1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * drm gem framebuffer helper functions
4 *
5 * Copyright (C) 2017 Noralf Trønnes
6 */
7
8 #include <linux/dma-buf.h>
9 #include <linux/dma-fence.h>
10 #include <linux/dma-resv.h>
11 #include <linux/slab.h>
12
13 #include <drm/drm_atomic.h>
14 #include <drm/drm_atomic_uapi.h>
15 #include <drm/drm_damage_helper.h>
16 #include <drm/drm_fb_helper.h>
17 #include <drm/drm_fourcc.h>
18 #include <drm/drm_framebuffer.h>
19 #include <drm/drm_gem.h>
20 #include <drm/drm_gem_framebuffer_helper.h>
21 #include <drm/drm_modeset_helper.h>
22 #include <drm/drm_simple_kms_helper.h>
23
24 /**
25 * DOC: overview
26 *
27 * This library provides helpers for drivers that don't subclass
28 * &drm_framebuffer and use &drm_gem_object for their backing storage.
29 *
30 * Drivers without additional needs to validate framebuffers can simply use
31 * drm_gem_fb_create() and everything is wired up automatically. Other drivers
32 * can use all parts independently.
33 */
34
35 /**
36 * drm_gem_fb_get_obj() - Get GEM object backing the framebuffer
37 * @fb: Framebuffer
38 * @plane: Plane index
39 *
40 * No additional reference is taken beyond the one that the &drm_frambuffer
41 * already holds.
42 *
43 * Returns:
44 * Pointer to &drm_gem_object for the given framebuffer and plane index or NULL
45 * if it does not exist.
46 */
47 struct drm_gem_object *drm_gem_fb_get_obj(struct drm_framebuffer *fb,
48 unsigned int plane)
49 {
50 if (plane >= 4)
51 return NULL;
52
53 return fb->obj[plane];
54 }
55 EXPORT_SYMBOL_GPL(drm_gem_fb_get_obj);
56
57 static struct drm_framebuffer *
58 drm_gem_fb_alloc(struct drm_device *dev,
59 const struct drm_mode_fb_cmd2 *mode_cmd,
60 struct drm_gem_object **obj, unsigned int num_planes,
61 const struct drm_framebuffer_funcs *funcs)
62 {
63 struct drm_framebuffer *fb;
64 int ret, i;
65
66 fb = kzalloc(sizeof(*fb), GFP_KERNEL);
67 if (!fb)
68 return ERR_PTR(-ENOMEM);
69
70 drm_helper_mode_fill_fb_struct(dev, fb, mode_cmd);
71
72 for (i = 0; i < num_planes; i++)
73 fb->obj[i] = obj[i];
74
75 ret = drm_framebuffer_init(dev, fb, funcs);
76 if (ret) {
77 DRM_DEV_ERROR(dev->dev, "Failed to init framebuffer: %d\n",
78 ret);
79 kfree(fb);
80 return ERR_PTR(ret);
81 }
82
83 return fb;
84 }
85
86 /**
87 * drm_gem_fb_destroy - Free GEM backed framebuffer
88 * @fb: Framebuffer
89 *
90 * Frees a GEM backed framebuffer with its backing buffer(s) and the structure
91 * itself. Drivers can use this as their &drm_framebuffer_funcs->destroy
92 * callback.
93 */
94 void drm_gem_fb_destroy(struct drm_framebuffer *fb)
95 {
96 int i;
97
98 for (i = 0; i < 4; i++)
99 drm_gem_object_put_unlocked(fb->obj[i]);
100
101 drm_framebuffer_cleanup(fb);
102 kfree(fb);
103 }
104 EXPORT_SYMBOL(drm_gem_fb_destroy);
105
106 /**
107 * drm_gem_fb_create_handle - Create handle for GEM backed framebuffer
108 * @fb: Framebuffer
109 * @file: DRM file to register the handle for
110 * @handle: Pointer to return the created handle
111 *
112 * This function creates a handle for the GEM object backing the framebuffer.
113 * Drivers can use this as their &drm_framebuffer_funcs->create_handle
114 * callback. The GETFB IOCTL calls into this callback.
115 *
116 * Returns:
117 * 0 on success or a negative error code on failure.
