[v5,0/4] mips: bmips: improve handling of RAC and CBR addr

Message

Christian Marangi May 11, 2024, 1:03 p.m. UTC

Hi,

this simple series improve handling of RAC and CBR address and try to
upstream these simple patch we have in OpenWrt for a while.

The first patch fix a straight kernel panic where some Bootloader might
enable RAC but misconfigure the CBR address. The current logic only
check if RAC is enabled but doesn't verify if the CBR address is usable.

The DMA sync function cause a kernel panic for invalid write. (as CBR is
0 or something like 0xa)

The second is preparation for making the CBR address configurable in DT.
Since this address doesn't change, we can cache it and reference it with
a local variable instead of calling the register to access the value.

The 4th patch make it configurable with 2 DT property, one to actually
set the reg and the other to force set it.

The first property is used when CBR is set to 0. The second property is
to force it if the Bootloader sets it to something wrong.

If the CBR value is not 0 and is not forced with the second property a
WARN is printed and the DT value is ignored.

The 4th patch enable RAC on BMIPS4350.

These has been tested on BCM6358 (HG556a) and BCM6368 (VH4032N) and
reported correct functionality.

Changes v5:
- Add Ack tags
- Improve DT descriptions as suggested by Conor
Changes v4:
- Fix compilation error with legacy brcm target
- Improve property description in DT commit (give
  CBR meaning and drop reference to linux functions)
- Use only __read_mostly as we can't add variable to
  multiple data sections
- In patch 4 use local cbr variable instead of global
  one.
Changes v3:
- Drop broken-cbr-reg property
- Fix anyOf+const with enum
Changes v2:
- Prefix brcm vendor in the added property
- Drop last patch (cpu switch from DMA sync)
- Validate CBR addr from DT to be outside DRAM
- Reduce indentation in DT CBR check
- Reduce delta and use local variable for CBR where possible
- Fix and improve typo and spelling mistake
- Use 0xf instead of 0xa for BCM6358 RAC enable

Christian Marangi (3):
  mips: bmips: rework and cache CBR addr handling
  dt-bindings: mips: brcm: Document brcm,bmips-cbr-reg property
  mips: bmips: setup: make CBR address configurable

Daniel González Cabanelas (1):
  mips: bmips: enable RAC on BMIPS4350

 .../devicetree/bindings/mips/brcm/soc.yaml    | 24 ++++++++++++++++
 arch/mips/bcm47xx/prom.c                      |  2 ++
 arch/mips/bcm63xx/prom.c                      |  3 ++
 arch/mips/bmips/dma.c                         |  2 +-
 arch/mips/bmips/setup.c                       | 28 +++++++++++++++++--
 arch/mips/include/asm/bmips.h                 |  1 +
 arch/mips/kernel/smp-bmips.c                  | 27 ++++++++++++++++--
 7 files changed, 82 insertions(+), 5 deletions(-)