drm_gem_dma_helper.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * drm gem DMA helper functions
  4 *
  5 * Copyright (C) 2012 Sascha Hauer, Pengutronix
  6 *
  7 * Based on Samsung Exynos code
  8 *
  9 * Copyright (c) 2011 Samsung Electronics Co., Ltd.
 10 */
 11
 12#include <linux/dma-buf.h>
 13#include <linux/dma-mapping.h>
 14#include <linux/export.h>
 15#include <linux/mm.h>
 16#include <linux/module.h>
 17#include <linux/mutex.h>
 18#include <linux/slab.h>
 19
 20#include <drm/drm.h>
 21#include <drm/drm_device.h>
 22#include <drm/drm_drv.h>
 23#include <drm/drm_dumb_buffers.h>
 24#include <drm/drm_gem_dma_helper.h>
 25#include <drm/drm_print.h>
 26#include <drm/drm_vma_manager.h>
 27
 28/**
 29 * DOC: dma helpers
 30 *
 31 * The DRM GEM/DMA helpers are a means to provide buffer objects that are
 32 * presented to the device as a contiguous chunk of memory. This is useful
 33 * for devices that do not support scatter-gather DMA (either directly or
 34 * by using an intimately attached IOMMU).
 35 *
 36 * For devices that access the memory bus through an (external) IOMMU then
 37 * the buffer objects are allocated using a traditional page-based
 38 * allocator and may be scattered through physical memory. However they
 39 * are contiguous in the IOVA space so appear contiguous to devices using
 40 * them.
 41 *
 42 * For other devices then the helpers rely on CMA to provide buffer
 43 * objects that are physically contiguous in memory.
 44 *
 45 * For GEM callback helpers in struct &drm_gem_object functions, see likewise
 46 * named functions with an _object_ infix (e.g., drm_gem_dma_object_vmap() wraps
 47 * drm_gem_dma_vmap()). These helpers perform the necessary type conversion.
 48 */
 49
 50static const struct drm_gem_object_funcs drm_gem_dma_default_funcs = {
 51	.free = drm_gem_dma_object_free,
 52	.print_info = drm_gem_dma_object_print_info,
 53	.get_sg_table = drm_gem_dma_object_get_sg_table,
 54	.vmap = drm_gem_dma_object_vmap,
 55	.mmap = drm_gem_dma_object_mmap,
 56	.vm_ops = &drm_gem_dma_vm_ops,
 57};
 58
 59/**
 60 * __drm_gem_dma_create - Create a GEM DMA object without allocating memory
 61 * @drm: DRM device
 62 * @size: size of the object to allocate
 63 * @private: true if used for internal purposes
 64 *
 65 * This function creates and initializes a GEM DMA object of the given size,
 66 * but doesn't allocate any memory to back the object.
 67 *
 68 * Returns:
 69 * A struct drm_gem_dma_object * on success or an ERR_PTR()-encoded negative
 70 * error code on failure.
 71 */
 72static struct drm_gem_dma_object *
 73__drm_gem_dma_create(struct drm_device *drm, size_t size, bool private)
 74{
 75	struct drm_gem_dma_object *dma_obj;
 76	struct drm_gem_object *gem_obj;
 77	int ret = 0;
 78
 79	if (drm->driver->gem_create_object) {
 80		gem_obj = drm->driver->gem_create_object(drm, size);
 81		if (IS_ERR(gem_obj))
 82			return ERR_CAST(gem_obj);
 83		dma_obj = to_drm_gem_dma_obj(gem_obj);
 84	} else {
 85		dma_obj = kzalloc(sizeof(*dma_obj), GFP_KERNEL);
 86		if (!dma_obj)
 87			return ERR_PTR(-ENOMEM);
 88		gem_obj = &dma_obj->base;
 89	}
 90
 91	if (!gem_obj->funcs)
 92		gem_obj->funcs = &drm_gem_dma_default_funcs;
 93
 94	if (private) {
 95		drm_gem_private_object_init(drm, gem_obj, size);
 96
 97		/* Always use writecombine for dma-buf mappings */
 98		dma_obj->map_noncoherent = false;
 99	} else {
100		ret = drm_gem_object_init(drm, gem_obj, size);
101	}
102	if (ret)
103		goto error;
104
105	ret = drm_gem_create_mmap_offset(gem_obj);
106	if (ret) {
107		drm_gem_object_release(gem_obj);
108		goto error;
109	}
110
111	return dma_obj;
112
113error:
114	kfree(dma_obj);
115	return ERR_PTR(ret);
116}
117
118/**
119 * drm_gem_dma_create - allocate an object with the given size
120 * @drm: DRM device
121 * @size: size of the object to allocate
122 *
123 * This function creates a DMA GEM object and allocates memory as backing store.
