locking: remove spin_lock_prefetch

The only remaining consumer is new_inode, where it showed up in 2001 as
commit c37fa164f793 ("v2.4.9.9 -> v2.4.9.10") in a historical repo [1]
with a changelog which does not mention it.

Since then the line got only touched up to keep compiling.

While it may have been of benefit back in the day, it is guaranteed to
at best not get in the way in the multicore setting -- as the code
performs *a lot* of work between the prefetch and actual lock acquire,
any contention means the cacheline is already invalid by the time the
routine calls spin_lock(). It adds spurious traffic, for short.

On top of it prefetch is notoriously tricky to use for single-threaded
purposes, making it questionable from the get go.

As such, remove it.

I admit upfront I did not see value in benchmarking this change, but I
can do it if that is deemed appropriate.

Removal from new_inode and of the entire thing are in the same patch as
requested by Linus, so whatever weird looks can be directed at that guy.

Link: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/fs/inode.c?id=c37fa164f793735b32aa3f53154ff1a7659e6442 [1]
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MIPS: Remove TX39XX support

No (active) developer owns this hardware, so let's remove Linux support.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>

MIPS: octeon: Remove ARCH_HAS_IRQ_PER_CPU

ARCH_HAS_IRQ_PER_CPU is unused anywhere in the kernel - remove the
definition.

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

MIPS: octeon: Remove cpu_has_saa

The cpu_has_saa feature macro was added along with Cavium Octeon CPU
support back in commit 5b3b16880f40 ("MIPS: Add Cavium OCTEON processor
support files to arch/mips/cavium-octeon.") but has never been used.

Remove the dead code.

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

MIPS: Octeon: Expose support for mips32r1, mips32r2 and mips64r1

Define Cavium Octeon as a CPU that has support for mips32r1, mips32r2 and
mips64r1. This will affect show_cpuinfo() that will now correctly expose
mips32r1, mips32r2 and mips64r1 as supported ISAs.

Signed-off-by: Petar Jovanovic <petar.jovanovic@rt-rk.com>
Reviewed-by: Maciej W. Rozycki <macro@imgtec.com>
Acked-by: David Daney <david.daney@cavium.com>
Cc: petar.jovanovic@imgtec.com
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15749/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Clean up RDHWR handling

No preprocessor definitions are used in the handling of the registers
accessible with the RDHWR instruction, nor the corresponding bits in the
CP0 HWREna register.

Add definitions for both the register numbers (MIPS_HWR_*) and HWREna
bits (MIPS_HWRENA_*) in asm/mipsregs.h and make use of them in the
initialisation of HWREna and emulation of the RDHWR instruction.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: David Daney <david.daney@cavium.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

MIPS: Octeon: Delete override of cpu_has_mips_r2_exec_hazard.

This is no longer needed with the fixed, new and improved definition
of cpu_has_mips_r2_exec_hazard in <asm/cpu-features.h>.

For a discussion, see http://patchwork.linux-mips.org/patch/9539/.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Use WSBH/DSBH/DSHD on Loongson 3A

Signed-off-by: chenj <chenj@lemote.com>
Cc: linux-mips@linux-mips.org
Cc: chenhc@lemote.com
Patchwork: https://patchwork.linux-mips.org/patch/7542/
Patchwork: https://patchwork.linux-mips.org/patch/7550/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: OCTEON: Enable use of FPU

Some versions of the assembler will not assemble CFC1 for OCTEON, so
override the ISA for these.

Add r4k_fpu.o to handle low level FPU initialization.

Modify octeon_switch.S to save the FPU registers. And include
r4k_switch.S to pick up more FPU support.

Get rid of "#define cpu_has_fpu 0"

Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Cc: James Hogan <james.hogan@imgtec.com>
Cc: kvm@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7006/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Hardwire detection of DSP ASE Rev 2 for systems, as required.

Most supported systems currently hardwire cpu_has_dsp to 0, so we also
can disable support for cpu_has_dsp2 resulting in a slightly smaller
kernel.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Replace 'kernel_uses_smartmips_rixi' with 'cpu_has_rixi'.

Remove usage of the 'kernel_uses_smartmips_rixi' macro from all files
and use new 'cpu_has_rixi' instead.

Signed-off-by: Steven J. Hill <sjhill@mips.com>
Acked-by: David Daney <david.daney@cavium.com>

MIPS: Octeon: Enable C0_UserLocal probing.

