dm: Reduce SPL device tree size

The SPL device tree size must be minimised to save memory. Only include
properties that are needed by SPL - this is determined by the presence
of the "u-boot,dm-pre-reloc" property. Also remove a predefined list of
unused properties from the nodes that remain.

Signed-off-by: Simon Glass <sjg@chromium.org>

diff --git a/Makefile b/Makefile
index b6f83a553052940a8e91d441350556d9d10ce1f1..0aa5e6ad7f4358cf445ee7a52fe62762f0495c16 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -1259,7 +1259,7 @@ u-boot.lds: $(LDSCRIPT) prepare FORCE
 
 spl/u-boot-spl.bin: spl/u-boot-spl
        @:
-spl/u-boot-spl: tools prepare
+spl/u-boot-spl: tools prepare $(if $(CONFIG_OF_SEPARATE),dts/dt.dtb)
        $(Q)$(MAKE) obj=spl -f $(srctree)/scripts/Makefile.spl all
 
 spl/sunxi-spl.bin: spl/u-boot-spl

diff --git a/arch/arm/cpu/u-boot-spl.lds b/arch/arm/cpu/u-boot-spl.lds
index a8be204038f94a937289f1e433aff5a02d21f293..4b6e0f6fa48480a8d462d6e55c268b5ae65c8a75 100644 (file)
--- a/arch/arm/cpu/u-boot-spl.lds
+++ b/arch/arm/cpu/u-boot-spl.lds
@@ -66,7 +66,7 @@ SECTIONS
                 . = ALIGN(4);
                __bss_end = .;
        }
-
+       __bss_size = __bss_end - __bss_start;
        .dynsym _image_binary_end : { *(.dynsym) }
        .dynbss : { *(.dynbss) }
        .dynstr : { *(.dynstr*) }

diff --git a/dts/Kconfig b/dts/Kconfig
index 957f5c7ffad2a2ab6637024169f84bfdc6489f75..09cfefbd35358adb5335fea0f2dc53eda94be99e 100644 (file)
--- a/dts/Kconfig
+++ b/dts/Kconfig
@@ -56,4 +56,16 @@ config DEFAULT_DEVICE_TREE
          It can be overridden from the command line:
          $ make DEVICE_TREE=<device-tree-name>
 
+config OF_SPL_REMOVE_PROPS
+       string "List of device tree properties to drop for SPL"
+       depends on OF_CONTROL && SPL
+       default "pinctrl-0 pinctrl-names clocks clock-names interrupt-parent"
+       help
+         Since SPL normally runs in a reduced memory space, the device tree
+         is cut down to only what is needed to load and start U-Boot. Only
+         nodes marked with the property "u-boot,dm-pre-reloc" will be
+         included. In addition, some properties are not used by U-Boot and
+         can be discarded. This option defines the list of properties to
+         discard.
+
 endmenu

diff --git a/scripts/Makefile.spl b/scripts/Makefile.spl
index fd572f4b47b3e561914deb3b3c2fd5c52874d894..bcc7ca2f894a8d434b87fe7a42d0e44e12177a4f 100644 (file)
--- a/scripts/Makefile.spl
+++ b/scripts/Makefile.spl
@@ -151,6 +151,8 @@ boot.bin: $(obj)/u-boot-spl.bin
 
 ALL-y  += $(obj)/$(SPL_BIN).bin $(obj)/$(SPL_BIN).cfg
 
+ALL-$(CONFIG_OF_SEPARATE) += $(obj)/$(SPL_BIN)-pad.bin $(obj)/$(SPL_BIN)-dtb.bin
+
 ifdef CONFIG_SAMSUNG
 ALL-y  += $(obj)/$(BOARD)-spl.bin
 endif
@@ -165,6 +167,32 @@ endif
 
 all:   $(ALL-y)
 
+quiet_cmd_cat = CAT     $@
+cmd_cat = cat $(filter-out $(PHONY), $^) > $@
+
+$(obj)/$(SPL_BIN)-dtb.bin: $(obj)/$(SPL_BIN).bin $(obj)/$(SPL_BIN)-pad.bin \
+               $(obj)/$(SPL_BIN).dtb FORCE
+       $(call if_changed,cat)
+
+# Create a file that pads from the end of u-boot-spl.bin to bss_end
+$(obj)/$(SPL_BIN)-pad.bin: $(obj)/$(SPL_BIN)
+       @bss_size_str=$(shell $(NM) $< | awk 'BEGIN {size = 0} /__bss_size/ {size = $$1} END {print "ibase=16; " toupper(size)}' | bc); \
+       dd if=/dev/zero of=$@ bs=1 count=$${bss_size_str} 2>/dev/null;
+
+# Pass the original device tree file through fdtgrep twice. The first pass
+# removes any unwanted nodes (i.e. those which don't have the
+# 'u-boot,dm-pre-reloc' property and thus are not needed by SPL. The second
+# pass removes various unused properties from the remaining nodes.
+# The output is typically a much smaller device tree file.
+quiet_cmd_fdtgrep = FDTGREP $@
+      cmd_fdtgrep = $(objtree)/tools/fdtgrep -b u-boot,dm-pre-reloc -RT $< \
+               -n /chosen -O dtb | \
+       $(objtree)/tools/fdtgrep -r -O dtb - -o $@ \
+               $(addprefix -P ,$(subst $\",,$(CONFIG_OF_SPL_REMOVE_PROPS)))
+
+$(obj)/$(SPL_BIN).dtb: dts/dt.dtb
+       $(call cmd,fdtgrep)
+
 quiet_cmd_cpp_cfg = CFG     $@
 cmd_cpp_cfg = $(CPP) -Wp,-MD,$(depfile) $(cpp_flags) $(LDPPFLAGS) -ansi \
        -DDO_DEPS_ONLY -D__ASSEMBLY__ -x assembler-with-cpp -P -dM -E -o $@ $<