124 * The allocated memory will occupy a contiguous chunk of bus address space.
125 *
126 * For devices that are directly connected to the memory bus then the allocated
127 * memory will be physically contiguous. For devices that access through an
128 * IOMMU, then the allocated memory is not expected to be physically contiguous
129 * because having contiguous IOVAs is sufficient to meet a devices DMA
130 * requirements.
131 *
132 * Returns:
133 * A struct drm_gem_dma_object * on success or an ERR_PTR()-encoded negative
134 * error code on failure.
135 */
136struct drm_gem_dma_object *drm_gem_dma_create(struct drm_device *drm,
137					      size_t size)
138{
139	struct drm_gem_dma_object *dma_obj;
140	int ret;
141
142	size = round_up(size, PAGE_SIZE);
143
144	dma_obj = __drm_gem_dma_create(drm, size, false);
145	if (IS_ERR(dma_obj))
146		return dma_obj;
147
148	if (dma_obj->map_noncoherent) {
149		dma_obj->vaddr = dma_alloc_noncoherent(drm->dev, size,
150						       &dma_obj->dma_addr,
151						       DMA_TO_DEVICE,
152						       GFP_KERNEL | __GFP_NOWARN);
153	} else {
154		dma_obj->vaddr = dma_alloc_wc(drm->dev, size,
155					      &dma_obj->dma_addr,
156					      GFP_KERNEL | __GFP_NOWARN);
157	}
158	if (!dma_obj->vaddr) {
159		drm_dbg(drm, "failed to allocate buffer with size %zu\n",
160			 size);
161		ret = -ENOMEM;
162		goto error;
163	}
164
165	return dma_obj;
166
167error:
168	drm_gem_object_put(&dma_obj->base);
169	return ERR_PTR(ret);
170}
171EXPORT_SYMBOL_GPL(drm_gem_dma_create);
172
173/**
174 * drm_gem_dma_create_with_handle - allocate an object with the given size and
175 *     return a GEM handle to it
176 * @file_priv: DRM file-private structure to register the handle for
177 * @drm: DRM device
178 * @size: size of the object to allocate
179 * @handle: return location for the GEM handle
180 *
181 * This function creates a DMA GEM object, allocating a chunk of memory as
182 * backing store. The GEM object is then added to the list of object associated
183 * with the given file and a handle to it is returned.
184 *
185 * The allocated memory will occupy a contiguous chunk of bus address space.
186 * See drm_gem_dma_create() for more details.
187 *
188 * Returns:
189 * A struct drm_gem_dma_object * on success or an ERR_PTR()-encoded negative
190 * error code on failure.
191 */
192static struct drm_gem_dma_object *
193drm_gem_dma_create_with_handle(struct drm_file *file_priv,
194			       struct drm_device *drm, size_t size,
195			       uint32_t *handle)
196{
197	struct drm_gem_dma_object *dma_obj;
198	struct drm_gem_object *gem_obj;
199	int ret;
200
201	dma_obj = drm_gem_dma_create(drm, size);
202	if (IS_ERR(dma_obj))
203		return dma_obj;
204
205	gem_obj = &dma_obj->base;
206
207	/*
208	 * allocate a id of idr table where the obj is registered
209	 * and handle has the id what user can see.
