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_prime_get_sg_table,
40 .vmap = drm_gem_cma_prime_vmap,
41 .vm_ops = &drm_gem_cma_vm_ops,
45 * __drm_gem_cma_create - Create a GEM CMA object without allocating memory
47 * @size: size of the object to allocate
49 * This function creates and initializes a GEM CMA object of the given size,
50 * but doesn't allocate any memory to back the object.
53 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
54 * error code on failure.
56 static struct drm_gem_cma_object *
57 __drm_gem_cma_create(struct drm_device *drm, size_t size)
59 struct drm_gem_cma_object *cma_obj;
60 struct drm_gem_object *gem_obj;
63 if (drm->driver->gem_create_object)
64 gem_obj = drm->driver->gem_create_object(drm, size);
66 gem_obj = kzalloc(sizeof(*cma_obj), GFP_KERNEL);
68 return ERR_PTR(-ENOMEM);
71 gem_obj->funcs = &drm_gem_cma_default_funcs;
73 cma_obj = container_of(gem_obj, struct drm_gem_cma_object, base);
75 ret = drm_gem_object_init(drm, gem_obj, size);
79 ret = drm_gem_create_mmap_offset(gem_obj);
81 drm_gem_object_release(gem_obj);
93 * drm_gem_cma_create - allocate an object with the given size
95 * @size: size of the object to allocate
97 * This function creates a CMA GEM object and allocates a contiguous chunk of
98 * memory as backing store. The backing memory has the writecombine attribute
102 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
103 * error code on failure.
105 struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
108 struct drm_gem_cma_object *cma_obj;
111 size = round_up(size, PAGE_SIZE);
113 cma_obj = __drm_gem_cma_create(drm, size);
117 cma_obj->vaddr = dma_alloc_wc(drm->dev, size, &cma_obj->paddr,
118 GFP_KERNEL | __GFP_NOWARN);
119 if (!cma_obj->vaddr) {
120 drm_dbg(drm, "failed to allocate buffer with size %zu\n",
129 drm_gem_object_put(&cma_obj->base);
132 EXPORT_SYMBOL_GPL(drm_gem_cma_create);
135 * drm_gem_cma_create_with_handle - allocate an object with the given size and
136 * return a GEM handle to it
137 * @file_priv: DRM file-private structure to register the handle for
139 * @size: size of the object to allocate
140 * @handle: return location for the GEM handle
142 * This function creates a CMA GEM object, allocating a physically contiguous
143 * chunk of memory as backing store. The GEM object is then added to the list
144 * of object associated with the given file and a handle to it is returned.
147 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
148 * error code on failure.
150 static struct drm_gem_cma_object *
151 drm_gem_cma_create_with_handle(struct drm_file *file_priv,
152 struct drm_device *drm, size_t size,
155 struct drm_gem_cma_object *cma_obj;
156 struct drm_gem_object *gem_obj;
159 cma_obj = drm_gem_cma_create(drm, size);
163 gem_obj = &cma_obj->base;
166 * allocate a id of idr table where the obj is registered
167 * and handle has the id what user can see.
169 ret = drm_gem_handle_create(file_priv, gem_obj, handle);
170 /* drop reference from allocate - handle holds it now. */
171 drm_gem_object_put(gem_obj);
179 * drm_gem_cma_free_object - free resources associated with a CMA GEM object
180 * @gem_obj: GEM object to free
182 * This function frees the backing memory of the CMA GEM object, cleans up the
183 * GEM object state and frees the memory used to store the object itself.
184 * If the buffer is imported and the virtual address is set, it is released.
185 * Drivers using the CMA helpers should set this as their
186 * &drm_gem_object_funcs.free callback.
