feat: support for USB mass storage devices, hotplugging

kernel/src/Drivers/USB/Xhci.hpp

@@ -238,6 +238,7 @@ namespace Drivers::USB::Xhci {
         uint8_t  InterfaceClass;
         uint8_t  InterfaceSubClass;
         uint8_t  InterfaceProtocol;
+        uint8_t  InterfaceNumber;
         uint8_t  DeviceClass;         // bDeviceClass from device descriptor
 
         // Interrupt IN endpoint
@@ -295,7 +296,7 @@ namespace Drivers::USB::Xhci {
     bool IsInitialized();
     bool HasDeferredWork();
 
-    // Deferred hot-plug processing (call from timer tick, not interrupt context)
+    // Deferred hot-plug processing (call outside interrupt context)
     void ProcessDeferredWork();
 
     // Send a command on the command ring, wait for completion.
@@ -318,6 +319,11 @@ namespace Drivers::USB::Xhci {
     void QueueBulkInTransfer(uint8_t slotId, uint8_t* data, uint64_t dataPhys, uint32_t length);
     void QueueBulkOutTransfer(uint8_t slotId, uint8_t* data, uint64_t dataPhys, uint32_t length);
 
+    // Queue a bulk transfer and wait for its completion. Used by storage-style
+    // class drivers that need command/response ordering on bulk pipes.
+    uint32_t BulkTransfer(uint8_t slotId, bool dirIn, void* data, uint64_t dataPhys,
+                          uint32_t length, uint32_t* actualLength = nullptr);
+
     // Register a transfer callback for a specific slot (used by non-HID class drivers)
     void RegisterTransferCallback(uint8_t slotId, TransferCallback cb);