Our current code to initialize boot_command_line is a mess. Some of this
is due to the addition of too many options over the years, and some of
this is due to workarounds for early_init_dt_scan_chosen() performing
actions specific to options from other architectures that probably
shouldn't be in generic code.

Clean this up by introducing a new bootcmdline_init() function that
simplifies the initialization somewhat. The major changes are:

- Because bootcmdline_init() is a function it can return early in the
  CONFIG_CMDLINE_OVERRIDE case.

- We clear boot_command_line rather than inheriting whatever
  early_init_dt_scan_chosen() may have left us. This means we no longer
  need to set boot_command_line to a space character in an attempt to
  prevent early_init_dt_scan_chosen() from copying CONFIG_CMDLINE into
  boot_command_line without us knowing about it.

- Indirection via USE_PROM_CMDLINE, USE_DTB_CMDLINE, EXTEND_WITH_PROM &
  BUILTIN_EXTEND_WITH_PROM macros is removed; they seemingly served only
  to obfuscate the code.

- The logic is cleaner, clearer & commented.

Two minor drawbacks of this approach are:

1) We call of_scan_flat_dt(), which means we scan through the DT again.
   The overhead is fairly minimal & shouldn't be noticeable.

2) cmdline_scan_chosen() duplicates a small amount of the logic from
   early_init_dt_scan_chosen(). Alternatives might be to allow the
   generic FDT code to keep & expose a copy of the arguments taken from
   the /chosen node's bootargs property, or to introduce a function like
   early_init_dt_scan_chosen() that retrieves them without modification
   to handle CONFIG_CMDLINE. Neither of these sounds particularly
   cleaner though, and this way we at least keep the extra work in
   arch/mips.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org

CMDLINE, CMDLINE_BOOL & CMDLINE_FORCE all explicitly specify default
values that are the same as the default value for their respective types
anyway (ie. n for booleans, and the empty string for strings).

Remove the redundant defaults.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Cc: linux-mips@vger.kernel.org

EARLY_PRINTK uses ArcWrite (via prom_putchar) on IP22/28, which needs
to not mess up PROMs data structures. ARC PROM gives out a list of
memory chunks, which are used and which are free. This fixes the
problem of not working early printk.

By using XKPHYS spaces more than 256MB memory on Indigo2 R4k machines
is working now, too.
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

IP22 started at physical 0x08000000. To avoid wasting memory for
page structs set PHYS_OFFSET.
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

Pointer arguments for 32bit ARC PROMs must reside in CKSEG0/1. While
the initial stack resides in CKSEG0 the first kernel thread stack
is already placed at a XKPHYS address, which ARC32 can't handle.
The workaround here is to use static variables, which are placed
into BSS and linked to a CKSEG0 address.
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

Instead of having a default y option with depends simply select
options for the platforms where they are needed.
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

When using a 64bit kernel with generic spaces setup stack is
also placed in XKPYHS, which the 32bit PROM can't handle.
By using call_o32 for ARC_CALLs a stack placed in KSEG0 is used
when calling PROM.
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

Current kernel uses only a few ARC calls. Drop all unused ARC functions.
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

We have assembly implementations of strcpy(), strncpy(), strcmp() &
strncmp() which:

 - Are simple byte-at-a-time loops with no particular optimizations. As
   a comment in the code describes, they're "rather naive".

 - Offer no clear performance advantage over the generic C
   implementations - in microbenchmarks performed by Alexander Lobakin
   the asm functions sometimes win & sometimes lose, but generally not
   by large margins in either direction.

 - Don't support 64-bit kernels, where we already make use of the
   generic C implementations.

 - Tend to bloat kernel code size due to inlining.

 - Don't support CONFIG_FORTIFY_SOURCE.

 - Won't support nanoMIPS without rework.

For all of these reasons, delete the asm implementations & make use of
the generic C implementations for 32-bit kernels just like we already do
for 64-bit kernels.
Signed-off-by: Paul Burton <paul.burton@mips.com>
URL: https://lore.kernel.org/linux-mips/a2a35f1cf58d6db19eb4af9b4ae21e35@dlink.ru/
Cc: Alexander Lobakin <alobakin@dlink.ru>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Cc: linux-mips@vger.kernel.org

Currently we have a lot of duplication in asm/r4kcache.h to handle
manually unrolling loops of cache ops for various line sizes, and we
have to explicitly handle the difference in cache op immediate width
between MIPSr6 & earlier ISA revisions with further duplication.

