Add pre-bootloader (pbl) image support ...

This allows for creating a pre-bootloader binary for
 - nand boot
 - mmc boot
 - compressed image

The pbl will be incharge of the lowlevel init if needed.
The barebox will skip it.

Import string functions from linux 3.4 (arch/arm/boot/compressed/string.c) and
implement a dummy panic.

For now on introduce dummy zbarebox* targets and c code that will contain later
the decompressor. This only implemeted on ARM.

This patch is based on Sascha Hauer <s.hauer@pengutronix.de>
Add compressed image support patch

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

ARM: move exception vector table to exceptions.S ...

start.c has nothing to do with the exception vector table anymore,
so move it next to the exception handling code in exceptions.S

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM startup: calculate offset instead of runtime address ...

Calculating the offset between runtime and linked address makes the
intention of the binary copy function a bit more clear.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: Enable unaligned accesses on armv6 and later ...

We have the following in the tree:

|commit af42feb
|Author: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
|Date:   Mon Jan 2 11:49:17 2012 +0100
|
|    ARM: set SCTRL[A] only when architecture does not support unaligned access
|
|    Recent gcc generates code with unaligned access when architecture
|    supports it. Setting A bit unconditionally causes data-aborts on such
|    code rendering barebox unusable.
|
|    Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
|    Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

What the patch tried is correct: We should set the A bit only when the architecture
does not support unaligned accesses. To figure out whether the architecture supports
unaligned accesses the patch tested for the U bit which is wrong. The U bit may be
0 after a reset, so instead of testing for the U bit we have to set it. This can
be done on armv6 and later. All others have the A bit set to trap unaligned accesses.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Merge branch 'pu/cache' into next

ARM startup: Do call __mmu_cache_flush during startup ...

Traditionally we call __mmu_cache_flush in early startup. There
is a problem with armv7 and hierarchical caches though, on these
systems __mmu_cache_flush uses the stack. Appearantly this was
seldomly a problem, because most of these systems have a ROM
bootloader which sets up some stack, but on a special i.MX6 system
this failed badly. We should not have to flush caches here. Every
sane system should pass control to the bootloader without stale
entries in the caches *), so it should be a safe assumption that the
cache flush can be removed.

Since __mmu_cache_flush is not called from early code anymore we can
also move it to the regular text section.

Be brave and give it a try.

*) omap3 seems to be a exception to this, but this has a cache flush
in arch_init_lowlevel already

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

fix typo funtion -> function ...

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM startup: invalidate I-cache before jumping to relocated binary ...

barebox can startup with I-cache enabled, so to be on the safe
side we should invalidate the I-cache before jumping to a binary
we just copied in place.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: use unconditional branch in exception vectors ...

If we want to trap the processer in the exception vectors
we have to use unconditional branch instructions. I don't
know what I thought when using bne :-/

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: Allow to compile in thumb-2 mode ...

This shrinks the resulting binary size by ~25%. Exceptions
are still handled in arm mode, so we have to explicitely
put .arm directives into the exception code. Thumb-2 mode
has been tested on i.MX51 Babbage board.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: get runtime offset of board_init_lowlevel_return by using separate section ...

We used to get the runtime offset of the board_init_lowlevel_return
by doing a &board_init_lowlevel_return. This does not work in thumb-2
mode, so use a separate linker section for this function instead.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: move exception vectors away from start of binary ...

Traditionally U-Boot and barebox have the exception vectors at
the start of the binary. There is no real reason in doing so,
because in the majority of cases this data will not be at 0x0
where it could be used as vectors directly anyway.
This patch puts the vectors into a separate linker section and
defines an head function which is placed at the start of the
image instead. Putting this in a separate function also has
the advantage that it can be placed at the start of images
which require an additional header like several Freescale i.MX
images. As the head function contains the barebox arm magic
those images can now also be detected as barebox images.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: set SCTRL[A] only when architecture does not support unaligned access ...

Recent gcc generates code with unaligned access when architecture
supports it. Setting A bit unconditionally causes data-aborts on such
code rendering barebox unusable.

Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: mark 'lr' as clobbered by inline assembler ...

When executing 'bl' in inline assembler, the 'lr' register must be
marked as clobbered too.

Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: remove unused exception ...

The exception vector at 0x14 is not used on arm, so no need
to bind this address to a exception handler. Remove the
corresponding code

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: compile in image size and magic into barebox image ...

This is useful to detect a barebox image and to be able
to copy only the image size if barebox is stored on
raw partitions which are bigger than the image.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: make exception handling optional ...

On several boards without MMU support the vectors cannot be mapped
to 0x0 and exception support is nonfunctional anyway, so make this
configurable.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM start.c: use sections.h header file for linker variables ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: support big-endian processors. ...

Signed-off-by: Krzysztof Hałasa <khc@pm.waw.pl>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: add missing call to arch_init_lowlevel ...

This got lost during the switch to implement the lowlevel
stuff in C.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arm start.c: Make runtime function address calculation tolerant for more compilers ...

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arm: reimplement startup code in C ...

Lets translate the startup code to a language we all understand better.
Tested on pcm038 (arm v5) and pcm043 (arm v6).

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>