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@xxxxxxxxxxx> Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx> --- arch/loongarch/Kconfig | 18 ++++++++++++++++++ arch/loongarch/Makefile | 10 ++++++++-- arch/loongarch/boot/dts/Makefile | 3 +-- arch/loongarch/kernel/setup.c | 9 +++++++-- 4 files changed, 34 insertions(+), 6 deletions(-) diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index ee123820a476..267de6191dfc 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -331,6 +331,24 @@ config 64KB_3LEVEL endchoice +config BUILTIN_DTB + bool "Enable builtin 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 LoongArch builtin 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 CMDLINE string "Built-in kernel command line" help diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile index 4ba8d67ddb09..5b84f43adb98 100644 --- a/arch/loongarch/Makefile +++ b/arch/loongarch/Makefile @@ -5,7 +5,8 @@ boot := arch/loongarch/boot -KBUILD_DEFCONFIG := loongson3_defconfig +KBUILD_DEFCONFIG := loongson3_defconfig +KBUILD_DTBS := dtbs image-name-y := vmlinux image-name-$(CONFIG_EFI_ZBOOT) := vmlinuz @@ -141,13 +142,16 @@ endif vdso-install-y += arch/loongarch/vdso/vdso.so.dbg -all: $(notdir $(KBUILD_IMAGE)) +all: $(notdir $(KBUILD_IMAGE)) $(KBUILD_DTBS) vmlinuz.efi: vmlinux.efi vmlinux.elf vmlinux.efi vmlinuz.efi: vmlinux $(Q)$(MAKE) $(build)=$(boot) $(bootvars-y) $(boot)/$@ +# device-trees +core-y += arch/loongarch/boot/dts/ + install: $(Q)install -D -m 755 $(KBUILD_IMAGE) $(INSTALL_PATH)/$(image-name-y)-$(KERNELRELEASE) $(Q)install -D -m 644 .config $(INSTALL_PATH)/config-$(KERNELRELEASE) @@ -155,5 +159,7 @@ install: define archhelp echo ' install - install kernel into $(INSTALL_PATH)' + echo ' dtbs - Device-tree blobs for enabled boards' + echo ' dtbs_install - Install dtbs to $(INSTALL_DTBS_PATH)' echo endef diff --git a/arch/loongarch/boot/dts/Makefile b/arch/loongarch/boot/dts/Makefile index 5f1f55e911ad..1e24cdb5180a 100644 --- a/arch/loongarch/boot/dts/Makefile +++ b/arch/loongarch/boot/dts/Makefile @@ -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)) diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c index d183a745fb85..6cf3b1e045f6 100644 --- a/arch/loongarch/kernel/setup.c +++ b/arch/loongarch/kernel/setup.c @@ -295,8 +295,13 @@ 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(); + /* We prefer to try to use built-in dtb, checking its legality first. */ + if (!fdt_check_header(__dtb_start)) + fdt_pointer = __dtb_start; + else + /* Fallback to efi dtb, when built-in dtb is not available. */ + fdt_pointer = efi_fdt_pointer(); + if (!fdt_pointer || fdt_check_header(fdt_pointer)) return; -- 2.39.3