210	 */
211	ret = drm_gem_handle_create(file_priv, gem_obj, handle);
212	/* drop reference from allocate - handle holds it now. */
213	drm_gem_object_put(gem_obj);
214	if (ret)
215		return ERR_PTR(ret);
216
217	return dma_obj;
218}
219
220/**
221 * drm_gem_dma_free - free resources associated with a DMA GEM object
222 * @dma_obj: DMA GEM object to free
223 *
224 * This function frees the backing memory of the DMA GEM object, cleans up the
225 * GEM object state and frees the memory used to store the object itself.
226 * If the buffer is imported and the virtual address is set, it is released.
227 */
228void drm_gem_dma_free(struct drm_gem_dma_object *dma_obj)
229{
230	struct drm_gem_object *gem_obj = &dma_obj->base;
231	struct iosys_map map = IOSYS_MAP_INIT_VADDR(dma_obj->vaddr);
232
233	if (drm_gem_is_imported(gem_obj)) {
234		if (dma_obj->vaddr)
235			dma_buf_vunmap_unlocked(gem_obj->import_attach->dmabuf, &map);
236		drm_prime_gem_destroy(gem_obj, dma_obj->sgt);
237	} else if (dma_obj->vaddr) {
238		if (dma_obj->map_noncoherent)
239			dma_free_noncoherent(gem_obj->dev->dev, dma_obj->base.size,
240					     dma_obj->vaddr, dma_obj->dma_addr,
241					     DMA_TO_DEVICE);
242		else
243			dma_free_wc(gem_obj->dev->dev, dma_obj->base.size,
244				    dma_obj->vaddr, dma_obj->dma_addr);
245	}
246
247	drm_gem_object_release(gem_obj);
248
249	kfree(dma_obj);
250}
251EXPORT_SYMBOL_GPL(drm_gem_dma_free);
252
253/**
254 * drm_gem_dma_dumb_create_internal - create a dumb buffer object
255 * @file_priv: DRM file-private structure to create the dumb buffer for
256 * @drm: DRM device
257 * @args: IOCTL data
258 *
259 * This aligns the pitch and size arguments to the minimum required. This is
260 * an internal helper that can be wrapped by a driver to account for hardware
261 * with more specific alignment requirements. It should not be used directly
262 * as their &drm_driver.dumb_create callback.
263 *
264 * Returns:
265 * 0 on success or a negative error code on failure.
266 */
267int drm_gem_dma_dumb_create_internal(struct drm_file *file_priv,
268				     struct drm_device *drm,
269				     struct drm_mode_create_dumb *args)
270{
271	unsigned int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
272	struct drm_gem_dma_object *dma_obj;
273
274	if (args->pitch < min_pitch)
275		args->pitch = min_pitch;
276
277	if (args->size < args->pitch * args->height)
278		args->size = args->pitch * args->height;
279
280	dma_obj = drm_gem_dma_create_with_handle(file_priv, drm, args->size,
281						 &args->handle);
282	return PTR_ERR_OR_ZERO(dma_obj);
283}
284EXPORT_SYMBOL_GPL(drm_gem_dma_dumb_create_internal);
285
286/**
287 * drm_gem_dma_dumb_create - create a dumb buffer object
288 * @file_priv: DRM file-private structure to create the dumb buffer for
289 * @drm: DRM device
290 * @args: IOCTL data
291 *
292 * This function computes the pitch of the dumb buffer and rounds it up to an
293 * integer number of bytes per pixel. Drivers for hardware that doesn't have
294 * any additional restrictions on the pitch can directly use this function as
295 * their &drm_driver.dumb_create callback.
296 *
297 * For hardware with additional restrictions, drivers can adjust the fields
298 * set up by userspace and pass the IOCTL data along to the
299 * drm_gem_dma_dumb_create_internal() function.
