text: /*
   * Copyright (c) 2021, Pankaj R <pankydev8@gmail.com>
   *
   * SPDX-License-Identifier: BSD-2-Clause
   */
  
  #pragma once
  
  #include <AK/NonnullRefPtr.h>
  #include <AK/NonnullRefPtrVector.h>
  #include <AK/OwnPtr.h>
  #include <AK/RefCounted.h>
  #include <AK/RefPtr.h>
  #include <AK/Types.h>
  #include <Kernel/Bus/PCI/Device.h>
  #include <Kernel/Interrupts/IRQHandler.h>
  #include <Kernel/Locking/Spinlock.h>
  #include <Kernel/Memory/MemoryManager.h>
  #include <Kernel/Memory/TypedMapping.h>
  #include <Kernel/Storage/NVMe/NVMeDefinitions.h>
  
  namespace Kernel {
  
  struct DoorbellRegister {
      u32 sq_tail;
      u32 cq_head;
  };
  
  class AsyncBlockDeviceRequest;
  class NVMeQueue : public RefCounted<NVMeQueue> {
  public:
      static ErrorOr<NonnullRefPtr<NVMeQueue>> try_create(u16 qid, Optional<u8> irq, u32 q_depth, OwnPtr<Memory::Region> cq_dma_region, NonnullRefPtrVector<Memory::PhysicalPage> cq_dma_page, OwnPtr<Memory::Region> sq_dma_region, NonnullRefPtrVector<Memory::PhysicalPage> sq_dma_page, Memory::TypedMapping<volatile DoorbellRegister> db_regs);
      bool is_admin_queue() { return m_admin_queue; };
      u16 submit_sync_sqe(NVMeSubmission&);
      void read(AsyncBlockDeviceRequest& request, u16 nsid, u64 index, u32 count);
      void write(AsyncBlockDeviceRequest& request, u16 nsid, u64 index, u32 count);
      virtual void submit_sqe(NVMeSubmission&);
      virtual ~NVMeQueue();
  
  protected:
      u32 process_cq();
      void update_sq_doorbell()
      {
          m_db_regs->sq_tail = m_sq_tail;
      }
      NVMeQueue(NonnullOwnPtr<Memory::Region> rw_dma_region, Memory::PhysicalPage const& rw_dma_page, u16 qid, u32 q_depth, OwnPtr<Memory::Region> cq_dma_region, NonnullRefPtrVector<Memory::PhysicalPage> cq_dma_page, OwnPtr<Memory::Region> sq_dma_region, NonnullRefPtrVector<Memory::PhysicalPage> sq_dma_page, Memory::TypedMapping<volatile DoorbellRegister> db_regs);
  
  private:
      bool cqe_available();
      void update_cqe_head();
      virtual void complete_current_request(u16 status) = 0;
      void update_cq_doorbell()
      {
          m_db_regs->cq_head = m_cq_head;
      }
  
  protected:
      Spinlock m_cq_lock { LockRank::Interrupts };
      RefPtr<AsyncBlockDeviceRequest> m_current_request;
      NonnullOwnPtr<Memory::Region> m_rw_dma_region;
      Spinlock m_request_lock;
  
  private:
      u16 m_qid {};
      u8 m_cq_valid_phase { 1 };
      u16 m_sq_tail {};
      u16 m_prev_sq_tail {};
      u16 m_cq_head {};
      bool m_admin_queue { false };
      u32 m_qdepth {};
      Spinlock m_sq_lock { LockRank::Interrupts };
      OwnPtr<Memory::Region> m_cq_dma_region;
      NonnullRefPtrVector<Memory::PhysicalPage> m_cq_dma_page;
      Span<NVMeSubmission> m_sqe_array;
      OwnPtr<Memory::Region> m_sq_dma_region;
      NonnullRefPtrVector<Memory::PhysicalPage> m_sq_dma_page;
      Span<NVMeCompletion> m_cqe_array;
      Memory::TypedMapping<volatile DoorbellRegister> m_db_regs;
      NonnullRefPtr<Memory::PhysicalPage> m_rw_dma_page;
  };
  }
  