Introduce an unroll() macro in asm/unroll.h which expands to a switch
statement which is used to call a function or expand a preprocessor
macro a compile-time constant number of times in a row - effectively
explicitly unrolling a loop. We make use of this here to remove the
cache op duplication & will use it further in later patches.

A nice side effect of this is that calculating the cache op offset
immediate is now the compiler's responsibility, so we're no longer
sensitive to the width change of that immediate in MIPSr6 & will be
similarly agnostic to immediate width in any future supported ISA.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org

Fix the following checkpatch errors:

$ ./scripts/checkpatch.pl --no-tree -f arch/mips/generic/init.c
ERROR: Use of const init definition must use __initconst
#23: FILE: arch/mips/generic/init.c:23:
+static __initdata const void *fdt;

ERROR: Use of const init definition must use __initconst
#24: FILE: arch/mips/generic/init.c:24:
+static __initdata const struct mips_machine *mach;

ERROR: Use of const init definition must use __initconst
#25: FILE: arch/mips/generic/init.c:25:
+static __initdata const void *mach_match_data;

Fixes: eed0eabd ("MIPS: generic: Introduce generic DT-based board support")
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: ralf@linux-mips.org
Cc: jhogan@kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

Commit 3c1d3f09 ("MIPS: futex: Emit Loongson3 sync workarounds
within asm") inadvertently removed the newlines following
__WEAK_LLSC_MB, which causes build failures for configurations in which
__WEAK_LLSC_MB expands to a sync instruction:

  {standard input}: Assembler messages:
  {standard input}:9346: Error: symbol `sync3' is already defined
  {standard input}:9380: Error: symbol `sync3' is already defined
  ...

Fix this by restoring the newlines to separate the sync instruction from
anything following it (such as the 3: label), preventing inadvertent
concatenation.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Fixes: 3c1d3f09 ("MIPS: futex: Emit Loongson3 sync workarounds within asm")

{save,restore}_dsp() internally checks if the cpu has dsp support.
Therefore, explicit check is not required before calling them in
{save,restore}_processor_state()
Signed-off-by: Aurabindo Jayamohanan <mail@aurabindo.in>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: ralf@linux-mips.org
Cc: jhogan@kernel.org
Cc: alexios.zavras@intel.com
Cc: gregkh@linuxfoundation.org
Cc: armijn@tjaldur.nl
Cc: allison@lohutok.net
Cc: tglx@linutronix.de
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

IOC3 chips in SGI system are conntected to a bridge ASIC, which has
a 1-wire prom attached with part number information. This changeset
uses this information to create PCI subsystem information, which
the MFD driver uses for further platform device setup.
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-rtc@vger.kernel.org
Cc: linux-serial@vger.kernel.org

nvmem_device_find provides a way to search for nvmem devices with
the help of a match function simlair to bus_find_device.
Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-rtc@vger.kernel.org
Cc: linux-serial@vger.kernel.org

Adding leds and related triggers.
Signed-off-by: Alexandre GRIVEAUX <agriveaux@deutnet.info>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: robh+dt@kernel.org
Cc: mark.rutland@arm.com
Cc: ralf@linux-mips.org
Cc: jhogan@kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: devicetree@vger.kernel.org

Add IW8103 Wifi + bluetooth module to device tree and related power domain.
Signed-off-by: Alexandre GRIVEAUX <agriveaux@deutnet.info>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: robh+dt@kernel.org
Cc: mark.rutland@arm.com
Cc: ralf@linux-mips.org
Cc: jhogan@kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: devicetree@vger.kernel.org

Adding missing I2C nodes and some peripheral:
- PMU
- RTC
Signed-off-by: Alexandre GRIVEAUX <agriveaux@deutnet.info>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: robh+dt@kernel.org
Cc: mark.rutland@arm.com
Cc: ralf@linux-mips.org
Cc: jhogan@kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: devicetree@vger.kernel.org

Add the devicetree nodes for the I2C core of the JZ4780 SoC, disabled
by default.
Signed-off-by: Alexandre GRIVEAUX <agriveaux@deutnet.info>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: robh+dt@kernel.org
Cc: mark.rutland@arm.com
Cc: ralf@linux-mips.org
Cc: jhogan@kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: devicetree@vger.kernel.org

FORTIFY_SOURCE detects various overflows at compile and run time.
(6974f0c4 ("include/linux/string.h:
add the option of fortified string.h functions)

ARCH_HAS_FORTIFY_SOURCE means that the architecture can be built and
run with CONFIG_FORTIFY_SOURCE.

