cbfs: Allow reading a file from a CBFS given its base addr

Currently we support reading a file from CBFS given the address of the end
of the ROM. Sometimes we only know the start of the CBFS. Add a function
to find a file given that.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

fs/cbfs/cbfs.c

@@ -413,6 +413,19 @@ int file_cbfs_find_uncached(ulong end_of_rom, const char *name,
 	return find_uncached(&priv, name, start, node);
 }
 
+int file_cbfs_find_uncached_base(ulong base, const char *name,
+				 struct cbfs_cachenode *node)
+{
+	struct cbfs_priv priv;
+	int ret;
+
+	ret = cbfs_load_header_ptr(&priv, base);
+	if (ret)
+		return ret;
+
+	return find_uncached(&priv, name, (void *)base, node);
+}
+
 const char *file_cbfs_name(const struct cbfs_cachenode *file)
 {
 	cbfs_s.result = CBFS_SUCCESS;

include/cbfs.h

@@ -174,6 +174,20 @@ int cbfs_init_mem(ulong base, ulong size, struct cbfs_priv **privp);
 int file_cbfs_find_uncached(ulong end_of_rom, const char *name,
 			    struct cbfs_cachenode *node);
 
+/**
+ * file_cbfs_find_uncached_base() - Find a file in CBFS given the base address
+ *
+ * Note that @node should be declared by the caller. This design is to avoid
+ * the need for allocation here.
+ *
+ * @base: Points to the base of the CBFS
+ * @name: The name to search for
+ * @node: Returns the contents of the node if found (i.e. copied into *node)
+ * @return 0 on success, -ENOENT if not found, -EFAULT on bad header
+ */
+int file_cbfs_find_uncached_base(ulong base, const char *name,
+				 struct cbfs_cachenode *node);
+
 /**
  * file_cbfs_name() - Get the name of a file in CBFS.
  *