1 /*
2 * drm gem CMA (contiguous memory allocator) helper functions
3 *
4 * Copyright (C) 2012 Sascha Hauer, Pengutronix
5 *
6 * Based on Samsung Exynos code
7 *
8 * Copyright (c) 2011 Samsung Electronics Co., Ltd.
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version 2
13 * of the License, or (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 */
19
20 #include <linux/mm.h>
21 #include <linux/slab.h>
22 #include <linux/mutex.h>
23 #include <linux/export.h>
24 #include <linux/dma-buf.h>
25 #include <linux/dma-mapping.h>
26
27 #include <drm/drmP.h>
28 #include <drm/drm.h>
29 #include <drm/drm_gem_cma_helper.h>
30 #include <drm/drm_vma_manager.h>
31
32 /**
33 * DOC: cma helpers
34 *
35 * The Contiguous Memory Allocator reserves a pool of memory at early boot
36 * that is used to service requests for large blocks of contiguous memory.
37 *
38 * The DRM GEM/CMA helpers use this allocator as a means to provide buffer
39 * objects that are physically contiguous in memory. This is useful for
40 * display drivers that are unable to map scattered buffers via an IOMMU.
41 */
42
43 /**
44 * __drm_gem_cma_create - Create a GEM CMA object without allocating memory
45 * @drm: DRM device
46 * @size: size of the object to allocate
47 *
48 * This function creates and initializes a GEM CMA object of the given size,
49 * but doesn't allocate any memory to back the object.
50 *
51 * Returns:
52 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
53 * error code on failure.
54 */
55 static struct drm_gem_cma_object *
__drm_gem_cma_create(struct drm_device * drm,size_t size)56 __drm_gem_cma_create(struct drm_device *drm, size_t size)
57 {
58 struct drm_gem_cma_object *cma_obj;
59 struct drm_gem_object *gem_obj;
60 int ret;
61
62 cma_obj = kzalloc(sizeof(*cma_obj), GFP_KERNEL);
63 if (!cma_obj)
64 return ERR_PTR(-ENOMEM);
65
66 gem_obj = &cma_obj->base;
67
68 ret = drm_gem_object_init(drm, gem_obj, size);
69 if (ret)
70 goto error;
71
72 ret = drm_gem_create_mmap_offset(gem_obj);
73 if (ret) {
74 drm_gem_object_release(gem_obj);
75 goto error;
76 }
77
78 return cma_obj;
79
80 error:
81 kfree(cma_obj);
82 return ERR_PTR(ret);
83 }
84
85 /**
86 * drm_gem_cma_create - allocate an object with the given size
87 * @drm: DRM device
88 * @size: size of the object to allocate
89 *
90 * This function creates a CMA GEM object and allocates a contiguous chunk of
91 * memory as backing store. The backing memory has the writecombine attribute
92 * set.
93 *
94 * Returns:
95 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
96 * error code on failure.
97 */
drm_gem_cma_create(struct drm_device * drm,size_t size)98 struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
99 size_t size)
100 {
101 struct drm_gem_cma_object *cma_obj;
102 int ret;
103
104 size = round_up(size, PAGE_SIZE);
105
106 cma_obj = __drm_gem_cma_create(drm, size);
107 if (IS_ERR(cma_obj))
108 return cma_obj;
109
110 cma_obj->vaddr = dma_alloc_writecombine(drm->dev, size,
111 &cma_obj->paddr, GFP_KERNEL | __GFP_NOWARN);
112 if (!cma_obj->vaddr) {
113 dev_err(drm->dev, "failed to allocate buffer with size %zu\n",
114 size);
115 ret = -ENOMEM;
116 goto error;
117 }
118
119 return cma_obj;
120
121 error:
122 drm_gem_cma_free_object(&cma_obj->base);
123 return ERR_PTR(ret);
124 }
125 EXPORT_SYMBOL_GPL(drm_gem_cma_create);
126
127 /**
128 * drm_gem_cma_create_with_handle - allocate an object with the given size and
129 * return a GEM handle to it
130 * @file_priv: DRM file-private structure to register the handle for
131 * @drm: DRM device
132 * @size: size of the object to allocate
133 * @handle: return location for the GEM handle
134 *
135 * This function creates a CMA GEM object, allocating a physically contiguous
136 * chunk of memory as backing store. The GEM object is then added to the list
137 * of object associated with the given file and a handle to it is returned.
