From 0a6815b7143a8ffd0e09777b5fbd12098d8884c2 Mon Sep 17 00:00:00 2001
From: Richard Qin <richard.qin.x@gmail.com>
Date: Wed, 31 Dec 2025 19:00:20 +0800
Subject: dev: PILC implementation

---
 src/drivers/plic.cc        | 60 ++++++++++++++++++++++++++++++++++++++++++++++
 src/kernel/trap/handler.cc | 17 +++++++++++++
 2 files changed, 77 insertions(+)
 create mode 100644 src/drivers/plic.cc

(limited to 'src')

diff --git a/src/drivers/plic.cc b/src/drivers/plic.cc
new file mode 100644
index 0000000..a13537c
--- /dev/null
+++ b/src/drivers/plic.cc
@@ -0,0 +1,60 @@
+#include "common/types.h"
+#include "kernel/riscv.h"
+#include "drivers/plic.h"
+
+// QEMU Virt PLIC address constants
+constexpr uint64 PLIC_BASE = 0x0c000000L;
+constexpr uint64 PLIC_PRIORITY = PLIC_BASE + 0x0;
+constexpr uint64 PLIC_PENDING = PLIC_BASE + 0x1000;
+
+// S-Mode interrupt enable register: each Hart occupies 0x100 bytes
+// Context 1 is Hart 0 S-Mode, Context 3 is Hart 1 S-Mode...
+inline uint64 PLIC_SENABLE(int hart)
+{
+    return PLIC_BASE + 0x2080 + static_cast<uint64>(hart) * 0x100;
+}
+
+// S-Mode priority threshold and claim register: 0x2000 bytes per Hart
+inline uint64 PLIC_STHRESHOLD(int hart)
+{
+    return PLIC_BASE + 0x201000 + static_cast<uint64>(hart) * 0x2000;
+}
+
+inline uint64 PLIC_SCLAIM(int hart)
+{
+    return PLIC_BASE + 0x201004 + static_cast<uint64>(hart) * 0x2000;
+}
+
+namespace PILC
+{
+    void init()
+    {
+        *reinterpret_cast<uint32 *>(PLIC_PRIORITY + 10 * 4) = 1; // UART
+        *reinterpret_cast<uint32 *>(PLIC_PRIORITY + 1 * 4) = 1; // VirtIO 0
+    }
+
+    void inithart()
+    {
+        int hart = static_cast<int>(r_tp()); // 获取当前 hartid
+
+        // Enable UART and VirtIO interrupts for the current Hart's S-Mode
+        // Set bit 10 and bit 1 in the register bitmap
+        *reinterpret_cast<uint32 *>(PLIC_SENABLE(hart)) = (1 << 10) | (1 << 1);
+
+        // Set the current Hart's S-Mode priority threshold to 0
+        // Only interrupts with a priority higher than this threshold will be delivered
+        *reinterpret_cast<uint32 *>(PLIC_STHRESHOLD(hart)) = 0;
+    }
+
+    int claim()
+    {
+        int hart = static_cast<int>(r_tp());
+        return *reinterpret_cast<uint32 *>(PLIC_SCLAIM(hart));
+    }
+
+    void complete(int irq)
+    {
+        int hart = static_cast<int>(r_tp());
+        *reinterpret_cast<uint32 *>(PLIC_SCLAIM(hart)) = static_cast<uint32>(irq);
+    }
+} // namespace PILC
diff --git a/src/kernel/trap/handler.cc b/src/kernel/trap/handler.cc
index f7f8725..d7f78de 100644
--- a/src/kernel/trap/handler.cc
+++ b/src/kernel/trap/handler.cc
@@ -5,6 +5,7 @@
 #include "kernel/syscall.h"
 #include "kernel/mm.h"
 #include "kernel/timer.h"
+#include "drivers/plic.h"
 #include "lib/string.h"
 
 
@@ -58,6 +59,22 @@ namespace Trap
         if (is_interrupt && code == 9)
         {
             // Supervisor External Interrupt (IRQ 9)
+            int irq = PILC::claim();
+
+            if (irq == 10)
+            {
+                // uart_intr();
+            }
+            else if (irq >= 1 && irq <= 8)
+            {
+                // virtio_disk_intr();
+            }
+
+            if (irq > 0)
+            {
+                PILC::complete(irq);
+            }
+
             return 1;
         }
         else if (is_interrupt && code == 5)
-- 
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