/*  RetroArch - A frontend for libretro.
 *  Copyright (C) 2010-2014 - Hans-Kristian Arntzen
 *  Copyright (C) 2011-2016 - Daniel De Matteis
 * 
 *  RetroArch 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 Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  RetroArch 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 RetroArch.
 *  If not, see <http://www.gnu.org/licenses/>.
 */

/* KMS/DRM context, running without any window manager.
 * Based on kmscube example by Rob Clark.
 */

#include <stdint.h>
#include <errno.h>
#include <unistd.h>
#include <math.h>

#include <sched.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/poll.h>

#include <libdrm/drm.h>
#include <gbm.h>

#include <lists/dir_list.h>
#include <streams/file_stream.h>

#include "../../verbosity.h"
#include "../../driver.h"
#include "../../runloop.h"
#include "../common/drm_common.h"

#ifdef HAVE_EGL
#include "../common/egl_common.h"
#endif

#if defined(HAVE_OPENGL) || defined(HAVE_OPENGLES)
#include "../common/gl_common.h"
#endif

#ifdef HAVE_CONFIG_H
#include "../../config.h"
#endif

#ifdef HAVE_OPENGLES

#ifndef EGL_OPENGL_ES3_BIT_KHR
#define EGL_OPENGL_ES3_BIT_KHR 0x0040
#endif

#endif

static volatile sig_atomic_t drm_quit = 0;

static enum gfx_ctx_api drm_api;

static struct gbm_bo *g_bo;
static struct gbm_bo *g_next_bo;
static struct gbm_surface *g_gbm_surface;
static struct gbm_device *g_gbm_dev;

static bool waiting_for_flip;

typedef struct gfx_ctx_drm_data
{
#ifdef HAVE_EGL
   egl_ctx_data_t egl;
#endif
   RFILE *drm;
   unsigned interval;
   unsigned fb_width;
   unsigned fb_height;

   bool core_hw_context_enable; 
} gfx_ctx_drm_data_t;

struct drm_fb
{
   struct gbm_bo *bo;
   uint32_t fb_id;
};

static void drm_sighandler(int sig)
{
   (void)sig;
   if (drm_quit) exit(1);
   drm_quit = 1;
}

static void drm_install_sighandler(void)
{
   struct sigaction sa;

   sa.sa_sigaction = NULL;
   sa.sa_handler   = drm_sighandler;
   sa.sa_flags     = SA_RESTART;
   sigemptyset(&sa.sa_mask);
   sigaction(SIGINT, &sa, NULL);
   sigaction(SIGTERM, &sa, NULL);
}

static void drm_fb_destroy_callback(struct gbm_bo *bo, void *data)
{
   struct drm_fb *fb = (struct drm_fb*)data;

   if (fb && fb->fb_id)
      drmModeRmFB(g_drm_fd, fb->fb_id);

   free(fb);
}

static struct drm_fb *drm_fb_get_from_bo(struct gbm_bo *bo)
{
   int ret;
   unsigned width, height, stride, handle;
   struct drm_fb *fb = (struct drm_fb*)gbm_bo_get_user_data(bo);
   if (fb)
      return fb;

   fb     = (struct drm_fb*)calloc(1, sizeof(*fb));
   fb->bo = bo;

   width  = gbm_bo_get_width(bo);
   height = gbm_bo_get_height(bo);
   stride = gbm_bo_get_stride(bo);
   handle = gbm_bo_get_handle(bo).u32;

   RARCH_LOG("[KMS]: New FB: %ux%u (stride: %u).\n",
         width, height, stride);

   ret = drmModeAddFB(g_drm_fd, width, height, 24, 32,
         stride, handle, &fb->fb_id);
   if (ret < 0)
      goto error;

   gbm_bo_set_user_data(bo, fb, drm_fb_destroy_callback);
   return fb;

error:
   RARCH_ERR("[KMS]: Failed to create FB: %s\n", strerror(errno));
   free(fb);
   return NULL;
}

static void gfx_ctx_drm_swap_interval(void *data, unsigned interval)
{
   gfx_ctx_drm_data_t *drm = (gfx_ctx_drm_data_t*)data;
   drm->interval           = interval;

   if (interval > 1)
      RARCH_WARN("[KMS]: Swap intervals > 1 currently not supported. Will use swap interval of 1.\n");
}

static void gfx_ctx_drm_check_window(void *data, bool *quit,
      bool *resize, unsigned *width, unsigned *height, unsigned frame_count)
{
   (void)data;
   (void)frame_count;
   (void)width;
   (void)height;