138 *
139 * Returns:
140 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
141 * error code on failure.
142 */
143 static struct drm_gem_cma_object *
drm_gem_cma_create_with_handle(struct drm_file * file_priv,struct drm_device * drm,size_t size,uint32_t * handle)144 drm_gem_cma_create_with_handle(struct drm_file *file_priv,
145 struct drm_device *drm, size_t size,
146 uint32_t *handle)
147 {
148 struct drm_gem_cma_object *cma_obj;
149 struct drm_gem_object *gem_obj;
150 int ret;
151
152 cma_obj = drm_gem_cma_create(drm, size);
153 if (IS_ERR(cma_obj))
154 return cma_obj;
155
156 gem_obj = &cma_obj->base;
157
158 /*
159 * allocate a id of idr table where the obj is registered
160 * and handle has the id what user can see.
161 */
162 ret = drm_gem_handle_create(file_priv, gem_obj, handle);
163 if (ret)
164 goto err_handle_create;
165
166 /* drop reference from allocate - handle holds it now. */
167 drm_gem_object_unreference_unlocked(gem_obj);
168
169 return cma_obj;
170
171 err_handle_create:
172 drm_gem_cma_free_object(gem_obj);
173
174 return ERR_PTR(ret);
175 }
176
177 /**
178 * drm_gem_cma_free_object - free resources associated with a CMA GEM object
179 * @gem_obj: GEM object to free
180 *
181 * This function frees the backing memory of the CMA GEM object, cleans up the
182 * GEM object state and frees the memory used to store the object itself.
183 * Drivers using the CMA helpers should set this as their DRM driver's
184 * ->gem_free_object() callback.
185 */
drm_gem_cma_free_object(struct drm_gem_object * gem_obj)186 void drm_gem_cma_free_object(struct drm_gem_object *gem_obj)
187 {
188 struct drm_gem_cma_object *cma_obj;
189
190 cma_obj = to_drm_gem_cma_obj(gem_obj);
191
192 if (cma_obj->vaddr) {
193 dma_free_writecombine(gem_obj->dev->dev, cma_obj->base.size,
194 cma_obj->vaddr, cma_obj->paddr);
195 } else if (gem_obj->import_attach) {
196 drm_prime_gem_destroy(gem_obj, cma_obj->sgt);
197 }
198
199 drm_gem_object_release(gem_obj);
200
201 kfree(cma_obj);
202 }
203 EXPORT_SYMBOL_GPL(drm_gem_cma_free_object);
204
205 /**
206 * drm_gem_cma_dumb_create_internal - create a dumb buffer object
207 * @file_priv: DRM file-private structure to create the dumb buffer for
208 * @drm: DRM device
209 * @args: IOCTL data
210 *
211 * This aligns the pitch and size arguments to the minimum required. This is
212 * an internal helper that can be wrapped by a driver to account for hardware
213 * with more specific alignment requirements. It should not be used directly
214 * as the ->dumb_create() callback in a DRM driver.
215 *
216 * Returns:
217 * 0 on success or a negative error code on failure.
