/*
 * Copyright (C) 2018 Red Hat
 * Copyright 2020 DisplayLink (UK) Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"

#include "backends/native/meta-kms-private.h"

#include "backends/native/meta-backend-native.h"
#include "backends/native/meta-kms-cursor-manager.h"
#include "backends/native/meta-kms-device-private.h"
#include "backends/native/meta-kms-impl.h"
#include "backends/native/meta-kms-update-private.h"
#include "backends/native/meta-thread-private.h"
#include "backends/native/meta-udev.h"
#include "cogl/cogl.h"

#include "meta-private-enum-types.h"

/**
 * SECTION:kms
 * @short description: KMS abstraction
 * @title: KMS abstraction
 *
 * The KMS abstraction consists of various building blocks for helping out with
 * interacting with the various drm API's, enabling users to use a
 * transactional API, aiming to hide all interaction with the underlying APIs.
 *
 * The subsystem defines two separate contexts, the "main" context, and the
 * "impl" context. The main context is the context of which mutter as a whole
 * runs in. It uses the main GLib main loop and main context and always runs in
 * the main thread.
 *
 * The impl context is where all underlying API is being executed. While in the
 * current state, it always runs in the main thread, the aim is to be able to
 * execute the impl context in a dedicated thread.
 *
 * The public facing MetaKms API is always assumed to be executed from the main
 * context.
 *
 * The KMS abstraction consists of the following public components:
 *
 * #MetaKms:
 *
 * Main entry point; used by the native backend to create devices, post updates
 * etc.
 *
 * #MetaKmsDevice:
 *
 * A device (usually /dev/dri/cardN, where N being a number). Used to get KMS
 * objects, such as connectors, CRTCs, planes, as well as basic meta data such
 * as device path etc.
 *
 * #MetaKmsCrtc:
 *
 * Represents a CRTC. It manages a representation of the current CRTC state,
 * including current mode, coordinates, possible clones.
 *
 * #MetaKmsConnector:
 *
 * Represents a connector, e.g. a display port connection. It also manages a
 * representation of the current state, including meta data such as physical
 * dimension of the connected, available modes, EDID, tile info etc. It also
 * contains helper functions for configuration, as well as methods for adding
 * configuration to a transaction (See #MetaKmsUpdate).
 *
 * #MetaKmsPlane:
 *
 * Represents a hardware plane. A plane is used to define the content of what
 * should be presented on a CRTC. Planes can either be primary planes, used as
 * a backdrop for CRTCs, overlay planes, and cursor planes.
 *
 * #MetaKmsMode:
 *
 * Represents a mode a CRTC and connector can be configured with.
 * Represents both modes directly derived from the devices, as well as
 * fall back modes when the CRTC supports scaling.
 *
 * #MetaKmsUpdate:
 *
 * A KMS transaction object, meant to be processed potentially atomically when
 * posted. An update consists of plane assignments, mode sets and KMS object
 * property entries. The user adds updates to the object, and then posts it via
 * MetaKms. It will then be processed by the MetaKms backend (See
 * #MetaKmsImpl), potentially atomically. Each #MetaKmsUpdate deals with
 * updating a single device.
 *
 *
 * There are also these private objects, without public facing API:
 *
 * #MetaKmsImpl:
 *
 * The KMS impl context object, managing things in the impl context.
 *
 * #MetaKmsImplDevice:
 *
 * An object linked to a #MetaKmsDevice, but where it is executed in the impl
 * context. It takes care of the updating of the various KMS object (CRTC,
 * connector, ..) states.
 *
 * This is an abstract type, with currently #MetaKmsImplDeviceSimple,
 * implementing mode setting and page flipping using legacy DRM API.
 *
 * #MetaKmsPageFlip:
 *
 * A object representing a page flip. It's created when a page flip is queued,
 * and contains information necessary to provide feedback to the one requesting
 * the page flip.
 *
 */

enum
{
  RESOURCES_CHANGED,

  N_SIGNALS
};

static int signals[N_SIGNALS];

struct _MetaKms
{
  MetaThread parent;

  MetaKmsFlags flags;

  gulong hotplug_handler_id;
  gulong removed_handler_id;

  MetaKmsImpl *impl;
  gboolean in_impl_task;
  gboolean waiting_for_impl_task;

