sys/external/bsd/drm/dist/bsd-core/drm_lock.c

   1 /*-
   2  * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
   3  * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
   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 "Software"),
   8  * to deal in the Software without restriction, including without limitation
   9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  10  * and/or sell copies of the Software, and to permit persons to whom the
  11  * Software is furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice (including the next
  14  * paragraph) shall be included in all copies or substantial portions of the
  15  * Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  21  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  22  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  23  * OTHER DEALINGS IN THE SOFTWARE.
  24  *
  25  * Authors:
  26  *    Rickard E. (Rik) Faith <faith@valinux.com>
  27  *    Gareth Hughes <gareth@valinux.com>
  28  *
  29  */
  30
  31 /** @file drm_lock.c
  32  * Implementation of the ioctls and other support code for dealing with the
  33  * hardware lock.
  34  *
  35  * The DRM hardware lock is a shared structure between the kernel and userland.
  36  *
  37  * On uncontended access where the new context was the last context, the
  38  * client may take the lock without dropping down into the kernel, using atomic
  39  * compare-and-set.
  40  *
  41  * If the client finds during compare-and-set that it was not the last owner
  42  * of the lock, it calls the DRM lock ioctl, which may sleep waiting for the
  43  * lock, and may have side-effects of kernel-managed context switching.
  44  *
  45  * When the client releases the lock, if the lock is marked as being contended
  46  * by another client, then the DRM unlock ioctl is called so that the
  47  * contending client may be woken up.
  48  */
  49
  50 #include "drmP.h"
  51
  52 int drm_lock(struct drm_device *dev, void *data, struct drm_file *file_priv)
  53 {
  54         struct drm_lock *lock = data;
  55         int ret = 0;
  56
  57         if (lock->context == DRM_KERNEL_CONTEXT) {
  58                 DRM_ERROR("Process %d using kernel context %d\n",
  59                     DRM_CURRENTPID, lock->context);
  60                 return EINVAL;
  61         }
  62
  63         DRM_DEBUG("%d (pid %d) requests lock (0x%08x), flags = 0x%08x\n",
  64             lock->context, DRM_CURRENTPID, dev->lock.hw_lock->lock,
  65             lock->flags);
  66
  67         if (drm_core_check_feature(dev, DRIVER_DMA_QUEUE) &&
  68             lock->context < 0)
  69                 return EINVAL;
  70
  71         DRM_LOCK();
  72         for (;;) {
  73                 if (drm_lock_take(&dev->lock, lock->context)) {
  74                         dev->lock.file_priv = file_priv;
  75                         dev->lock.lock_time = jiffies;
  76                         atomic_inc(&dev->counts[_DRM_STAT_LOCKS]);
  77                         break;  /* Got lock */
  78                 }
  79
  80                 /* Contention */
  81 #if defined(__FreeBSD__)
  82                 ret = mtx_sleep((void *)&dev->lock.lock_queue, &dev->dev_lock,
  83                     PCATCH, "drmlk2", 0);
  84 #elif   defined(__NetBSD__)
  85         ret = mtsleep((void *)&dev->lock.lock_queue, PCATCH, "drmlk2", 0,
  86                 &dev->dev_lock);
  87 #endif
  88                 if (ret != 0)
  89                         break;
  90         }
  91         DRM_UNLOCK();
  92         DRM_DEBUG("%d %s\n", lock->context, ret ? "interrupted" : "has lock");
  93
  94         if (ret != 0)
  95                 return ret;
  96
  97         /* XXX: Add signal blocking here */
  98
  99         if (dev->driver->dma_quiescent != NULL &&
 100             (lock->flags & _DRM_LOCK_QUIESCENT))
 101                 dev->driver->dma_quiescent(dev);
 102
 103         return 0;
 104 }
 105
 106 int drm_unlock(struct drm_device *dev, void *data, struct drm_file *file_priv)
 107 {
 108         struct drm_lock *lock = data;
 109
 110         DRM_DEBUG("%d (pid %d) requests unlock (0x%08x), flags = 0x%08x\n",
 111             lock->context, DRM_CURRENTPID, dev->lock.hw_lock->lock,
 112             lock->flags);
 113
 114         if (lock->context == DRM_KERNEL_CONTEXT) {
 115                 DRM_ERROR("Process %d using kernel context %d\n",
 116                     DRM_CURRENTPID, lock->context);
 117                 return EINVAL;
 118         }
 119
 120         atomic_inc(&dev->counts[_DRM_STAT_UNLOCKS]);
 121
 122         DRM_LOCK();
 123         drm_lock_transfer(&dev->lock, DRM_KERNEL_CONTEXT);
 124
 125         if (drm_lock_free(&dev->lock, DRM_KERNEL_CONTEXT)) {
 126                 DRM_ERROR("\n");
 127         }
 128         DRM_UNLOCK();
 129
 130         return 0;
 131 }
 132
 133 int drm_lock_take(struct drm_lock_data *lock_data, unsigned int context)
 134 {
 135         volatile unsigned int *lock = &lock_data->hw_lock->lock;
 136         unsigned int old, new;
 137
 138         do {
 139                 old = *lock;
 140                 if (old & _DRM_LOCK_HELD)
 141                         new = old | _DRM_LOCK_CONT;
 142                 else
 143                         new = context | _DRM_LOCK_HELD;
 144         } while (!atomic_cmpset_int(lock, old, new));
 145
 146         if (_DRM_LOCKING_CONTEXT(old) == context) {
 147                 if (old & _DRM_LOCK_HELD) {
 148                         if (context != DRM_KERNEL_CONTEXT) {
 149                                 DRM_ERROR("%d holds heavyweight lock\n",
 150                                     context);
 151                         }
 152                         return 0;
 153                 }
 154         }
 155         if (new == (context | _DRM_LOCK_HELD)) {
 156                 /* Have lock */
 157                 return 1;
 158         }
 159         return 0;
 160 }
 161
 162 /* This takes a lock forcibly and hands it to context.  Should ONLY be used
 163    inside *_unlock to give lock to kernel before calling *_dma_schedule. */
 164 int drm_lock_transfer(struct drm_lock_data *lock_data, unsigned int context)
 165 {
 166         volatile unsigned int *lock = &lock_data->hw_lock->lock;
 167         unsigned int old, new;
 168
 169         lock_data->file_priv = NULL;
 170         do {
 171                 old = *lock;
 172                 new = context | _DRM_LOCK_HELD;
 173         } while (!atomic_cmpset_int(lock, old, new));
 174
 175         return 1;
 176 }
 177
 178 int drm_lock_free(struct drm_lock_data *lock_data, unsigned int context)
 179 {
 180         volatile unsigned int *lock = &lock_data->hw_lock->lock;
 181         unsigned int old, new;
 182
 183         lock_data->file_priv = NULL;
 184         do {
 185                 old = *lock;
 186                 new = 0;
 187         } while (!atomic_cmpset_int(lock, old, new));
 188
 189         if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
 190                 DRM_ERROR("%d freed heavyweight lock held by %d\n",
 191                     context, _DRM_LOCKING_CONTEXT(old));
 192                 return 1;
 193         }
 194         DRM_WAKEUP_INT((void *)&lock_data->lock_queue);
 195         return 0;
 196 }