218 */
drm_gem_cma_dumb_create_internal(struct drm_file * file_priv,struct drm_device * drm,struct drm_mode_create_dumb * args)219 int drm_gem_cma_dumb_create_internal(struct drm_file *file_priv,
220 struct drm_device *drm,
221 struct drm_mode_create_dumb *args)
222 {
223 unsigned int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
224 struct drm_gem_cma_object *cma_obj;
225
226 if (args->pitch < min_pitch)
227 args->pitch = min_pitch;
228
229 if (args->size < args->pitch * args->height)
230 args->size = args->pitch * args->height;
231
232 cma_obj = drm_gem_cma_create_with_handle(file_priv, drm, args->size,
233 &args->handle);
234 return PTR_ERR_OR_ZERO(cma_obj);
235 }
236 EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_create_internal);
237
238 /**
239 * drm_gem_cma_dumb_create - create a dumb buffer object
240 * @file_priv: DRM file-private structure to create the dumb buffer for
241 * @drm: DRM device
242 * @args: IOCTL data
243 *
244 * This function computes the pitch of the dumb buffer and rounds it up to an
245 * integer number of bytes per pixel. Drivers for hardware that doesn't have
246 * any additional restrictions on the pitch can directly use this function as
247 * their ->dumb_create() callback.
248 *
249 * For hardware with additional restrictions, drivers can adjust the fields
250 * set up by userspace and pass the IOCTL data along to the
251 * drm_gem_cma_dumb_create_internal() function.
252 *
253 * Returns:
254 * 0 on success or a negative error code on failure.
255 */
drm_gem_cma_dumb_create(struct drm_file * file_priv,struct drm_device * drm,struct drm_mode_create_dumb * args)256 int drm_gem_cma_dumb_create(struct drm_file *file_priv,
257 struct drm_device *drm,
258 struct drm_mode_create_dumb *args)
259 {
260 struct drm_gem_cma_object *cma_obj;
261
262 args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
263 args->size = args->pitch * args->height;
264
265 cma_obj = drm_gem_cma_create_with_handle(file_priv, drm, args->size,
266 &args->handle);
267 return PTR_ERR_OR_ZERO(cma_obj);
268 }
269 EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_create);
270
271 /**
272 * drm_gem_cma_dumb_map_offset - return the fake mmap offset for a CMA GEM
273 * object
274 * @file_priv: DRM file-private structure containing the GEM object
275 * @drm: DRM device
276 * @handle: GEM object handle
277 * @offset: return location for the fake mmap offset
278 *
279 * This function look up an object by its handle and returns the fake mmap
280 * offset associated with it. Drivers using the CMA helpers should set this
281 * as their DRM driver's ->dumb_map_offset() callback.
282 *
283 * Returns:
284 * 0 on success or a negative error code on failure.
285 */
drm_gem_cma_dumb_map_offset(struct drm_file * file_priv,struct drm_device * drm,u32 handle,u64 * offset)286 int drm_gem_cma_dumb_map_offset(struct drm_file *file_priv,
287 struct drm_device *drm, u32 handle,
288 u64 *offset)
289 {
290 struct drm_gem_object *gem_obj;
291
292 gem_obj = drm_gem_object_lookup(drm, file_priv, handle);
293 if (!gem_obj) {
294 dev_err(drm->dev, "failed to lookup GEM object\n");
295 return -EINVAL;
296 }
297
298 *offset = drm_vma_node_offset_addr(&gem_obj->vma_node);
299
300 drm_gem_object_unreference_unlocked(gem_obj);
301
302 return 0;
303 }
304 EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_map_offset);
305
306 const struct vm_operations_struct drm_gem_cma_vm_ops = {
307 .open = drm_gem_vm_open,
308 .close = drm_gem_vm_close,
309 };
310 EXPORT_SYMBOL_GPL(drm_gem_cma_vm_ops);
311
drm_gem_cma_mmap_obj(struct drm_gem_cma_object * cma_obj,struct vm_area_struct * vma)312 static int drm_gem_cma_mmap_obj(struct drm_gem_cma_object *cma_obj,
313 struct vm_area_struct *vma)
314 {
315 int ret;
316
317 /*
318 * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
319 * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map
320 * the whole buffer.