  GList *devices;

  GList *pending_updates;

  GList *pending_callbacks;
  guint callback_source_id;

  int kernel_thread_inhibit_count;

  MetaKmsCursorManager *cursor_manager;
};

G_DEFINE_TYPE (MetaKms, meta_kms, META_TYPE_THREAD)

G_DEFINE_QUARK (-meta-kms-error-quark, meta_kms_error)

static void
invoke_result_listener (MetaThread *thread,
                        gpointer    user_data)
{
  MetaKmsResultListener *listener = user_data;

  meta_kms_result_listener_notify (listener);
}

void
meta_kms_queue_result_callback (MetaKms               *kms,
                                MetaKmsResultListener *listener)
{
  GMainContext *main_context =
    meta_kms_result_listener_get_main_context (listener);

  meta_kms_queue_callback  (kms,
                            main_context,
                            invoke_result_listener,
                            listener,
                            (GDestroyNotify) meta_kms_result_listener_free);
}

static gpointer
meta_kms_discard_pending_page_flips_in_impl (MetaThreadImpl  *thread_impl,
                                             gpointer         user_data,
                                             GError         **error)
{
  MetaKmsImpl *impl = META_KMS_IMPL (thread_impl);

  meta_kms_impl_discard_pending_page_flips (impl);
  return GINT_TO_POINTER (TRUE);
}

void
meta_kms_discard_pending_page_flips (MetaKms *kms)
{
  meta_kms_run_impl_task_sync (kms,
                               meta_kms_discard_pending_page_flips_in_impl,
                               NULL,
                               NULL);
}

static gpointer
meta_kms_notify_modes_set_in_impl (MetaThreadImpl  *thread_impl,
                                   gpointer         user_data,
                                   GError         **error)
{
  MetaKmsImpl *impl = META_KMS_IMPL (thread_impl);

  meta_kms_impl_notify_modes_set (impl);
  return GINT_TO_POINTER (TRUE);
}

void
meta_kms_notify_modes_set (MetaKms *kms)
{
  MetaThread *thread = META_THREAD (kms);

  meta_thread_run_impl_task_sync (thread,
                                  meta_kms_notify_modes_set_in_impl,
                                  NULL,
                                  NULL);
}

void
meta_kms_queue_callback (MetaKms            *kms,
                         GMainContext       *main_context,
                         MetaThreadCallback  callback,
                         gpointer            user_data,
                         GDestroyNotify      user_data_destroy)
{
  MetaThread *thread = META_THREAD (kms);

  meta_thread_queue_callback (thread,
                              main_context,
                              callback,
                              user_data,
                              user_data_destroy);
}

gpointer
meta_kms_run_impl_task_sync (MetaKms             *kms,
                             MetaThreadTaskFunc   func,
                             gpointer             user_data,
                             GError             **error)
{
  MetaThread *thread = META_THREAD (kms);

  return meta_thread_run_impl_task_sync (thread, func, user_data, error);
}

gboolean
meta_kms_in_impl_task (MetaKms *kms)
{
  MetaThread *thread = META_THREAD (kms);

  return meta_thread_is_in_impl_task (thread);
}

gboolean
meta_kms_is_waiting_for_impl_task (MetaKms *kms)
{
  MetaThread *thread = META_THREAD (kms);

  return meta_thread_is_waiting_for_impl_task (thread);
}

typedef struct _UpdateStatesData
{
  const char *device_path;
  uint32_t crtc_id;
  uint32_t connector_id;
} UpdateStatesData;

static MetaKmsResourceChanges
meta_kms_update_states_in_impl (MetaKms          *kms,
                                UpdateStatesData *update_data)
{
  MetaKmsResourceChanges changes = META_KMS_RESOURCE_CHANGE_NONE;
  GList *l;