188 void drm_gem_cma_free_object(struct drm_gem_object *gem_obj)
190 struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(gem_obj);
191 struct dma_buf_map map = DMA_BUF_MAP_INIT_VADDR(cma_obj->vaddr);
193 if (gem_obj->import_attach) {
195 dma_buf_vunmap(gem_obj->import_attach->dmabuf, &map);
196 drm_prime_gem_destroy(gem_obj, cma_obj->sgt);
197 } else if (cma_obj->vaddr) {
198 dma_free_wc(gem_obj->dev->dev, cma_obj->base.size,
199 cma_obj->vaddr, cma_obj->paddr);
202 drm_gem_object_release(gem_obj);
206 EXPORT_SYMBOL_GPL(drm_gem_cma_free_object);
209 * drm_gem_cma_dumb_create_internal - create a dumb buffer object
210 * @file_priv: DRM file-private structure to create the dumb buffer for
214 * This aligns the pitch and size arguments to the minimum required. This is
215 * an internal helper that can be wrapped by a driver to account for hardware
216 * with more specific alignment requirements. It should not be used directly
217 * as their &drm_driver.dumb_create callback.
220 * 0 on success or a negative error code on failure.
222 int drm_gem_cma_dumb_create_internal(struct drm_file *file_priv,
223 struct drm_device *drm,
224 struct drm_mode_create_dumb *args)
226 unsigned int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
227 struct drm_gem_cma_object *cma_obj;
229 if (args->pitch < min_pitch)
230 args->pitch = min_pitch;
232 if (args->size < args->pitch * args->height)
233 args->size = args->pitch * args->height;
235 cma_obj = drm_gem_cma_create_with_handle(file_priv, drm, args->size,
237 return PTR_ERR_OR_ZERO(cma_obj);
239 EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_create_internal);
242 * drm_gem_cma_dumb_create - create a dumb buffer object
243 * @file_priv: DRM file-private structure to create the dumb buffer for
247 * This function computes the pitch of the dumb buffer and rounds it up to an
248 * integer number of bytes per pixel. Drivers for hardware that doesn't have
249 * any additional restrictions on the pitch can directly use this function as
250 * their &drm_driver.dumb_create callback.
252 * For hardware with additional restrictions, drivers can adjust the fields
253 * set up by userspace and pass the IOCTL data along to the
254 * drm_gem_cma_dumb_create_internal() function.
257 * 0 on success or a negative error code on failure.
259 int drm_gem_cma_dumb_create(struct drm_file *file_priv,
260 struct drm_device *drm,
261 struct drm_mode_create_dumb *args)
263 struct drm_gem_cma_object *cma_obj;
265 args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
266 args->size = args->pitch * args->height;
268 cma_obj = drm_gem_cma_create_with_handle(file_priv, drm, args->size,
270 return PTR_ERR_OR_ZERO(cma_obj);
272 EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_create);
274 const struct vm_operations_struct drm_gem_cma_vm_ops = {
275 .open = drm_gem_vm_open,
276 .close = drm_gem_vm_close,
278 EXPORT_SYMBOL_GPL(drm_gem_cma_vm_ops);
280 static int drm_gem_cma_mmap_obj(struct drm_gem_cma_object *cma_obj,
281 struct vm_area_struct *vma)
286 * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
287 * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map
290 vma->vm_flags &= ~VM_PFNMAP;
293 ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
294 cma_obj->paddr, vma->vm_end - vma->vm_start);
296 drm_gem_vm_close(vma);
302 * drm_gem_cma_mmap - memory-map a CMA GEM object
304 * @vma: VMA for the area to be mapped
306 * This function implements an augmented version of the GEM DRM file mmap
307 * operation for CMA objects: In addition to the usual GEM VMA setup it
308 * immediately faults in the entire object instead of using on-demaind
309 * faulting. Drivers which employ the CMA helpers should use this function
310 * as their ->mmap() handler in the DRM device file's file_operations
313 * Instead of directly referencing this function, drivers should use the
314 * DEFINE_DRM_GEM_CMA_FOPS().macro.
317 * 0 on success or a negative error code on failure.