321 */
322 vma->vm_flags &= ~VM_PFNMAP;
323 vma->vm_pgoff = 0;
324
325 ret = dma_mmap_writecombine(cma_obj->base.dev->dev, vma,
326 cma_obj->vaddr, cma_obj->paddr,
327 vma->vm_end - vma->vm_start);
328 if (ret)
329 drm_gem_vm_close(vma);
330
331 return ret;
332 }
333
334 /**
335 * drm_gem_cma_mmap - memory-map a CMA GEM object
336 * @filp: file object
337 * @vma: VMA for the area to be mapped
338 *
339 * This function implements an augmented version of the GEM DRM file mmap
340 * operation for CMA objects: In addition to the usual GEM VMA setup it
341 * immediately faults in the entire object instead of using on-demaind
342 * faulting. Drivers which employ the CMA helpers should use this function
343 * as their ->mmap() handler in the DRM device file's file_operations
344 * structure.
345 *
346 * Returns:
347 * 0 on success or a negative error code on failure.
348 */
drm_gem_cma_mmap(struct file * filp,struct vm_area_struct * vma)349 int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
350 {
351 struct drm_gem_cma_object *cma_obj;
352 struct drm_gem_object *gem_obj;
353 int ret;
354
355 ret = drm_gem_mmap(filp, vma);
356 if (ret)
357 return ret;
358
359 gem_obj = vma->vm_private_data;
360 cma_obj = to_drm_gem_cma_obj(gem_obj);
361
362 return drm_gem_cma_mmap_obj(cma_obj, vma);
363 }
364 EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
365
366 #ifdef CONFIG_DEBUG_FS
367 /**
368 * drm_gem_cma_describe - describe a CMA GEM object for debugfs
369 * @cma_obj: CMA GEM object
370 * @m: debugfs file handle
371 *
372 * This function can be used to dump a human-readable representation of the
373 * CMA GEM object into a synthetic file.
374 */
drm_gem_cma_describe(struct drm_gem_cma_object * cma_obj,struct seq_file * m)375 void drm_gem_cma_describe(struct drm_gem_cma_object *cma_obj,
376 struct seq_file *m)
377 {
378 struct drm_gem_object *obj = &cma_obj->base;
379 uint64_t off;
380
381 off = drm_vma_node_start(&obj->vma_node);
382
383 seq_printf(m, "%2d (%2d) %08llx %pad %p %zu",
384 obj->name, obj->refcount.refcount.counter,
385 off, &cma_obj->paddr, cma_obj->vaddr, obj->size);
386
387 seq_printf(m, "\n");
388 }
389 EXPORT_SYMBOL_GPL(drm_gem_cma_describe);
390 #endif
391
392 /**
393 * drm_gem_cma_prime_get_sg_table - provide a scatter/gather table of pinned
394 * pages for a CMA GEM object
395 * @obj: GEM object
396 *
397 * This function exports a scatter/gather table suitable for PRIME usage by
398 * calling the standard DMA mapping API. Drivers using the CMA helpers should
399 * set this as their DRM driver's ->gem_prime_get_sg_table() callback.
400 *
401 * Returns:
402 * A pointer to the scatter/gather table of pinned pages or NULL on failure.
403 */
drm_gem_cma_prime_get_sg_table(struct drm_gem_object * obj)404 struct sg_table *drm_gem_cma_prime_get_sg_table(struct drm_gem_object *obj)
405 {
406 struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
407 struct sg_table *sgt;
408 int ret;
409
410 sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
411 if (!sgt)
412 return NULL;
413
414 ret = dma_get_sgtable(obj->dev->dev, sgt, cma_obj->vaddr,
415 cma_obj->paddr, obj->size);
416 if (ret < 0)
417 goto out;
418
419 return sgt;
420
421 out:
422 kfree(sgt);
423 return NULL;
424 }
425 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_get_sg_table);
426
427 /**
428 * drm_gem_cma_prime_import_sg_table - produce a CMA GEM object from another
429 * driver's scatter/gather table of pinned pages
430 * @dev: device to import into
431 * @attach: DMA-BUF attachment
432 * @sgt: scatter/gather table of pinned pages
433 *
434 * This function imports a scatter/gather table exported via DMA-BUF by
435 * another driver. Imported buffers must be physically contiguous in memory
436 * (i.e. the scatter/gather table must contain a single entry). Drivers that
437 * use the CMA helpers should set this as their DRM driver's
438 * ->gem_prime_import_sg_table() callback.