Octeon2 processor cores have a UserLocal register. Remove the hard
coded negative probe and allow the standard probing to detect this
feature.

Signed-off-by: David Daney <david.daney@cavium.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2578/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Octeon: Enable Read Inhibit / eXecute Inhibit on Octeon II.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Patchwork: http://patchwork.linux-mips.org/patch/1666/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Octeon: Adjust top of DMA32 zone.

On OCTEON, we reserve the last 256MB of 32-bit PCI address space, mapping
the RAM in this region at a high DMA address. This makes memory in this
region unavailable for 32-bit DMA.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Patchwork: http://patchwork.linux-mips.org/patch/1634/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Octeon: Implement delays with cycle counter.

Power throttling make deterministic delay loops impossible.
Re-implement delays using the cycle counter. This also allows us to
get rid of the code that calculates loops per jiffy.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1317/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Octeon: Define ARCH_HAS_USABLE_BUILTIN_POPCOUNT for OCTEON.

OCTEON implements __builtin_popcount with a single instruction, so lets use it.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Cc: David Daney <ddaney@caviumnetworks.com>
Patchwork: https://patchwork.linux-mips.org/patch/1431/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Enable Read Inhibit/eXecute Inhibit for Octeon+ CPUs

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/955/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Octeon: Set kernel_uses_llsc to false on non-SMP builds.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Move Cavium CP0 hwrena impl bits to cpu-feature-overrides.h

We had an ugly #ifdef for Cavium Octeon hwrena bits in traps.c, remove
it to mach-cavium-octeon/cpu-feature-overrides.h

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Remove execution hazard barriers for Octeon.

The Octeon has no execution hazards, so we can remove them and save an
instruction per TLB handler invocation.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Reviewed by: David VomLehn <dvomlehn@cisco.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

MIPS: Add Cavium OCTEON processor support files to arch/mips/cavium-octeon.

These are the rest of the new files needed to add OCTEON processor
support to the Linux kernel. Other than Makefile and Kconfig which
should be obvious, we have:

csrc-octeon.c -- Clock source driver for OCTEON.
dma-octeon.c -- Helper functions for mapping DMA memory.
flash_setup.c -- Register on-board flash with the MTD subsystem.
octeon-irq.c -- OCTEON interrupt controller managment.
octeon-memcpy.S -- Optimized memcpy() implementation.
serial.c -- Register 8250 platform driver and early console.
setup.c -- Early architecture initialization.
smp.c -- OCTEON SMP support.
octeon_switch.S -- Scheduler context switch for OCTEON.
c-octeon.c -- OCTEON cache controller support.
cex-oct.S -- OCTEON cache exception handler.

asm/mach-cavium-octeon/*.h -- Architecture include files.

Signed-off-by: Tomaso Paoletti <tpaoletti@caviumnetworks.com>
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

create mode 100644 arch/mips/cavium-octeon/Kconfig
create mode 100644 arch/mips/cavium-octeon/Makefile
create mode 100644 arch/mips/cavium-octeon/csrc-octeon.c
create mode 100644 arch/mips/cavium-octeon/dma-octeon.c
create mode 100644 arch/mips/cavium-octeon/flash_setup.c
create mode 100644 arch/mips/cavium-octeon/octeon-irq.c
create mode 100644 arch/mips/cavium-octeon/octeon-memcpy.S
create mode 100644 arch/mips/cavium-octeon/serial.c
create mode 100644 arch/mips/cavium-octeon/setup.c
create mode 100644 arch/mips/cavium-octeon/smp.c
create mode 100644 arch/mips/include/asm/mach-cavium-octeon/cpu-feature-overrides.h
create mode 100644 arch/mips/include/asm/mach-cavium-octeon/dma-coherence.h
create mode 100644 arch/mips/include/asm/mach-cavium-octeon/irq.h
create mode 100644 arch/mips/include/asm/mach-cavium-octeon/kernel-entry-init.h
create mode 100644 arch/mips/include/asm/mach-cavium-octeon/war.h
create mode 100644 arch/mips/include/asm/octeon/octeon.h
create mode 100644 arch/mips/kernel/octeon_switch.S
create mode 100644 arch/mips/mm/c-octeon.c
create mode 100644 arch/mips/mm/cex-oct.S