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27 /*
28  * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
29  */
30 /** @file ttm_object.h
31  *
32  * Base- and reference object implementation for the various
33  * ttm objects. Implements reference counting, minimal security checks
34  * and release on file close.
35  */
36 
37 #ifndef _TTM_OBJECT_H_
38 #define _TTM_OBJECT_H_
39 
40 #include <linux/dma-buf.h>
41 #include <linux/kref.h>
42 #include <linux/list.h>
43 #include <linux/rcupdate.h>
44 
45 /**
46  * enum ttm_object_type
47  *
48  * One entry per ttm object type.
49  * Device-specific types should use the
50  * ttm_driver_typex types.
51  */
52 
53 enum ttm_object_type {
54 	ttm_fence_type,
55 	ttm_lock_type,
56 	ttm_prime_type,
57 	ttm_driver_type0 = 256,
58 	ttm_driver_type1,
59 	ttm_driver_type2,
60 	ttm_driver_type3,
61 	ttm_driver_type4,
62 	ttm_driver_type5
63 };
64 
65 struct ttm_object_file;
66 struct ttm_object_device;
67 
68 /**
69  * struct ttm_base_object
70  *
71  * @hash: hash entry for the per-device object hash.
72  * @type: derived type this object is base class for.
73  * @shareable: Other ttm_object_files can access this object.
74  *
75  * @tfile: Pointer to ttm_object_file of the creator.
76  * NULL if the object was not created by a user request.
77  * (kernel object).
78  *
79  * @refcount: Number of references to this object, not
80  * including the hash entry. A reference to a base object can
81  * only be held by a ref object.
82  *
83  * @refcount_release: A function to be called when there are
84  * no more references to this object. This function should
85  * destroy the object (or make sure destruction eventually happens),
86  * and when it is called, the object has
87  * already been taken out of the per-device hash. The parameter
88  * "base" should be set to NULL by the function.
89  *
90  * @ref_obj_release: A function to be called when a reference object
91  * with another ttm_ref_type than TTM_REF_USAGE is deleted.
92  * This function may, for example, release a lock held by a user-space
93  * process.
94  *
95  * This struct is intended to be used as a base struct for objects that
96  * are visible to user-space. It provides a global name, race-safe
97  * access and refcounting, minimal access control and hooks for unref actions.
98  */
99 
100 struct ttm_base_object {
101 	struct rcu_head rhead;
102 	struct ttm_object_file *tfile;
103 	struct kref refcount;
104 	void (*refcount_release) (struct ttm_base_object **base);
105 	u64 handle;
106 	enum ttm_object_type object_type;
107 	u32 shareable;
108 };
109 
110 
111 /**
112  * struct ttm_prime_object - Modified base object that is prime-aware
113  *
114  * @base: struct ttm_base_object that we derive from
115  * @mutex: Mutex protecting the @dma_buf member.
116  * @size: Size of the dma_buf associated with this object
117  * @real_type: Type of the underlying object. Needed since we're setting
118  * the value of @base::object_type to ttm_prime_type
119  * @dma_buf: Non ref-coutned pointer to a struct dma_buf created from this
120  * object.
121  * @refcount_release: The underlying object's release method. Needed since
122  * we set @base::refcount_release to our own release method.
123  */
124 
125 struct ttm_prime_object {
126 	struct ttm_base_object base;
127 	struct mutex mutex;
128 	size_t size;
129 	enum ttm_object_type real_type;
130 	struct dma_buf *dma_buf;
131 	void (*refcount_release) (struct ttm_base_object **);
132 };
133 
134 /**
135  * ttm_base_object_init
136  *
137  * @tfile: Pointer to a struct ttm_object_file.
138  * @base: The struct ttm_base_object to initialize.
139  * @shareable: This object is shareable with other applications.
140  * (different @tfile pointers.)
141  * @type: The object type.
142  * @refcount_release: See the struct ttm_base_object description.
143  * @ref_obj_release: See the struct ttm_base_object description.
144  *
145  * Initializes a struct ttm_base_object.
146  */
147 
148 extern int ttm_base_object_init(struct ttm_object_file *tfile,
149 				struct ttm_base_object *base,
150 				bool shareable,
151 				enum ttm_object_type type,
152 				void (*refcount_release) (struct ttm_base_object
153 							  **));
154 
155 /**
156  * ttm_base_object_lookup
157  *
158  * @tfile: Pointer to a struct ttm_object_file.
159  * @key: Hash key
160  *
161  * Looks up a struct ttm_base_object with the key @key.
162  */
163 
164 extern struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file
165 						      *tfile, uint64_t key);
166 
167 /**
168  * ttm_base_object_lookup_for_ref
169  *
170  * @tdev: Pointer to a struct ttm_object_device.
171  * @key: Hash key
172  *
173  * Looks up a struct ttm_base_object with the key @key.
174  * This function should only be used when the struct tfile associated with the
175  * caller doesn't yet have a reference to the base object.
