Add uboot "fdt_high" enviroment variable

Add a new "fdt_high" enviroment variable. This can be used to control (or prevent) the
relocation of the flattened device tree on boot. It can be used to prevent relocation
of the fdt into highmem.  The variable behaves similarly to the existing "initrd_high"
variable.

Signed-off-by: David A. Long <dave.long@linaro.org>

1 files changed, 49 insertions, 11 deletions

diff --git a/common/image.c b/common/image.c
index e542a5736..c6cd85ef9 100644
--- a/common/image.c
+++ b/common/image.c
@@ -1234,8 +1234,10 @@ int boot_relocate_fdt (struct lmb *lmb, char **of_flat_tree, ulong *of_size)
 {
 	void	*fdt_blob = *of_flat_tree;
 	void	*of_start = 0;
+	char	*fdt_high;
 	ulong	of_len = 0;
 	int	err;
+	int	disable_relocation = 0;
 
 	/* nothing to do */
 	if (*of_size == 0)
@@ -1249,26 +1251,62 @@ int boot_relocate_fdt (struct lmb *lmb, char **of_flat_tree, ulong *of_size)
 	/* position on a 4K boundary before the alloc_current */
 	/* Pad the FDT by a specified amount */
 	of_len = *of_size + CONFIG_SYS_FDT_PAD;
-	of_start = (void *)(unsigned long)lmb_alloc_base(lmb, of_len, 0x1000,
-			getenv_bootm_mapsize() + getenv_bootm_low());
+
+	/* If fdt_high is set use it to select the relocation address */
+	fdt_high = getenv("fdt_high");
+	if (fdt_high) {
+		void *desired_addr = (void *)simple_strtoul(fdt_high, NULL, 16);
+
+		if (((ulong) desired_addr) == ~0UL) {
+			/* All ones means use fdt in place */
+			desired_addr = fdt_blob;
+			disable_relocation = 1;
+		}
+		if (desired_addr) {
+			of_start =
+			    (void *)(ulong) lmb_alloc_base(lmb, of_len, 0x1000,
+							   ((ulong)
+							    desired_addr)
+							   + of_len);
+			if (desired_addr && of_start != desired_addr) {
+				puts("Failed using fdt_high value for Device Tree");
+				goto error;
+			}
+		} else {
+			of_start =
+			    (void *)(ulong) mb_alloc(lmb, of_len, 0x1000);
+		}
+	} else {
+		of_start =
+		    (void *)(ulong) lmb_alloc_base(lmb, of_len, 0x1000,
+						   getenv_bootm_mapsize()
+						   + getenv_bootm_low());
+	}
 
 	if (of_start == 0) {
 		puts("device tree - allocation error\n");
 		goto error;
 	}
 
-	debug ("## device tree at %p ... %p (len=%ld [0x%lX])\n",
-		fdt_blob, fdt_blob + *of_size - 1, of_len, of_len);
+	if (disable_relocation) {
+		/* We assume there is space after the existing fdt to use for padding */
+		fdt_set_totalsize(of_start, of_len);
+		printf("   Using Device Tree in place at %p, end %p\n",
+		       of_start, of_start + of_len - 1);
+	} else {
+		debug ("## device tree at %p ... %p (len=%ld [0x%lX])\n",
+			fdt_blob, fdt_blob + *of_size - 1, of_len, of_len);
 
-	printf ("   Loading Device Tree to %p, end %p ... ",
-		of_start, of_start + of_len - 1);
+		printf ("   Loading Device Tree to %p, end %p ... ",
+			of_start, of_start + of_len - 1);
 
-	err = fdt_open_into (fdt_blob, of_start, of_len);
-	if (err != 0) {
-		fdt_error ("fdt move failed");
-		goto error;
+		err = fdt_open_into (fdt_blob, of_start, of_len);
+		if (err != 0) {
+			fdt_error ("fdt move failed");
+			goto error;
+		}
+		puts ("OK\n");
 	}
-	puts ("OK\n");
 
 	*of_flat_tree = of_start;
 	*of_size = of_len;