118 */
119 int drm_gem_fb_create_handle(struct drm_framebuffer *fb, struct drm_file *file,
120 unsigned int *handle)
121 {
122 return drm_gem_handle_create(file, fb->obj[0], handle);
123 }
124 EXPORT_SYMBOL(drm_gem_fb_create_handle);
125
126 /**
127 * drm_gem_fb_create_with_funcs() - Helper function for the
128 * &drm_mode_config_funcs.fb_create
129 * callback
130 * @dev: DRM device
131 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
132 * @mode_cmd: Metadata from the userspace framebuffer creation request
133 * @funcs: vtable to be used for the new framebuffer object
134 *
135 * This function can be used to set &drm_framebuffer_funcs for drivers that need
136 * custom framebuffer callbacks. Use drm_gem_fb_create() if you don't need to
137 * change &drm_framebuffer_funcs. The function does buffer size validation.
138 *
139 * Returns:
140 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
141 */
142 struct drm_framebuffer *
143 drm_gem_fb_create_with_funcs(struct drm_device *dev, struct drm_file *file,
144 const struct drm_mode_fb_cmd2 *mode_cmd,
145 const struct drm_framebuffer_funcs *funcs)
146 {
147 const struct drm_format_info *info;
148 struct drm_gem_object *objs[4];
149 struct drm_framebuffer *fb;
150 int ret, i;
151
152 info = drm_get_format_info(dev, mode_cmd);
153 if (!info)
154 return ERR_PTR(-EINVAL);
155
156 for (i = 0; i < info->num_planes; i++) {
157 unsigned int width = mode_cmd->width / (i ? info->hsub : 1);
158 unsigned int height = mode_cmd->height / (i ? info->vsub : 1);
159 unsigned int min_size;
160
161 objs[i] = drm_gem_object_lookup(file, mode_cmd->handles[i]);
162 if (!objs[i]) {
163 DRM_DEBUG_KMS("Failed to lookup GEM object\n");
164 ret = -ENOENT;
165 goto err_gem_object_put;
166 }
167
168 min_size = (height - 1) * mode_cmd->pitches[i]
169 + drm_format_info_min_pitch(info, i, width)
170 + mode_cmd->offsets[i];
171
172 if (objs[i]->size < min_size) {
173 drm_gem_object_put_unlocked(objs[i]);
174 ret = -EINVAL;
175 goto err_gem_object_put;
176 }
177 }
178
179 fb = drm_gem_fb_alloc(dev, mode_cmd, objs, i, funcs);
180 if (IS_ERR(fb)) {
181 ret = PTR_ERR(fb);
182 goto err_gem_object_put;
183 }
184
185 return fb;
186
187 err_gem_object_put:
188 for (i--; i >= 0; i--)
189 drm_gem_object_put_unlocked(objs[i]);
190
191 return ERR_PTR(ret);
192 }
193 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_funcs);
194
195 static const struct drm_framebuffer_funcs drm_gem_fb_funcs = {
196 .destroy = drm_gem_fb_destroy,
197 .create_handle = drm_gem_fb_create_handle,
198 };
199
200 /**
201 * drm_gem_fb_create() - Helper function for the
202 * &drm_mode_config_funcs.fb_create callback
203 * @dev: DRM device
204 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
205 * @mode_cmd: Metadata from the userspace framebuffer creation request
206 *
207 * This function creates a new framebuffer object described by
208 * &drm_mode_fb_cmd2. This description includes handles for the buffer(s)
209 * backing the framebuffer.
210 *
211 * If your hardware has special alignment or pitch requirements these should be
212 * checked before calling this function. The function does buffer size
213 * validation. Use drm_gem_fb_create_with_dirty() if you need framebuffer
214 * flushing.
215 *
216 * Drivers can use this as their &drm_mode_config_funcs.fb_create callback.
217 * The ADDFB2 IOCTL calls into this callback.
