feat: implement IRQ Manager with dynamic interrupt dispatch and atomic handler registration

1 files changed, 84 insertions, 0 deletions

diff --git a/na/include/lume/irq.h b/na/include/lume/irq.h
new file mode 100644
index 0000000..f5f34e4
--- /dev/null
+++ b/na/include/lume/irq.h
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (C) 2026 Richard Qin */
+
+#pragma once
+
+/*
+ * IRQ Manager — Dynamic Interrupt Dispatch
+ *
+ * Drivers register ISR callbacks at init time via register_handler().
+ * The MI trap layer calls dispatch() when an external interrupt arrives.
+ * dispatch() runs in interrupt context — handlers must be short and
+ * non-blocking.
+ *
+ * Lock contract:
+ *   - lock_ protects register/unregister (cold path).
+ *   - dispatch() is lock-free: handler pointers are published with RELEASE
+ *     semantics and read with ACQUIRE in dispatch().
+ *   - Handlers must not acquire VmSpace::lock or sleep.
+ *
+ * Reference: docs/specs/trap.md §3.3
+ */
+
+#include <lume/atomic.h>
+#include <lume/types.h>
+
+/* IRQ handler callback signature */
+using IrqHandler = void (*)(uint32 irq, void *arg);
+
+/* Abstract Interrupt Controller Interface */
+struct IrqChip {
+  const char* name;
+  uint32 (*claim)();
+  void (*complete)(uint32 irq);
+  void (*init_ap)();
+  void (*enable)(uint32 irq);
+  void (*disable)(uint32 irq);
+  void (*set_priority)(uint32 irq, uint32 priority);
+};
+
+class IrqManager {
+public:
+  void init();
+
+  /* Register an ISR for the given IRQ number.
+   * Returns 0 on success, -EINVAL if irq out of range, -EBUSY if already
+   * registered. */
+  int register_handler(uint32 irq, IrqHandler handler, void *arg);
+
+  /* Unregister the ISR for the given IRQ number. */
+  void unregister_handler(uint32 irq);
+
+  /* Dispatch an interrupt to the registered handler.
+   * Called from MI trap layer in interrupt context. Lock-free. */
+  void dispatch(uint32 irq);
+
+  /* Set the active interrupt controller chip */
+  void set_chip(const IrqChip* chip);
+  const IrqChip* get_chip() const { return chip_; }
+
+  /* Architecture-independent claim and complete for the active IRQ chip */
+  uint32 claim() const;
+  void complete(uint32 irq) const;
+  void init_ap() const;
+  void enable(uint32 irq) const;
+  void disable(uint32 irq) const;
+  void set_priority(uint32 irq, uint32 priority) const;
+
+  /* Check if a handler is registered for the given IRQ. */
+  bool has_handler(uint32 irq) const;
+
+  static constexpr uint32 kMaxIrqs = 64;
+
+private:
+  struct IrqEntry {
+    lume::atomic<uint64> handler_ptr; // Stored as uint64 for atomic access
+    void *arg = nullptr;
+  };
+
+  const IrqChip* chip_ = nullptr;
+  IrqEntry entries_[kMaxIrqs];
+};
+
+/* Global IRQ manager singleton */
+extern IrqManager g_irq_manager;