Kernel/USB: Add support for async & interrupt transfers

Add support for async transfers by using a separate kernel task to poll
a list of active async transfers on a set time interval, and invoke
their user-provided callback function when they are complete. Also add
support for the interrupt class of transfers, building off of this async
functionality.

1 files changed, 5 insertions, 2 deletions

diff --git a/Kernel/Bus/USB/USBTransfer.h b/Kernel/Bus/USB/USBTransfer.h
index 5923542d6c..c506650d9e 100644
--- a/Kernel/Bus/USB/USBTransfer.h
+++ b/Kernel/Bus/USB/USBTransfer.h
@@ -20,7 +20,7 @@ namespace Kernel::USB {
 
 class Transfer final : public AtomicRefCounted<Transfer> {
 public:
-    static ErrorOr<NonnullLockRefPtr<Transfer>> try_create(Pipe&, u16 length, Memory::Region& dma_buffer);
+    static ErrorOr<NonnullLockRefPtr<Transfer>> create(Pipe&, u16 length, Memory::Region& dma_buffer, USBAsyncCallback callback = nullptr);
 
     Transfer() = delete;
     ~Transfer();
@@ -41,14 +41,17 @@ public:
     bool complete() const { return m_complete; }
     bool error_occurred() const { return m_error_occurred; }
 
+    void invoke_async_callback();
+
 private:
-    Transfer(Pipe& pipe, u16 len, Memory::Region& dma_buffer);
+    Transfer(Pipe& pipe, u16 len, Memory::Region& dma_buffer, USBAsyncCallback callback);
     Pipe& m_pipe;                    // Pipe that initiated this transfer
     Memory::Region& m_dma_buffer;    // DMA buffer
     USBRequestData m_request;        // USB request
     u16 m_transfer_data_size { 0 };  // Size of the transfer's data stage
     bool m_complete { false };       // Has this transfer been completed?
     bool m_error_occurred { false }; // Did an error occur during this transfer?
+    USBAsyncCallback m_callback { nullptr };
 };
 
 }