fit: Add device tree compression

This patch adds support for compressing individual device trees in the
FIT image. In order to make this efficient, we'll have to pull the
compatible property out of the FDT and store it directly in the config
node of the FIT image, so that we don't have to scan (and therefore
decompress) every single FDT on boot. Device tree compression is only
supported for FIT images that have this external compatible property.
For older images with no compression, we still support fallback to
scanning the FDT for the property.

This patch was adapted from depthcharge's http://crosreview.com/1553458

Change-Id: Ifcb6997782c480c8ef6692df17b66ad96264e623
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32872
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

1 files changed, 36 insertions, 24 deletions

diff --git a/src/lib/fit.c b/src/lib/fit.c
index 5fbcd77407..befedde9cf 100644
--- a/src/lib/fit.c
+++ b/src/lib/fit.c
@@ -136,6 +136,8 @@ static void config_node(struct device_tree_node *node)
 			config->fdt = find_image(prop->prop.data);
 		else if (!strcmp("ramdisk", prop->prop.name))
 			config->ramdisk = find_image(prop->prop.data);
+		else if (!strcmp("compatible", prop->prop.name))
+			config->compat = prop->prop;
 	}
 
 	list_insert_after(&config->list_node, &config_nodes);
@@ -391,35 +393,45 @@ void fit_update_memory(struct device_tree *tree)
  */
 static int fit_update_compat(struct fit_config_node *config)
 {
-	if (config->fdt->compression != CBFS_COMPRESS_NONE) {
-		printk(BIOS_ERR,
-		       "FDT compression not yet supported, skipping %s.\n",
-		       config->name);
-		return -1;
-	}
+	// If there was no "compatible" property in config node, this is a
+	// legacy FIT image. Must extract compat prop from FDT itself.
+	if (!config->compat.name) {
+		void *fdt_blob = config->fdt->data;
+		const struct fdt_header *fdt_header = fdt_blob;
+		uint32_t fdt_offset = be32_to_cpu(fdt_header->structure_offset);
+
+		if (config->fdt->compression != CBFS_COMPRESS_NONE) {
+			printk(BIOS_ERR,
+			       "ERROR: config %s has a compressed FDT without "
+			       "external compatible property, skipping.\n",
+			       config->name);
+			return -1;
+		}
 
-	void *fdt_blob = config->fdt->data;
-	struct compat_string_entry *compat_node;
-	const struct fdt_header *fdt_header =
-		(const struct fdt_header *)fdt_blob;
-	uint32_t fdt_offset = be32_to_cpu(fdt_header->structure_offset);
-	size_t i = 0;
+		if (fdt_find_compat(fdt_blob, fdt_offset, &config->compat)) {
+			printk(BIOS_ERR,
+			       "ERROR: Can't find compat string in FDT %s "
+			       "for config %s, skipping.\n",
+			       config->fdt->name, config->name);
+			return -1;
+		}
+	}
 
 	config->compat_pos = -1;
 	config->compat_rank = -1;
-	if (!fdt_find_compat(fdt_blob, fdt_offset, &config->compat)) {
-		list_for_each(compat_node, compat_strings, list_node) {
-			int pos = fit_check_compat(&config->compat,
-						   compat_node->compat_string);
-			if (pos >= 0) {
-				config->compat_pos = pos;
-				config->compat_rank = i;
-				config->compat_string =
-					compat_node->compat_string;
-				break;
-			}
-			i++;
+	size_t i = 0;
+	struct compat_string_entry *compat_node;
+	list_for_each(compat_node, compat_strings, list_node) {
+		int pos = fit_check_compat(&config->compat,
+					   compat_node->compat_string);
+		if (pos >= 0) {
+			config->compat_pos = pos;
+			config->compat_rank = i;
+			config->compat_string =
+				compat_node->compat_string;
+			break;
 		}
+		i++;
 	}
 
 	return 0;