Kernel: Move the Storage directory to be a new directory under Devices

The Storage subsystem, like the Audio and HID subsystems, exposes Unix
device files (for example, in the /dev directory). To ensure consistency
across the repository, we should make the Storage subsystem to reside in
the Kernel/Devices directory like the two other mentioned subsystems.

Kernel/Devices/Storage/NVMe/NVMeController.h

@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2021, Pankaj R <pankydev8@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/OwnPtr.h>
+#include <AK/Time.h>
+#include <AK/Tuple.h>
+#include <AK/Types.h>
+#include <Kernel/Bus/PCI/Device.h>
+#include <Kernel/Devices/Storage/NVMe/NVMeDefinitions.h>
+#include <Kernel/Devices/Storage/NVMe/NVMeNameSpace.h>
+#include <Kernel/Devices/Storage/NVMe/NVMeQueue.h>
+#include <Kernel/Devices/Storage/StorageController.h>
+#include <Kernel/Library/LockRefPtr.h>
+#include <Kernel/Library/NonnullLockRefPtr.h>
+#include <Kernel/Locking/Spinlock.h>
+#include <Kernel/Memory/TypedMapping.h>
+
+namespace Kernel {
+
+class NVMeController : public PCI::Device
+    , public StorageController {
+public:
+    static ErrorOr<NonnullRefPtr<NVMeController>> try_initialize(PCI::DeviceIdentifier const&, bool is_queue_polled);
+    ErrorOr<void> initialize(bool is_queue_polled);
+    LockRefPtr<StorageDevice> device(u32 index) const override;
+    size_t devices_count() const override;
+    virtual StringView device_name() const override { return "NVMeController"sv; }
+
+protected:
+    ErrorOr<void> reset() override;
+    ErrorOr<void> shutdown() override;
+    void complete_current_request(AsyncDeviceRequest::RequestResult result) override;
+
+public:
+    ErrorOr<void> reset_controller();
+    ErrorOr<void> start_controller();
+    u32 get_admin_q_dept();
+
+    u16 submit_admin_command(NVMeSubmission& sub, bool sync = false)
+    {
+        // First queue is always the admin queue
+        if (sync) {
+            return m_admin_queue->submit_sync_sqe(sub);
+        }
+        m_admin_queue->submit_sqe(sub);
+        return 0;
+    }
+
+    bool is_admin_queue_ready() { return m_admin_queue_ready; };
+    void set_admin_queue_ready_flag() { m_admin_queue_ready = true; };
+
+private:
+    NVMeController(PCI::DeviceIdentifier const&, u32 hardware_relative_controller_id);
+
+    ErrorOr<void> identify_and_init_namespaces();
+    Tuple<u64, u8> get_ns_features(IdentifyNamespace& identify_data_struct);
+    ErrorOr<void> create_admin_queue(QueueType queue_type);
+    ErrorOr<void> create_io_queue(u8 qid, QueueType queue_type);
+    void calculate_doorbell_stride()
+    {
+        m_dbl_stride = (m_controller_regs->cap >> CAP_DBL_SHIFT) & CAP_DBL_MASK;
+    }
+    bool wait_for_ready(bool);
+
+private:
+    LockRefPtr<NVMeQueue> m_admin_queue;
+    Vector<NonnullLockRefPtr<NVMeQueue>> m_queues;
+    Vector<NonnullLockRefPtr<NVMeNameSpace>> m_namespaces;
+    Memory::TypedMapping<ControllerRegister volatile> m_controller_regs;
+    bool m_admin_queue_ready { false };
+    size_t m_device_count { 0 };
+    AK::Duration m_ready_timeout;
+    u32 m_bar { 0 };
+    u8 m_dbl_stride { 0 };
+    PCI::InterruptType m_irq_type;
+    QueueType m_queue_type { QueueType::IRQ };
+    static Atomic<u8> s_controller_id;
+};
+}