  COGL_TRACE_BEGIN_SCOPED (MetaKmsUpdateStates,
                           "KMS (update states)");

  meta_assert_in_kms_impl (kms);

  if (!kms->devices)
    return META_KMS_RESOURCE_CHANGE_NO_DEVICES;

  for (l = kms->devices; l; l = l->next)
    {
      MetaKmsDevice *kms_device = META_KMS_DEVICE (l->data);
      const char *kms_device_path = meta_kms_device_get_path (kms_device);

      if (update_data->device_path &&
          g_strcmp0 (kms_device_path, update_data->device_path) != 0)
        continue;

      if (update_data->crtc_id > 0 &&
          !meta_kms_device_find_crtc_in_impl (kms_device, update_data->crtc_id))
        continue;

      if (update_data->connector_id > 0 &&
          !meta_kms_device_find_connector_in_impl (kms_device,
                                                   update_data->connector_id))
        continue;

      changes |=
        meta_kms_device_update_states_in_impl (kms_device,
                                               update_data->crtc_id,
                                               update_data->connector_id);
    }

  return changes;
}

static gpointer
update_states_in_impl (MetaThreadImpl  *thread_impl,
                       gpointer         user_data,
                       GError         **error)
{
  UpdateStatesData *data = user_data;
  MetaKmsImpl *impl = META_KMS_IMPL (thread_impl);
  MetaKms *kms = meta_kms_impl_get_kms (impl);

  return GUINT_TO_POINTER (meta_kms_update_states_in_impl (kms, data));
}

MetaKmsResourceChanges
meta_kms_update_states_sync (MetaKms     *kms,
                             GUdevDevice *udev_device)
{
  UpdateStatesData data = {};
  gpointer ret;

  if (udev_device)
    {
      data.device_path = g_udev_device_get_device_file (udev_device);
      data.crtc_id =
        CLAMP (g_udev_device_get_property_as_int (udev_device, "CRTC"),
               0, UINT32_MAX);
      data.connector_id =
        CLAMP (g_udev_device_get_property_as_int (udev_device, "CONNECTOR"),
               0, UINT32_MAX);
    }

  ret = meta_kms_run_impl_task_sync (kms, update_states_in_impl, &data, NULL);

  return GPOINTER_TO_UINT (ret);
}

static void
handle_hotplug_event (MetaKms                *kms,
                      GUdevDevice            *udev_device,
                      MetaKmsResourceChanges  changes)
{
  changes |= meta_kms_update_states_sync (kms, udev_device);

  if (changes != META_KMS_RESOURCE_CHANGE_NONE)
    meta_kms_emit_resources_changed (kms, changes);
}

void
meta_kms_resume (MetaKms *kms)
{
  handle_hotplug_event (kms, NULL, META_KMS_RESOURCE_CHANGE_FULL);
}

static void
on_udev_hotplug (MetaUdev    *udev,
                 GUdevDevice *udev_device,
                 MetaKms     *kms)
{
  handle_hotplug_event (kms, udev_device, META_KMS_RESOURCE_CHANGE_NONE);
}

static void
on_udev_device_removed (MetaUdev    *udev,
                        GUdevDevice *device,
                        MetaKms     *kms)
{
  handle_hotplug_event (kms, NULL, META_KMS_RESOURCE_CHANGE_NONE);
}

MetaBackend *
meta_kms_get_backend (MetaKms *kms)
{
  return meta_thread_get_backend (META_THREAD (kms));
}

GList *
meta_kms_get_devices (MetaKms *kms)
{
  return kms->devices;
}

MetaKmsDevice *
meta_kms_create_device (MetaKms            *kms,
                        const char         *path,
                        MetaKmsDeviceFlag   flags,
                        GError            **error)
{
  MetaKmsDevice *device;

  if (kms->flags & META_KMS_FLAG_NO_MODE_SETTING)
    flags |= META_KMS_DEVICE_FLAG_NO_MODE_SETTING;

  device = meta_kms_device_new (kms, path, flags, error);
  if (!device)
    return NULL;

  kms->devices = g_list_append (kms->devices, device);

  return device;
}

static gpointer
prepare_shutdown_in_impl (MetaThreadImpl  *thread_impl,
                          gpointer         user_data,
                          GError         **error)
{
  MetaKmsImpl *impl = META_KMS_IMPL (thread_impl);

  meta_kms_impl_prepare_shutdown (impl);
  return GINT_TO_POINTER (TRUE);
}

static void
on_prepare_shutdown (MetaBackend *backend,
                     MetaKms     *kms)
{
  meta_kms_run_impl_task_sync (kms, prepare_shutdown_in_impl, NULL, NULL);
  meta_thread_flush_callbacks (META_THREAD (kms));