300 *
301 * Returns:
302 * 0 on success or a negative error code on failure.
303 */
304int drm_gem_dma_dumb_create(struct drm_file *file_priv,
305			    struct drm_device *drm,
306			    struct drm_mode_create_dumb *args)
307{
308	struct drm_gem_dma_object *dma_obj;
309	int ret;
310
311	ret = drm_mode_size_dumb(drm, args, 0, 0);
312	if (ret)
313		return ret;
314
315	dma_obj = drm_gem_dma_create_with_handle(file_priv, drm, args->size,
316						 &args->handle);
317	return PTR_ERR_OR_ZERO(dma_obj);
318}
319EXPORT_SYMBOL_GPL(drm_gem_dma_dumb_create);
320
321const struct vm_operations_struct drm_gem_dma_vm_ops = {
322	.open = drm_gem_vm_open,
323	.close = drm_gem_vm_close,
324};
325EXPORT_SYMBOL_GPL(drm_gem_dma_vm_ops);
326
327#ifndef CONFIG_MMU
328/**
329 * drm_gem_dma_get_unmapped_area - propose address for mapping in noMMU cases
330 * @filp: file object
331 * @addr: memory address
332 * @len: buffer size
333 * @pgoff: page offset
334 * @flags: memory flags
335 *
336 * This function is used in noMMU platforms to propose address mapping
337 * for a given buffer.
338 * It's intended to be used as a direct handler for the struct
339 * &file_operations.get_unmapped_area operation.
340 *
341 * Returns:
342 * mapping address on success or a negative error code on failure.
343 */
344unsigned long drm_gem_dma_get_unmapped_area(struct file *filp,
345					    unsigned long addr,
346					    unsigned long len,
347					    unsigned long pgoff,
348					    unsigned long flags)
349{
350	struct drm_gem_dma_object *dma_obj;
351	struct drm_gem_object *obj = NULL;
352	struct drm_file *priv = filp->private_data;
353	struct drm_device *dev = priv->minor->dev;
354	struct drm_vma_offset_node *node;
355
356	if (drm_dev_is_unplugged(dev))
357		return -ENODEV;
358
359	drm_vma_offset_lock_lookup(dev->vma_offset_manager);
360	node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
361						  pgoff,
362						  len >> PAGE_SHIFT);
363	if (likely(node)) {
364		obj = container_of(node, struct drm_gem_object, vma_node);
365		/*
366		 * When the object is being freed, after it hits 0-refcnt it
367		 * proceeds to tear down the object. In the process it will
368		 * attempt to remove the VMA offset and so acquire this
369		 * mgr->vm_lock.  Therefore if we find an object with a 0-refcnt
370		 * that matches our range, we know it is in the process of being
371		 * destroyed and will be freed as soon as we release the lock -
372		 * so we have to check for the 0-refcnted object and treat it as
373		 * invalid.
374		 */
375		if (!kref_get_unless_zero(&obj->refcount))
376			obj = NULL;
377	}
378
379	drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
380
381	if (!obj)
382		return -EINVAL;
383
384	if (!drm_vma_node_is_allowed(node, priv)) {
385		drm_gem_object_put(obj);
386		return -EACCES;
387	}
388
389	dma_obj = to_drm_gem_dma_obj(obj);
390
391	drm_gem_object_put(obj);
392
393	return dma_obj->vaddr ? (unsigned long)dma_obj->vaddr : -EINVAL;
394}
395EXPORT_SYMBOL_GPL(drm_gem_dma_get_unmapped_area);
396#endif
397
398/**
399 * drm_gem_dma_print_info() - Print &drm_gem_dma_object info for debugfs
400 * @dma_obj: DMA GEM object
401 * @p: DRM printer
402 * @indent: Tab indentation level
403 *
404 * This function prints dma_addr and vaddr for use in e.g. debugfs output.
