1. 根目录:
2. include
3. drm
4. drm_gem.h

#ifndef __DRM_GEM_H__
#define __DRM_GEM_H__

/*
 * GEM Graphics Execution Manager Driver Interfaces
 *
 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
 * Copyright (c) 2009-2010, Code Aurora Forum.
 * All rights reserved.
 * Copyright © 2014 Intel Corporation
 *   Daniel Vetter <daniel.vetter@ffwll.ch>
 *
 * Author: Rickard E. (Rik) Faith <faith@valinux.com>
 * Author: Gareth Hughes <gareth@valinux.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

/**
 * This structure defines the drm_mm memory object, which will be used by the
 * DRM for its buffer objects.
 */
struct drm_gem_object {
	/** Reference count of this object */
	struct kref refcount;

	/**
	 * handle_count - gem file_priv handle count of this object
	 *
	 * Each handle also holds a reference. Note that when the handle_count
	 * drops to 0 any global names (e.g. the id in the flink namespace) will
	 * be cleared.
	 *
	 * Protected by dev->object_name_lock.
	 * */
	unsigned handle_count;

	/** Related drm device */
	struct drm_device *dev;

	/** File representing the shmem storage */
	struct file *filp;

	/* Mapping info for this object */
	struct drm_vma_offset_node vma_node;

	/**
	 * Size of the object, in bytes.  Immutable over the object's
	 * lifetime.
	 */
	size_t size;

	/**
	 * Global name for this object, starts at 1. 0 means unnamed.
	 * Access is covered by the object_name_lock in the related drm_device
	 */
	int name;

	/**
	 * Memory domains. These monitor which caches contain read/write data
	 * related to the object. When transitioning from one set of domains
	 * to another, the driver is called to ensure that caches are suitably
	 * flushed and invalidated
	 */
	uint32_t read_domains;
	uint32_t write_domain;

	/**
	 * While validating an exec operation, the
	 * new read/write domain values are computed here.
	 * They will be transferred to the above values
	 * at the point that any cache flushing occurs
	 */
	uint32_t pending_read_domains;
	uint32_t pending_write_domain;

	/**
	 * dma_buf - dma buf associated with this GEM object
	 *
	 * Pointer to the dma-buf associated with this gem object (either
	 * through importing or exporting). We break the resulting reference
	 * loop when the last gem handle for this object is released.
	 *
	 * Protected by obj->object_name_lock
	 */
	struct dma_buf *dma_buf;

	/**
	 * import_attach - dma buf attachment backing this object
	 *
	 * Any foreign dma_buf imported as a gem object has this set to the
	 * attachment point for the device. This is invariant over the lifetime
	 * of a gem object.
	 *
	 * The driver's ->gem_free_object callback is responsible for cleaning
	 * up the dma_buf attachment and references acquired at import time.
	 *
	 * Note that the drm gem/prime core does not depend upon drivers setting
	 * this field any more. So for drivers where this doesn't make sense
	 * (e.g. virtual devices or a displaylink behind an usb bus) they can
	 * simply leave it as NULL.
	 */
	struct dma_buf_attachment *import_attach;
};

void drm_gem_object_release(struct drm_gem_object *obj);
void drm_gem_object_free(struct kref *kref);
int drm_gem_object_init(struct drm_device *dev,
			struct drm_gem_object *obj, size_t size);
void drm_gem_private_object_init(struct drm_device *dev,
				 struct drm_gem_object *obj, size_t size);
void drm_gem_vm_open(struct vm_area_struct *vma);
void drm_gem_vm_close(struct vm_area_struct *vma);
int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
		     struct vm_area_struct *vma);
int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma);

static inline void
drm_gem_object_reference(struct drm_gem_object *obj)
{
	kref_get(&obj->refcount);
}

static inline void
drm_gem_object_unreference(struct drm_gem_object *obj)
{
	if (obj != NULL)
		kref_put(&obj->refcount, drm_gem_object_free);
}

static inline void
drm_gem_object_unreference_unlocked(struct drm_gem_object *obj)
{
	if (obj && !atomic_add_unless(&obj->refcount.refcount, -1, 1)) {
		struct drm_device *dev = obj->dev;

		mutex_lock(&dev->struct_mutex);
		if (likely(atomic_dec_and_test(&obj->refcount.refcount)))
			drm_gem_object_free(&obj->refcount);
		mutex_unlock(&dev->struct_mutex);
	}
}

int drm_gem_handle_create(struct drm_file *file_priv,
			  struct drm_gem_object *obj,
			  u32 *handlep);
int drm_gem_handle_delete(struct drm_file *filp, u32 handle);


void drm_gem_free_mmap_offset(struct drm_gem_object *obj);
int drm_gem_create_mmap_offset(struct drm_gem_object *obj);
int drm_gem_create_mmap_offset_size(struct drm_gem_object *obj, size_t size);

struct page **drm_gem_get_pages(struct drm_gem_object *obj);
void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,
		bool dirty, bool accessed);

struct drm_gem_object *drm_gem_object_lookup(struct drm_device *dev,
					     struct drm_file *filp,
					     u32 handle);
int drm_gem_dumb_destroy(struct drm_file *file,
			 struct drm_device *dev,
			 uint32_t handle);

#endif /* __DRM_GEM_H__ */