This commit changes the working directory
where the build process occurs.

Before this commit, build process occurred under the source
tree for both in-tree and out-of-tree build.

That's why we needed to add $(obj) prefix to all generated
files in makefiles like follows:
  $(obj)u-boot.bin:  $(obj)u-boot

Here, $(obj) is empty for in-tree build, whereas it points
to the output directory for out-of-tree build.

And our old build system changes the current working directory
with "make -C <sub-dir>" syntax when descending into the
sub-directories.

On the other hand, Kbuild uses a different idea
to handle out-of-tree build and directory descending.

The build process of Kbuild always occurs under the output tree.
When "O=dir/to/store/output/files" is given, the build system
changes the current working directory to that directory and
restarts the make.

Kbuild uses "make -f $(srctree)/scripts/Makefile.build obj=<sub-dir>"
syntax for descending into sub-directories.
(We can write it like "make $(obj)=<sub-dir>" with a shorthand.)
This means the current working directory is always the top
of the output directory.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Tested-by: Gerhard Sittig <gsi@denx.de>

This commit adjusts some files to use Kbuild.include.

 - Use cc-option defined in Kbuild.include
    (Delete cc-option in config.mk)
 - Use cc-version defined in
    (Delete cc-version in config.mk)
 - Move binutils-version and dtc-version to Kbuild.include
     by analogy to cc-version

This commit also adds srctree (same as SRCTREE)
to use Kbuild scripts.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

This commit moves suffix rules from config.mk
to scripts/Makefile.build, which will allow us
to switch smoothly to real Kbuild.

Note1:
post/lib_powerpc/fpu/Makefile has
its own rule to compile C sources.
We need to tweak it to keep the same behavior.

Note2:
There are two file2 with the same name:
arch/arm/lib/crt0.S and eamples/api/crt0.S.
To keep the same build behavior,
examples/api/Makefile also has to be treaked.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

This commit adds scripts/Makefile.host.tmp which will
be used in the next commit to convert makefiles
under tools/ directory to Kbuild style.

Notice this script, scripts/Makefile.host.tmp
is temporary.

When switching over to real Kbuild,
it will be replaced with scripts/Makefile.host of Linux Kernel.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

We have some scripts imported from Linux Kernel:
setlocalversion, checkstack.pl, checkpatch.pl, cleanpatch

They are located under tools/ directory in U-Boot now.
But they were originally located under scripts/ directory
in Linux Kernel.

This commit moves them to the original location.

It is true that binutils-version.sh and dtc-version.sh
do not originate in Linux Kernel, but they should
be moved by analogy to gcc-version.sh.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

The support for COBJS, COBJS-y, SOBJS, SOBJS-y, GLCOBJS, GLSOBJS
from scripts/Makefile.build.
Going forward we need to use Kbuild style consistently.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

This patch tweaks scripts/Makefile.build to allow
the build system to descend into subdirectories like Kbuild.

To use this feature, use "obj-y += foo/" syntax.

Example:
    obj-$(CONFIG_FOO) += foo/

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Simon Glass <sjg@chromium.org>

Every makefile in sub directories has common lines
at the top and the bottom.
This commit pushes the common parts into script/Makefile.build.

Going forward sub-makefiles only need to describe this part:

    COBJS := ...
    COBJS += ...
    SOBJS := ...

But using obj-y is preferable to prepare for switching to Kbuild.

The conventional (non-Kbuild) Makefile style is still supported.
This is achieved by greping the Makefile before entering into it.
U-Boot conventional sub makefiles always include some other makefiles.
So the build system searches a line beginning with "include" keyword
in the makefile in order to distinguish which style it is.
If the Makefile include a "include" line, we assume it is a conventional
U-Boot style. Otherwise, it is treated as a Kbuild-style makefile.

With this tweak, we can switch sub-makefiles
from U-Boot style to Kbuild style little by little.

obj-y := foo/
syntax (descending into the sub directory) is not supportd yet.
It will be implemented in the upcomming commit.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@ti.com>