Determine XHCI controller addresses

src/hulk/pci.d

@@ -60,6 +60,8 @@ struct Pci
             {
                 map_memory_regions();
             }
+
+            spawn_device_instance();
         }
 
         private void map_memory_regions()

src/hulk/usb/xhci.d

@@ -10,6 +10,7 @@ module hulk.usb.xhci;
 
 import hulk.pci;
 import hulk.hurl.a1;
+import hulk.klog;
 
 struct XHCI
 {
@@ -74,8 +75,22 @@ struct XHCI
     }
     static assert(DoorbellRegister.sizeof == 4u);
 
+    private CapabilityRegisters * m_capability_registers;
+    private OperationalRegisters * m_operational_registers;
+    private PortRegisters * m_port_registers;
+    private RuntimeRegisters * m_runtime_registers;
+    private DoorbellRegister * m_doorbell_registers;
+
     void initialize(Pci.Device * pci_device)
     {
+        void * base_address = pci_device.memory_ranges[0].address;
+        Klog.writefln("Found XHCI controller at address %x", base_address);
+        m_capability_registers = cast(CapabilityRegisters *)base_address;
+        m_operational_registers = cast(OperationalRegisters *)(base_address + m_capability_registers.capability_length);
+        /* TODO: confirm if 0x400 offset is from m_operation_registers or base_address. */
+        m_port_registers = cast(PortRegisters *)(cast(void *)m_operational_registers + 0x400);
+        m_runtime_registers = cast(RuntimeRegisters *)(base_address + m_capability_registers.rts_offset);
+        m_doorbell_registers = cast(DoorbellRegister *)(base_address + m_capability_registers.doorbell_offset);
     }
 
     static void build(Pci.Device * pci_device)