405 */
406void drm_gem_dma_print_info(const struct drm_gem_dma_object *dma_obj,
407			    struct drm_printer *p, unsigned int indent)
408{
409	drm_printf_indent(p, indent, "dma_addr=%pad\n", &dma_obj->dma_addr);
410	drm_printf_indent(p, indent, "vaddr=%p\n", dma_obj->vaddr);
411}
412EXPORT_SYMBOL(drm_gem_dma_print_info);
413
414/**
415 * drm_gem_dma_get_sg_table - provide a scatter/gather table of pinned
416 *     pages for a DMA GEM object
417 * @dma_obj: DMA GEM object
418 *
419 * This function exports a scatter/gather table by calling the standard
420 * DMA mapping API.
421 *
422 * Returns:
423 * A pointer to the scatter/gather table of pinned pages or NULL on failure.
424 */
425struct sg_table *drm_gem_dma_get_sg_table(struct drm_gem_dma_object *dma_obj)
426{
427	struct drm_gem_object *obj = &dma_obj->base;
428	struct sg_table *sgt;
429	int ret;
430
431	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
432	if (!sgt)
433		return ERR_PTR(-ENOMEM);
434
435	ret = dma_get_sgtable(obj->dev->dev, sgt, dma_obj->vaddr,
436			      dma_obj->dma_addr, obj->size);
437	if (ret < 0)
438		goto out;
439
440	return sgt;
441
442out:
443	kfree(sgt);
444	return ERR_PTR(ret);
445}
446EXPORT_SYMBOL_GPL(drm_gem_dma_get_sg_table);
447
448/**
449 * drm_gem_dma_prime_import_sg_table - produce a DMA GEM object from another
450 *     driver's scatter/gather table of pinned pages
451 * @dev: device to import into
452 * @attach: DMA-BUF attachment
453 * @sgt: scatter/gather table of pinned pages
454 *
455 * This function imports a scatter/gather table exported via DMA-BUF by
456 * another driver. Imported buffers must be physically contiguous in memory
457 * (i.e. the scatter/gather table must contain a single entry). Drivers that
458 * use the DMA helpers should set this as their
459 * &drm_driver.gem_prime_import_sg_table callback.
460 *
461 * Returns:
462 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
463 * error code on failure.
464 */
465struct drm_gem_object *
466drm_gem_dma_prime_import_sg_table(struct drm_device *dev,
467				  struct dma_buf_attachment *attach,
468				  struct sg_table *sgt)
469{
470	struct drm_gem_dma_object *dma_obj;
471
472	/* check if the entries in the sg_table are contiguous */
473	if (drm_prime_get_contiguous_size(sgt) < attach->dmabuf->size)
474		return ERR_PTR(-EINVAL);
475
476	/* Create a DMA GEM buffer. */
477	dma_obj = __drm_gem_dma_create(dev, attach->dmabuf->size, true);
478	if (IS_ERR(dma_obj))
479		return ERR_CAST(dma_obj);
480
481	dma_obj->dma_addr = sg_dma_address(sgt->sgl);
482	dma_obj->sgt = sgt;
483
484	drm_dbg_prime(dev, "dma_addr = %pad, size = %zu\n", &dma_obj->dma_addr,
485		      attach->dmabuf->size);
486
487	return &dma_obj->base;
488}
489EXPORT_SYMBOL_GPL(drm_gem_dma_prime_import_sg_table);
490
491/**
492 * drm_gem_dma_vmap - map a DMA GEM object into the kernel's virtual
493 *     address space
494 * @dma_obj: DMA GEM object
495 * @map: Returns the kernel virtual address of the DMA GEM object's backing
496 *       store.
497 *
498 * This function maps a buffer into the kernel's virtual address space.
499 * Since the DMA buffers are already mapped into the kernel virtual address
500 * space this simply returns the cached virtual address.
501 *
502 * Returns:
503 * 0 on success, or a negative error code otherwise.
