1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * drm gem CMA (contiguous memory allocator) helper functions
5 * Copyright (C) 2012 Sascha Hauer, Pengutronix
7 * Based on Samsung Exynos code
9 * Copyright (c) 2011 Samsung Electronics Co., Ltd.
12 #include <linux/dma-buf.h>
13 #include <linux/dma-mapping.h>
14 #include <linux/export.h>
16 #include <linux/mutex.h>
17 #include <linux/slab.h>
20 #include <drm/drm_device.h>
21 #include <drm/drm_drv.h>
22 #include <drm/drm_gem_cma_helper.h>
23 #include <drm/drm_vma_manager.h>
28 * The Contiguous Memory Allocator reserves a pool of memory at early boot
29 * that is used to service requests for large blocks of contiguous memory.
31 * The DRM GEM/CMA helpers use this allocator as a means to provide buffer
32 * objects that are physically contiguous in memory. This is useful for
33 * display drivers that are unable to map scattered buffers via an IOMMU.
36 static const struct drm_gem_object_funcs drm_gem_cma_default_funcs = {
37 .free = drm_gem_cma_free_object,
38 .print_info = drm_gem_cma_print_info,
39 .get_sg_table = drm_gem_cma_get_sg_table,
40 .vmap = drm_gem_cma_vmap,
41 .mmap = drm_gem_cma_mmap,
42 .vm_ops = &drm_gem_cma_vm_ops,
46 * __drm_gem_cma_create - Create a GEM CMA object without allocating memory
48 * @size: size of the object to allocate
49 * @private: true if used for internal purposes
51 * This function creates and initializes a GEM CMA object of the given size,
52 * but doesn't allocate any memory to back the object.
55 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
56 * error code on failure.
58 static struct drm_gem_cma_object *
59 __drm_gem_cma_create(struct drm_device *drm, size_t size, bool private)
61 struct drm_gem_cma_object *cma_obj;
62 struct drm_gem_object *gem_obj;
65 if (drm->driver->gem_create_object)
66 gem_obj = drm->driver->gem_create_object(drm, size);
68 gem_obj = kzalloc(sizeof(*cma_obj), GFP_KERNEL);
70 return ERR_PTR(-ENOMEM);
73 gem_obj->funcs = &drm_gem_cma_default_funcs;
75 cma_obj = container_of(gem_obj, struct drm_gem_cma_object, base);
78 drm_gem_private_object_init(drm, gem_obj, size);
80 /* Always use writecombine for dma-buf mappings */
81 cma_obj->map_noncoherent = false;
83 ret = drm_gem_object_init(drm, gem_obj, size);
88 ret = drm_gem_create_mmap_offset(gem_obj);
90 drm_gem_object_release(gem_obj);
102 * drm_gem_cma_create - allocate an object with the given size
104 * @size: size of the object to allocate
106 * This function creates a CMA GEM object and allocates a contiguous chunk of
107 * memory as backing store.
110 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
111 * error code on failure.
113 struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
116 struct drm_gem_cma_object *cma_obj;
119 size = round_up(size, PAGE_SIZE);
121 cma_obj = __drm_gem_cma_create(drm, size, false);
125 if (cma_obj->map_noncoherent) {
126 cma_obj->vaddr = dma_alloc_noncoherent(drm->dev, size,
129 GFP_KERNEL | __GFP_NOWARN);
131 cma_obj->vaddr = dma_alloc_wc(drm->dev, size, &cma_obj->paddr,
132 GFP_KERNEL | __GFP_NOWARN);
134 if (!cma_obj->vaddr) {
135 drm_dbg(drm, "failed to allocate buffer with size %zu\n",
144 drm_gem_object_put(&cma_obj->base);
147 EXPORT_SYMBOL_GPL(drm_gem_cma_create);
150 * drm_gem_cma_create_with_handle - allocate an object with the given size and
151 * return a GEM handle to it
152 * @file_priv: DRM file-private structure to register the handle for
154 * @size: size of the object to allocate
155 * @handle: return location for the GEM handle
157 * This function creates a CMA GEM object, allocating a physically contiguous
158 * chunk of memory as backing store. The GEM object is then added to the list
159 * of object associated with the given file and a handle to it is returned.
