[PATCH v3 6/9] efi_loader: return binary from efi_dp_from_lo()

[Heinrich Schuchardt]

For finding distro supplied device-trees we need to know from which device
we are booting. This can be identified via the device-path of the binary.

Up to now efi_dp_from_lo() only could return the initrd or fdt device-path.
Allow returning the binary device-path, too.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
---
v3:
	No change
v2:
	no change
---
 lib/efi_loader/efi_device_path.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
index c8c8d54f733..52e3313c23a 100644
--- a/lib/efi_loader/efi_device_path.c
+++ b/lib/efi_loader/efi_device_path.c
@@ -1133,17 +1133,18 @@ ssize_t efi_dp_check_length(const struct efi_device_path *dp,
 }
 
 /**
- * efi_dp_from_lo() - Get the instance of a VenMedia node in a
- *                    multi-instance device path that matches
- *                    a specific GUID. This kind of device paths
- *                    is found in Boot#### options describing an
- *                    initrd location
+ * efi_dp_from_lo() - get device-path from load option
  *
- * @lo:		EFI_LOAD_OPTION containing a valid device path
- * @guid:	guid to search for
+ * The load options in U-Boot may contain multiple concatenated device-paths.
+ * The first device-path indicates the EFI binary to execute. Subsequent
+ * device-paths start with a VenMedia node where the GUID identifies the
+ * function (initrd or fdt).
+ *
+ * @lo:		EFI load option containing a valid device path
+ * @guid:	GUID identifying device-path or NULL for the EFI binary
  *
  * Return:
- * device path including the VenMedia node or NULL.
+ * device path excluding the matched VenMedia node or NULL.
  * Caller must free the returned value.
  */
 struct
@@ -1154,6 +1155,9 @@ efi_device_path *efi_dp_from_lo(struct efi_load_option *lo,
 	struct efi_device_path_vendor *vendor;
 	int lo_len = lo->file_path_length;
 
+	if (!guid)
+		return efi_dp_dup(fp);
+
 	for (; lo_len >=  sizeof(struct efi_device_path);
 	     lo_len -= fp->length, fp = (void *)fp + fp->length) {
 		if (lo_len < 0 || efi_dp_check_length(fp, lo_len) < 0)
-- 
2.43.0