319 int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
321 struct drm_gem_cma_object *cma_obj;
322 struct drm_gem_object *gem_obj;
325 ret = drm_gem_mmap(filp, vma);
329 gem_obj = vma->vm_private_data;
330 cma_obj = to_drm_gem_cma_obj(gem_obj);
332 return drm_gem_cma_mmap_obj(cma_obj, vma);
334 EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
338 * drm_gem_cma_get_unmapped_area - propose address for mapping in noMMU cases
340 * @addr: memory address
342 * @pgoff: page offset
343 * @flags: memory flags
345 * This function is used in noMMU platforms to propose address mapping
346 * for a given buffer.
347 * It's intended to be used as a direct handler for the struct
348 * &file_operations.get_unmapped_area operation.
351 * mapping address on success or a negative error code on failure.
353 unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
359 struct drm_gem_cma_object *cma_obj;
360 struct drm_gem_object *obj = NULL;
361 struct drm_file *priv = filp->private_data;
362 struct drm_device *dev = priv->minor->dev;
363 struct drm_vma_offset_node *node;
365 if (drm_dev_is_unplugged(dev))
368 drm_vma_offset_lock_lookup(dev->vma_offset_manager);
369 node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
373 obj = container_of(node, struct drm_gem_object, vma_node);
375 * When the object is being freed, after it hits 0-refcnt it
376 * proceeds to tear down the object. In the process it will
377 * attempt to remove the VMA offset and so acquire this
378 * mgr->vm_lock. Therefore if we find an object with a 0-refcnt
379 * that matches our range, we know it is in the process of being
380 * destroyed and will be freed as soon as we release the lock -
381 * so we have to check for the 0-refcnted object and treat it as
384 if (!kref_get_unless_zero(&obj->refcount))
388 drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
393 if (!drm_vma_node_is_allowed(node, priv)) {
394 drm_gem_object_put(obj);
398 cma_obj = to_drm_gem_cma_obj(obj);
400 drm_gem_object_put(obj);
402 return cma_obj->vaddr ? (unsigned long)cma_obj->vaddr : -EINVAL;
404 EXPORT_SYMBOL_GPL(drm_gem_cma_get_unmapped_area);
408 * drm_gem_cma_print_info() - Print &drm_gem_cma_object info for debugfs
410 * @indent: Tab indentation level
413 * This function can be used as the &drm_driver->gem_print_info callback.
414 * It prints paddr and vaddr for use in e.g. debugfs output.
416 void drm_gem_cma_print_info(struct drm_printer *p, unsigned int indent,
417 const struct drm_gem_object *obj)
419 const struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
421 drm_printf_indent(p, indent, "paddr=%pad\n", &cma_obj->paddr);
422 drm_printf_indent(p, indent, "vaddr=%p\n", cma_obj->vaddr);
424 EXPORT_SYMBOL(drm_gem_cma_print_info);
427 * drm_gem_cma_prime_get_sg_table - provide a scatter/gather table of pinned
428 * pages for a CMA GEM object
431 * This function exports a scatter/gather table suitable for PRIME usage by
432 * calling the standard DMA mapping API. Drivers using the CMA helpers should
433 * set this as their &drm_gem_object_funcs.get_sg_table callback.
436 * A pointer to the scatter/gather table of pinned pages or NULL on failure.
438 struct sg_table *drm_gem_cma_prime_get_sg_table(struct drm_gem_object *obj)
440 struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
441 struct sg_table *sgt;
444 sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
446 return ERR_PTR(-ENOMEM);
448 ret = dma_get_sgtable(obj->dev->dev, sgt, cma_obj->vaddr,
449 cma_obj->paddr, obj->size);
459 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_get_sg_table);
462 * drm_gem_cma_prime_import_sg_table - produce a CMA GEM object from another
463 * driver's scatter/gather table of pinned pages
464 * @dev: device to import into
465 * @attach: DMA-BUF attachment
466 * @sgt: scatter/gather table of pinned pages
468 * This function imports a scatter/gather table exported via DMA-BUF by
469 * another driver. Imported buffers must be physically contiguous in memory
470 * (i.e. the scatter/gather table must contain a single entry). Drivers that
471 * use the CMA helpers should set this as their
472 * &drm_driver.gem_prime_import_sg_table callback.
475 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
476 * error code on failure.
