efi: Create a new CONFIG_EFI

Create a Kconfig which indicates that EFI functionality is in use,
either as a client (EFI app / stub) or provider (EFI loader). This will
make it easier to share code between these two parts of U-Boot

Signed-off-by: Simon Glass <sjg@chromium.org>

doc/develop/uefi/u-boot_on_efi.rst

@@ -45,9 +45,9 @@ First choose a board that has EFI support and obtain an EFI implementation
 for that board. It will be either 32-bit or 64-bit. Alternatively, you can
 opt for using QEMU [1] and the OVMF [2], as detailed below.
 
-To build U-Boot as an EFI application, enable CONFIG_EFI_CLIENT and CONFIG_EFI_APP.
-The efi-x86_app32 and efi-x86_app64 configs are set up for this. Just build
-U-Boot as normal, e.g.::
+To build U-Boot as an EFI application, enable CONFIG_EFI_CLIENT and
+CONFIG_EFI_APP. The efi-x86_app32 and efi-x86_app64 configs are set up for
+this. Just build U-Boot as normal, e.g.::
 
    make efi-x86_app32_defconfig
    make

lib/efi/Kconfig

@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# Copyright 2025 Simon Glass <sjg@chromium.org>
+#
+
+config EFI
+	bool
+	help
+	  Indicates that EFI functionality is enabled, either via EFI_CLIENT or
+	  EFI_LOADER
+
+	  This is used to provide libraries shared by both.

lib/efi_client/Kconfig

@@ -5,6 +5,7 @@ config EFI_CLIENT
 	bool "Support running U-Boot from EFI"
 	depends on X86
 	imply X86_TSC_READ_BASE
+	select EFI
 	help
 	  U-Boot can be started from EFI on certain platforms. This allows
 	  EFI to perform most of the system init and then jump to U-Boot for

lib/efi_loader/Kconfig

@@ -16,6 +16,7 @@ config EFI_LOADER
 	depends on !EFI_STUB || !X86 || X86_64 || EFI_STUB_32BIT
 	depends on !EFI_APP
 	default y if !ARM || SYS_CPU = armv7 || SYS_CPU = armv8
+	select EFI
 	select CHARSET
 	# We need to send DM events, dynamically, in the EFI block driver
 	select DM_EVENT
@@ -597,4 +598,6 @@ endif
 
 source "lib/efi_client/Kconfig"
 
+source "lib/efi/Kconfig"
+
 endmenu