efi_loader: split efi_init_obj_list() into two stages

In the next commit, CONFIG_EFI_SETUP_EARLY will become mandated
in order to support dynamic enumeration of efi_disk objects.

This can, however, be problematic particularly in case of file-based
variable storage (efi_variable.c, default).
Non-volatile variables are to be restored from EFI system partition
by efi_init_variables() in efi_init_obj_list(). When efi_init_obj_list()
is called in board_init_r(), we don't know yet what disk devices
we have since none of device probing commands (say, scsi rescan) has not
been executed at that stage.

So in this commit, a preparatory change is made; efi_init_obj_list() is
broken into the two functions;
   * efi_init_early(), and
   * new efi_init_obj_list()

Only efi_init_early() will be called in board_init_r(), which allows
us to execute any of device probing commands, either though "preboot"
variable or normal command line, before calling efi_init_obj_list() which
is to be invoked at the first execution of an efi-related command
(or at efi_launch_capsules()) as used to be.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

common/board_r.c

@@ -795,7 +795,7 @@ static init_fnc_t init_sequence_r[] = {
 	initr_mem,
 #endif
 #ifdef CONFIG_EFI_SETUP_EARLY
-	(init_fnc_t)efi_init_obj_list,
+	efi_init_early,
 #endif
 	run_main_loop,
 };

common/main.c

@@ -54,8 +54,11 @@ void main_loop(void)
 	if (IS_ENABLED(CONFIG_UPDATE_TFTP))
 		update_tftp(0UL, NULL, NULL);
 
-	if (IS_ENABLED(CONFIG_EFI_CAPSULE_ON_DISK_EARLY))
-		efi_launch_capsules();
+	if (IS_ENABLED(CONFIG_EFI_CAPSULE_ON_DISK_EARLY)) {
+		/* efi_init_early() already called */
+		if (efi_init_obj_list() == EFI_SUCCESS)
+			efi_launch_capsules();
+	}
 
 	s = bootdelay_process();
 	if (cli_process_fdt(&s))

include/efi_loader.h

@@ -493,6 +493,8 @@ struct efi_register_notify_event {
 /* List of all events registered by RegisterProtocolNotify() */
 extern struct list_head efi_register_notify_events;
 
+/* called at pre-initialization */
+int efi_init_early(void);
 /* Initialize efi execution environment */
 efi_status_t efi_init_obj_list(void);
 /* Install device tree */

lib/efi_loader/efi_setup.c

@@ -174,20 +174,18 @@ static efi_status_t efi_init_os_indications(void)
 				    &os_indications_supported, false);
 }
 
-
 /**
- * efi_init_obj_list() - Initialize and populate EFI object list
+ * __efi_init_early() - handle initialization at early stage
+ *
+ * This function is called in efi_init_obj_list() only if
+ * !CONFIG_EFI_SETUP_EARLY.
  *
  * Return:	status code
  */
-efi_status_t efi_init_obj_list(void)
+static efi_status_t __efi_init_early(void)
 {
 	efi_status_t ret = EFI_SUCCESS;
 
-	/* Initialize once only */
-	if (efi_obj_list_initialized != OBJ_LIST_NOT_INITIALIZED)
-		return efi_obj_list_initialized;
-
 	/* Allow unaligned memory access */
 	allow_unaligned();
 
@@ -202,9 +200,51 @@ efi_status_t efi_init_obj_list(void)
 
 #ifdef CONFIG_PARTITIONS
 	ret = efi_disk_register();
-	if (ret != EFI_SUCCESS)
-		goto out;
 #endif
+out:
+	return ret;
+}
+
+/**
+ * efi_init_early() - handle initialization at early stage
+ *
+ * external version of __efi_init_early(); expected to be called in
+ * board_init_r().
+ *
+ * Return:	status code
+ */
+int efi_init_early(void)
+{
+	efi_status_t ret;
+
+	ret = __efi_init_early();
+	if (ret != EFI_SUCCESS) {
+		/* never re-init UEFI subsystem */
+		efi_obj_list_initialized = ret;
+		return -1;
+	}
+	return 0;
+}
+
+/**
+ * efi_init_obj_list() - Initialize and populate EFI object list
+ *
+ * Return:	status code
+ */
+efi_status_t efi_init_obj_list(void)
+{
+	efi_status_t ret = EFI_SUCCESS;
+
+	/* Initialize once only */
+	if (efi_obj_list_initialized != OBJ_LIST_NOT_INITIALIZED)
+		return efi_obj_list_initialized;
+
+	if (!IS_ENABLED(CONFIG_EFI_SETUP_EARLY)) {
+		ret = __efi_init_early();
+		if (ret != EFI_SUCCESS)
+			goto out;
+	}
+
 	if (IS_ENABLED(CONFIG_EFI_RNG_PROTOCOL)) {
 		ret = efi_rng_register();
 		if (ret != EFI_SUCCESS)