sys/dev/drm/drm_lock.c

   1 /* lock.c -- IOCTLs for locking -*- linux-c -*-
   2  * Created: Tue Feb  2 08:37:54 1999 by faith@valinux.com
   3  */
   4 /*-
   5  * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
   6  * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
   7  * All Rights Reserved.
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a
  10  * copy of this software and associated documentation files (the "Software"),
  11  * to deal in the Software without restriction, including without limitation
  12  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  13  * and/or sell copies of the Software, and to permit persons to whom the
  14  * Software is furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice (including the next
  17  * paragraph) shall be included in all copies or substantial portions of the
  18  * Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  23  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  24  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  25  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  26  * OTHER DEALINGS IN THE SOFTWARE.
  27  *
  28  * Authors:
  29  *    Rickard E. (Rik) Faith <faith@valinux.com>
  30  *    Gareth Hughes <gareth@valinux.com>
  31  *
  32  */
  33
  34 #include <sys/cdefs.h>
  35 __FBSDID("$FreeBSD$");
  36
  37 #include "dev/drm/drmP.h"
  38
  39 int drm_lock_take(__volatile__ unsigned int *lock, unsigned int context)
  40 {
  41         unsigned int old, new;
  42
  43         do {
  44                 old = *lock;
  45                 if (old & _DRM_LOCK_HELD) new = old | _DRM_LOCK_CONT;
  46                 else                      new = context | _DRM_LOCK_HELD;
  47         } while (!atomic_cmpset_int(lock, old, new));
  48
  49         if (_DRM_LOCKING_CONTEXT(old) == context) {
  50                 if (old & _DRM_LOCK_HELD) {
  51                         if (context != DRM_KERNEL_CONTEXT) {
  52                                 DRM_ERROR("%d holds heavyweight lock\n",
  53                                           context);
  54                         }
  55                         return 0;
  56                 }
  57         }
  58         if (new == (context | _DRM_LOCK_HELD)) {
  59                                 /* Have lock */
  60                 return 1;
  61         }
  62         return 0;
  63 }
  64
  65 /* This takes a lock forcibly and hands it to context.  Should ONLY be used
  66    inside *_unlock to give lock to kernel before calling *_dma_schedule. */
  67 int drm_lock_transfer(drm_device_t *dev,
  68                        __volatile__ unsigned int *lock, unsigned int context)
  69 {
  70         unsigned int old, new;
  71
  72         dev->lock.filp = NULL;
  73         do {
  74                 old  = *lock;
  75                 new  = context | _DRM_LOCK_HELD;
  76         } while (!atomic_cmpset_int(lock, old, new));
  77
  78         return 1;
  79 }
  80
  81 int drm_lock_free(drm_device_t *dev,
  82                    __volatile__ unsigned int *lock, unsigned int context)
  83 {
  84         unsigned int old, new;
  85
  86         dev->lock.filp = NULL;
  87         do {
  88                 old  = *lock;
  89                 new  = 0;
  90         } while (!atomic_cmpset_int(lock, old, new));
  91
  92         if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
  93                 DRM_ERROR("%d freed heavyweight lock held by %d\n",
  94                           context, _DRM_LOCKING_CONTEXT(old));
  95                 return 1;
  96         }
  97         DRM_WAKEUP_INT((void *)&dev->lock.lock_queue);
  98         return 0;
  99 }
 100
 101 int drm_lock(DRM_IOCTL_ARGS)
 102 {
 103         DRM_DEVICE;
 104         drm_lock_t lock;
 105         int ret = 0;
 106
 107         DRM_COPY_FROM_USER_IOCTL(lock, (drm_lock_t *)data, sizeof(lock));
 108
 109         if (lock.context == DRM_KERNEL_CONTEXT) {
 110                 DRM_ERROR("Process %d using kernel context %d\n",
 111                     DRM_CURRENTPID, lock.context);
 112                 return EINVAL;
 113         }
 114
 115         DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
 116             lock.context, DRM_CURRENTPID, dev->lock.hw_lock->lock, lock.flags);
 117
 118         if (dev->driver.use_dma_queue && lock.context < 0)
 119                 return EINVAL;
 120
 121         DRM_LOCK();
 122         for (;;) {
 123                 if (drm_lock_take(&dev->lock.hw_lock->lock, lock.context)) {
 124                         dev->lock.filp = (void *)(uintptr_t)DRM_CURRENTPID;
 125                         dev->lock.lock_time = jiffies;
 126                         atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
 127                         break;  /* Got lock */
 128                 }
 129
 130                 /* Contention */
 131 #if defined(__FreeBSD__) && __FreeBSD_version > 500000
 132                 ret = msleep((void *)&dev->lock.lock_queue, &dev->dev_lock,
 133                     PZERO | PCATCH, "drmlk2", 0);
 134 #else
 135                 ret = tsleep((void *)&dev->lock.lock_queue, PZERO | PCATCH,
 136                     "drmlk2", 0);
 137 #endif
 138                 if (ret != 0)
 139                         break;
 140         }
 141         DRM_UNLOCK();
 142         DRM_DEBUG("%d %s\n", lock.context, ret ? "interrupted" : "has lock");
 143
 144         if (ret != 0)
 145                 return ret;
 146
 147         /* XXX: Add signal blocking here */
 148
 149         if (dev->driver.dma_quiescent != NULL &&
 150             (lock.flags & _DRM_LOCK_QUIESCENT))
 151                 dev->driver.dma_quiescent(dev);
 152
 153         return 0;
 154 }
 155
 156 int drm_unlock(DRM_IOCTL_ARGS)
 157 {
 158         DRM_DEVICE;
 159         drm_lock_t lock;
 160
 161         DRM_COPY_FROM_USER_IOCTL(lock, (drm_lock_t *)data, sizeof(lock));
 162
 163         if (lock.context == DRM_KERNEL_CONTEXT) {
 164                 DRM_ERROR("Process %d using kernel context %d\n",
 165                     DRM_CURRENTPID, lock.context);
 166                 return EINVAL;
 167         }
 168
 169         atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
 170
 171         DRM_LOCK();
 172         drm_lock_transfer(dev, &dev->lock.hw_lock->lock, DRM_KERNEL_CONTEXT);
 173
 174         if (drm_lock_free(dev, &dev->lock.hw_lock->lock, DRM_KERNEL_CONTEXT)) {
 175                 DRM_ERROR("\n");
 176         }
 177         DRM_UNLOCK();
 178
 179         return 0;
 180 }