478 struct drm_gem_object *
479 drm_gem_cma_prime_import_sg_table(struct drm_device *dev,
480 struct dma_buf_attachment *attach,
481 struct sg_table *sgt)
483 struct drm_gem_cma_object *cma_obj;
485 /* check if the entries in the sg_table are contiguous */
486 if (drm_prime_get_contiguous_size(sgt) < attach->dmabuf->size)
487 return ERR_PTR(-EINVAL);
489 /* Create a CMA GEM buffer. */
490 cma_obj = __drm_gem_cma_create(dev, attach->dmabuf->size);
492 return ERR_CAST(cma_obj);
494 cma_obj->paddr = sg_dma_address(sgt->sgl);
497 DRM_DEBUG_PRIME("dma_addr = %pad, size = %zu\n", &cma_obj->paddr, attach->dmabuf->size);
499 return &cma_obj->base;
501 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_import_sg_table);
504 * drm_gem_cma_prime_mmap - memory-map an exported CMA GEM object
506 * @vma: VMA for the area to be mapped
508 * This function maps a buffer imported via DRM PRIME into a userspace
509 * process's address space. Drivers that use the CMA helpers should set this
510 * as their &drm_driver.gem_prime_mmap callback.
513 * 0 on success or a negative error code on failure.
515 int drm_gem_cma_prime_mmap(struct drm_gem_object *obj,
516 struct vm_area_struct *vma)
518 struct drm_gem_cma_object *cma_obj;
521 ret = drm_gem_mmap_obj(obj, obj->size, vma);
525 cma_obj = to_drm_gem_cma_obj(obj);
526 return drm_gem_cma_mmap_obj(cma_obj, vma);
528 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_mmap);
531 * drm_gem_cma_prime_vmap - map a CMA GEM object into the kernel's virtual
534 * @map: Returns the kernel virtual address of the CMA GEM object's backing
537 * This function maps a buffer exported via DRM PRIME into the kernel's
538 * virtual address space. Since the CMA buffers are already mapped into the
539 * kernel virtual address space this simply returns the cached virtual
540 * address. Drivers using the CMA helpers should set this as their DRM
541 * driver's &drm_gem_object_funcs.vmap callback.
544 * 0 on success, or a negative error code otherwise.
546 int drm_gem_cma_prime_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
548 struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
550 dma_buf_map_set_vaddr(map, cma_obj->vaddr);
554 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_vmap);
557 * drm_gem_cma_prime_import_sg_table_vmap - PRIME import another driver's
558 * scatter/gather table and get the virtual address of the buffer
560 * @attach: DMA-BUF attachment
561 * @sgt: Scatter/gather table of pinned pages
563 * This function imports a scatter/gather table using
564 * drm_gem_cma_prime_import_sg_table() and uses dma_buf_vmap() to get the kernel
565 * virtual address. This ensures that a CMA GEM object always has its virtual
566 * address set. This address is released when the object is freed.
568 * This function can be used as the &drm_driver.gem_prime_import_sg_table
569 * callback. The &DRM_GEM_CMA_DRIVER_OPS_VMAP macro provides a shortcut to set
570 * the necessary DRM driver operations.
573 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
574 * error code on failure.
576 struct drm_gem_object *
577 drm_gem_cma_prime_import_sg_table_vmap(struct drm_device *dev,
578 struct dma_buf_attachment *attach,
579 struct sg_table *sgt)
581 struct drm_gem_cma_object *cma_obj;
582 struct drm_gem_object *obj;
583 struct dma_buf_map map;
586 ret = dma_buf_vmap(attach->dmabuf, &map);
588 DRM_ERROR("Failed to vmap PRIME buffer\n");
592 obj = drm_gem_cma_prime_import_sg_table(dev, attach, sgt);
594 dma_buf_vunmap(attach->dmabuf, &map);
598 cma_obj = to_drm_gem_cma_obj(obj);
599 cma_obj->vaddr = map.vaddr;
603 EXPORT_SYMBOL(drm_gem_cma_prime_import_sg_table_vmap);