drivers/gpu/drm/drm_gem_framebuffer_helper.c

   1 /*
   2  * drm gem framebuffer helper functions
   3  *
   4  * Copyright (C) 2017 Noralf Trønnes
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  */
  11
  12 #include <linux/dma-buf.h>
  13 #include <linux/dma-fence.h>
  14 #include <linux/reservation.h>
  15 #include <linux/slab.h>
  16
  17 #include <drm/drmP.h>
  18 #include <drm/drm_atomic.h>
  19 #include <drm/drm_fb_helper.h>
  20 #include <drm/drm_fourcc.h>
  21 #include <drm/drm_framebuffer.h>
  22 #include <drm/drm_gem.h>
  23 #include <drm/drm_gem_framebuffer_helper.h>
  24 #include <drm/drm_modeset_helper.h>
  25
  26 /**
  27  * DOC: overview
  28  *
  29  * This library provides helpers for drivers that don't subclass
  30  * &drm_framebuffer and use &drm_gem_object for their backing storage.
  31  *
  32  * Drivers without additional needs to validate framebuffers can simply use
  33  * drm_gem_fb_create() and everything is wired up automatically. Other drivers
  34  * can use all parts independently.
  35  */
  36
  37 /**
  38  * drm_gem_fb_get_obj() - Get GEM object backing the framebuffer
  39  * @fb: Framebuffer
  40  * @plane: Plane index
  41  *
  42  * No additional reference is taken beyond the one that the &drm_frambuffer
  43  * already holds.
  44  *
  45  * Returns:
  46  * Pointer to &drm_gem_object for the given framebuffer and plane index or NULL
  47  * if it does not exist.
  48  */
  49 struct drm_gem_object *drm_gem_fb_get_obj(struct drm_framebuffer *fb,
  50                                           unsigned int plane)
  51 {
  52         if (plane >= 4)
  53                 return NULL;
  54
  55         return fb->obj[plane];
  56 }
  57 EXPORT_SYMBOL_GPL(drm_gem_fb_get_obj);
  58
  59 static struct drm_framebuffer *
  60 drm_gem_fb_alloc(struct drm_device *dev,
  61                  const struct drm_mode_fb_cmd2 *mode_cmd,
  62                  struct drm_gem_object **obj, unsigned int num_planes,
  63                  const struct drm_framebuffer_funcs *funcs)
  64 {
  65         struct drm_framebuffer *fb;
  66         int ret, i;
  67
  68         fb = kzalloc(sizeof(*fb), GFP_KERNEL);
  69         if (!fb)
  70                 return ERR_PTR(-ENOMEM);
  71
  72         drm_helper_mode_fill_fb_struct(dev, fb, mode_cmd);
  73
  74         for (i = 0; i < num_planes; i++)
  75                 fb->obj[i] = obj[i];
  76
  77         ret = drm_framebuffer_init(dev, fb, funcs);
  78         if (ret) {
  79                 DRM_DEV_ERROR(dev->dev, "Failed to init framebuffer: %d\n",
  80                               ret);
  81                 kfree(fb);
  82                 return ERR_PTR(ret);
  83         }
  84
  85         return fb;
  86 }
  87
  88 /**
  89  * drm_gem_fb_destroy - Free GEM backed framebuffer
  90  * @fb: Framebuffer
  91  *
  92  * Frees a GEM backed framebuffer with its backing buffer(s) and the structure
  93  * itself. Drivers can use this as their &drm_framebuffer_funcs->destroy
  94  * callback.
  95  */
  96 void drm_gem_fb_destroy(struct drm_framebuffer *fb)
  97 {
  98         int i;
  99
 100         for (i = 0; i < 4; i++)
 101                 drm_gem_object_put_unlocked(fb->obj[i]);
 102
 103         drm_framebuffer_cleanup(fb);
 104         kfree(fb);
 105 }
 106 EXPORT_SYMBOL(drm_gem_fb_destroy);
 107
 108 /**
 109  * drm_gem_fb_create_handle - Create handle for GEM backed framebuffer
 110  * @fb: Framebuffer
 111  * @file: DRM file to register the handle for
 112  * @handle: Pointer to return the created handle
 113  *
 114  * This function creates a handle for the GEM object backing the framebuffer.
 115  * Drivers can use this as their &drm_framebuffer_funcs->create_handle
 116  * callback. The GETFB IOCTL calls into this callback.
