[PATCH 0/9] T-Head: Allow read access to th.mxstatus CSR

[Christoph Müllner]

On T-Head C9xx harts, the th.mxstatus CSR provides valuable information
about the available vendor extensions. As this CSR is only accessible in
M-mode, we need to provide a mechanism for other modes to access this
information. This patchset solves this by extending the existing
platform abstraction such that platforms (or platform overrides)
can provide a CSR read/write handler.

A CSR read-handler for th.mxstatus is then added that is utilized by
the Allwinner D1, the T-Head TH1520, and the Sophgo SG2042.
Further, a generic mvendorid-based platform override is added that also
enables the CSR read-handler for th.mxstatus (needed for QEMU).

The CSR is documented here:
  https://github.com/T-head-Semi/thead-extension-spec/pull/45

For QEMU this patch depends on
  https://lists.gnu.org/archive/html/qemu-devel/2024-03/msg06368.html

Christoph Müllner (9):
  sbi_platform: Add mechanism to handle CSR reads/writes in platform
  platform: generic: Add mechanism to handle CSR reads/writes in
    overrides
  lib: sbi_emulate_csr: Utilize platform hooks for unknown CSRs
  platform: generic: thead: Add CSR read handler for T-Head C9xx
  {allwinner/sun20i-d1,sophgo/sg2042,thead-generic}: Enable T-Head CSR
    read access
  platform: thead: Rename thead-generic to thead-th1520
  platform: generic: Add mechanism to match via mvendorid
  platform: generic: thead: Add definition of T-Head's vendor ID
  platform: generic: Add generic T-Head override

 include/sbi/sbi_platform.h                    | 48 +++++++++++++++
 lib/sbi/sbi_emulate_csr.c                     |  8 ++-
 platform/generic/Kconfig                      | 12 +++-
 platform/generic/allwinner/sun20i-d1.c        |  2 +
 platform/generic/configs/defconfig            |  3 +-
 platform/generic/include/platform_override.h  |  5 ++
 platform/generic/include/thead/c9xx_csr.h     | 16 +++++
 .../generic/include/thead/c9xx_encoding.h     |  2 +
 platform/generic/platform.c                   | 58 ++++++++++++++++++-
 platform/generic/sophgo/sg2042.c              |  2 +
 platform/generic/thead/Kconfig                |  4 ++
 platform/generic/thead/objects.mk             |  9 ++-
 platform/generic/thead/thead-generic.c        | 42 +++-----------
 platform/generic/thead/thead-th1520.c         | 55 ++++++++++++++++++
 platform/generic/thead/thead_c9xx_csr.c       | 30 ++++++++++
 15 files changed, 252 insertions(+), 44 deletions(-)
 create mode 100644 platform/generic/include/thead/c9xx_csr.h
 create mode 100644 platform/generic/thead/thead-th1520.c
 create mode 100644 platform/generic/thead/thead_c9xx_csr.c

-- 
2.44.0