text: /*
   * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
   *
   * SPDX-License-Identifier: BSD-2-Clause
   */
  
  #include <AK/Singleton.h>
  #include <Kernel/Devices/Device.h>
  #include <Kernel/FileSystem/InodeMetadata.h>
  #include <LibC/errno_numbers.h>
  
  namespace Kernel {
  
  static AK::Singleton<HashMap<u32, Device*>> s_all_devices;
  
  HashMap<u32, Device*>& Device::all_devices()
  {
      return *s_all_devices;
  }
  
  void Device::for_each(Function<void(Device&)> callback)
  {
      for (auto& entry : all_devices())
          callback(*entry.value);
  }
  
  Device* Device::get_device(unsigned major, unsigned minor)
  {
      auto it = all_devices().find(encoded_device(major, minor));
      if (it == all_devices().end())
          return nullptr;
      return it->value;
  }
  
  Device::Device(unsigned major, unsigned minor)
      : m_major(major)
      , m_minor(minor)
  {
      u32 device_id = encoded_device(major, minor);
      auto it = all_devices().find(device_id);
      if (it != all_devices().end()) {
          dbgln("Already registered {},{}: {}", major, minor, it->value->class_name());
      }
      VERIFY(!all_devices().contains(device_id));
      all_devices().set(device_id, this);
  }
  
  Device::~Device()
  {
      all_devices().remove(encoded_device(m_major, m_minor));
  }
  
  String Device::absolute_path() const
  {
      return String::formatted("device:{},{} ({})", m_major, m_minor, class_name());
  }
  
  String Device::absolute_path(const FileDescription&) const
  {
      return absolute_path();
  }
  
  void Device::process_next_queued_request(Badge<AsyncDeviceRequest>, const AsyncDeviceRequest& completed_request)
  {
      ScopedSpinLock lock(m_requests_lock);
      VERIFY(!m_requests.is_empty());
      VERIFY(m_requests.first().ptr() == &completed_request);
      m_requests.remove(m_requests.begin());
      if (!m_requests.is_empty()) {
          auto* next_request = m_requests.first().ptr();
          next_request->do_start(move(lock));
      }
  
      evaluate_block_conditions();
  }
  
  }
  