dtc: Add Kconfig option to pad device tree blob

This will allow arch(s) that use device tree blobs to pad the end of the
device tree so they can be modified by board files at run time. This will
help prevent errors such as FDT_ERR_NOSPACE from occurring.

Signed-off-by: Eric Schikschneit <eric.schikschneit@novatechautomation.com>
[trini: Change default order so that X86 && EFI_APP works correctly]

diff --git a/arch/Kconfig b/arch/Kconfig
index ea33d07..597b40f 100644 (file)
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -63,6 +63,13 @@ config SYS_CACHELINE_SIZE
        default 64 if RISCV
        default 32 if MIPS
 
+config SYS_DTC_PAD_BYTES
+       int "Size in bytes to pad device tree blob"
+       default 32768 if X86 && EFI_APP
+       default 4096 if ARC || ARM64 || M68K || MICROBLAZE || NIOS2 \
+               || RISCV || SANDBOX || X86
+       default 0
+
 config LINKER_LIST_ALIGN
        int
        default 32 if SANDBOX

diff --git a/arch/arc/dts/Makefile b/arch/arc/dts/Makefile
index fe6ad7b..87c627c 100644 (file)
--- a/arch/arc/dts/Makefile
+++ b/arch/arc/dts/Makefile
@@ -11,4 +11,4 @@ dtb-$(CONFIG_TARGET_IOT_DEVKIT) +=  iot_devkit.dtb
 include $(srctree)/scripts/Makefile.dts
 
 # Add any required device tree compiler flags here
-DTC_FLAGS += -R 4 -p 0x1000
+DTC_FLAGS += -R 4

diff --git a/arch/m68k/dts/Makefile b/arch/m68k/dts/Makefile
index 8b354b9..0f06109 100644 (file)
--- a/arch/m68k/dts/Makefile
+++ b/arch/m68k/dts/Makefile
@@ -21,4 +21,4 @@ dtb-$(CONFIG_TARGET_STMARK2) += stmark2.dtb
 include $(srctree)/scripts/Makefile.dts
 
 # Add any required device tree compiler flags here
-DTC_FLAGS += -R 4 -p 0x1000
+DTC_FLAGS += -R 4

diff --git a/arch/microblaze/dts/Makefile b/arch/microblaze/dts/Makefile
index 9be902d..0f3a747 100644 (file)
--- a/arch/microblaze/dts/Makefile
+++ b/arch/microblaze/dts/Makefile
@@ -5,4 +5,4 @@ dtb-y += $(shell echo $(CONFIG_DEFAULT_DEVICE_TREE)).dtb
 include $(srctree)/scripts/Makefile.dts
 
 # Add any required device tree compiler flags here
-DTC_FLAGS += -R 4 -p 0x1000
+DTC_FLAGS += -R 4

diff --git a/arch/nios2/dts/Makefile b/arch/nios2/dts/Makefile
index d77db97..7595116 100644 (file)
--- a/arch/nios2/dts/Makefile
+++ b/arch/nios2/dts/Makefile
@@ -5,4 +5,4 @@ dtb-y += $(CONFIG_DEFAULT_DEVICE_TREE:"%"=%).dtb
 include $(srctree)/scripts/Makefile.dts
 
 # Add any required device tree compiler flags here
-DTC_FLAGS += -R 4 -p 0x1000
+DTC_FLAGS += -R 4

diff --git a/arch/riscv/dts/Makefile b/arch/riscv/dts/Makefile
index cf1872f..2b10c2d 100644 (file)
--- a/arch/riscv/dts/Makefile
+++ b/arch/riscv/dts/Makefile
@@ -19,4 +19,4 @@ dtb-$(CONFIG_TARGET_ASPEED_AST2700_IBEX) += ast2700-ibex.dtb
 include $(srctree)/scripts/Makefile.dts
 
 # Add any required device tree compiler flags here
-DTC_FLAGS += -R 4 -p 0x1000
+DTC_FLAGS += -R 4

diff --git a/arch/sandbox/dts/Makefile b/arch/sandbox/dts/Makefile
index 1c9fb4a..0d7b0b8 100644 (file)
--- a/arch/sandbox/dts/Makefile
+++ b/arch/sandbox/dts/Makefile
@@ -11,4 +11,4 @@ dtb-$(CONFIG_CMD_EXTENSION) += overlay0.dtbo overlay1.dtbo
 include $(srctree)/scripts/Makefile.dts
 