504 */
505int drm_gem_dma_vmap(struct drm_gem_dma_object *dma_obj,
506		     struct iosys_map *map)
507{
508	iosys_map_set_vaddr(map, dma_obj->vaddr);
509
510	return 0;
511}
512EXPORT_SYMBOL_GPL(drm_gem_dma_vmap);
513
514/**
515 * drm_gem_dma_mmap - memory-map an exported DMA GEM object
516 * @dma_obj: DMA GEM object
517 * @vma: VMA for the area to be mapped
518 *
519 * This function maps a buffer into a userspace process's address space.
520 * In addition to the usual GEM VMA setup it immediately faults in the entire
521 * object instead of using on-demand faulting.
522 *
523 * Returns:
524 * 0 on success or a negative error code on failure.
525 */
526int drm_gem_dma_mmap(struct drm_gem_dma_object *dma_obj, struct vm_area_struct *vma)
527{
528	struct drm_gem_object *obj = &dma_obj->base;
529	int ret;
530
531	/*
532	 * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
533	 * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map
534	 * the whole buffer.
535	 */
536	vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);
537	vm_flags_mod(vma, VM_DONTEXPAND, VM_PFNMAP);
538
539	if (dma_obj->map_noncoherent) {
540		vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
541
542		ret = dma_mmap_pages(dma_obj->base.dev->dev,
543				     vma, vma->vm_end - vma->vm_start,
544				     virt_to_page(dma_obj->vaddr));
545	} else {
546		ret = dma_mmap_wc(dma_obj->base.dev->dev, vma, dma_obj->vaddr,
547				  dma_obj->dma_addr,
548				  vma->vm_end - vma->vm_start);
549	}
550	if (ret)
551		drm_gem_vm_close(vma);
552
553	return ret;
554}
555EXPORT_SYMBOL_GPL(drm_gem_dma_mmap);
556
557/**
558 * drm_gem_dma_prime_import_sg_table_vmap - PRIME import another driver's
559 *	scatter/gather table and get the virtual address of the buffer
560 * @dev: DRM device
561 * @attach: DMA-BUF attachment
562 * @sgt: Scatter/gather table of pinned pages
563 *
564 * This function imports a scatter/gather table using
565 * drm_gem_dma_prime_import_sg_table() and uses dma_buf_vmap() to get the kernel
566 * virtual address. This ensures that a DMA GEM object always has its virtual
567 * address set. This address is released when the object is freed.
568 *
569 * This function can be used as the &drm_driver.gem_prime_import_sg_table
570 * callback. The &DRM_GEM_DMA_DRIVER_OPS_VMAP macro provides a shortcut to set
571 * the necessary DRM driver operations.
572 *
573 * Returns:
574 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
575 * error code on failure.
576 */
577struct drm_gem_object *
578drm_gem_dma_prime_import_sg_table_vmap(struct drm_device *dev,
579				       struct dma_buf_attachment *attach,
580				       struct sg_table *sgt)
581{
582	struct drm_gem_dma_object *dma_obj;
583	struct drm_gem_object *obj;
584	struct iosys_map map;
585	int ret;
586
587	ret = dma_buf_vmap_unlocked(attach->dmabuf, &map);
588	if (ret) {
589		drm_err(dev, "Failed to vmap PRIME buffer\n");
590		return ERR_PTR(ret);
591	}
592
593	obj = drm_gem_dma_prime_import_sg_table(dev, attach, sgt);
594	if (IS_ERR(obj)) {
595		dma_buf_vunmap_unlocked(attach->dmabuf, &map);
596		return obj;
597	}
598
599	dma_obj = to_drm_gem_dma_obj(obj);
600	dma_obj->vaddr = map.vaddr;
601
602	return obj;
603}
604EXPORT_SYMBOL(drm_gem_dma_prime_import_sg_table_vmap);
605
606MODULE_DESCRIPTION("DRM DMA memory-management helpers");
607MODULE_IMPORT_NS("DMA_BUF");
608MODULE_LICENSE("GPL");