[U-Boot] [PATCH] efi_loader: add back optional efi_handler::open()

[Rob Clark <robdclark@gmail.com>]

In some cases it is useful to defer creation of the protocol interface
object.  So add back an optional ->open() hook that is used if
protcol_interface is NULL.

I've slightly simplified the fxn ptr signature to remove unneeded args,
and so compiler will complain if patches that used the "old way" are,
and which do not need this extra complexity, are rebased.

Signed-off-by: Rob Clark <robdclark@gmail.com>
---
 include/efi_loader.h          | 9 ++++++++-
 lib/efi_loader/efi_boottime.c | 7 +++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/include/efi_loader.h b/include/efi_loader.h
index 90411cdbab..3da0477fdc 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -41,10 +41,17 @@ extern unsigned int __efi_runtime_rel_start, __efi_runtime_rel_stop;
 /*
  * When the UEFI payload wants to open a protocol on an object to get its
  * interface (usually a struct with callback functions), this struct maps the
- * protocol GUID to the respective protocol interface */
+ * protocol GUID to the respective protocol interface.
+ *
+ * The optional ->open() fxn can be used for cases where the protocol
+ * interface is constructed on-demand, and is called if protocol_interface
+ * is NULL.
+ */
 struct efi_handler {
 	const efi_guid_t *guid;
 	void *protocol_interface;
+	efi_status_t (EFIAPI *open)(void *handle, efi_guid_t *protocol,
+			void **protocol_interface);
 };
 
 /*
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index 7d45c18ff7..21f41866d0 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -1063,6 +1063,13 @@ static efi_status_t EFIAPI efi_open_protocol(
 			if (!guidcmp(hprotocol, protocol)) {
 				if (attributes !=
 				    EFI_OPEN_PROTOCOL_TEST_PROTOCOL) {
+					if (!handler->protocol_interface) {
+						r = handler->open(efiobj->handle,
+								protocol,
+								&handler->protocol_interface);
+						if (r != EFI_SUCCESS)
+							goto out;
+					}
 					*protocol_interface =
 						handler->protocol_interface;
 				}
-- 
2.13.0