[PATCH v2 0/9] Linux RISC-V AIA Support

[Anup Patel]

The RISC-V AIA specification is now frozen as-per the RISC-V international
process. The latest frozen specifcation can be found at:
https://github.com/riscv/riscv-aia/releases/download/1.0-RC1/riscv-interrupts-1.0-RC1.pdf

At a high-level, the AIA specification adds three things:
1) AIA CSRs
   - Improved local interrupt support
2) Incoming Message Signaled Interrupt Controller (IMSIC)
   - Per-HART MSI controller
   - Support MSI virtualization
   - Support IPI along with virtualization
3) Advanced Platform-Level Interrupt Controller (APLIC)
   - Wired interrupt controller
   - In MSI-mode, converts wired interrupt into MSIs (i.e. MSI generator)
   - In Direct-mode, injects external interrupts directly into HARTs

For an overview of the AIA specification, refer the recent AIA virtualization
talk at KVM Forum 2022:
https://static.sched.com/hosted_files/kvmforum2022/a1/AIA_Virtualization_in_KVM_RISCV_final.pdf
https://www.youtube.com/watch?v=r071dL8Z0yo

This series adds required Linux irqchip drivers for AIA and it depends on
the recent "RISC-V IPI Improvements".
(Refer, https://lore.kernel.org/lkml/20221101143400.690000-1-apatel@xxxxxxxxxxxxxxxx/t/)

To test this series, use QEMU v7.2 (or higher) and OpenSBI v1.2 (or higher).

These patches can also be found in the riscv_aia_v2 branch at:
https://github.com/avpatel/linux.git

Changes since v1:
 - Rebased on Linux-6.2-rc2
 - Addressed comments on IMSIC DT bindings for PATCH4
 - Use raw_spin_lock_irqsave() on ids_lock for PATCH5
 - Improved MMIO alignment checks in PATCH5 to allow MMIO regions
   with holes.
 - Addressed comments on APLIC DT bindings for PATCH6
 - Fixed warning splat in aplic_msi_write_msg() caused by
   zeroed MSI message in PATCH7
 - Dropped DT property riscv,slow-ipi instead will have module
   parameter in future.

Anup Patel (9):
  RISC-V: Add AIA related CSR defines
  RISC-V: Detect AIA CSRs from ISA string
  irqchip/riscv-intc: Add support for RISC-V AIA
  dt-bindings: interrupt-controller: Add RISC-V incoming MSI controller
  irqchip: Add RISC-V incoming MSI controller driver
  dt-bindings: interrupt-controller: Add RISC-V advanced PLIC
  irqchip: Add RISC-V advanced PLIC driver
  RISC-V: Select APLIC and IMSIC drivers
  MAINTAINERS: Add entry for RISC-V AIA drivers

 .../interrupt-controller/riscv,aplic.yaml     |  159 +++
 .../interrupt-controller/riscv,imsics.yaml    |  168 +++
 MAINTAINERS                                   |   12 +
 arch/riscv/Kconfig                            |    2 +
 arch/riscv/include/asm/csr.h                  |   92 ++
 arch/riscv/include/asm/hwcap.h                |    8 +
 arch/riscv/kernel/cpu.c                       |    2 +
 arch/riscv/kernel/cpufeature.c                |    2 +
 drivers/irqchip/Kconfig                       |   20 +-
 drivers/irqchip/Makefile                      |    2 +
 drivers/irqchip/irq-riscv-aplic.c             |  670 ++++++++++
 drivers/irqchip/irq-riscv-imsic.c             | 1174 +++++++++++++++++
 drivers/irqchip/irq-riscv-intc.c              |   37 +-
 include/linux/irqchip/riscv-aplic.h           |  117 ++
 include/linux/irqchip/riscv-imsic.h           |   92 ++
 15 files changed, 2550 insertions(+), 7 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/interrupt-controller/riscv,aplic.yaml
 create mode 100644 Documentation/devicetree/bindings/interrupt-controller/riscv,imsics.yaml
 create mode 100644 drivers/irqchip/irq-riscv-aplic.c
 create mode 100644 drivers/irqchip/irq-riscv-imsic.c
 create mode 100644 include/linux/irqchip/riscv-aplic.h
 create mode 100644 include/linux/irqchip/riscv-imsic.h

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2.34.1