   *resize = false;
   *quit   = drm_quit;
}


static void drm_flip_handler(int fd, unsigned frame,
      unsigned sec, unsigned usec, void *data)
{
   static unsigned first_page_flip;
   static unsigned last_page_flip;

   (void)fd;
   (void)sec;
   (void)usec;

   if (!first_page_flip)
      first_page_flip = frame;

   if (last_page_flip)
   {
      unsigned missed = frame - last_page_flip - 1;
      if (missed)
         RARCH_LOG("[KMS]: Missed %u VBlank(s) (Frame: %u, DRM frame: %u).\n",
               missed, frame - first_page_flip, frame);
   }

   last_page_flip = frame;
   *(bool*)data = false;
}

static bool gfx_ctx_drm_wait_flip(bool block)
{
   int timeout = 0;

   if (!waiting_for_flip)
      return false;
   
   if (block)
      timeout = -1;

   while (waiting_for_flip)
   {
      if (!drm_wait_flip(timeout))
         break;
   }

   if (waiting_for_flip)
      return true;

   /* Page flip has taken place. */

   /* This buffer is not on-screen anymore. Release it to GBM. */
   gbm_surface_release_buffer(g_gbm_surface, g_bo);
   /* This buffer is being shown now. */
   g_bo = g_next_bo; 

   return false;
}

static bool gfx_ctx_drm_queue_flip(void)
{
   struct drm_fb *fb = NULL;
   g_next_bo         = gbm_surface_lock_front_buffer(g_gbm_surface);
   fb                = (struct drm_fb*)drm_fb_get_from_bo(g_next_bo);

   if (drmModePageFlip(g_drm_fd, g_crtc_id, fb->fb_id,
         DRM_MODE_PAGE_FLIP_EVENT, &waiting_for_flip) == 0)
      return true;
   
   /* Failed to queue page flip. */
   return false;
}

static void gfx_ctx_drm_swap_buffers(void *data)
{
   gfx_ctx_drm_data_t *drm = (gfx_ctx_drm_data_t*)data;

   switch (drm_api)
   {
      case GFX_CTX_OPENGL_API:
      case GFX_CTX_OPENGL_ES_API:
      case GFX_CTX_OPENVG_API:
#ifdef HAVE_EGL
         egl_swap_buffers(&drm->egl);
#endif
         break;
      default:
         break;
   }

   /* I guess we have to wait for flip to have taken 
    * place before another flip can be queued up.
    *
    * If true, we are still waiting for a flip
    * (nonblocking mode, so just drop the frame). */
   if (gfx_ctx_drm_wait_flip(drm->interval))
      return;

   waiting_for_flip = gfx_ctx_drm_queue_flip();

   if (gbm_surface_has_free_buffers(g_gbm_surface))
      return;

   /* We have to wait for this flip to finish. 
    * This shouldn't happen as we have triple buffered page-flips. */
   RARCH_WARN("[KMS]: Triple buffering is not working correctly ...\n");
   gfx_ctx_drm_wait_flip(true);  
}

static bool gfx_ctx_drm_set_resize(void *data,
      unsigned width, unsigned height)
{
   (void)data;
   (void)width;
   (void)height;

   return false;
}

static void gfx_ctx_drm_update_window_title(void *data)
{
   char buf[128];
   char buf_fps[128];
   settings_t *settings = config_get_ptr();

   video_monitor_get_fps(buf, sizeof(buf),
         buf_fps, sizeof(buf_fps));
   if (settings->fps_show)
      runloop_msg_queue_push( buf_fps, 1, 1, false);
}

static void gfx_ctx_drm_get_video_size(void *data,
      unsigned *width, unsigned *height)
{
   gfx_ctx_drm_data_t *drm = (gfx_ctx_drm_data_t*)data;

   if (!drm)
      return;

   *width  = drm->fb_width;
   *height = drm->fb_height;
}

static void free_drm_resources(gfx_ctx_drm_data_t *drm)
{
   if (!drm)
      return;

   if (g_gbm_surface)
      gbm_surface_destroy(g_gbm_surface);

   if (g_gbm_dev)
      gbm_device_destroy(g_gbm_dev);

   drm_free();

   if (g_drm_fd >= 0)
      filestream_close(drm->drm);

   g_gbm_surface      = NULL;
   g_gbm_dev          = NULL;
   g_drm_fd           = -1;
}

static void gfx_ctx_drm_destroy_resources(gfx_ctx_drm_data_t *drm)
{
   if (!drm)
      return;

