cbfs: Support reading compression information

CBFS now supports compressed filed. Add support for reading this
information so that the correct decompression can be applied. The
decompression itself is not implemented in CBFS.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/fs/cbfs/cbfs.c b/fs/cbfs/cbfs.c
index 9e534d1..443a148 100644
--- a/fs/cbfs/cbfs.c
+++ b/fs/cbfs/cbfs.c
@@ -91,6 +91,7 @@
 		     struct cbfs_fileheader *header)
 {
 	uint name_len;
+	uint offset;
 
 	/* Check the header is large enough */
 	if (header->offset < sizeof(struct cbfs_fileheader))
@@ -104,6 +105,27 @@
 	node->name = start + sizeof(struct cbfs_fileheader);
 	node->name_length = name_len;
 	node->attr_offset = header->attributes_offset;
+	node->comp_algo = CBFS_COMPRESS_NONE;
+	node->decomp_size = 0;
+
+	for (offset = node->attr_offset; offset < header->offset;) {
+		const struct cbfs_file_attribute *attr;
+		uint tag, len;
+
+		attr = start + offset;
+		tag = be32_to_cpu(attr->tag);
+		len = be32_to_cpu(attr->len);
+		if (tag == CBFS_FILE_ATTR_TAG_COMPRESSION) {
+			struct cbfs_file_attr_compression *comp;
+
+			comp = start + offset;
+			node->comp_algo = be32_to_cpu(comp->compression);
+			node->decomp_size =
+				be32_to_cpu(comp->decompressed_size);
+		}
+
+		offset += len;
+	}
 
 	return 0;
 }
diff --git a/include/cbfs.h b/include/cbfs.h
index 055edba..ae94f1d 100644
--- a/include/cbfs.h
+++ b/include/cbfs.h
@@ -75,6 +75,15 @@
 	char filename[];
 } __packed;
 
+/**
+ * These are standard values for the known compression alogrithms that coreboot
+ * knows about for stages and payloads.  Of course, other CBFS users can use
+ * whatever values they want, as long as they understand them.
+ */
+#define CBFS_COMPRESS_NONE  0
+#define CBFS_COMPRESS_LZMA  1
+#define CBFS_COMPRESS_LZ4   2
+
 /*
  * Depending on how the header was initialized, it may be backed with 0x00 or
  * 0xff, so support both
@@ -119,6 +128,8 @@
 	u32 data_length;
 	u32 name_length;
 	u32 attr_offset;
+	u32 comp_algo;
+	u32 decomp_size;
 };
 
 /**