Since mips can be built and run with that flag,
select ARCH_HAS_FORTIFY_SOURCE as default.
Signed-off-by: Dmitry Korotin <dkorotin@wavecomp.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org

CSR IPI and legacy MMIO use the same infrastructure, but CSR IPI is
faster than legacy MMIO IPI. This patch enable CSR IPI if possible
(except for MailBox, because CSR IPI is too complicated for MailBox).
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: linux-mips@vger.kernel.org
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Cc: Huacai Chen <chenhuacai@gmail.com>

All Loongson-3 CPU family:

Code-name         Brand-name       PRId
Loongson-3A R1    Loongson-3A1000  0x6305
Loongson-3A R2    Loongson-3A2000  0x6308
Loongson-3A R2.1  Loongson-3A2000  0x630c
Loongson-3A R3    Loongson-3A3000  0x6309
Loongson-3A R3.1  Loongson-3A3000  0x630d
Loongson-3A R4    Loongson-3A4000  0xc000
Loongson-3B R1    Loongson-3B1000  0x6306
Loongson-3B R2    Loongson-3B1500  0x6307

Features of R4 revision of Loongson-3A:

  - All R2/R3 features, including SFB, V-Cache, FTLB, RIXI, DSP, etc.
  - Support variable ASID bits.
  - Support MSA and VZ extensions.
  - Support CPUCFG (CPU config) and CSR (Control and Status Register)
      extensions.
  - 64 entries of VTLB (classic TLB), 2048 entries of FTLB (8-way
      set-associative).

Now 64-bit Loongson processors has three types of PRID.IMP: 0x6300 is
the classic one so we call it PRID_IMP_LOONGSON_64C (e.g., Loongson-2E/
2F/3A1000/3B1000/3B1500/3A2000/3A3000), 0x6100 is for some processors
which has reduced capabilities so we call it PRID_IMP_LOONGSON_64R
(e.g., Loongson-2K), 0xc000 is supposed to cover all new processors in
general (e.g., Loongson-3A4000+) so we call it PRID_IMP_LOONGSON_64G.
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: linux-mips@vger.kernel.org
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Cc: Huacai Chen <chenhuacai@gmail.com>

Loongson-3A R4+ (Loongson-3A4000 and newer) has CPUCFG (CPU config) and
CSR (Control and Status Register) extensions. This patch add read/write
functionalities for them.
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: linux-mips@vger.kernel.org
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Cc: Huacai Chen <chenhuacai@gmail.com>

The memory initialization of SGI-IP27 is already half-way to support
SPARSEMEM. It only had free_bootmem_with_active_regions() left-overs
interfering with sparse_memory_present_with_active_regions().

Replace these calls with simpler memblocks_present() call in prom_meminit()
and adjust arch/mips/Kconfig to enable SPARSEMEM and SPARSEMEM_EXTREME for
SGI-IP27.
Co-developed-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

When Loongson3 LL/SC errata workarounds are enabled (ie.
CONFIG_CPU_LOONGSON3_WORKAROUNDS=y) run a tool to scan through the
compiled kernel & ensure that the workaround is applied correctly. That
is, ensure that:

  - Every LL or LLD instruction is preceded by a sync instruction.

  - Any branches from within an LL/SC loop to outside of that loop
    target a sync instruction.

Reasoning for these conditions can be found by reading the comment above
the definition of __SYNC_loongson3_war in arch/mips/include/asm/sync.h.

This tool will help ensure that we don't inadvertently introduce code
paths that miss the required workarounds.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

In ejtag_debug_handler() we must reload the address of
ejtag_debug_buffer_spinlock if an sc fails, since the address in k0 will
have been clobbered by the result of the sc instruction. In the case
where we simply load a non-zero value (ie. there's contention for the
lock) the address will not be clobbered & we can simply branch back to
repeat the load from memory without reloading the address into k0.

