/northbridge/intel/haswell/haswell.h
+++ b/src/northbridge/intel/haswell/haswell.h
@@ -202,6 +202,7 @@ void intel_northbridge_haswell_finalize_smm(void);
 #else /* !__SMM__ */
 void haswell_early_initialization(int chipset_type);
 void haswell_late_initialization(void);
+void set_translation_table(int start, int end, u64 base, int inc);
 
 /* debugging functions */
 void print_pci_devices(void);