162 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
163 * error code on failure.
165 static struct drm_gem_cma_object *
166 drm_gem_cma_create_with_handle(struct drm_file *file_priv,
167 struct drm_device *drm, size_t size,
170 struct drm_gem_cma_object *cma_obj;
171 struct drm_gem_object *gem_obj;
174 cma_obj = drm_gem_cma_create(drm, size);
178 gem_obj = &cma_obj->base;
181 * allocate a id of idr table where the obj is registered
182 * and handle has the id what user can see.
184 ret = drm_gem_handle_create(file_priv, gem_obj, handle);
185 /* drop reference from allocate - handle holds it now. */
186 drm_gem_object_put(gem_obj);
194 * drm_gem_cma_free_object - free resources associated with a CMA GEM object
195 * @gem_obj: GEM object to free
197 * This function frees the backing memory of the CMA GEM object, cleans up the
198 * GEM object state and frees the memory used to store the object itself.
199 * If the buffer is imported and the virtual address is set, it is released.
200 * Drivers using the CMA helpers should set this as their
201 * &drm_gem_object_funcs.free callback.
203 void drm_gem_cma_free_object(struct drm_gem_object *gem_obj)
205 struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(gem_obj);
206 struct dma_buf_map map = DMA_BUF_MAP_INIT_VADDR(cma_obj->vaddr);
208 if (gem_obj->import_attach) {
210 dma_buf_vunmap(gem_obj->import_attach->dmabuf, &map);
211 drm_prime_gem_destroy(gem_obj, cma_obj->sgt);
212 } else if (cma_obj->vaddr) {
213 dma_free_wc(gem_obj->dev->dev, cma_obj->base.size,
214 cma_obj->vaddr, cma_obj->paddr);
217 drm_gem_object_release(gem_obj);
221 EXPORT_SYMBOL_GPL(drm_gem_cma_free_object);
224 * drm_gem_cma_dumb_create_internal - create a dumb buffer object
225 * @file_priv: DRM file-private structure to create the dumb buffer for
229 * This aligns the pitch and size arguments to the minimum required. This is
230 * an internal helper that can be wrapped by a driver to account for hardware
231 * with more specific alignment requirements. It should not be used directly
232 * as their &drm_driver.dumb_create callback.
235 * 0 on success or a negative error code on failure.
237 int drm_gem_cma_dumb_create_internal(struct drm_file *file_priv,
238 struct drm_device *drm,
239 struct drm_mode_create_dumb *args)
241 unsigned int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
242 struct drm_gem_cma_object *cma_obj;
244 if (args->pitch < min_pitch)
245 args->pitch = min_pitch;
247 if (args->size < args->pitch * args->height)
248 args->size = args->pitch * args->height;
250 cma_obj = drm_gem_cma_create_with_handle(file_priv, drm, args->size,
252 return PTR_ERR_OR_ZERO(cma_obj);
254 EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_create_internal);
257 * drm_gem_cma_dumb_create - create a dumb buffer object
258 * @file_priv: DRM file-private structure to create the dumb buffer for
262 * This function computes the pitch of the dumb buffer and rounds it up to an
263 * integer number of bytes per pixel. Drivers for hardware that doesn't have
264 * any additional restrictions on the pitch can directly use this function as
265 * their &drm_driver.dumb_create callback.
267 * For hardware with additional restrictions, drivers can adjust the fields
268 * set up by userspace and pass the IOCTL data along to the
269 * drm_gem_cma_dumb_create_internal() function.
272 * 0 on success or a negative error code on failure.
274 int drm_gem_cma_dumb_create(struct drm_file *file_priv,
275 struct drm_device *drm,
276 struct drm_mode_create_dumb *args)
278 struct drm_gem_cma_object *cma_obj;
280 args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
281 args->size = args->pitch * args->height;
283 cma_obj = drm_gem_cma_create_with_handle(file_priv, drm, args->size,
285 return PTR_ERR_OR_ZERO(cma_obj);
287 EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_create);
289 const struct vm_operations_struct drm_gem_cma_vm_ops = {
290 .open = drm_gem_vm_open,
291 .close = drm_gem_vm_close,
293 EXPORT_SYMBOL_GPL(drm_gem_cma_vm_ops);
297 * drm_gem_cma_get_unmapped_area - propose address for mapping in noMMU cases
299 * @addr: memory address
301 * @pgoff: page offset
302 * @flags: memory flags
304 * This function is used in noMMU platforms to propose address mapping
305 * for a given buffer.
