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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/list.h>
41 #include "drm_hashtab.h"
42 #include <linux/kref.h>
43 #include <ttm/ttm_memory.h>
44 
45 /**
46  * enum ttm_ref_type
47  *
48  * Describes what type of reference a ref object holds.
49  *
50  * TTM_REF_USAGE is a simple refcount on a base object.
51  *
52  * TTM_REF_SYNCCPU_READ is a SYNCCPU_READ reference on a
53  * buffer object.
54  *
55  * TTM_REF_SYNCCPU_WRITE is a SYNCCPU_WRITE reference on a
56  * buffer object.
57  *
58  */
59 
60 enum ttm_ref_type {
61 	TTM_REF_USAGE,
62 	TTM_REF_SYNCCPU_READ,
63 	TTM_REF_SYNCCPU_WRITE,
64 	TTM_REF_NUM
65 };
66 
67 /**
68  * enum ttm_object_type
69  *
70  * One entry per ttm object type.
71  * Device-specific types should use the
72  * ttm_driver_typex types.
73  */
74 
75 enum ttm_object_type {
76 	ttm_fence_type,
77 	ttm_buffer_type,
78 	ttm_lock_type,
79 	ttm_driver_type0 = 256,
80 	ttm_driver_type1,
81 	ttm_driver_type2,
82 	ttm_driver_type3,
83 	ttm_driver_type4,
84 	ttm_driver_type5
85 };
86 
87 struct ttm_object_file;
88 struct ttm_object_device;
89 
90 /**
91  * struct ttm_base_object
92  *
93  * @hash: hash entry for the per-device object hash.
94  * @type: derived type this object is base class for.
95  * @shareable: Other ttm_object_files can access this object.
96  *
97  * @tfile: Pointer to ttm_object_file of the creator.
98  * NULL if the object was not created by a user request.
99  * (kernel object).
100  *
101  * @refcount: Number of references to this object, not
102  * including the hash entry. A reference to a base object can
103  * only be held by a ref object.
104  *
105  * @refcount_release: A function to be called when there are
106  * no more references to this object. This function should
107  * destroy the object (or make sure destruction eventually happens),
108  * and when it is called, the object has
109  * already been taken out of the per-device hash. The parameter
110  * "base" should be set to NULL by the function.
111  *
112  * @ref_obj_release: A function to be called when a reference object
113  * with another ttm_ref_type than TTM_REF_USAGE is deleted.
114  * This function may, for example, release a lock held by a user-space
115  * process.
116  *
117  * This struct is intended to be used as a base struct for objects that
118  * are visible to user-space. It provides a global name, race-safe
119  * access and refcounting, minimal access contol and hooks for unref actions.
120  */
121 
122 struct ttm_base_object {
123 	struct drm_hash_item hash;
124 	enum ttm_object_type object_type;
125 	bool shareable;
126 	struct ttm_object_file *tfile;
127 	struct kref refcount;
128 	void (*refcount_release) (struct ttm_base_object **base);
129 	void (*ref_obj_release) (struct ttm_base_object *base,
130 				 enum ttm_ref_type ref_type);
131 };
132 
133 /**
134  * ttm_base_object_init
135  *
136  * @tfile: Pointer to a struct ttm_object_file.
137  * @base: The struct ttm_base_object to initialize.
138  * @shareable: This object is shareable with other applcations.
139  * (different @tfile pointers.)
140  * @type: The object type.
141  * @refcount_release: See the struct ttm_base_object description.
142  * @ref_obj_release: See the struct ttm_base_object description.
143  *
144  * Initializes a struct ttm_base_object.
145  */
146 
147 extern int ttm_base_object_init(struct ttm_object_file *tfile,
148 				struct ttm_base_object *base,
149 				bool shareable,
150 				enum ttm_object_type type,
151 				void (*refcount_release) (struct ttm_base_object
152 							  **),
153 				void (*ref_obj_release) (struct ttm_base_object
154 							 *,
155 							 enum ttm_ref_type
156 							 ref_type));
157 
158 /**
159  * ttm_base_object_lookup
160  *
161  * @tfile: Pointer to a struct ttm_object_file.