 # Add any required device tree compiler flags here
-DTC_FLAGS += -R 4 -p 0x1000
+DTC_FLAGS += -R 4

diff --git a/arch/x86/dts/Makefile b/arch/x86/dts/Makefile
index 9a46726..725991e 100644 (file)
--- a/arch/x86/dts/Makefile
+++ b/arch/x86/dts/Makefile
@@ -24,4 +24,4 @@ dtb-y += bayleybay.dtb \
 
 include $(srctree)/scripts/Makefile.dts
 
-DTC_FLAGS += -R 4 -p $(if $(CONFIG_EFI_APP),0x8000,0x1000)
+DTC_FLAGS += -R 4

diff --git a/doc/board/broadcom/bcm7xxx.rst b/doc/board/broadcom/bcm7xxx.rst
index f1994d9..f559d5c 100644 (file)
--- a/doc/board/broadcom/bcm7xxx.rst
+++ b/doc/board/broadcom/bcm7xxx.rst
@@ -149,10 +149,8 @@ and with a generic ARMv7 root file system.
                                 * to the Linux source tree as a .dts file.
                                 *
                                 * To support modifications to the device tree
-                                * in-place in U-Boot, add to Linux's
-                                * arch/arm/boot/dts/Makefile:
-                                *
-                                * DTC_FLAGS ?= -p 4096
+                                * in-place in U-Boot, set the config variable
+                                * CONFIG_SYS_DTC_PAD_BYTES as needed.
                                 *
                                 * This will leave some padding in the DTB and
                                 * thus reserve room for node additions.

diff --git a/doc/develop/makefiles.rst b/doc/develop/makefiles.rst
index 37a7dea..593556f 100644 (file)
--- a/doc/develop/makefiles.rst
+++ b/doc/develop/makefiles.rst
@@ -1430,10 +1430,13 @@ When kbuild executes, the following steps are followed (roughly):
        A central rule exists to create `$(obj)/%.dtb` from `$(src)/%.dts`;
        architecture Makefiles do no need to explicitly write out that rule.
 
+        The device tree can now be padded by the specified number of bytes
+        by setting CONFIG_SYS_DTC_PAD_BYTES instead of explicitly setting
+        DTC_FLAGS with the -p option.
+
        Example::
 
                targets += $(dtb-y)
-               DTC_FLAGS ?= -p 1024
 
 7.9 Preprocessing linker scripts
 --------------------------------

diff --git a/dts/upstream/src/arm64/Makefile b/dts/upstream/src/arm64/Makefile
index b6db0dc..01a5265 100644 (file)
--- a/dts/upstream/src/arm64/Makefile
+++ b/dts/upstream/src/arm64/Makefile
@@ -6,5 +6,5 @@ include $(srctree)/scripts/Makefile.dts
 DTC_FLAGS += -a 0x8
 
 ifdef CONFIG_RCAR_64
-DTC_FLAGS += -R 4 -p 0x1000
+       DTC_FLAGS += -R 4
 endif

diff --git a/dts/upstream/src/riscv/Makefile b/dts/upstream/src/riscv/Makefile
index 980617e..43351f8 100644 (file)
--- a/dts/upstream/src/riscv/Makefile
+++ b/dts/upstream/src/riscv/Makefile
@@ -2,5 +2,5 @@
 
 include $(srctree)/scripts/Makefile.dts
 
-DTC_FLAGS += -R 4 -p 0x1000
+DTC_FLAGS += -R 4
 

diff --git a/scripts/Makefile.dts b/scripts/Makefile.dts
index 685e337..3871a4a 100644 (file)
--- a/scripts/Makefile.dts
+++ b/scripts/Makefile.dts
@@ -16,6 +16,10 @@ dtb-y += $(subst $(dt_dir)/,,$(dtb-vendor_dts))
 
 endif
 
+ifneq ($(CONFIG_SYS_DTC_PAD_BYTES),0)
+DTC_FLAGS += -p $(CONFIG_SYS_DTC_PAD_BYTES)
+endif
+
 targets += $(dtb-y)
 
 PHONY += dtbs