306 * It's intended to be used as a direct handler for the struct
307 * &file_operations.get_unmapped_area operation.
310 * mapping address on success or a negative error code on failure.
312 unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
318 struct drm_gem_cma_object *cma_obj;
319 struct drm_gem_object *obj = NULL;
320 struct drm_file *priv = filp->private_data;
321 struct drm_device *dev = priv->minor->dev;
322 struct drm_vma_offset_node *node;
324 if (drm_dev_is_unplugged(dev))
327 drm_vma_offset_lock_lookup(dev->vma_offset_manager);
328 node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
332 obj = container_of(node, struct drm_gem_object, vma_node);
334 * When the object is being freed, after it hits 0-refcnt it
335 * proceeds to tear down the object. In the process it will
336 * attempt to remove the VMA offset and so acquire this
337 * mgr->vm_lock. Therefore if we find an object with a 0-refcnt
338 * that matches our range, we know it is in the process of being
339 * destroyed and will be freed as soon as we release the lock -
340 * so we have to check for the 0-refcnted object and treat it as
343 if (!kref_get_unless_zero(&obj->refcount))
347 drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
352 if (!drm_vma_node_is_allowed(node, priv)) {
353 drm_gem_object_put(obj);
357 cma_obj = to_drm_gem_cma_obj(obj);
359 drm_gem_object_put(obj);
361 return cma_obj->vaddr ? (unsigned long)cma_obj->vaddr : -EINVAL;
363 EXPORT_SYMBOL_GPL(drm_gem_cma_get_unmapped_area);
367 * drm_gem_cma_print_info() - Print &drm_gem_cma_object info for debugfs
369 * @indent: Tab indentation level
372 * This function can be used as the &drm_driver->gem_print_info callback.
373 * It prints paddr and vaddr for use in e.g. debugfs output.
375 void drm_gem_cma_print_info(struct drm_printer *p, unsigned int indent,
376 const struct drm_gem_object *obj)
378 const struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
380 drm_printf_indent(p, indent, "paddr=%pad\n", &cma_obj->paddr);
381 drm_printf_indent(p, indent, "vaddr=%p\n", cma_obj->vaddr);
383 EXPORT_SYMBOL(drm_gem_cma_print_info);
386 * drm_gem_cma_get_sg_table - provide a scatter/gather table of pinned
387 * pages for a CMA GEM object
390 * This function exports a scatter/gather table by
391 * calling the standard DMA mapping API. Drivers using the CMA helpers should
392 * set this as their &drm_gem_object_funcs.get_sg_table callback.
395 * A pointer to the scatter/gather table of pinned pages or NULL on failure.
397 struct sg_table *drm_gem_cma_get_sg_table(struct drm_gem_object *obj)
399 struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
400 struct sg_table *sgt;
403 sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
405 return ERR_PTR(-ENOMEM);
407 ret = dma_get_sgtable(obj->dev->dev, sgt, cma_obj->vaddr,
408 cma_obj->paddr, obj->size);
418 EXPORT_SYMBOL_GPL(drm_gem_cma_get_sg_table);
421 * drm_gem_cma_prime_import_sg_table - produce a CMA GEM object from another
422 * driver's scatter/gather table of pinned pages
423 * @dev: device to import into
424 * @attach: DMA-BUF attachment
425 * @sgt: scatter/gather table of pinned pages
427 * This function imports a scatter/gather table exported via DMA-BUF by
428 * another driver. Imported buffers must be physically contiguous in memory
429 * (i.e. the scatter/gather table must contain a single entry). Drivers that
430 * use the CMA helpers should set this as their
431 * &drm_driver.gem_prime_import_sg_table callback.
434 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
435 * error code on failure.