439 *
440 * Returns:
441 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
442 * error code on failure.
443 */
444 struct drm_gem_object *
drm_gem_cma_prime_import_sg_table(struct drm_device * dev,struct dma_buf_attachment * attach,struct sg_table * sgt)445 drm_gem_cma_prime_import_sg_table(struct drm_device *dev,
446 struct dma_buf_attachment *attach,
447 struct sg_table *sgt)
448 {
449 struct drm_gem_cma_object *cma_obj;
450
451 if (sgt->nents != 1)
452 return ERR_PTR(-EINVAL);
453
454 /* Create a CMA GEM buffer. */
455 cma_obj = __drm_gem_cma_create(dev, attach->dmabuf->size);
456 if (IS_ERR(cma_obj))
457 return ERR_CAST(cma_obj);
458
459 cma_obj->paddr = sg_dma_address(sgt->sgl);
460 cma_obj->sgt = sgt;
461
462 DRM_DEBUG_PRIME("dma_addr = %pad, size = %zu\n", &cma_obj->paddr, attach->dmabuf->size);
463
464 return &cma_obj->base;
465 }
466 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_import_sg_table);
467
468 /**
469 * drm_gem_cma_prime_mmap - memory-map an exported CMA GEM object
470 * @obj: GEM object
471 * @vma: VMA for the area to be mapped
472 *
473 * This function maps a buffer imported via DRM PRIME into a userspace
474 * process's address space. Drivers that use the CMA helpers should set this
475 * as their DRM driver's ->gem_prime_mmap() callback.
476 *
477 * Returns:
478 * 0 on success or a negative error code on failure.
479 */
drm_gem_cma_prime_mmap(struct drm_gem_object * obj,struct vm_area_struct * vma)480 int drm_gem_cma_prime_mmap(struct drm_gem_object *obj,
481 struct vm_area_struct *vma)
482 {
483 struct drm_gem_cma_object *cma_obj;
484 int ret;
485
486 ret = drm_gem_mmap_obj(obj, obj->size, vma);
487 if (ret < 0)
488 return ret;
489
490 cma_obj = to_drm_gem_cma_obj(obj);
491 return drm_gem_cma_mmap_obj(cma_obj, vma);
492 }
493 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_mmap);
494
495 /**
496 * drm_gem_cma_prime_vmap - map a CMA GEM object into the kernel's virtual
497 * address space
498 * @obj: GEM object
499 *
500 * This function maps a buffer exported via DRM PRIME into the kernel's
501 * virtual address space. Since the CMA buffers are already mapped into the
502 * kernel virtual address space this simply returns the cached virtual
503 * address. Drivers using the CMA helpers should set this as their DRM
504 * driver's ->gem_prime_vmap() callback.
505 *
506 * Returns:
507 * The kernel virtual address of the CMA GEM object's backing store.
508 */
drm_gem_cma_prime_vmap(struct drm_gem_object * obj)509 void *drm_gem_cma_prime_vmap(struct drm_gem_object *obj)
510 {
511 struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
512
513 return cma_obj->vaddr;
514 }
515 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_vmap);
516
517 /**
518 * drm_gem_cma_prime_vunmap - unmap a CMA GEM object from the kernel's virtual
519 * address space
520 * @obj: GEM object
521 * @vaddr: kernel virtual address where the CMA GEM object was mapped
522 *
523 * This function removes a buffer exported via DRM PRIME from the kernel's
524 * virtual address space. This is a no-op because CMA buffers cannot be
525 * unmapped from kernel space. Drivers using the CMA helpers should set this
526 * as their DRM driver's ->gem_prime_vunmap() callback.
527 */
drm_gem_cma_prime_vunmap(struct drm_gem_object * obj,void * vaddr)528 void drm_gem_cma_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
529 {
530 /* Nothing to do */
531 }
532 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_vunmap);
533