Commit 5f346a6e authored by Binbin Zhou's avatar Binbin Zhou Committed by Huacai Chen
Browse files

LoongArch: Allow device trees be built into the kernel 



During the upstream progress of those DT-based drivers, DT properties
are changed a lot so very different from those in existing bootloaders.
It is inevitably that some existing systems do not provide a standard,
canonical device tree to the kernel at boot time. So let's provide a
device tree table in the kernel, keyed by the dts filename, containing
the relevant DTBs.

We can use the built-in dts files as references. Each SoC has only one
built-in dts file which describes all possible device information of
that SoC, so the dts files are good examples during development.

And as a reference, our built-in dts file only enables the most basic
bootable combinations (so it is generic enough), acts as an alternative
in case the dts in the bootloader is unexpected.

Signed-off-by: default avatarBinbin Zhou <zhoubinbin@loongson.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent db8ce240

arch/loongarch/Kbuild

+1 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ obj-y += net/ 
obj-y += vdso/



obj-$(CONFIG_KVM) += kvm/

obj-$(CONFIG_BUILTIN_DTB) += boot/dts/



# for cleaning

subdir- += boot

arch/loongarch/Kconfig

+18 −0
Original line number Diff line number Diff line
@@ -375,6 +375,24 @@ config CMDLINE_FORCE 


endchoice



config BUILTIN_DTB

	bool "Enable built-in dtb in kernel"

	depends on OF

	help

	  Some existing systems do not provide a canonical device tree to

	  the kernel at boot time. Let's provide a device tree table in the

	  kernel, keyed by the dts filename, containing the relevant DTBs.



	  Built-in DTBs are generic enough and can be used as references.



config BUILTIN_DTB_NAME

	string "Source file for built-in dtb"

	depends on BUILTIN_DTB

	help

	  Base name (without suffix, relative to arch/loongarch/boot/dts/)

	  for the DTS file that will be used to produce the DTB linked into

	  the kernel.



config DMI

	bool "Enable DMI scanning"

	select DMI_SCAN_MACHINE_NON_EFI_FALLBACK

arch/loongarch/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
boot	:= arch/loongarch/boot



KBUILD_DEFCONFIG := loongson3_defconfig

KBUILD_DTBS      := dtbs



image-name-y			:= vmlinux

image-name-$(CONFIG_EFI_ZBOOT)	:= vmlinuz
@@ -144,7 +145,7 @@ endif 


vdso-install-y += arch/loongarch/vdso/vdso.so.dbg



all:	$(notdir $(KBUILD_IMAGE))

all:	$(notdir $(KBUILD_IMAGE)) $(KBUILD_DTBS)



vmlinuz.efi: vmlinux.efi

arch/loongarch/boot/dts/Makefile

+1 −2
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0-only

dtstree	:= $(srctree)/$(src)



dtb-y := $(patsubst $(dtstree)/%.dts,%.dtb, $(wildcard $(dtstree)/*.dts))
 
obj-$(CONFIG_BUILTIN_DTB)	+= $(addsuffix .dtb.o, $(CONFIG_BUILTIN_DTB_NAME))

arch/loongarch/kernel/setup.c

+9 −3
Original line number Diff line number Diff line
@@ -295,8 +295,12 @@ static void __init fdt_setup(void) 
	if (acpi_os_get_root_pointer())

		return;



	/* Look for a device tree configuration table entry */

	fdt_pointer = efi_fdt_pointer();

	/* Prefer to use built-in dtb, checking its legality first. */

	if (!fdt_check_header(__dtb_start))

		fdt_pointer = __dtb_start;

	else

		fdt_pointer = efi_fdt_pointer(); /* Fallback to firmware dtb */



	if (!fdt_pointer || fdt_check_header(fdt_pointer))

		return;
@@ -330,7 +334,9 @@ static void __init bootcmdline_init(char **cmdline_p) 
		if (boot_command_line[0])

			strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);



		if (!strstr(boot_command_line, init_command_line))

			strlcat(boot_command_line, init_command_line, COMMAND_LINE_SIZE);



		goto out;

	}

#endif