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LoongArch: Allow device trees be built into the kernel

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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: Binbin Zhou <zhoubinbin@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Binbin Zhou 2024-01-17 12:43:00 +08:00 committed by Huacai Chen
parent db8ce24070
commit 5f346a6e59
5 changed files with 31 additions and 6 deletions
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1
arch/loongarch/Kbuild
View File

@ -4,6 +4,7 @@ obj-y += net/
obj-y += vdso/
obj-$(CONFIG_KVM) += kvm/
obj-$(CONFIG_BUILTIN_DTB) += boot/dts/
# for cleaning
subdir- += boot

18
arch/loongarch/Kconfig
View File

@ -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

3
arch/loongarch/Makefile
View File

@ -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

3
arch/loongarch/boot/dts/Makefile
View File

@ -1,4 +1,3 @@
# 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))

12
arch/loongarch/kernel/setup.c
View File

@ -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);
strlcat(boot_command_line, init_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