include/drm/ttm/ttm_object.h

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