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 */
 49struct 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}
 57EXPORT_SYMBOL_GPL(drm_gem_fb_get_obj);
 58
 59static struct drm_framebuffer *
 60drm_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 */
 96void 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}
106EXPORT_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 */
121int 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}
126EXPORT_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 */
145struct drm_framebuffer *
146drm_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
190err_gem_object_put:
191	for (i--; i >= 0; i--)
192		drm_gem_object_put_unlocked(objs[i]);
193
194	return ERR_PTR(ret);
195}
196EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_funcs);
197
198static 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 */
225struct drm_framebuffer *
226drm_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}
232EXPORT_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 */
249int 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}
266EXPORT_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 */
284struct drm_framebuffer *
285drm_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}
309EXPORT_SYMBOL(drm_gem_fbdev_fb_create);