sys/dev/drm/drm_lock.h

   1 /* lock.c -- IOCTLs for locking -*- linux-c -*-
   2  * Created: Tue Feb  2 08:37:54 1999 by faith@valinux.com
   3  *
   4  * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
   5  * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
   6  * All Rights Reserved.
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice (including the next
  16  * paragraph) shall be included in all copies or substantial portions of the
  17  * Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  22  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  23  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  24  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  25  * OTHER DEALINGS IN THE SOFTWARE.
  26  *
  27  * Authors:
  28  *    Rickard E. (Rik) Faith <faith@valinux.com>
  29  *    Gareth Hughes <gareth@valinux.com>
  30  *
  31  * $FreeBSD: src/sys/dev/drm/drm_lock.h,v 1.3.2.1 2003/04/26 07:05:28 anholt Exp $
  32  * $DragonFly: src/sys/dev/drm/drm_lock.h,v 1.2 2003/06/17 06:28:24 dillon Exp $
  33  */
  34
  35 #include "dev/drm/drmP.h"
  36
  37 int DRM(lock_take)(__volatile__ unsigned int *lock, unsigned int context)
  38 {
  39         unsigned int old, new;
  40
  41         do {
  42                 old = *lock;
  43                 if (old & _DRM_LOCK_HELD) new = old | _DRM_LOCK_CONT;
  44                 else                      new = context | _DRM_LOCK_HELD;
  45         } while (!atomic_cmpset_int(lock, old, new));
  46
  47         if (_DRM_LOCKING_CONTEXT(old) == context) {
  48                 if (old & _DRM_LOCK_HELD) {
  49                         if (context != DRM_KERNEL_CONTEXT) {
  50                                 DRM_ERROR("%d holds heavyweight lock\n",
  51                                           context);
  52                         }
  53                         return 0;
  54                 }
  55         }
  56         if (new == (context | _DRM_LOCK_HELD)) {
  57                                 /* Have lock */
  58                 return 1;
  59         }
  60         return 0;
  61 }
  62
  63 /* This takes a lock forcibly and hands it to context.  Should ONLY be used
  64    inside *_unlock to give lock to kernel before calling *_dma_schedule. */
  65 int DRM(lock_transfer)(drm_device_t *dev,
  66                        __volatile__ unsigned int *lock, unsigned int context)
  67 {
  68         unsigned int old, new;
  69
  70         dev->lock.filp = NULL;
  71         do {
  72                 old  = *lock;
  73                 new  = context | _DRM_LOCK_HELD;
  74         } while (!atomic_cmpset_int(lock, old, new));
  75
  76         return 1;
  77 }
  78
  79 int DRM(lock_free)(drm_device_t *dev,
  80                    __volatile__ unsigned int *lock, unsigned int context)
  81 {
  82         unsigned int old, new;
  83
  84         dev->lock.filp = NULL;
  85         do {
  86                 old  = *lock;
  87                 new  = 0;
  88         } while (!atomic_cmpset_int(lock, old, new));
  89
  90         if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
  91                 DRM_ERROR("%d freed heavyweight lock held by %d\n",
  92                           context, _DRM_LOCKING_CONTEXT(old));
  93                 return 1;
  94         }
  95         DRM_WAKEUP_INT((void *)&dev->lock.lock_queue);
  96         return 0;
  97 }
  98