When U-Boot is started from another firmware program, not just a prior phase of U-Boot, special behaviour is typically used. In particular, the device tree may come from that prior stage.
At present this is sort-of indicated by OF_BOARD, although the correlation is not 1:1, since that option simply means that the board has a custom mechanism for obtaining the device tree. For example, sandbox defines OF_BOARD. Also the board_fdt_blob_setup() function can in fact make use of the devicetree in U-Boot if it wishes, as used by dragonboard410c until very recently.
Add an explicit Kconfig for this situation. Define it for boards which use this feature. Update the OF_BOARD option to more-accurately reflect what it is doing, e.g. for sandbox.
Signed-off-by: Simon Glass sjg@chromium.org ---
Changes in v7: - Add new patch to add a Kconfig for boards with a prior stage
arch/arm/Kconfig | 8 ++++++++ arch/arm/mach-bcm283x/Kconfig | 1 + board/emulation/qemu-riscv/Kconfig | 1 + dts/Kconfig | 31 ++++++++++++++++++++++++++---- lib/fdtdec.c | 1 + 5 files changed, 38 insertions(+), 4 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index eed27af74e8..d26461029af 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -635,6 +635,7 @@ config ARCH_BCMSTB select GPIO_EXTRA_HEADER select OF_CONTROL imply CMD_DM + imply OF_HAS_PRIOR_STAGE help This enables support for Broadcom ARM-based set-top box chipsets, including the 7445 family of chips. @@ -713,6 +714,7 @@ config ARCH_HIGHBANK select AHCI select DM_ETH select PHYS_64BIT + imply OF_HAS_PRIOR_STAGE
config ARCH_INTEGRATOR bool "ARM Ltd. Integrator family" @@ -966,6 +968,7 @@ config ARCH_QEMU imply DM_RNG imply DM_RTC imply RTC_PL031 + imply OF_HAS_PRIOR_STAGE
config ARCH_RMOBILE bool "Renesas ARM SoCs" @@ -1251,6 +1254,7 @@ config TARGET_VEXPRESS64_JUNO select DM_ETH select BLK select USB + imply OF_HAS_PRIOR_STAGE
config TARGET_TOTAL_COMPUTE bool "Support Total Compute Platform" @@ -1907,6 +1911,7 @@ config ARCH_OCTEONTX select OF_LIVE select BOARD_LATE_INIT select SYS_CACHE_SHIFT_7 + imply OF_HAS_PRIOR_STAGE
config ARCH_OCTEONTX2 bool "Support OcteonTX2 SoCs" @@ -1918,6 +1923,7 @@ config ARCH_OCTEONTX2 select OF_LIVE select BOARD_LATE_INIT select SYS_CACHE_SHIFT_7 + imply OF_HAS_PRIOR_STAGE
config TARGET_THUNDERX_88XX bool "Support ThunderX 88xx" @@ -1954,6 +1960,8 @@ config TARGET_XENGUEST_ARM64 select LINUX_KERNEL_IMAGE_HEADER select XEN_SERIAL select SSCANF + imply OF_HAS_PRIOR_STAGE + endchoice
config SUPPORT_PASSING_ATAGS diff --git a/arch/arm/mach-bcm283x/Kconfig b/arch/arm/mach-bcm283x/Kconfig index b3287ce8bce..2eb3802d9ae 100644 --- a/arch/arm/mach-bcm283x/Kconfig +++ b/arch/arm/mach-bcm283x/Kconfig @@ -188,6 +188,7 @@ config TARGET_RPI_4
This option creates a build targeting the ARMv8/AArch64 ISA. select BCM2711_64B + imply OF_HAS_PRIOR_STAGE
config TARGET_RPI_ARM64 bool "Raspberry Pi one binary 64-bit build" diff --git a/board/emulation/qemu-riscv/Kconfig b/board/emulation/qemu-riscv/Kconfig index 1bbf1bc84af..a380db61a0f 100644 --- a/board/emulation/qemu-riscv/Kconfig +++ b/board/emulation/qemu-riscv/Kconfig @@ -65,5 +65,6 @@ config BOARD_SPECIFIC_OPTIONS # dummy imply VIRTIO_BLK imply MTD_NOR_FLASH imply CFI_FLASH + imply OF_HAS_PRIOR_STAGE
endif diff --git a/dts/Kconfig b/dts/Kconfig index 5dcc79d5192..803d0899556 100644 --- a/dts/Kconfig +++ b/dts/Kconfig @@ -100,11 +100,34 @@ config OF_BOARD bool "Provided by the board (e.g a previous loader) at runtime" default y if SANDBOX help - If this option is enabled, the device tree will be provided by - the board at runtime if the board supports it. The device tree bundled - with the image (if any) will be overridden / ignored. + If this option is enabled, the device tree is provided at runtime by + a custom function called board_fdt_blob_setup(). The board must + implement this function if it wishes to provide special behaviour.
- A device tree file must be provided in the tree. + With this option, the device tree build by U-Boot may be overridden or + ignored. See OF_HAS_PRIOR_STAGE. + + Note: Boards which use this to handle a device tree passed from an + earlier stage should enable OF_HAS_PRIOR_STAGE. + +config OF_HAS_PRIOR_STAGE + bool + help + Indicates that a prior stage of the firmware (before U-Boot proper) + makes use of device tree and this board normally boots with that prior + stage, that provides a devicetree to U-Boot. + + This means that the device tree built in U-Boot should not be packaged + in the firmware image. Instead, the prior stage's device tree should + be so packaged. At runtime, the prior stage reads this, does any + necessary fix-ups, then passes it to U-Boot. See OF_BOARD. + + This option does not preclude using the U-Boot device tree, e.g. for + development purposes, but it is not recommended, and likely will not + even work, for production systems. + + Note: This option must be set in Kconfig and cannot be enabled or + disabled in the board's defconfig file.
config DEFAULT_DEVICE_TREE string "Default Device Tree for DT control" diff --git a/lib/fdtdec.c b/lib/fdtdec.c index 118c100b389..280cda61a72 100644 --- a/lib/fdtdec.c +++ b/lib/fdtdec.c @@ -1595,6 +1595,7 @@ int fdtdec_set_carveout(void *blob, const char *node, const char *prop_name, return 0; }
+/* TODO(sjg@chromium.org): This function should not be weak */ __weak int fdtdec_board_setup(const void *fdt_blob) { return 0;