2 * drm gem CMA (contiguous memory allocator) helper functions
4 * Copyright (C) 2012 Sascha Hauer, Pengutronix
6 * Based on Samsung Exynos code
8 * Copyright (c) 2011 Samsung Electronics Co., Ltd.
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.
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>
29 #include <drm/drm_gem_cma_helper.h>
30 #include <drm/drm_vma_manager.h>
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.
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.
44 * __drm_gem_cma_create - Create a GEM CMA object without allocating memory
46 * @size: size of the object to allocate
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.
52 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
53 * error code on failure.
55 static struct drm_gem_cma_object *
56 __drm_gem_cma_create(struct drm_device *drm, size_t size)
58 struct drm_gem_cma_object *cma_obj;
59 struct drm_gem_object *gem_obj;
62 if (drm->driver->gem_create_object)
63 gem_obj = drm->driver->gem_create_object(drm, size);
65 gem_obj = kzalloc(sizeof(*cma_obj), GFP_KERNEL);
67 return ERR_PTR(-ENOMEM);
68 cma_obj = container_of(gem_obj, struct drm_gem_cma_object, base);
70 ret = drm_gem_object_init(drm, gem_obj, size);
74 ret = drm_gem_create_mmap_offset(gem_obj);
76 drm_gem_object_release(gem_obj);
88 * drm_gem_cma_create - allocate an object with the given size
90 * @size: size of the object to allocate
92 * This function creates a CMA GEM object and allocates a contiguous chunk of
93 * memory as backing store. The backing memory has the writecombine attribute
97 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
98 * error code on failure.
100 struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
103 struct drm_gem_cma_object *cma_obj;
106 size = round_up(size, PAGE_SIZE);
108 cma_obj = __drm_gem_cma_create(drm, size);
112 cma_obj->vaddr = dma_alloc_writecombine(drm->dev, size,
113 &cma_obj->paddr, GFP_KERNEL | __GFP_NOWARN);
114 if (!cma_obj->vaddr) {
115 dev_err(drm->dev, "failed to allocate buffer with size %zu\n",
124 drm->driver->gem_free_object(&cma_obj->base);
127 EXPORT_SYMBOL_GPL(drm_gem_cma_create);
130 * drm_gem_cma_create_with_handle - allocate an object with the given size and
131 * return a GEM handle to it
132 * @file_priv: DRM file-private structure to register the handle for
134 * @size: size of the object to allocate
135 * @handle: return location for the GEM handle
137 * This function creates a CMA GEM object, allocating a physically contiguous
138 * chunk of memory as backing store. The GEM object is then added to the list
139 * of object associated with the given file and a handle to it is returned.
142 * A struct drm_gem_cma_object * on success or an ERR_PTR()-encoded negative
143 * error code on failure.
145 static struct drm_gem_cma_object *
146 drm_gem_cma_create_with_handle(struct drm_file *file_priv,
147 struct drm_device *drm, size_t size,
150 struct drm_gem_cma_object *cma_obj;
151 struct drm_gem_object *gem_obj;
154 cma_obj = drm_gem_cma_create(drm, size);
158 gem_obj = &cma_obj->base;
161 * allocate a id of idr table where the obj is registered
162 * and handle has the id what user can see.
164 ret = drm_gem_handle_create(file_priv, gem_obj, handle);
166 goto err_handle_create;
168 /* drop reference from allocate - handle holds it now. */
169 drm_gem_object_unreference_unlocked(gem_obj);
174 drm->driver->gem_free_object(gem_obj);
180 * drm_gem_cma_free_object - free resources associated with a CMA GEM object
181 * @gem_obj: GEM object to free
183 * This function frees the backing memory of the CMA GEM object, cleans up the
184 * GEM object state and frees the memory used to store the object itself.
185 * Drivers using the CMA helpers should set this as their DRM driver's
186 * ->gem_free_object() callback.
188 void drm_gem_cma_free_object(struct drm_gem_object *gem_obj)
190 struct drm_gem_cma_object *cma_obj;
192 cma_obj = to_drm_gem_cma_obj(gem_obj);
194 if (cma_obj->vaddr) {
195 dma_free_writecombine(gem_obj->dev->dev, cma_obj->base.size,
196 cma_obj->vaddr, cma_obj->paddr);
197 } else if (gem_obj->import_attach) {
198 drm_prime_gem_destroy(gem_obj, cma_obj->sgt);
201 drm_gem_object_release(gem_obj);
205 EXPORT_SYMBOL_GPL(drm_gem_cma_free_object);
208 * drm_gem_cma_dumb_create_internal - create a dumb buffer object
209 * @file_priv: DRM file-private structure to create the dumb buffer for
213 * This aligns the pitch and size arguments to the minimum required. This is
214 * an internal helper that can be wrapped by a driver to account for hardware
215 * with more specific alignment requirements. It should not be used directly
216 * as the ->dumb_create() callback in a DRM driver.
