kernel/ATA: Handle drive IRQs in compatibility mode

kernel/src/arch/x86_64/disk/ATA.cpp

@@ -5,6 +5,11 @@
 
 SharedPtr<ATA::Controller> g_controller;
 
+static void irq_handler(Registers* regs, void* ctx)
+{
+    ((ATA::Channel*)ctx)->irq_handler(regs);
+}
+
 namespace ATA
 {
     Result<void> Controller::scan()
@@ -85,6 +90,22 @@ namespace ATA
         m_current_drive = drive;
     }
 
+    void Channel::irq_handler(Registers*)
+    {
+        // FIXME: Read the Busmaster register to make sure the IRQ is for this channel.
+
+        // FIXME: Also read it in case there was a DMA read error.
+
+        m_thread->wake_up();
+    }
+
+    void Channel::wait_for_irq()
+    {
+        m_thread = Scheduler::current();
+
+        kernel_wait_for_event();
+    }
+
     bool Channel::initialize()
     {
         int offset = m_channel_index ? 2 : 0;
@@ -113,6 +134,14 @@ namespace ATA
         else
             m_interrupt_line = m_channel_index ? 15 : 14;
 
+        bool ok = CPU::register_interrupt(m_interrupt_line, ::irq_handler, this);
+        if (!ok)
+        {
+            kerrorln("ata: Failed to register IRQ handler for ATA channel %d (IRQ %d)", m_channel_index,
+                     m_interrupt_line);
+            return false;
+        }
+
         for (u8 drive = 0; drive < 2; drive++)
         {
             ScopedKMutexLock<100> lock(m_lock);

kernel/src/arch/x86_64/disk/ATA.h

@@ -52,6 +52,9 @@ namespace ATA
 
         void delay_400ns();
 
+        void wait_for_irq();
+        void irq_handler(Registers*);
+
         void select(u8 drive);
 
         bool initialize();
@@ -65,6 +68,8 @@ namespace ATA
 
         KMutex<100> m_lock {};
 
+        Thread* m_thread;
+
         u16 m_io_base;
         u16 m_control_base;