device_tree: Match debug output format to dtc -O dts output

This patch updates the device tree dumping functions (not compiled by
default but available for debugging) to output properties and nodes in a
format similar to .dts files that is very close to what dtc outputs when
you decompile a .dtb with it. This makes it easier to match device tree
dumps from coreboot with device tree dumps generated by other device
tree tooling.

This patch was adapted from depthcharge's http://crosreview.com/1536386

Change-Id: Ib40e50d906aff05473a70c4fc9b124d63232558c
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32867
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

1 files changed, 38 insertions, 11 deletions

diff --git a/src/lib/device_tree.c b/src/lib/device_tree.c
index bbcd7c06f6..3c4bd24462 100644
--- a/src/lib/device_tree.c
+++ b/src/lib/device_tree.c
@@ -80,21 +80,36 @@ static int dt_prop_is_phandle(struct device_tree_property *prop)
 
 static void print_indent(int depth)
 {
-	while (depth--)
-		printk(BIOS_DEBUG, "  ");
+	printk(BIOS_DEBUG, "%*s", depth * 8, "");
 }
 
 static void print_property(const struct fdt_property *prop, int depth)
 {
+	int is_string = prop->size > 0 &&
+			((char *)prop->data)[prop->size - 1] == '\0';
+
+	if (is_string)
+		for (const char *c = prop->data; *c != '\0'; c++)
+			if (!isprint(*c))
+				is_string = 0;
+
 	print_indent(depth);
-	printk(BIOS_DEBUG, "prop \"%s\" (%d bytes).\n", prop->name, prop->size);
-	print_indent(depth + 1);
-	for (int i = 0; i < MIN(25, prop->size); i++) {
-		printk(BIOS_DEBUG, "%02x ", ((uint8_t *)prop->data)[i]);
+	if (is_string) {
+		printk(BIOS_DEBUG, "%s = \"%s\";\n",
+		       prop->name, (const char *)prop->data);
+	} else {
+		printk(BIOS_DEBUG, "%s = < ", prop->name);
+		for (int i = 0; i < MIN(128, prop->size); i += 4) {
+			uint32_t val = 0;
+			for (int j = 0; j < MIN(4, prop->size - i); j++)
+				val |= ((uint8_t *)prop->data)[i + j] <<
+					(24 - j * 8);
+			printk(BIOS_DEBUG, "%#.2x ", val);
+		}
+		if (prop->size > 128)
+			printk(BIOS_DEBUG, "...");
+		printk(BIOS_DEBUG, ">;\n");
 	}
-	if (prop->size > 25)
-		printk(BIOS_DEBUG, "...");
-	printk(BIOS_DEBUG, "\n");
 }
 
 static int print_flat_node(const void *blob, uint32_t start_offset, int depth)
@@ -109,7 +124,7 @@ static int print_flat_node(const void *blob, uint32_t start_offset, int depth)
 	offset += size;
 
 	print_indent(depth);
-	printk(BIOS_DEBUG, "name = %s\n", name);
+	printk(BIOS_DEBUG, "%s {\n", name);
 
 	struct fdt_property prop;
 	while ((size = fdt_next_property(blob, offset, &prop))) {
@@ -118,9 +133,14 @@ static int print_flat_node(const void *blob, uint32_t start_offset, int depth)
 		offset += size;
 	}
 
+	printk(BIOS_DEBUG, "\n");	// empty line between props and nodes
+
 	while ((size = print_flat_node(blob, offset, depth + 1)))
 		offset += size;
 
+	print_indent(depth);
+	printk(BIOS_DEBUG, "}\n");
+
 	return offset - start_offset + sizeof(uint32_t);
 }
 
@@ -458,15 +478,22 @@ void dt_flatten(const struct device_tree *tree, void *start_dest)
 static void print_node(const struct device_tree_node *node, int depth)
 {
 	print_indent(depth);
-	printk(BIOS_DEBUG, "name = %s\n", node->name);
+	if (depth == 0)		// root node has no name, print a starting slash
+		printk(BIOS_DEBUG, "/");
+	printk(BIOS_DEBUG, "%s {\n", node->name);
 
 	struct device_tree_property *prop;
 	list_for_each(prop, node->properties, list_node)
 		print_property(&prop->prop, depth + 1);
 
+	printk(BIOS_DEBUG, "\n");	// empty line between props and nodes
+
 	struct device_tree_node *child;
 	list_for_each(child, node->children, list_node)
 		print_node(child, depth + 1);
+
+	print_indent(depth);
+	printk(BIOS_DEBUG, "};\n");
 }
 
 void dt_print_node(const struct device_tree_node *node)