Some systems are configured such that multiple CPUs begin running from
their reset vector following a system reset. If this occurs then U-Boot
will be run on multiple CPUs simultaneously, which causes all sorts of
issues as the multiple instances of U-Boot clobber each other.

Prevent this from happening by simply hanging with an infinite loop if
we run on a CPU whose ID, as determined by GlobalNumber or EBase.CPUNum
as appropriate, is non-zero.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>

The relocate_code function was handling cache maintenance incorrectly.
It copied U-Boot to its new location, flushed the caches & then
proceeded to apply relocations & jump to the new code without flushing
the caches again. This is problematic as the instruction cache could
potentially have already fetched instructions that hadn't had relocs
applied.

Rework this to perform the flush_cache call using the code in the
original copy of U-Boot, after having applied relocations to the new
copy of U-Boot. The new U-Boot can then be jumped to safely once that
cache flush has been performed.

As part of this, since the old U-Boot is used up until after that cache
flush, complexity around loading values from the GOT using a jump & link
instruction & loads from a table is removed. Instead we can simply load
the needed values with PTR_LA fromt the original GOT.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>

During boot we set Config.K0=2 (uncached) such that any accesses to the
kseg0 memory region are performed uncached before the caches are
initialised. This write to the Config register introduces an execution
hazard between it & any following memory accesses (such as the load of
_gp), which we need to clear in order to ensure those memory accesses
are actually performed uncached. Clear this execution hazard with the
insertion of an ehb execution hazard barrier instruction.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>

Map the Global Control Registers (GCRs) provided by the MIPS Coherence
Manager (CM) in preparation for using some of them in later patches.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>

On systems where cache initialisation doesn't require zeroed memory (ie.
systems where CONFIG_SYS_MIPS_CACHE_INIT_RAM_LOAD is not defined)
perform cache initialisation prior to lowlevel_init & DDR
initialisation. This allows for DDR initialisation code to run cached &
thus significantly faster.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>

The coprocessor 0 Config register includes 9 implementation defined
bits, which in some processors do things like enable write combining or
other functionality. We ought not to wipe them to 0 during boot. Rather
than doing so, preserve their value & only clear the bits standardised
by the MIPS architecture.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>

Enable use of the instruction cache immediately after it has been
initialised. This will only take effect if U-Boot was linked to run from
kseg0 rather than kseg1, but when this is the case the data cache
initialisation code will run cached & thus significantly faster.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>

Rather than probing the cache line sizes on every call of any cache
maintenance function, probe them once during boot & store the values in
the global data structure for later use. This will reduce the overhead
of the cache maintenance functions, which isn't a big deal yet but
becomes more important once L2 caches which may expose their properties
via coprocessor 2 or the CM are supported.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>

Provide a default linker script for SPL binaries. Start address
and size of text section and BSS section are configurable. All
sections are arranged in a way that only relevant sections are
kept in the code section for maximum size reduction. All other
sections are kept but moved outside the code section to help
with debugging.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Acked-by: Marek Vasut <marex@denx.de>

In MIPS assembly there have historically been 2 variants of immediate
addition - the standard "addi" which traps if an overflow occurs, and
the unchecked "addiu" which does not trap on overflow. In release 6 of
the MIPS architecture the trapping variants of immediate addition &
subtraction have been removed. In preparation for supporting MIPSr6,
stop using the trapping instructions from assembly & switch to their
unchecked variants.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>