ttm_object.h

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 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
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/*
 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
 */
/** @file ttm_object.h
 *
 * Base- and reference object implementation for the various
 * ttm objects. Implements reference counting, minimal security checks
 * and release on file close.
 */

#ifndef _TTM_OBJECT_H_
#define _TTM_OBJECT_H_

#include <linux/list.h>
#include "drm_hashtab.h"
#include <linux/kref.h>
#include <ttm/ttm_memory.h>

/**
 * enum ttm_ref_type
 *
 * Describes what type of reference a ref object holds.
 *
 * TTM_REF_USAGE is a simple refcount on a base object.
 *
 * TTM_REF_SYNCCPU_READ is a SYNCCPU_READ reference on a
 * buffer object.
 *
 * TTM_REF_SYNCCPU_WRITE is a SYNCCPU_WRITE reference on a
 * buffer object.
 *
 */

enum ttm_ref_type {
	TTM_REF_USAGE,
	TTM_REF_SYNCCPU_READ,
	TTM_REF_SYNCCPU_WRITE,
	TTM_REF_NUM
};

/**
 * enum ttm_object_type
 *
 * One entry per ttm object type.
 * Device-specific types should use the
 * ttm_driver_typex types.
 */

enum ttm_object_type {
	ttm_fence_type,
	ttm_buffer_type,
	ttm_lock_type,
	ttm_driver_type0 = 256,
	ttm_driver_type1,
	ttm_driver_type2,
	ttm_driver_type3,
	ttm_driver_type4,
	ttm_driver_type5
};

struct ttm_object_file;
struct ttm_object_device;

/**
 * struct ttm_base_object
 *
 * @hash: hash entry for the per-device object hash.
 * @type: derived type this object is base class for.
 * @shareable: Other ttm_object_files can access this object.
 *
 * @tfile: Pointer to ttm_object_file of the creator.
 * NULL if the object was not created by a user request.
 * (kernel object).
 *
 * @refcount: Number of references to this object, not
 * including the hash entry. A reference to a base object can
 * only be held by a ref object.
 *
 * @refcount_release: A function to be called when there are
 * no more references to this object. This function should
 * destroy the object (or make sure destruction eventually happens),
 * and when it is called, the object has
 * already been taken out of the per-device hash. The parameter
 * "base" should be set to NULL by the function.
 *
 * @ref_obj_release: A function to be called when a reference object
 * with another ttm_ref_type than TTM_REF_USAGE is deleted.
 * this function may, for example, release a lock held by a user-space
 * process.
 *
 * This struct is intended to be used as a base struct for objects that
 * are visible to user-space. It provides a global name, race-safe
 * access and refcounting, minimal access contol and hooks for unref actions.
 */

struct ttm_base_object {
	struct drm_hash_item hash;
	enum ttm_object_type object_type;
	bool shareable;
	struct ttm_object_file *tfile;
	struct kref refcount;
	void (*refcount_release) (struct ttm_base_object **base);
	void (*ref_obj_release) (struct ttm_base_object *base,
				 enum ttm_ref_type ref_type);
};

/**
 * ttm_base_object_init
 *
 * @tfile: Pointer to a struct ttm_object_file.
 * @base: The struct ttm_base_object to initialize.
 * @shareable: This object is shareable with other applcations.
 * (different @tfile pointers.)
 * @type: The object type.
 * @refcount_release: See the struct ttm_base_object description.
 * @ref_obj_release: See the struct ttm_base_object description.
 *
 * Initializes a struct ttm_base_object.
 */

extern int ttm_base_object_init(struct ttm_object_file *tfile,
				struct ttm_base_object *base,
				bool shareable,
				enum ttm_object_type type,
				void (*refcount_release) (struct ttm_base_object
							  **),
				void (*ref_obj_release) (struct ttm_base_object
							 *,
							 enum ttm_ref_type
							 ref_type));

/**
 * ttm_base_object_lookup
 *
 * @tfile: Pointer to a struct ttm_object_file.
 * @key: Hash key
 *
 * Looks up a struct ttm_base_object with the key @key.
 * Also verifies that the object is visible to the application, by
 * comparing the @tfile argument and checking the object shareable flag.
 */

extern struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file
						      *tfile, uint32_t key);

/**
 * ttm_base_object_unref
 *
 * @p_base: Pointer to a pointer referncing a struct ttm_base_object.
 *
 * Decrements the base object refcount and clears the pointer pointed to by
 * p_base.
 */

extern void ttm_base_object_unref(struct ttm_base_object **p_base);

/**
 * ttm_ref_object_add.
 *
 * @tfile: A struct ttm_object_file representing the application owning the
 * ref_object.
 * @base: The base object to reference.
 * @ref_type: The type of reference.
 * @existed: Upon completion, indicates that an identical reference object
 * already existed, and the refcount was upped on that object instead.
 *
 * Adding a ref object to a base object is basically like referencing the
 * base object, but a user-space application holds the reference. When the
 * file corresponding to @tfile is closed, all its reference objects are
 * deleted. A reference object can have different types depending on what
 * it's intended for. It can be refcounting to prevent object destruction,
 * When user-space takes a lock, it can add a ref object to that lock to
 * make sure the lock is released if the application dies. A ref object
 * will hold a single reference on a base object.
 */
extern int ttm_ref_object_add(struct ttm_object_file *tfile,
			      struct ttm_base_object *base,
			      enum ttm_ref_type ref_type, bool *existed);
/**
 * ttm_ref_object_base_unref
 *
 * @key: Key representing the base object.
 * @ref_type: Ref type of the ref object to be dereferenced.
 *
 * Unreference a ref object with type @ref_type
 * on the base object identified by @key. If there are no duplicate
 * references, the ref object will be destroyed and the base object
 * will be unreferenced.
 */
extern int ttm_ref_object_base_unref(struct ttm_object_file *tfile,
				     unsigned long key,
				     enum ttm_ref_type ref_type);

/**
 * ttm_object_file_init - initialize a struct ttm_object file
 *
 * @tdev: A struct ttm_object device this file is initialized on.
 * @hash_order: Order of the hash table used to hold the reference objects.
 *
 * This is typically called by the file_ops::open function.
 */

extern struct ttm_object_file *ttm_object_file_init(struct ttm_object_device
						    *tdev,
						    unsigned int hash_order);

/**
 * ttm_object_file_release - release data held by a ttm_object_file
 *
 * @p_tfile: Pointer to pointer to the ttm_object_file object to release.
 * *p_tfile will be set to NULL by this function.
 *
 * Releases all data associated by a ttm_object_file.
 * Typically called from file_ops::release. The caller must
 * ensure that there are no concurrent users of tfile.
 */

extern void ttm_object_file_release(struct ttm_object_file **p_tfile);

/**
 * ttm_object device init - initialize a struct ttm_object_device
 *
 * @hash_order: Order of hash table used to hash the base objects.
 *
 * This function is typically called on device initialization to prepare
 * data structures needed for ttm base and ref objects.
 */

extern struct ttm_object_device *ttm_object_device_init
    (struct ttm_mem_global *mem_glob, unsigned int hash_order);

/**
 * ttm_object_device_release - release data held by a ttm_object_device
 *
 * @p_tdev: Pointer to pointer to the ttm_object_device object to release.
 * *p_tdev will be set to NULL by this function.
 *
 * Releases all data associated by a ttm_object_device.
 * Typically called from driver::unload before the destruction of the
 * device private data structure.
 */

extern void ttm_object_device_release(struct ttm_object_device **p_tdev);

#endif