 117  *
 118  * Returns:
 119  * 0 on success or a negative error code on failure.
 120  */
 121 int drm_gem_fb_create_handle(struct drm_framebuffer *fb, struct drm_file *file,
 122                              unsigned int *handle)
 123 {
 124         return drm_gem_handle_create(file, fb->obj[0], handle);
 125 }
 126 EXPORT_SYMBOL(drm_gem_fb_create_handle);
 127
 128 /**
 129  * drm_gem_fb_create_with_funcs() - Helper function for the
 130  *                                  &drm_mode_config_funcs.fb_create
 131  *                                  callback
 132  * @dev: DRM device
 133  * @file: DRM file that holds the GEM handle(s) backing the framebuffer
 134  * @mode_cmd: Metadata from the userspace framebuffer creation request
 135  * @funcs: vtable to be used for the new framebuffer object
 136  *
 137  * This can be used to set &drm_framebuffer_funcs for drivers that need the
 138  * &drm_framebuffer_funcs.dirty callback. Use drm_gem_fb_create() if you don't
 139  * need to change &drm_framebuffer_funcs.
 140  * The function does buffer size validation.
 141  *
 142  * Returns:
 143  * Pointer to a &drm_framebuffer on success or an error pointer on failure.
 144  */
 145 struct drm_framebuffer *
 146 drm_gem_fb_create_with_funcs(struct drm_device *dev, struct drm_file *file,
 147                              const struct drm_mode_fb_cmd2 *mode_cmd,
 148                              const struct drm_framebuffer_funcs *funcs)
 149 {
 150         const struct drm_format_info *info;
 151         struct drm_gem_object *objs[4];
 152         struct drm_framebuffer *fb;
 153         int ret, i;
 154
 155         info = drm_get_format_info(dev, mode_cmd);
 156         if (!info)
 157                 return ERR_PTR(-EINVAL);
 158
 159         for (i = 0; i < info->num_planes; i++) {
 160                 unsigned int width = mode_cmd->width / (i ? info->hsub : 1);
 161                 unsigned int height = mode_cmd->height / (i ? info->vsub : 1);
 162                 unsigned int min_size;
 163
 164                 objs[i] = drm_gem_object_lookup(file, mode_cmd->handles[i]);
 165                 if (!objs[i]) {
 166                         DRM_DEBUG_KMS("Failed to lookup GEM object\n");
 167                         ret = -ENOENT;
 168                         goto err_gem_object_put;
 169                 }
 170
 171                 min_size = (height - 1) * mode_cmd->pitches[i]
 172                          + width * info->cpp[i]
 173                          + mode_cmd->offsets[i];
 174
 175                 if (objs[i]->size < min_size) {
 176                         drm_gem_object_put_unlocked(objs[i]);
 177                         ret = -EINVAL;
 178                         goto err_gem_object_put;
 179                 }
 180         }
 181
 182         fb = drm_gem_fb_alloc(dev, mode_cmd, objs, i, funcs);
 183         if (IS_ERR(fb)) {
 184                 ret = PTR_ERR(fb);
 185                 goto err_gem_object_put;
 186         }
 187
 188         return fb;
 189
 190 err_gem_object_put:
 191         for (i--; i >= 0; i--)
 192                 drm_gem_object_put_unlocked(objs[i]);
 193
 194         return ERR_PTR(ret);
 195 }
 196 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_funcs);
 197
 198 static const struct drm_framebuffer_funcs drm_gem_fb_funcs = {
 199         .destroy        = drm_gem_fb_destroy,
 200         .create_handle  = drm_gem_fb_create_handle,
 201 };
 202
 203 /**
 204  * drm_gem_fb_create() - Helper function for the
 205  *                       &drm_mode_config_funcs.fb_create callback
 206  * @dev: DRM device
 207  * @file: DRM file that holds the GEM handle(s) backing the framebuffer
 208  * @mode_cmd: Metadata from the userspace framebuffer creation request
 209  *
 210  * This function creates a new framebuffer object described by
 211  * &drm_mode_fb_cmd2. This description includes handles for the buffer(s)
 212  * backing the framebuffer.
 213  *
 214  * If your hardware has special alignment or pitch requirements these should be
 215  * checked before calling this function. The function does buffer size
 216  * validation. Use drm_gem_fb_create_with_funcs() if you need to set
 217  * &drm_framebuffer_funcs.dirty.