219 * 0 on success or a negative error code on failure.
221 int drm_gem_cma_dumb_create_internal(struct drm_file *file_priv,
222 struct drm_device *drm,
223 struct drm_mode_create_dumb *args)
225 unsigned int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
226 struct drm_gem_cma_object *cma_obj;
228 if (args->pitch < min_pitch)
229 args->pitch = min_pitch;
231 if (args->size < args->pitch * args->height)
232 args->size = args->pitch * args->height;
234 cma_obj = drm_gem_cma_create_with_handle(file_priv, drm, args->size,
236 return PTR_ERR_OR_ZERO(cma_obj);
238 EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_create_internal);
241 * drm_gem_cma_dumb_create - create a dumb buffer object
242 * @file_priv: DRM file-private structure to create the dumb buffer for
246 * This function computes the pitch of the dumb buffer and rounds it up to an
247 * integer number of bytes per pixel. Drivers for hardware that doesn't have
248 * any additional restrictions on the pitch can directly use this function as
249 * their ->dumb_create() callback.
251 * For hardware with additional restrictions, drivers can adjust the fields
252 * set up by userspace and pass the IOCTL data along to the
253 * drm_gem_cma_dumb_create_internal() function.
256 * 0 on success or a negative error code on failure.
258 int drm_gem_cma_dumb_create(struct drm_file *file_priv,
259 struct drm_device *drm,
260 struct drm_mode_create_dumb *args)
262 struct drm_gem_cma_object *cma_obj;
264 args->pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
265 args->size = args->pitch * args->height;
267 cma_obj = drm_gem_cma_create_with_handle(file_priv, drm, args->size,
269 return PTR_ERR_OR_ZERO(cma_obj);
271 EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_create);
274 * drm_gem_cma_dumb_map_offset - return the fake mmap offset for a CMA GEM
276 * @file_priv: DRM file-private structure containing the GEM object
278 * @handle: GEM object handle
279 * @offset: return location for the fake mmap offset
281 * This function look up an object by its handle and returns the fake mmap
282 * offset associated with it. Drivers using the CMA helpers should set this
283 * as their DRM driver's ->dumb_map_offset() callback.
286 * 0 on success or a negative error code on failure.
288 int drm_gem_cma_dumb_map_offset(struct drm_file *file_priv,
289 struct drm_device *drm, u32 handle,
292 struct drm_gem_object *gem_obj;
294 gem_obj = drm_gem_object_lookup(drm, file_priv, handle);
296 dev_err(drm->dev, "failed to lookup GEM object\n");
300 *offset = drm_vma_node_offset_addr(&gem_obj->vma_node);
302 drm_gem_object_unreference_unlocked(gem_obj);
306 EXPORT_SYMBOL_GPL(drm_gem_cma_dumb_map_offset);
308 const struct vm_operations_struct drm_gem_cma_vm_ops = {
309 .open = drm_gem_vm_open,
310 .close = drm_gem_vm_close,
312 EXPORT_SYMBOL_GPL(drm_gem_cma_vm_ops);
314 static int drm_gem_cma_mmap_obj(struct drm_gem_cma_object *cma_obj,
315 struct vm_area_struct *vma)
320 * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
321 * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map
324 vma->vm_flags &= ~VM_PFNMAP;
327 ret = dma_mmap_writecombine(cma_obj->base.dev->dev, vma,
328 cma_obj->vaddr, cma_obj->paddr,
329 vma->vm_end - vma->vm_start);
331 drm_gem_vm_close(vma);
337 * drm_gem_cma_mmap - memory-map a CMA GEM object
339 * @vma: VMA for the area to be mapped
341 * This function implements an augmented version of the GEM DRM file mmap
342 * operation for CMA objects: In addition to the usual GEM VMA setup it
343 * immediately faults in the entire object instead of using on-demaind
344 * faulting. Drivers which employ the CMA helpers should use this function
345 * as their ->mmap() handler in the DRM device file's file_operations
349 * 0 on success or a negative error code on failure.
351 int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
353 struct drm_gem_cma_object *cma_obj;
354 struct drm_gem_object *gem_obj;
357 ret = drm_gem_mmap(filp, vma);
361 gem_obj = vma->vm_private_data;
362 cma_obj = to_drm_gem_cma_obj(gem_obj);
364 return drm_gem_cma_mmap_obj(cma_obj, vma);
366 EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
368 #ifdef CONFIG_DEBUG_FS
370 * drm_gem_cma_describe - describe a CMA GEM object for debugfs
371 * @cma_obj: CMA GEM object
372 * @m: debugfs file handle
374 * This function can be used to dump a human-readable representation of the
375 * CMA GEM object into a synthetic file.