   /* Make sure we acknowledge all page-flips. */
   gfx_ctx_drm_wait_flip(true);

   switch (drm_api)
   {
      case GFX_CTX_OPENGL_API:
      case GFX_CTX_OPENGL_ES_API:
      case GFX_CTX_OPENVG_API:
#ifdef HAVE_EGL
         egl_destroy(&drm->egl);
#endif
         break;
      case GFX_CTX_NONE:
      default:
         break;
   }

   /* Restore original CRTC. */
   drm_restore_crtc();
   free_drm_resources(drm);

   g_drm_mode          = NULL;
   g_crtc_id           = 0;
   g_connector_id      = 0;

   drm->fb_width       = 0;
   drm->fb_height      = 0;

   g_bo                = NULL;
   g_next_bo           = NULL;
}

static void *gfx_ctx_drm_init(void *video_driver)
{
   int fd, i;
   unsigned monitor_index;
   unsigned gpu_index                   = 0;
   const char *gpu                      = NULL;
   struct string_list *gpu_descriptors  = NULL;
   gfx_ctx_drm_data_t *drm          = (gfx_ctx_drm_data_t*)
      calloc(1, sizeof(gfx_ctx_drm_data_t));

   if (!drm)
      return NULL;

   fd   = -1;
   gpu_descriptors = dir_list_new("/dev/dri", NULL, false, false);

nextgpu:
   drm_restore_crtc();
   free_drm_resources(drm);

   if (!gpu_descriptors || gpu_index == gpu_descriptors->size)
   {
      RARCH_ERR("[KMS]: Couldn't find a suitable DRM device.\n");
      goto error;
   }
   gpu = gpu_descriptors->elems[gpu_index++].data;

   drm->drm    = filestream_open(gpu, RFILE_MODE_READ_WRITE, -1);
   if (!drm->drm)
   {
      RARCH_WARN("[KMS]: Couldn't open DRM device.\n");
      goto nextgpu;
   }

   fd = filestream_get_fd(drm->drm);

   if (!drm_get_resources(fd))
      goto nextgpu;

   if (!drm_get_connector(fd))
      goto nextgpu;

   if (!drm_get_encoder(fd))
      goto nextgpu;

   drm_setup(fd);

   /* First mode is assumed to be the "optimal" 
    * one for get_video_size() purposes. */
   drm->fb_width    = g_drm_connector->modes[0].hdisplay;
   drm->fb_height   = g_drm_connector->modes[0].vdisplay;

   g_gbm_dev        = gbm_create_device(fd);

   if (!g_gbm_dev)
   {
      RARCH_WARN("[KMS]: Couldn't create GBM device.\n");
      goto nextgpu;
   }

   dir_list_free(gpu_descriptors);

   /* Setup the flip handler. */
   g_drm_fds.fd                   = fd;
   g_drm_fds.events               = POLLIN;
   g_drm_evctx.version            = DRM_EVENT_CONTEXT_VERSION;
   g_drm_evctx.page_flip_handler  = drm_flip_handler;

   g_drm_fd                       = fd;

   return drm;

error:
   dir_list_free(gpu_descriptors);

   gfx_ctx_drm_destroy_resources(drm);

   if (drm)
      free(drm);

   return NULL;
}

static EGLint *gfx_ctx_drm_egl_fill_attribs(
      gfx_ctx_drm_data_t *drm, EGLint *attr)
{
   switch (drm_api)
   {
#ifdef EGL_KHR_create_context
      case GFX_CTX_OPENGL_API:
      {
         bool debug       = false;
#ifdef HAVE_OPENGL
         unsigned version = drm->egl.major * 1000 + drm->egl.minor;
         bool core        = version >= 3001;
#ifdef GL_DEBUG
         debug            = true;
#else
         struct retro_hw_render_callback *hwr = video_driver_get_hw_context();
         debug           = hwr->debug_context;
#endif

         if (core)
         {
            *attr++ = EGL_CONTEXT_MAJOR_VERSION_KHR;
            *attr++ = drm->egl.major;
            *attr++ = EGL_CONTEXT_MINOR_VERSION_KHR;
            *attr++ = drm->egl.minor;

