riscv: Add Ssqosid and initial CBQRI resctrl support

This series adds initial RISC-V QoS support: the Ssqosid extension [1]
(srmcfg CSR), the CBQRI controller interface [2] integrated with resctrl
[3], and DT-based platform driver for cache controllers. It has been
tested both on the Tenstorrent Ascalon Shared Cache controller as well
as a Qemu implementation [4].

Note that this series only implements support for resctrl CAT using
CBQRI capacity allocation control. cc_block_mask maps onto resctrl's
existing cbm schema. However, cc_cunits is not supported as there is no
existing equivalent for capacity units in the resctrl schemata.

I had previously been iterating on an RFC series [5] that did a full
implementation of CBQRI including capacity monitoring, bandwidth
allocation and monitoring, as well as a parser for the ACPI RQSC table.
The bandwidth controls for CBQRI do not fit well into resctrl's existing
throttle based MB schemata. I believe that the path forward is
Reinette's generic schema description proof of concept [6] but that will
take time to mature. My plan is to rebase the full support of CBQRI on
to the generic schema once it is ready.

[1] https://github.com/riscv/riscv-ssqosid/releases/tag/v1.0
[2] https://github.com/riscv-non-isa/riscv-cbqri/releases/tag...
[3] https://docs.kernel.org/filesystems/resctrl.html
[4] https://github.com/riscv-non-isa/riscv-rqsc/blob/main/src/
[5] https://lore.kernel.org/linux-riscv/20260601-ssqosid-cbqr...
[6] https://lore.kernel.org/all/aab804b9-e8b5-40ad-a85b-af703...

---
Drew Fustini (8):
      dt-bindings: riscv: Add Ssqosid extension description
      riscv: Detect the Ssqosid extension
      riscv: Add support for srmcfg CSR from Ssqosid extension
      riscv_cbqri: Add capacity controller probe and allocation device ops
      riscv_cbqri: resctrl: Add cache allocation via capacity block mask
      riscv: Enable resctrl filesystem for Ssqosid
      dt-bindings: riscv: Add generic CBQRI controller binding
      riscv_cbqri: Add CBQRI cache capacity-allocation platform driver

 .../devicetree/bindings/riscv/extensions.yaml      |   6 +
 .../devicetree/bindings/riscv/riscv,cbqri.yaml     | 109 +++
 MAINTAINERS                                        |  15 +
 arch/riscv/Kconfig                                 |  20 +
 arch/riscv/include/asm/csr.h                       |   5 +
 arch/riscv/include/asm/hwcap.h                     |   1 +
 arch/riscv/include/asm/processor.h                 |   3 +
 arch/riscv/include/asm/qos.h                       |  86 +++
 arch/riscv/include/asm/resctrl.h                   | 152 ++++
 arch/riscv/include/asm/switch_to.h                 |   3 +
 arch/riscv/kernel/Makefile                         |   2 +
 arch/riscv/kernel/cpufeature.c                     |   1 +
 arch/riscv/kernel/qos.c                            |  91 +++
 drivers/resctrl/Kconfig                            |  44 ++
 drivers/resctrl/Makefile                           |   7 +
 drivers/resctrl/cbqri_capacity.c                   | 132 ++++
 drivers/resctrl/cbqri_devices.c                    | 511 ++++++++++++++
 drivers/resctrl/cbqri_internal.h                   | 110 +++
 drivers/resctrl/cbqri_resctrl.c                    | 774 +++++++++++++++++++++
 include/linux/riscv_cbqri.h                        |  47 ++
 20 files changed, 2119 insertions(+)
---
base-commit: 4fa3f5fabb30bf00d7475d5a33459ea83d639bf9
change-id: 20260610-dfustini-atl-sc-cbqri-dt-410c8e2711dd

Best regards,
--  
Drew Fustini <fustini@kernel.org>