 218  *
 219  * Drivers can use this as their &drm_mode_config_funcs.fb_create callback.
 220  * The ADDFB2 IOCTL calls into this callback.
 221  *
 222  * Returns:
 223  * Pointer to a &drm_framebuffer on success or an error pointer on failure.
 224  */
 225 struct drm_framebuffer *
 226 drm_gem_fb_create(struct drm_device *dev, struct drm_file *file,
 227                   const struct drm_mode_fb_cmd2 *mode_cmd)
 228 {
 229         return drm_gem_fb_create_with_funcs(dev, file, mode_cmd,
 230                                             &drm_gem_fb_funcs);
 231 }
 232 EXPORT_SYMBOL_GPL(drm_gem_fb_create);
 233
 234 /**
 235  * drm_gem_fb_prepare_fb() - Prepare a GEM backed framebuffer
 236  * @plane: Plane
 237  * @state: Plane state the fence will be attached to
 238  *
 239  * This function prepares a GEM backed framebuffer for scanout by checking if
 240  * the plane framebuffer has a DMA-BUF attached. If it does, it extracts the
 241  * exclusive fence and attaches it to the plane state for the atomic helper to
 242  * wait on. This function can be used as the &drm_plane_helper_funcs.prepare_fb
 243  * callback.
 244  *
 245  * There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple
 246  * gem based framebuffer drivers which have their buffers always pinned in
 247  * memory.
 248  */
 249 int drm_gem_fb_prepare_fb(struct drm_plane *plane,
 250                           struct drm_plane_state *state)
 251 {
 252         struct dma_buf *dma_buf;
 253         struct dma_fence *fence;
 254
 255         if (plane->state->fb == state->fb || !state->fb)
 256                 return 0;
 257
 258         dma_buf = drm_gem_fb_get_obj(state->fb, 0)->dma_buf;
 259         if (dma_buf) {
 260                 fence = reservation_object_get_excl_rcu(dma_buf->resv);
 261                 drm_atomic_set_fence_for_plane(state, fence);
 262         }
 263
 264         return 0;
 265 }
 266 EXPORT_SYMBOL_GPL(drm_gem_fb_prepare_fb);
 267
 268 /**
 269  * drm_gem_fbdev_fb_create - Create a GEM backed &drm_framebuffer for fbdev
 270  *                           emulation
 271  * @dev: DRM device
 272  * @sizes: fbdev size description
 273  * @pitch_align: Optional pitch alignment
 274  * @obj: GEM object backing the framebuffer
 275  * @funcs: Optional vtable to be used for the new framebuffer object when the
 276  *         dirty callback is needed.
 277  *
 278  * This function creates a framebuffer from a &drm_fb_helper_surface_size
 279  * description for use in the &drm_fb_helper_funcs.fb_probe callback.
 280  *
 281  * Returns:
 282  * Pointer to a &drm_framebuffer on success or an error pointer on failure.
 283  */
 284 struct drm_framebuffer *
 285 drm_gem_fbdev_fb_create(struct drm_device *dev,
 286                         struct drm_fb_helper_surface_size *sizes,
 287                         unsigned int pitch_align, struct drm_gem_object *obj,
 288                         const struct drm_framebuffer_funcs *funcs)
 289 {
 290         struct drm_mode_fb_cmd2 mode_cmd = { 0 };
 291
 292         mode_cmd.width = sizes->surface_width;
 293         mode_cmd.height = sizes->surface_height;
 294         mode_cmd.pitches[0] = sizes->surface_width *
 295                               DIV_ROUND_UP(sizes->surface_bpp, 8);
 296         if (pitch_align)
 297                 mode_cmd.pitches[0] = roundup(mode_cmd.pitches[0],
 298                                               pitch_align);
 299         mode_cmd.pixel_format = drm_mode_legacy_fb_format(sizes->surface_bpp,
 300                                                         sizes->surface_depth);
 301         if (obj->size < mode_cmd.pitches[0] * mode_cmd.height)
 302                 return ERR_PTR(-EINVAL);
 303
 304         if (!funcs)
 305                 funcs = &drm_gem_fb_funcs;
 306
 307         return drm_gem_fb_alloc(dev, &mode_cmd, &obj, 1, funcs);
 308 }
 309 EXPORT_SYMBOL(drm_gem_fbdev_fb_create);