            /* Technically, we don't have core/compat until 3.2.
             * Version 3.1 is either compat or not depending 
             * on GL_ARB_compatibility. */
            if (version >= 3002)
            {
               *attr++ = EGL_CONTEXT_OPENGL_PROFILE_MASK_KHR;
               *attr++ = EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT_KHR;
            }
         }

         if (debug)
         {
            *attr++ = EGL_CONTEXT_FLAGS_KHR;
            *attr++ = EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR;
         }
         break;
#endif
      }
#endif

      case GFX_CTX_OPENGL_ES_API:
#ifdef HAVE_OPENGLES
         *attr++ = EGL_CONTEXT_CLIENT_VERSION;
         *attr++ = drm->egl.major 
            ? (EGLint)drm->egl.major : 2;
#ifdef EGL_KHR_create_context
         if (drm->egl.minor > 0)
         {
            *attr++ = EGL_CONTEXT_MINOR_VERSION_KHR;
            *attr++ = drm->egl.minor;
         }
#endif
#endif
         break;
      case GFX_CTX_NONE:
      default:
         break;
   }

   *attr = EGL_NONE;
   return attr;
}

#ifdef HAVE_EGL
#define DRM_EGL_ATTRIBS_BASE \
   EGL_SURFACE_TYPE,    EGL_WINDOW_BIT, \
   EGL_RED_SIZE,        1, \
   EGL_GREEN_SIZE,      1, \
   EGL_BLUE_SIZE,       1, \
   EGL_ALPHA_SIZE,      0, \
   EGL_DEPTH_SIZE,      0

static bool gfx_ctx_drm_egl_set_video_mode(gfx_ctx_drm_data_t *drm)
{
   const EGLint *attrib_ptr    = NULL;
   static const EGLint egl_attribs_gl[] = {
      DRM_EGL_ATTRIBS_BASE,
      EGL_RENDERABLE_TYPE, EGL_OPENGL_BIT,
      EGL_NONE,
   };

   static const EGLint egl_attribs_gles[] = {
      DRM_EGL_ATTRIBS_BASE,
      EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
      EGL_NONE,
   };

#ifdef EGL_KHR_create_context
   static const EGLint egl_attribs_gles3[] = {
      DRM_EGL_ATTRIBS_BASE,
      EGL_RENDERABLE_TYPE, EGL_OPENGL_ES3_BIT_KHR,
      EGL_NONE,
   };
#endif

#ifdef HAVE_VG
   static const EGLint egl_attribs_vg[] = {
      DRM_EGL_ATTRIBS_BASE,
      EGL_RENDERABLE_TYPE, EGL_OPENVG_BIT,
      EGL_NONE,
   };
#endif
   EGLint major;
   EGLint minor;
   EGLint n;
   EGLint egl_attribs[16];
   EGLint *egl_attribs_ptr     = NULL;
   EGLint *attr                = NULL;

   switch (drm_api)
   {
      case GFX_CTX_OPENGL_API:
#ifdef HAVE_OPENGL
         attrib_ptr = egl_attribs_gl;
         break;
      case GFX_CTX_OPENGL_ES_API:
#ifdef EGL_KHR_create_context
         if (drm->egl.major >= 3)
            attrib_ptr = egl_attribs_gles3;
         else
#endif
         attrib_ptr = egl_attribs_gles;
#endif
         break;
      case GFX_CTX_OPENVG_API:
#ifdef HAVE_VG
         attrib_ptr = egl_attribs_vg;
#endif
         break;
      case GFX_CTX_NONE:
      default:
         break;
   }

   switch (drm_api)
   {
      case GFX_CTX_OPENGL_API:
      case GFX_CTX_OPENGL_ES_API:
      case GFX_CTX_OPENVG_API:
#ifdef HAVE_EGL
         if (!egl_init_context(&drm->egl, (EGLNativeDisplayType)g_gbm_dev, &major,
                  &minor, &n, attrib_ptr))
            goto error;

         attr            = gfx_ctx_drm_egl_fill_attribs(drm, egl_attribs);
         egl_attribs_ptr = &egl_attribs[0];

         if (!egl_create_context(&drm->egl, (attr != egl_attribs_ptr) 
                  ? egl_attribs_ptr : NULL))
            goto error;