162  * @key: Hash key
163  *
164  * Looks up a struct ttm_base_object with the key @key.
165  * Also verifies that the object is visible to the application, by
166  * comparing the @tfile argument and checking the object shareable flag.
167  */
168 
169 extern struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file
170 						      *tfile, uint32_t key);
171 
172 /**
173  * ttm_base_object_unref
174  *
175  * @p_base: Pointer to a pointer referencing a struct ttm_base_object.
176  *
177  * Decrements the base object refcount and clears the pointer pointed to by
178  * p_base.
179  */
180 
181 extern void ttm_base_object_unref(struct ttm_base_object **p_base);
182 
183 /**
184  * ttm_ref_object_add.
185  *
186  * @tfile: A struct ttm_object_file representing the application owning the
187  * ref_object.
188  * @base: The base object to reference.
189  * @ref_type: The type of reference.
190  * @existed: Upon completion, indicates that an identical reference object
191  * already existed, and the refcount was upped on that object instead.
192  *
193  * Adding a ref object to a base object is basically like referencing the
194  * base object, but a user-space application holds the reference. When the
195  * file corresponding to @tfile is closed, all its reference objects are
196  * deleted. A reference object can have different types depending on what
197  * it's intended for. It can be refcounting to prevent object destruction,
198  * When user-space takes a lock, it can add a ref object to that lock to
199  * make sure the lock is released if the application dies. A ref object
200  * will hold a single reference on a base object.
201  */
202 extern int ttm_ref_object_add(struct ttm_object_file *tfile,
203 			      struct ttm_base_object *base,
204 			      enum ttm_ref_type ref_type, bool *existed);
205 /**
206  * ttm_ref_object_base_unref
207  *
208  * @key: Key representing the base object.
209  * @ref_type: Ref type of the ref object to be dereferenced.
210  *
211  * Unreference a ref object with type @ref_type
212  * on the base object identified by @key. If there are no duplicate
213  * references, the ref object will be destroyed and the base object
214  * will be unreferenced.
215  */
216 extern int ttm_ref_object_base_unref(struct ttm_object_file *tfile,
217 				     unsigned long key,
218 				     enum ttm_ref_type ref_type);
219 
220 /**
221  * ttm_object_file_init - initialize a struct ttm_object file
222  *
223  * @tdev: A struct ttm_object device this file is initialized on.
224  * @hash_order: Order of the hash table used to hold the reference objects.
225  *
226  * This is typically called by the file_ops::open function.
227  */
228 
229 extern struct ttm_object_file *ttm_object_file_init(struct ttm_object_device
230 						    *tdev,
231 						    unsigned int hash_order);
232 
233 /**
234  * ttm_object_file_release - release data held by a ttm_object_file
235  *
236  * @p_tfile: Pointer to pointer to the ttm_object_file object to release.
237  * *p_tfile will be set to NULL by this function.
238  *
239  * Releases all data associated by a ttm_object_file.
240  * Typically called from file_ops::release. The caller must
241  * ensure that there are no concurrent users of tfile.
242  */
243 
244 extern void ttm_object_file_release(struct ttm_object_file **p_tfile);
245 
246 /**
247  * ttm_object device init - initialize a struct ttm_object_device
248  *
249  * @hash_order: Order of hash table used to hash the base objects.
250  *
251  * This function is typically called on device initialization to prepare
252  * data structures needed for ttm base and ref objects.
253  */
254 
255 extern struct ttm_object_device *ttm_object_device_init
256     (struct ttm_mem_global *mem_glob, unsigned int hash_order);
257 
258 /**
259  * ttm_object_device_release - release data held by a ttm_object_device
260  *
261  * @p_tdev: Pointer to pointer to the ttm_object_device object to release.
262  * *p_tdev will be set to NULL by this function.
263  *
264  * Releases all data associated by a ttm_object_device.
265  * Typically called from driver::unload before the destruction of the
266  * device private data structure.
267  */
268 
269 extern void ttm_object_device_release(struct ttm_object_device **p_tdev);
270 
271 #endif
272