437 struct drm_gem_object *
438 drm_gem_cma_prime_import_sg_table(struct drm_device *dev,
439 struct dma_buf_attachment *attach,
440 struct sg_table *sgt)
442 struct drm_gem_cma_object *cma_obj;
444 /* check if the entries in the sg_table are contiguous */
445 if (drm_prime_get_contiguous_size(sgt) < attach->dmabuf->size)
446 return ERR_PTR(-EINVAL);
448 /* Create a CMA GEM buffer. */
449 cma_obj = __drm_gem_cma_create(dev, attach->dmabuf->size, true);
451 return ERR_CAST(cma_obj);
453 cma_obj->paddr = sg_dma_address(sgt->sgl);
456 DRM_DEBUG_PRIME("dma_addr = %pad, size = %zu\n", &cma_obj->paddr, attach->dmabuf->size);
458 return &cma_obj->base;
460 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_import_sg_table);
463 * drm_gem_cma_vmap - map a CMA GEM object into the kernel's virtual
466 * @map: Returns the kernel virtual address of the CMA GEM object's backing
469 * This function maps a buffer into the kernel's
470 * virtual address space. Since the CMA buffers are already mapped into the
471 * kernel virtual address space this simply returns the cached virtual
472 * address. Drivers using the CMA helpers should set this as their DRM
473 * driver's &drm_gem_object_funcs.vmap callback.
476 * 0 on success, or a negative error code otherwise.
478 int drm_gem_cma_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
480 struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
482 dma_buf_map_set_vaddr(map, cma_obj->vaddr);
486 EXPORT_SYMBOL_GPL(drm_gem_cma_vmap);
489 * drm_gem_cma_mmap - memory-map an exported CMA GEM object
491 * @vma: VMA for the area to be mapped
493 * This function maps a buffer into a userspace process's address space.
494 * In addition to the usual GEM VMA setup it immediately faults in the entire
495 * object instead of using on-demand faulting. Drivers that use the CMA
496 * helpers should set this as their &drm_gem_object_funcs.mmap callback.
499 * 0 on success or a negative error code on failure.
501 int drm_gem_cma_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
503 struct drm_gem_cma_object *cma_obj;
507 * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
508 * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map
511 vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);
512 vma->vm_flags &= ~VM_PFNMAP;
514 cma_obj = to_drm_gem_cma_obj(obj);
516 if (cma_obj->map_noncoherent) {
517 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
519 ret = dma_mmap_pages(cma_obj->base.dev->dev,
520 vma, vma->vm_end - vma->vm_start,
521 virt_to_page(cma_obj->vaddr));
523 ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
524 cma_obj->paddr, vma->vm_end - vma->vm_start);
527 drm_gem_vm_close(vma);
531 EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
534 * drm_gem_cma_prime_import_sg_table_vmap - PRIME import another driver's
535 * scatter/gather table and get the virtual address of the buffer
537 * @attach: DMA-BUF attachment
538 * @sgt: Scatter/gather table of pinned pages
540 * This function imports a scatter/gather table using
541 * drm_gem_cma_prime_import_sg_table() and uses dma_buf_vmap() to get the kernel
542 * virtual address. This ensures that a CMA GEM object always has its virtual
543 * address set. This address is released when the object is freed.
545 * This function can be used as the &drm_driver.gem_prime_import_sg_table
546 * callback. The &DRM_GEM_CMA_DRIVER_OPS_VMAP macro provides a shortcut to set
547 * the necessary DRM driver operations.
550 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
551 * error code on failure.
553 struct drm_gem_object *
554 drm_gem_cma_prime_import_sg_table_vmap(struct drm_device *dev,
555 struct dma_buf_attachment *attach,
556 struct sg_table *sgt)
558 struct drm_gem_cma_object *cma_obj;
559 struct drm_gem_object *obj;
560 struct dma_buf_map map;
563 ret = dma_buf_vmap(attach->dmabuf, &map);
565 DRM_ERROR("Failed to vmap PRIME buffer\n");
569 obj = drm_gem_cma_prime_import_sg_table(dev, attach, sgt);
571 dma_buf_vunmap(attach->dmabuf, &map);
575 cma_obj = to_drm_gem_cma_obj(obj);
576 cma_obj->vaddr = map.vaddr;
580 EXPORT_SYMBOL(drm_gem_cma_prime_import_sg_table_vmap);