         if (!egl_create_surface(&drm->egl, (EGLNativeWindowType)g_gbm_surface))
            return false;
#if defined(HAVE_OPENGL) || defined(HAVE_OPENGLES)
         glClear(GL_COLOR_BUFFER_BIT);
#endif
#endif
         break;
      case GFX_CTX_NONE:
      default:
         break;
   }

   egl_swap_buffers(drm);

   return true;

error:
   egl_report_error();
   return false;
}
#endif

static bool gfx_ctx_drm_set_video_mode(void *data,
      unsigned width, unsigned height,
      bool fullscreen)
{
   float refresh_mod;
   int i, ret                  = 0;
   struct drm_fb *fb           = NULL;
   settings_t *settings        = config_get_ptr();
   gfx_ctx_drm_data_t *drm     = (gfx_ctx_drm_data_t*)data;

   if (!drm)
      return false;

   drm_install_sighandler();

   /* If we use black frame insertion, 
    * we fake a 60 Hz monitor for 120 Hz one, 
    * etc, so try to match that. */
   refresh_mod = settings->video.black_frame_insertion 
      ? 0.5f : 1.0f;

   /* Find desired video mode, and use that.
    * If not fullscreen, we get desired windowed size, 
    * which is not appropriate. */
   if ((width == 0 && height == 0) || !fullscreen)
      g_drm_mode = &g_drm_connector->modes[0];
   else
   {
      /* Try to match settings->video.refresh_rate 
       * as closely as possible.
       *
       * Lower resolutions tend to have multiple supported 
       * refresh rates as well.
       */
      float minimum_fps_diff = 0.0f;

      /* Find best match. */
      for (i = 0; i < g_drm_connector->count_modes; i++)
      {
         float diff;
         if (width != g_drm_connector->modes[i].hdisplay || 
               height != g_drm_connector->modes[i].vdisplay)
            continue;

         diff = fabsf(refresh_mod * g_drm_connector->modes[i].vrefresh
               - settings->video.refresh_rate);

         if (!g_drm_mode || diff < minimum_fps_diff)
         {
            g_drm_mode = &g_drm_connector->modes[i];
            minimum_fps_diff = diff;
         }
      }
   }

   if (!g_drm_mode)
   {
      RARCH_ERR("[KMS/EGL]: Did not find suitable video mode for %u x %u.\n",
            width, height);
      goto error;
   }

   drm->fb_width    = g_drm_mode->hdisplay;
   drm->fb_height   = g_drm_mode->vdisplay;

   /* Create GBM surface. */
   g_gbm_surface = gbm_surface_create(
         g_gbm_dev,
         drm->fb_width,
         drm->fb_height,
         GBM_FORMAT_XRGB8888,
         GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING);

   if (!g_gbm_surface)
   {
      RARCH_ERR("[KMS/EGL]: Couldn't create GBM surface.\n");
      goto error;
   }


   switch (drm_api)
   {
      case GFX_CTX_OPENGL_API:
      case GFX_CTX_OPENGL_ES_API:
      case GFX_CTX_OPENVG_API:
#ifdef HAVE_EGL
         if (!gfx_ctx_drm_egl_set_video_mode(drm))
            goto error;
#endif
         break;
      case GFX_CTX_NONE:
      default:
         break;
   }

   g_bo = gbm_surface_lock_front_buffer(g_gbm_surface);
   fb   = drm_fb_get_from_bo(g_bo);

   ret  = drmModeSetCrtc(g_drm_fd,
         g_crtc_id, fb->fb_id, 0, 0, &g_connector_id, 1, g_drm_mode);
   if (ret < 0)
      goto error;

   return true;

error:
   gfx_ctx_drm_destroy_resources(drm);

   if (drm)
      free(drm);

   return false;
}


static void gfx_ctx_drm_destroy(void *data)
{
   gfx_ctx_drm_data_t *drm = (gfx_ctx_drm_data_t*)data;

   if (!drm)
      return;

   gfx_ctx_drm_destroy_resources(drm);
   free(drm);
}

static void gfx_ctx_drm_input_driver(void *data,
      const input_driver_t **input, void **input_data)
{
   (void)data;
   *input = NULL;
   *input_data = NULL;
}

static bool gfx_ctx_drm_has_focus(void *data)
{
   return true;
}

static bool gfx_ctx_drm_suppress_screensaver(void *data, bool enable)
{
   (void)data;
   (void)enable;
   return false;
}

static bool gfx_ctx_drm_has_windowed(void *data)
{
   (void)data;
   return false;
}

static bool gfx_ctx_drm_bind_api(void *video_driver,
      enum gfx_ctx_api api, unsigned major, unsigned minor)
{
   (void)video_driver;

