nios2: migrate to the generic rule for built-in DTB

Commit 654102d ("kbuild: add generic support for built-in boot
DTBs") introduced generic support for built-in DTBs.

Select GENERIC_BUILTIN_DTB when built-in DTB support is enabled.

To keep consistency across architectures, this commit also renames
CONFIG_NIOS2_DTB_SOURCE_BOOL to CONFIG_BUILTIN_DTB, and
CONFIG_NIOS2_DTB_SOURCE to CONFIG_BUILTIN_DTB_NAME.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Author: masahir0y

arch/nios2/Kbuild

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
-obj-y += kernel/ mm/ platform/ boot/dts/
+obj-y += kernel/ mm/ platform/
 
 # for cleaning
 subdir- += boot

arch/nios2/boot/dts/Makefile

@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
 
-obj-y := $(patsubst %.dts,%.dtb.o,$(CONFIG_NIOS2_DTB_SOURCE))
+dtb-y := $(addsuffix .dtb, $(CONFIG_BUILTIN_DTB_NAME))
 
-dtb-$(CONFIG_OF_ALL_DTBS) := $(patsubst $(src)/%.dts,%.dtb, $(wildcard $(src)/*.dts))
+dtb-$(CONFIG_OF_ALL_DTBS) += $(patsubst $(src)/%.dts,%.dtb, $(wildcard $(src)/*.dts))

arch/nios2/kernel/prom.c

@@ -32,7 +32,7 @@ void __init early_init_devtree(void *params)
 	}
 #endif
 
-#ifdef CONFIG_NIOS2_DTB_SOURCE_BOOL
+#ifdef CONFIG_BUILTIN_DTB
 	if (be32_to_cpu((__be32) *dtb) == OF_DT_HEADER)
 		params = (void *)__dtb_start;
 #endif

arch/nios2/platform/Kconfig.platform

@@ -35,19 +35,20 @@ config NIOS2_DTB_PHYS_ADDR
 	help
 	  Physical address of a dtb blob.
 
-config NIOS2_DTB_SOURCE_BOOL
+config BUILTIN_DTB
 	bool "Compile and link device tree into kernel image"
 	depends on !COMPILE_TEST
+	select GENERIC_BUILTIN_DTB
 	help
 	  This allows you to specify a dts (device tree source) file
 	  which will be compiled and linked into the kernel image.
 
-config NIOS2_DTB_SOURCE
-	string "Device tree source file"
-	depends on NIOS2_DTB_SOURCE_BOOL
+config BUILTIN_DTB_NAME
+	string "Built-in device tree name"
+	depends on BUILTIN_DTB
 	default ""
 	help
-	  Absolute path to the device tree source (dts) file describing your
+	  Relative path to the device tree without suffix describing your
 	  system.
 
 comment "Nios II instructions"