  g_clear_object (&kms->cursor_manager);
}

MetaKms *
meta_kms_new (MetaBackend   *backend,
              MetaKmsFlags   flags,
              GError       **error)
{
  MetaBackendNative *backend_native = META_BACKEND_NATIVE (backend);
  MetaUdev *udev = meta_backend_native_get_udev (backend_native);
  MetaKms *kms;
  const char *thread_type_string;
  MetaThreadType thread_type = META_THREAD_TYPE_KERNEL;

  thread_type_string = g_getenv ("MUTTER_DEBUG_KMS_THREAD_TYPE");
  if (thread_type_string)
    {
      if (g_strcmp0 (thread_type_string, "user") == 0)
        thread_type = META_THREAD_TYPE_USER;
      else if (g_strcmp0 (thread_type_string, "kernel") == 0)
        thread_type = META_THREAD_TYPE_KERNEL;
      else
        g_assert_not_reached ();
    }

  kms = g_initable_new (META_TYPE_KMS,
                        NULL, error,
                        "backend", backend,
                        "name", "KMS thread",
                        "thread-type", thread_type,
                        "wants-realtime", TRUE,
                        NULL);
  kms->flags = flags;

  if (!(flags & META_KMS_FLAG_NO_MODE_SETTING))
    {
      kms->hotplug_handler_id =
        g_signal_connect (udev, "hotplug", G_CALLBACK (on_udev_hotplug), kms);
    }

  kms->removed_handler_id =
    g_signal_connect (udev, "device-removed",
                      G_CALLBACK (on_udev_device_removed), kms);

  g_signal_connect (backend, "prepare-shutdown",
                    G_CALLBACK (on_prepare_shutdown),
                    kms);

  return kms;
}

static void
meta_kms_finalize (GObject *object)
{
  MetaKms *kms = META_KMS (object);
  MetaBackend *backend = meta_thread_get_backend (META_THREAD (kms));
  MetaBackendNative *backend_native = META_BACKEND_NATIVE (backend);
  MetaUdev *udev = meta_backend_native_get_udev (backend_native);

  g_list_free_full (kms->devices, g_object_unref);

  g_clear_signal_handler (&kms->hotplug_handler_id, udev);
  g_clear_signal_handler (&kms->removed_handler_id, udev);

  G_OBJECT_CLASS (meta_kms_parent_class)->finalize (object);
}

static void
meta_kms_init (MetaKms *kms)
{
  kms->cursor_manager = meta_kms_cursor_manager_new (kms);
}

static void
meta_kms_class_init (MetaKmsClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);
  MetaThreadClass *thread_class = META_THREAD_CLASS (klass);

  object_class->finalize = meta_kms_finalize;

  signals[RESOURCES_CHANGED] =
    g_signal_new ("resources-changed",
                  G_TYPE_FROM_CLASS (klass),
                  G_SIGNAL_RUN_LAST,
                  0,
                  NULL, NULL, NULL,
                  G_TYPE_NONE, 1,
                  META_TYPE_KMS_RESOURCE_CHANGES);

  meta_thread_class_register_impl_type (thread_class, META_TYPE_KMS_IMPL);
}

void
meta_kms_emit_resources_changed (MetaKms                *kms,
                                 MetaKmsResourceChanges  changes)
{
  g_signal_emit (kms, signals[RESOURCES_CHANGED], 0, changes);
}

void
meta_kms_inhibit_kernel_thread (MetaKms *kms)
{
  kms->kernel_thread_inhibit_count++;

  if (kms->kernel_thread_inhibit_count == 1)
    meta_thread_reset_thread_type (META_THREAD (kms), META_THREAD_TYPE_USER);
}

void
meta_kms_uninhibit_kernel_thread (MetaKms *kms)
{
  g_return_if_fail (kms->kernel_thread_inhibit_count > 0);

  kms->kernel_thread_inhibit_count--;

  if (kms->kernel_thread_inhibit_count == 0)
    meta_thread_reset_thread_type (META_THREAD (kms), META_THREAD_TYPE_KERNEL);
}

MetaKmsCursorManager *
meta_kms_get_cursor_manager (MetaKms *kms)
{
  return kms->cursor_manager;
}