97 lines
2.9 KiB
C
97 lines
2.9 KiB
C
/* lock.c -- IOCTLs for locking -*- linux-c -*-
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* Created: Tue Feb 2 08:37:54 1999 by faith@valinux.com
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*
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* Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
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* Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
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* All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*
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* Authors:
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* Rickard E. (Rik) Faith <faith@valinux.com>
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* Gareth Hughes <gareth@valinux.com>
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*
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*/
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#include "drmP.h"
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int DRM(lock_take)(__volatile__ unsigned int *lock, unsigned int context)
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{
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unsigned int old, new;
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do {
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old = *lock;
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if (old & _DRM_LOCK_HELD) new = old | _DRM_LOCK_CONT;
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else new = context | _DRM_LOCK_HELD;
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} while (!atomic_cmpset_int(lock, old, new));
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if (_DRM_LOCKING_CONTEXT(old) == context) {
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if (old & _DRM_LOCK_HELD) {
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if (context != DRM_KERNEL_CONTEXT) {
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DRM_ERROR("%d holds heavyweight lock\n",
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context);
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}
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return 0;
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}
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}
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if (new == (context | _DRM_LOCK_HELD)) {
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/* Have lock */
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return 1;
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}
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return 0;
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}
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/* This takes a lock forcibly and hands it to context. Should ONLY be used
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inside *_unlock to give lock to kernel before calling *_dma_schedule. */
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int DRM(lock_transfer)(drm_device_t *dev,
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__volatile__ unsigned int *lock, unsigned int context)
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{
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unsigned int old, new;
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dev->lock.filp = NULL;
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do {
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old = *lock;
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new = context | _DRM_LOCK_HELD;
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} while (!atomic_cmpset_int(lock, old, new));
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return 1;
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}
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int DRM(lock_free)(drm_device_t *dev,
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__volatile__ unsigned int *lock, unsigned int context)
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{
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unsigned int old, new;
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dev->lock.filp = NULL;
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do {
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old = *lock;
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new = 0;
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} while (!atomic_cmpset_int(lock, old, new));
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if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
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DRM_ERROR("%d freed heavyweight lock held by %d\n",
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context, _DRM_LOCKING_CONTEXT(old));
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return 1;
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}
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DRM_WAKEUP_INT((void *)&dev->lock.lock_queue);
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return 0;
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}
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