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 */
 47struct 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}
 55EXPORT_SYMBOL_GPL(drm_gem_fb_get_obj);
 56
 57static struct drm_framebuffer *
 58drm_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 */
 94void 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}
104EXPORT_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 */
119int 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}
124EXPORT_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 */
142struct drm_framebuffer *
143drm_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
187err_gem_object_put:
188	for (i--; i >= 0; i--)
189		drm_gem_object_put_unlocked(objs[i]);
190
191	return ERR_PTR(ret);
192}
193EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_funcs);
194
195static 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 */
222struct drm_framebuffer *
223drm_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}
229EXPORT_SYMBOL_GPL(drm_gem_fb_create);
230
231static 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 */
260struct drm_framebuffer *
261drm_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}
267EXPORT_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 */
287int 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}
302EXPORT_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 */
319int 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}
324EXPORT_SYMBOL(drm_gem_fb_simple_display_pipe_prepare_fb);