Kernel/USB: Move the USB components as a subfolder to the Bus directory

Author: https://github.com/supercomputer7
Commit: 5073bf8e75
Pull-request: https://github.com/SerenityOS/serenity/pull/8241
Issue: https://github.com/SerenityOS/serenity/issues/6948
Issue: https://github.com/SerenityOS/serenity/issues/7445
Issue: https://github.com/SerenityOS/serenity/issues/8331
Reviewed-by: https://github.com/IdanHo
Reviewed-by: https://github.com/awesomekling

Kernel/Bus/USB/USBTransfer.cpp

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2021, Jesse Buhagiar <jooster669@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/Bus/USB/USBTransfer.h>
+#include <Kernel/VM/MemoryManager.h>
+
+namespace Kernel::USB {
+
+RefPtr<Transfer> Transfer::try_create(Pipe& pipe, u16 len)
+{
+    auto vmobject = ContiguousVMObject::create_with_size(PAGE_SIZE);
+    if (!vmobject)
+        return nullptr;
+
+    return AK::try_create<Transfer>(pipe, len, *vmobject);
+}
+
+Transfer::Transfer(Pipe& pipe, u16 len, ContiguousVMObject& vmobject)
+    : m_pipe(pipe)
+    , m_transfer_data_size(len)
+{
+    // Initialize data buffer for transfer
+    // This will definitely need to be refactored in the future, I doubt this will scale well...
+    m_data_buffer = MemoryManager::the().allocate_kernel_region_with_vmobject(vmobject, PAGE_SIZE, "USB Transfer Buffer", Region::Access::Read | Region::Access::Write);
+}
+
+Transfer::~Transfer()
+{
+}
+
+void Transfer::set_setup_packet(const USBRequestData& request)
+{
+    // Kind of a nasty hack... Because the kernel isn't in the business
+    // of handing out physical pointers that we can directly write to,
+    // we set the address of the setup packet to be the first 8 bytes of
+    // the data buffer, which we then set to the physical address.
+    auto* request_data = reinterpret_cast<USBRequestData*>(buffer().as_ptr());
+
+    request_data->request_type = request.request_type;
+    request_data->request = request.request;
+    request_data->value = request.value;
+    request_data->index = request.index;
+    request_data->length = request.length;
+
+    m_request = request;
+}
+
+}