The primary motivation for this change is that it moves the target of
the bnez instruction to an instruction within the LL/SC loop (the LL
itself), which we know contains no other memory accesses & therefore
isn't affected by Loongson3 LL/SC errata.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

In ejtag_debug_handler we use LL & SC instructions to acquire & release
an open-coded spinlock. For Loongson3 systems affected by LL/SC errata
this requires that we insert a sync instruction prior to the LL in order
to ensure correct behavior of the LL/SC loop.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

Loongson3 systems with CONFIG_CPU_LOONGSON3_WORKAROUNDS enabled already
emit a full completion barrier as part of the inline assembly containing
LL/SC loops for atomic operations. As such the barrier emitted by
__smp_mb__before_atomic() is redundant, and we can remove it.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

The loongson_llsc_mb() macro is no longer used - instead barriers are
emitted as part of inline asm using the __SYNC() macro. Remove the
now-defunct loongson_llsc_mb() macro.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

Generate the sync instructions required to workaround Loongson3 LL/SC
errata within inline asm blocks, which feels a little safer than doing
it from C where strictly speaking the compiler would be well within its
rights to insert a memory access between the separate asm statements we
previously had, containing sync & ll instructions respectively.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

Generate the sync instructions required to workaround Loongson3 LL/SC
errata within inline asm blocks, which feels a little safer than doing
it from C where strictly speaking the compiler would be well within its
rights to insert a memory access between the separate asm statements we
previously had, containing sync & ll instructions respectively.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

When building a kernel configured to support Loongson3 LL/SC workarounds
(ie. CONFIG_CPU_LOONGSON3_WORKAROUNDS=y) the inline assembly in
__xchg_asm() & __cmpxchg_asm() already emits completion barriers, and as
such we don't need to emit extra barriers from the xchg() or cmpxchg()
macros. Add compile-time constant checks causing us to omit the
redundant memory barriers.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

Generate the sync instructions required to workaround Loongson3 LL/SC
errata within inline asm blocks, which feels a little safer than doing
it from C where strictly speaking the compiler would be well within its
rights to insert a memory access between the separate asm statements we
previously had, containing sync & ll instructions respectively.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

Use smp_mb__before_atomic() rather than smp_mb__before_llsc() in
test_and_set_bit(), test_and_clear_bit() & test_and_change_bit(). The
_atomic() versions make semantic sense in these cases, and will allow a
later patch to omit redundant barriers for Loongson3 systems that
already include a barrier within __test_bit_op().
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

Generate the sync instructions required to workaround Loongson3 LL/SC
errata within inline asm blocks, which feels a little safer than doing
it from C where strictly speaking the compiler would be well within its
rights to insert a memory access between the separate asm statements we
previously had, containing sync & ll instructions respectively.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

Rather than using custom SZLONG_LOG & SZLONG_MASK macros to shift & mask
a bit index to form word & bit offsets respectively, make use of the
standard BIT_WORD() & BITS_PER_LONG macros for the same purpose.

volatile is added to the definition of pointers to the long-sized word
we'll operate on, in order to prevent the compiler complaining that we
cast away the volatile qualifier of the addr argument. This should have
no effect on generated code, which in the LL/SC case is inline asm
anyway & in the non-LLSC case access is constrained by compiler barriers
provided by raw_local_irq_{save,restore}().
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

Introduce __bit_op() & __test_bit_op() macros which abstract away the
implementation of LL/SC loops. This cuts down on a lot of duplicate
boilerplate code, and also allows R10000_LLSC_WAR to be handled outside
of the individual bitop functions.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

The IRQ-disabling non-LLSC fallbacks for bitops on UP systems already
return a zero or one, so there's no need to perform another comparison
against zero. Move these comparisons into the LLSC paths to avoid the
redundant work.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

Use the BIT() macro in asm/bitops.h rather than open-coding its
equivalent.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org

The logical operations or & xor used in the test_and_set_bit_lock(),
test_and_clear_bit() & test_and_change_bit() functions currently force
the value 1<<bit to be placed in a register. If the bit is compile-time
constant & fits within the immediate field of an or/xor instruction (ie.
16 bits) then we can make use of the ori/xori instruction variants &
avoid the use of an extra register. Add the extra "i" constraints in
order to allow use of these immediate encodings.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-kernel@vger.kernel.org