176  */
177 
178 extern struct ttm_base_object *
179 ttm_base_object_lookup_for_ref(struct ttm_object_device *tdev, uint64_t key);
180 
181 /**
182  * ttm_base_object_unref
183  *
184  * @p_base: Pointer to a pointer referencing a struct ttm_base_object.
185  *
186  * Decrements the base object refcount and clears the pointer pointed to by
187  * p_base.
188  */
189 
190 extern void ttm_base_object_unref(struct ttm_base_object **p_base);
191 
192 /**
193  * ttm_ref_object_add.
194  *
195  * @tfile: A struct ttm_object_file representing the application owning the
196  * ref_object.
197  * @base: The base object to reference.
198  * @ref_type: The type of reference.
199  * @existed: Upon completion, indicates that an identical reference object
200  * already existed, and the refcount was upped on that object instead.
201  * @require_existed: Fail with -EPERM if an identical ref object didn't
202  * already exist.
203  *
204  * Checks that the base object is shareable and adds a ref object to it.
205  *
206  * Adding a ref object to a base object is basically like referencing the
207  * base object, but a user-space application holds the reference. When the
208  * file corresponding to @tfile is closed, all its reference objects are
209  * deleted. A reference object can have different types depending on what
210  * it's intended for. It can be refcounting to prevent object destruction,
211  * When user-space takes a lock, it can add a ref object to that lock to
212  * make sure the lock is released if the application dies. A ref object
213  * will hold a single reference on a base object.
214  */
215 extern int ttm_ref_object_add(struct ttm_object_file *tfile,
216 			      struct ttm_base_object *base,
217 			      bool *existed,
218 			      bool require_existed);
219 
220 /**
221  * ttm_ref_object_base_unref
222  *
223  * @key: Key representing the base object.
224  * @ref_type: Ref type of the ref object to be dereferenced.
225  *
226  * Unreference a ref object with type @ref_type
227  * on the base object identified by @key. If there are no duplicate
228  * references, the ref object will be destroyed and the base object
229  * will be unreferenced.
230  */
231 extern int ttm_ref_object_base_unref(struct ttm_object_file *tfile,
232 				     unsigned long key);
233 
234 /**
235  * ttm_object_file_init - initialize a struct ttm_object file
236  *
237  * @tdev: A struct ttm_object device this file is initialized on.
238  *
239  * This is typically called by the file_ops::open function.
240  */
241 
242 extern struct ttm_object_file *ttm_object_file_init(struct ttm_object_device
243 						    *tdev);
244 
245 /**
246  * ttm_object_file_release - release data held by a ttm_object_file
247  *
248  * @p_tfile: Pointer to pointer to the ttm_object_file object to release.
249  * *p_tfile will be set to NULL by this function.
250  *
251  * Releases all data associated by a ttm_object_file.
252  * Typically called from file_ops::release. The caller must
253  * ensure that there are no concurrent users of tfile.
254  */
255 
256 extern void ttm_object_file_release(struct ttm_object_file **p_tfile);
257 
258 /**
259  * ttm_object device init - initialize a struct ttm_object_device
260  *
261  * @ops: DMA buf ops for prime objects of this device.
262  *
263  * This function is typically called on device initialization to prepare
264  * data structures needed for ttm base and ref objects.
265  */
266 
267 extern struct ttm_object_device *
268 ttm_object_device_init(const struct dma_buf_ops *ops);
269 
270 /**
271  * ttm_object_device_release - release data held by a ttm_object_device
272  *
273  * @p_tdev: Pointer to pointer to the ttm_object_device object to release.
274  * *p_tdev will be set to NULL by this function.
275  *
276  * Releases all data associated by a ttm_object_device.
277  * Typically called from driver::unload before the destruction of the
278  * device private data structure.
279  */
280 
281 extern void ttm_object_device_release(struct ttm_object_device **p_tdev);
282 
283 #define ttm_base_object_kfree(__object, __base)\
284 	kfree_rcu(__object, __base.rhead)
285 
286 extern int ttm_prime_object_init(struct ttm_object_file *tfile,
287 				 size_t size,
288 				 struct ttm_prime_object *prime,
289 				 bool shareable,
290 				 enum ttm_object_type type,
291 				 void (*refcount_release)
292 				 (struct ttm_base_object **));
293 
294 static inline enum ttm_object_type
ttm_base_object_type(struct ttm_base_object * base)295 ttm_base_object_type(struct ttm_base_object *base)
296 {
297 	return (base->object_type == ttm_prime_type) ?
298 		container_of(base, struct ttm_prime_object, base)->real_type :
299 		base->object_type;
300 }
301 extern int ttm_prime_fd_to_handle(struct ttm_object_file *tfile,
302 				  int fd, u32 *handle);
303 extern int ttm_prime_handle_to_fd(struct ttm_object_file *tfile,
304 				  uint32_t handle, uint32_t flags,
305 				  int *prime_fd);
306 
307 #define ttm_prime_object_kfree(__obj, __prime)		\
308 	kfree_rcu(__obj, __prime.base.rhead)
309 
310 #endif
311