377 void drm_gem_cma_describe(struct drm_gem_cma_object *cma_obj,
380 struct drm_gem_object *obj = &cma_obj->base;
383 off = drm_vma_node_start(&obj->vma_node);
385 seq_printf(m, "%2d (%2d) %08llx %pad %p %zu",
386 obj->name, obj->refcount.refcount.counter,
387 off, &cma_obj->paddr, cma_obj->vaddr, obj->size);
391 EXPORT_SYMBOL_GPL(drm_gem_cma_describe);
395 * drm_gem_cma_prime_get_sg_table - provide a scatter/gather table of pinned
396 * pages for a CMA GEM object
399 * This function exports a scatter/gather table suitable for PRIME usage by
400 * calling the standard DMA mapping API. Drivers using the CMA helpers should
401 * set this as their DRM driver's ->gem_prime_get_sg_table() callback.
404 * A pointer to the scatter/gather table of pinned pages or NULL on failure.
406 struct sg_table *drm_gem_cma_prime_get_sg_table(struct drm_gem_object *obj)
408 struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
409 struct sg_table *sgt;
412 sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
416 ret = dma_get_sgtable(obj->dev->dev, sgt, cma_obj->vaddr,
417 cma_obj->paddr, obj->size);
427 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_get_sg_table);
430 * drm_gem_cma_prime_import_sg_table - produce a CMA GEM object from another
431 * driver's scatter/gather table of pinned pages
432 * @dev: device to import into
433 * @attach: DMA-BUF attachment
434 * @sgt: scatter/gather table of pinned pages
436 * This function imports a scatter/gather table exported via DMA-BUF by
437 * another driver. Imported buffers must be physically contiguous in memory
438 * (i.e. the scatter/gather table must contain a single entry). Drivers that
439 * use the CMA helpers should set this as their DRM driver's
440 * ->gem_prime_import_sg_table() callback.
443 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
444 * error code on failure.
446 struct drm_gem_object *
447 drm_gem_cma_prime_import_sg_table(struct drm_device *dev,
448 struct dma_buf_attachment *attach,
449 struct sg_table *sgt)
451 struct drm_gem_cma_object *cma_obj;
454 return ERR_PTR(-EINVAL);
456 /* Create a CMA GEM buffer. */
457 cma_obj = __drm_gem_cma_create(dev, attach->dmabuf->size);
459 return ERR_CAST(cma_obj);
461 cma_obj->paddr = sg_dma_address(sgt->sgl);
464 DRM_DEBUG_PRIME("dma_addr = %pad, size = %zu\n", &cma_obj->paddr, attach->dmabuf->size);
466 return &cma_obj->base;
468 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_import_sg_table);
471 * drm_gem_cma_prime_mmap - memory-map an exported CMA GEM object
473 * @vma: VMA for the area to be mapped
475 * This function maps a buffer imported via DRM PRIME into a userspace
476 * process's address space. Drivers that use the CMA helpers should set this
477 * as their DRM driver's ->gem_prime_mmap() callback.
480 * 0 on success or a negative error code on failure.
482 int drm_gem_cma_prime_mmap(struct drm_gem_object *obj,
483 struct vm_area_struct *vma)
485 struct drm_gem_cma_object *cma_obj;
488 ret = drm_gem_mmap_obj(obj, obj->size, vma);
492 cma_obj = to_drm_gem_cma_obj(obj);
493 return drm_gem_cma_mmap_obj(cma_obj, vma);
495 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_mmap);
498 * drm_gem_cma_prime_vmap - map a CMA GEM object into the kernel's virtual
502 * This function maps a buffer exported via DRM PRIME into the kernel's
503 * virtual address space. Since the CMA buffers are already mapped into the
504 * kernel virtual address space this simply returns the cached virtual
505 * address. Drivers using the CMA helpers should set this as their DRM
506 * driver's ->gem_prime_vmap() callback.
509 * The kernel virtual address of the CMA GEM object's backing store.
511 void *drm_gem_cma_prime_vmap(struct drm_gem_object *obj)
513 struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
515 return cma_obj->vaddr;
517 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_vmap);
520 * drm_gem_cma_prime_vunmap - unmap a CMA GEM object from the kernel's virtual
523 * @vaddr: kernel virtual address where the CMA GEM object was mapped
525 * This function removes a buffer exported via DRM PRIME from the kernel's
526 * virtual address space. This is a no-op because CMA buffers cannot be
527 * unmapped from kernel space. Drivers using the CMA helpers should set this
528 * as their DRM driver's ->gem_prime_vunmap() callback.
530 void drm_gem_cma_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
534 EXPORT_SYMBOL_GPL(drm_gem_cma_prime_vunmap);