efi_loader: capsule: add capsule_on_disk support

Capsule data can be loaded into the system either via UpdateCapsule
runtime service or files on a file system (of boot device).
The latter case is called "capsules on disk", and actual updates will
take place at the next boot time.

In this commit, we will support capsule on disk mechanism.

Please note that U-Boot itself has no notion of "boot device" and
all the capsule files to be executed will be detected only if they
are located in a specific directory, \EFI\UpdateCapsule, on a device
that is identified as a boot device by "BootXXXX" variables.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index 1681b37..23ba065 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -105,6 +105,28 @@
 	  Select this option if you want to use UpdateCapsule and
 	  QueryCapsuleCapabilities API's.
 
+config EFI_CAPSULE_ON_DISK
+	bool "Enable capsule-on-disk support"
+	select EFI_HAVE_CAPSULE_SUPPORT
+	default n
+	help
+	  Select this option if you want to use capsule-on-disk feature,
+	  that is, capsules can be fetched and executed from files
+	  under a specific directory on UEFI system partition instead of
+	  via UpdateCapsule API.
+
+config EFI_CAPSULE_ON_DISK_EARLY
+	bool "Initiate capsule-on-disk at U-Boot boottime"
+	depends on EFI_CAPSULE_ON_DISK
+	default n
+	select EFI_SETUP_EARLY
+	help
+	  Normally, without this option enabled, capsules will be
+	  executed only at the first time of invoking one of efi command.
+	  If this option is enabled, capsules will be enforced to be
+	  executed as part of U-Boot initialisation so that they will
+	  surely take place whatever is set to distro_bootcmd.
+
 config EFI_DEVICE_PATH_TO_TEXT
 	bool "Device path to text protocol"
 	default y