#ifdef HAVE_EGL
   g_egl_major = major;
   g_egl_minor = minor;
#endif
   drm_api     = api;

   switch (api)
   {
      case GFX_CTX_OPENGL_API:
#if defined(HAVE_EGL) && defined(HAVE_OPENGL)

#ifndef EGL_KHR_create_context
         if ((major * 1000 + minor) >= 3001)
            return false;
#endif
         return eglBindAPI(EGL_OPENGL_API);
#else
         break;
#endif
      case GFX_CTX_OPENGL_ES_API:
#if defined(HAVE_EGL) && defined(HAVE_OPENGLES)

#ifndef EGL_KHR_create_context
         if (major >= 3)
            return false;
#endif
         return eglBindAPI(EGL_OPENGL_ES_API);
#else
         break;
#endif
      case GFX_CTX_OPENVG_API:
#if defined(HAVE_EGL) && defined(HAVE_VG)
         return eglBindAPI(EGL_OPENVG_API);
#endif
      case GFX_CTX_NONE:
      default:
         break;
   }

   return false;
}

static gfx_ctx_proc_t gfx_ctx_drm_get_proc_address(const char *symbol)
{
   switch (drm_api)
   {
      case GFX_CTX_OPENGL_API:
      case GFX_CTX_OPENGL_ES_API:
      case GFX_CTX_OPENVG_API:
#ifdef HAVE_EGL
         return egl_get_proc_address(symbol);
#else
         break;
#endif
      case GFX_CTX_NONE:
      default:
         break;
   }

   return NULL;
}

static void gfx_ctx_drm_bind_hw_render(void *data, bool enable)
{
   gfx_ctx_drm_data_t *drm     = (gfx_ctx_drm_data_t*)data;

   switch (drm_api)
   {
      case GFX_CTX_OPENGL_API:
      case GFX_CTX_OPENGL_ES_API:
      case GFX_CTX_OPENVG_API:
#ifdef HAVE_EGL
         egl_bind_hw_render(&drm->egl, enable);
#endif
         break;
      case GFX_CTX_NONE:
      default:
         break;
   }
}

static uint32_t gfx_ctx_drm_get_flags(void *data)
{
   uint32_t             flags = 0;
   gfx_ctx_drm_data_t    *drm = (gfx_ctx_drm_data_t*)data;

   if (drm->core_hw_context_enable)
   {
      BIT32_SET(flags, GFX_CTX_FLAGS_GL_CORE_CONTEXT);
   }
   else
      BIT32_SET(flags, GFX_CTX_FLAGS_NONE);

   return flags;
}

static void gfx_ctx_drm_set_flags(void *data, uint32_t flags)
{
   gfx_ctx_drm_data_t *drm     = (gfx_ctx_drm_data_t*)data;
   if (BIT32_GET(flags, GFX_CTX_FLAGS_GL_CORE_CONTEXT))
      drm->core_hw_context_enable = true;
}

const gfx_ctx_driver_t gfx_ctx_drm = {
   gfx_ctx_drm_init,
   gfx_ctx_drm_destroy,
   gfx_ctx_drm_bind_api,
   gfx_ctx_drm_swap_interval,
   gfx_ctx_drm_set_video_mode,
   gfx_ctx_drm_get_video_size,
   NULL, /* get_video_output_size */
   NULL, /* get_video_output_prev */
   NULL, /* get_video_output_next */
   NULL, /* get_metrics */
   NULL,
   gfx_ctx_drm_update_window_title,
   gfx_ctx_drm_check_window,
   gfx_ctx_drm_set_resize,
   gfx_ctx_drm_has_focus,
   gfx_ctx_drm_suppress_screensaver,
   gfx_ctx_drm_has_windowed,
   gfx_ctx_drm_swap_buffers,
   gfx_ctx_drm_input_driver,
   gfx_ctx_drm_get_proc_address,
   NULL,
   NULL,
   NULL,
   "kms",
   gfx_ctx_drm_get_flags,
   gfx_ctx_drm_set_flags,
   gfx_ctx_drm_bind_hw_render
};