[RFC v2 PATCH 0/2] Introduce irqchip and VIRQ layer prototypes

[Raymond Mao]

From: Raymond Mao <raymond.mao at riscstar.com>

This RFC introduces irqchip abstraction and VIRQ layers for APLIC
wired interrupt support in OpenSBI.

In the current OpenSBI implementation, APLIC support primarily focuses
on initialization and delegation, while external interrupt handling
for wired interrupts remains largely stubbed. As a result:
- There is no generic mechanism for OpenSBI drivers or platforms to
  register handlers for wired interrupt lines.
- Interrupt dispatch remains tightly coupled to specific irqchip
  implementations.

The goal is to introduce a small, extensible abstraction for irqchip
to hide the HW details and provide abstract operations like interrupt
provider registration, claim/complete/mask/unmask operations.

VIRQ (Virtual IRQ) layer is on top of INTC, providing IRQ state
management via per-(domain,hart) IRQ pending queue, with courier
dispatching and interface to enqueue/pop/complete an IRQ and map hwirq
to virtual IRQ number to avoid exposure of hwirq.

Raymond Mao (2):
  lib: sbi: introduce abstraction for wired interrupt handling
  lib: sbi: Add VIRQ interrupt abstraction

Changes in v2:
- Move INTC to irqchip
- Move hwirq mapping to VIRQ
- Remove get_caps and pass in max_src during provider registration
- All irqchip interface use hwirq as parameter

 include/sbi/sbi_irqchip.h | 52 ++++++++++++++++++++++
 include/sbi/sbi_virq.h    | 90 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 142 insertions(+)
 create mode 100644 include/sbi/sbi_virq.h

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