text: /*
   * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #pragma once
  
  #include <Kernel/Devices/Device.h>
  
  namespace Kernel {
  
  class BlockDevice;
  
  class AsyncBlockDeviceRequest : public AsyncDeviceRequest {
  public:
      enum RequestType {
          Read,
          Write
      };
      AsyncBlockDeviceRequest(Device& block_device, RequestType request_type,
          u32 block_index, u32 block_count, const UserOrKernelBuffer& buffer, size_t buffer_size);
  
      RequestType request_type() const { return m_request_type; }
      u32 block_index() const { return m_block_index; }
      u32 block_count() const { return m_block_count; }
      UserOrKernelBuffer& buffer() { return m_buffer; }
      const UserOrKernelBuffer& buffer() const { return m_buffer; }
      size_t buffer_size() const { return m_buffer_size; }
  
      virtual void start() override;
      virtual const char* name() const override
      {
          switch (m_request_type) {
          case Read:
              return "BlockDeviceRequest (read)";
          case Write:
              return "BlockDeviceRequest (write)";
          default:
              ASSERT_NOT_REACHED();
          }
      }
  
  private:
      BlockDevice& m_block_device;
      const RequestType m_request_type;
      const u32 m_block_index;
      const u32 m_block_count;
      UserOrKernelBuffer m_buffer;
      const size_t m_buffer_size;
  };
  
  class BlockDevice : public Device {
  public:
      virtual ~BlockDevice() override;
  
      size_t block_size() const { return m_block_size; }
      virtual bool is_seekable() const override { return true; }
  
      bool read_block(unsigned index, UserOrKernelBuffer&);
      bool write_block(unsigned index, const UserOrKernelBuffer&);
  
      virtual void start_request(AsyncBlockDeviceRequest&) = 0;
  
  protected:
      BlockDevice(unsigned major, unsigned minor, size_t block_size = PAGE_SIZE)
          : Device(major, minor)
          , m_block_size(block_size)
      {
      }
  
  private:
      virtual bool is_block_device() const final { return true; }
  
      size_t m_block_size { 0 };
  };
  
  }
  