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[0/4] sparc32: Use CAS for atomic support

Message ID 20231229200604.GA4033529@ravnborg.org
Headers show
Series sparc32: Use CAS for atomic support | expand

Message

Sam Ravnborg Dec. 29, 2023, 8:06 p.m. UTC 
With sparc limited to leon3 the next step was to address the atomic
support which this patch set does.

Gaisler already had an implementation in their kernel patch stack, that
co-existed with sparc v8 without CAS support.

As the sparc v8 without CAS is no longer supported this patch set takes
a different approach. Using the current best practices the atomic support
is implemented in three steps.

The cmpxchg is updated to use casa/swap.
The atomic bitops are implemented in their own file and uses a minimal of
inline assembly.
The atomic operations are implemented based on the template found in
asm-generic.

Some notes:
- The code uses __always_inlin almost everywhere, where inline could be
  enough. Not sure what is best here.
- The new (and replaced) files uses the SPDX tag: GPL-2.0
  No sure if this is best practice today, I am happy to change the
  license.
- Build tested and booted using qemu.

The patches are on top of the sun4m and sun4d sunset patches.

Review feedback appreciated!

	Sam

---
Sam Ravnborg (4):
      sparc32: Add support for specifying -mcpu
      sparc32: Add cmpxchg support using CAS
      sparc32: Add atomic bitops support using CAS
      sparc32: Add atomic support using CAS
 
 arch/sparc/Kconfig                        |  24 +++++++++++
 arch/sparc/Makefile                       |  13 +++---
 arch/sparc/include/asm/atomic_32.h        | 151 ++++++++++++++++++++++++++++++++++++++++++++-----------------------
 arch/sparc/include/asm/bitops/atomic_32.h | 124 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 arch/sparc/include/asm/bitops_32.h        |  71 +-------------------------------
 arch/sparc/include/asm/cmpxchg_32.h       |  72 ++++++++++++++++++--------------
 arch/sparc/lib/Makefile                   |   2 +-
 arch/sparc/lib/atomic32.c                 | 202 ------------------------------------------------------------------------------------------
 8 files changed, 296 insertions(+), 363 deletions(-)