1/**************************************************************************
2 *
3 * Copyright (c) 2007-2009 VMware, Inc., Palo Alto, CA., USA
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
21 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
22 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
23 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
24 * USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27/*
28 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
29 */
30/* $FreeBSD$ */
31
32/** @file ttm_lock.h
33 * This file implements a simple replacement for the buffer manager use
34 * of the DRM heavyweight hardware lock.
35 * The lock is a read-write lock. Taking it in read mode and write mode
36 * is relatively fast, and intended for in-kernel use only.
37 *
38 * The vt mode is used only when there is a need to block all
39 * user-space processes from validating buffers.
40 * It's allowed to leave kernel space with the vt lock held.
41 * If a user-space process dies while having the vt-lock,
42 * it will be released during the file descriptor release. The vt lock
43 * excludes write lock and read lock.
44 *
45 * The suspend mode is used to lock out all TTM users when preparing for
46 * and executing suspend operations.
47 *
48 */
49
50#ifndef _TTM_LOCK_H_
51#define _TTM_LOCK_H_
52
53#include <dev/drm2/drmP.h>
54#include <dev/drm2/drm.h>
55#include <dev/drm2/ttm/ttm_object.h>
56
57/**
58 * struct ttm_lock
59 *
60 * @base: ttm base object used solely to release the lock if the client
61 * holding the lock dies.
62 * @queue: Queue for processes waiting for lock change-of-status.
63 * @lock: Spinlock protecting some lock members.
64 * @rw: Read-write lock counter. Protected by @lock.
65 * @flags: Lock state. Protected by @lock.
66 * @kill_takers: Boolean whether to kill takers of the lock.
67 * @signal: Signal to send when kill_takers is true.
68 */
69
70struct ttm_lock {
71	struct ttm_base_object base;
72	struct mtx lock;
73	int32_t rw;
74	uint32_t flags;
75	bool kill_takers;
76	int signal;
77	struct ttm_object_file *vt_holder;
78};
79
80
81/**
82 * ttm_lock_init
83 *
84 * @lock: Pointer to a struct ttm_lock
85 * Initializes the lock.
86 */
87extern void ttm_lock_init(struct ttm_lock *lock);
88
89/**
90 * ttm_read_unlock
91 *
92 * @lock: Pointer to a struct ttm_lock
93 *
94 * Releases a read lock.
95 */
96extern void ttm_read_unlock(struct ttm_lock *lock);
97
98/**
99 * ttm_read_lock
100 *
101 * @lock: Pointer to a struct ttm_lock
102 * @interruptible: Interruptible sleeping while waiting for a lock.
103 *
104 * Takes the lock in read mode.
105 * Returns:
106 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
107 */
108extern int ttm_read_lock(struct ttm_lock *lock, bool interruptible);
109
110/**
111 * ttm_read_trylock
112 *
113 * @lock: Pointer to a struct ttm_lock
114 * @interruptible: Interruptible sleeping while waiting for a lock.
115 *
116 * Tries to take the lock in read mode. If the lock is already held
117 * in write mode, the function will return -EBUSY. If the lock is held
118 * in vt or suspend mode, the function will sleep until these modes
119 * are unlocked.
120 *
121 * Returns:
122 * -EBUSY The lock was already held in write mode.
123 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
124 */
125extern int ttm_read_trylock(struct ttm_lock *lock, bool interruptible);
126
127/**
128 * ttm_lock_downgrade
129 *
130 * @lock: Pointer to a struct ttm_lock
131 *
132 * Downgrades a write lock to a read lock.
133 */
134extern void ttm_lock_downgrade(struct ttm_lock *lock);
135
136/**
137 * ttm_suspend_lock
138 *
139 * @lock: Pointer to a struct ttm_lock
140 *
141 * Takes the lock in suspend mode. Excludes read and write mode.
142 */
143extern void ttm_suspend_lock(struct ttm_lock *lock);
144
145/**
146 * ttm_suspend_unlock
147 *
148 * @lock: Pointer to a struct ttm_lock
149 *
150 * Releases a suspend lock
151 */
152extern void ttm_suspend_unlock(struct ttm_lock *lock);
153
154/**
155 * ttm_vt_lock
156 *
157 * @lock: Pointer to a struct ttm_lock
158 * @interruptible: Interruptible sleeping while waiting for a lock.
159 * @tfile: Pointer to a struct ttm_object_file to register the lock with.
160 *
161 * Takes the lock in vt mode.
162 * Returns:
163 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
164 * -ENOMEM: Out of memory when locking.
165 */
166extern int ttm_vt_lock(struct ttm_lock *lock, bool interruptible,
167		       struct ttm_object_file *tfile);
168
169/**
170 * ttm_vt_unlock
171 *
172 * @lock: Pointer to a struct ttm_lock
173 *
174 * Releases a vt lock.
175 * Returns:
176 * -EINVAL If the lock was not held.
177 */
178extern int ttm_vt_unlock(struct ttm_lock *lock);
179
180/**
181 * ttm_write_unlock
182 *
183 * @lock: Pointer to a struct ttm_lock
184 *
185 * Releases a write lock.
186 */
187extern void ttm_write_unlock(struct ttm_lock *lock);
188
189/**
190 * ttm_write_lock
191 *
192 * @lock: Pointer to a struct ttm_lock
193 * @interruptible: Interruptible sleeping while waiting for a lock.
194 *
195 * Takes the lock in write mode.
196 * Returns:
197 * -ERESTARTSYS If interrupted by a signal and interruptible is true.
198 */
199extern int ttm_write_lock(struct ttm_lock *lock, bool interruptible);
200
201void ttm_write_lock_downgrade(struct ttm_lock *lock);
202
203/**
204 * ttm_lock_set_kill
205 *
206 * @lock: Pointer to a struct ttm_lock
207 * @val: Boolean whether to kill processes taking the lock.
208 * @signal: Signal to send to the process taking the lock.
209 *
210 * The kill-when-taking-lock functionality is used to kill processes that keep
211 * on using the TTM functionality when its resources has been taken down, for
212 * example when the X server exits. A typical sequence would look like this:
213 * - X server takes lock in write mode.
214 * - ttm_lock_set_kill() is called with @val set to true.
215 * - As part of X server exit, TTM resources are taken down.
216 * - X server releases the lock on file release.
217 * - Another dri client wants to render, takes the lock and is killed.
218 *
219 */
220static inline void ttm_lock_set_kill(struct ttm_lock *lock, bool val,
221				     int signal)
222{
223	lock->kill_takers = val;
224	if (val)
225		lock->signal = signal;
226}
227
228#endif
229