218 *
219 * Returns:
220 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
221 */
222 struct drm_framebuffer *
223 drm_gem_fb_create(struct drm_device *dev, struct drm_file *file,
224 const struct drm_mode_fb_cmd2 *mode_cmd)
225 {
226 return drm_gem_fb_create_with_funcs(dev, file, mode_cmd,
227 &drm_gem_fb_funcs);
228 }
229 EXPORT_SYMBOL_GPL(drm_gem_fb_create);
230
231 static const struct drm_framebuffer_funcs drm_gem_fb_funcs_dirtyfb = {
232 .destroy = drm_gem_fb_destroy,
233 .create_handle = drm_gem_fb_create_handle,
234 .dirty = drm_atomic_helper_dirtyfb,
235 };
236
237 /**
238 * drm_gem_fb_create_with_dirty() - Helper function for the
239 * &drm_mode_config_funcs.fb_create callback
240 * @dev: DRM device
241 * @file: DRM file that holds the GEM handle(s) backing the framebuffer
242 * @mode_cmd: Metadata from the userspace framebuffer creation request
243 *
244 * This function creates a new framebuffer object described by
245 * &drm_mode_fb_cmd2. This description includes handles for the buffer(s)
246 * backing the framebuffer. drm_atomic_helper_dirtyfb() is used for the dirty
247 * callback giving framebuffer flushing through the atomic machinery. Use
248 * drm_gem_fb_create() if you don't need the dirty callback.
249 * The function does buffer size validation.
250 *
251 * Drivers should also call drm_plane_enable_fb_damage_clips() on all planes
252 * to enable userspace to use damage clips also with the ATOMIC IOCTL.
253 *
254 * Drivers can use this as their &drm_mode_config_funcs.fb_create callback.
255 * The ADDFB2 IOCTL calls into this callback.
256 *
257 * Returns:
258 * Pointer to a &drm_framebuffer on success or an error pointer on failure.
259 */
260 struct drm_framebuffer *
261 drm_gem_fb_create_with_dirty(struct drm_device *dev, struct drm_file *file,
262 const struct drm_mode_fb_cmd2 *mode_cmd)
263 {
264 return drm_gem_fb_create_with_funcs(dev, file, mode_cmd,
265 &drm_gem_fb_funcs_dirtyfb);
266 }
267 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_dirty);
268
269 /**
270 * drm_gem_fb_prepare_fb() - Prepare a GEM backed framebuffer
271 * @plane: Plane
272 * @state: Plane state the fence will be attached to
273 *
274 * This function extracts the exclusive fence from &drm_gem_object.resv and
275 * attaches it to plane state for the atomic helper to wait on. This is
276 * necessary to correctly implement implicit synchronization for any buffers
277 * shared as a struct &dma_buf. This function can be used as the
278 * &drm_plane_helper_funcs.prepare_fb callback.
279 *
280 * There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple
281 * gem based framebuffer drivers which have their buffers always pinned in
282 * memory.
283 *
284 * See drm_atomic_set_fence_for_plane() for a discussion of implicit and
285 * explicit fencing in atomic modeset updates.
286 */
287 int drm_gem_fb_prepare_fb(struct drm_plane *plane,
288 struct drm_plane_state *state)
289 {
290 struct drm_gem_object *obj;
291 struct dma_fence *fence;
292
293 if (!state->fb)
294 return 0;
295
296 obj = drm_gem_fb_get_obj(state->fb, 0);
297 fence = dma_resv_get_excl_rcu(obj->resv);
298 drm_atomic_set_fence_for_plane(state, fence);
299
300 return 0;
301 }
302 EXPORT_SYMBOL_GPL(drm_gem_fb_prepare_fb);
303
304 /**
305 * drm_gem_fb_simple_display_pipe_prepare_fb - prepare_fb helper for
306 * &drm_simple_display_pipe
307 * @pipe: Simple display pipe
308 * @plane_state: Plane state
309 *
310 * This function uses drm_gem_fb_prepare_fb() to extract the exclusive fence
311 * from &drm_gem_object.resv and attaches it to plane state for the atomic
312 * helper to wait on. This is necessary to correctly implement implicit
313 * synchronization for any buffers shared as a struct &dma_buf. Drivers can use
314 * this as their &drm_simple_display_pipe_funcs.prepare_fb callback.
315 *
316 * See drm_atomic_set_fence_for_plane() for a discussion of implicit and
317 * explicit fencing in atomic modeset updates.
318 */
319 int drm_gem_fb_simple_display_pipe_prepare_fb(struct drm_simple_display_pipe *pipe,
320 struct drm_plane_state *plane_state)
321 {
322 return drm_gem_fb_prepare_fb(&pipe->plane, plane_state);
323 }
324 EXPORT_SYMBOL(drm_gem_fb_simple_display_pipe_prepare_fb);