linux-kernel - [PATCH v2 0/2] ARM: implement cacheinfo support (for v7/v7m)

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Message-Id: <20241014-armv7-cacheinfo-v2-0-38ab76d2b7fa@linaro.org>
Date: Mon, 14 Oct 2024 16:55:19 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Sudeep Holla <sudeep.holla@....com>, Ard Biesheuvel <ardb@...nel.org>, 
 Russell King <linux@...linux.org.uk>
Cc: linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Bjorn Andersson <andersson@...nel.org>, 
 Konrad Dybcio <konradybcio@...nel.org>, Arnd Bergmann <arnd@...db.de>
Subject: [PATCH v2 0/2] ARM: implement cacheinfo support (for v7/v7m)

Follow the ARM64 platform and implement simple cache information driver.
As it reads data from CTR (ARMv6+) and CLIDR (ARMv7+) registers, it is
limited to the ARMv7 / ARMv7M, providing simple fallback or just
returning -EOPNOTSUPP in case of older platforms.

In theory we should be able to skip CLIDR reading and assume that Dcache
and Icache (or unified L1 cache) always exist if CTR is supported and
returns sensible value. However I think this better be handled by the
maintainers of corresponding platforms.

Other than just providing information to the userspace, this patchset is
required in order to implement L2 cache driver (and in the end CPU
frequency scaling) on ARMv7-based Qualcomm devices.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
---
Changes in v2:
- Handle cores like ARM1176, which have cpu_architecture() ==
  CPU_ARCH_ARMv7 (because of VMSAv7 implementation), but no CLIDR
  register (because they are ARMv6) (Arnd).
- Link to v1: https://lore.kernel.org/r/20231231-armv7-cacheinfo-v1-0-9e8d440b59d9@linaro.org

---
Dmitry Baryshkov (2):
      ARM: add CLIDR accessor functions
      ARM: implement cacheinfo support

 arch/arm/Kconfig                 |   1 +
 arch/arm/include/asm/cache.h     |   6 ++
 arch/arm/include/asm/cachetype.h |  13 +++
 arch/arm/kernel/Makefile         |   1 +
 arch/arm/kernel/cacheinfo.c      | 173 +++++++++++++++++++++++++++++++++++++++
 include/linux/cacheinfo.h        |   2 +-
 6 files changed, 195 insertions(+), 1 deletion(-)
---
base-commit: 7f773fd61baa9b136faa5c4e6555aa64c758d07c
change-id: 20231231-armv7-cacheinfo-9fa533ae371e

Best regards,
-- 
Dmitry Baryshkov <dmitry.baryshkov@...aro.org>