/* lock.c -- IOCTLs for locking -*- linux-c -*-
 * Created: Tue Feb  2 08:37:54 1999 by faith@precisioninsight.com
 *
 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 * 
 * Authors:
 *    Rickard E. (Rik) Faith <faith@valinux.com>
 *
 */

#define __NO_VERSION__
#include "drmP.h"

int drm_block(struct inode *inode, struct file *filp, unsigned int cmd,
              unsigned long arg)
{
        DRM_DEBUG("\n");
        return 0;
}

int drm_unblock(struct inode *inode, struct file *filp, unsigned int cmd,
                unsigned long arg)
{
        DRM_DEBUG("\n");
        return 0;
}

int drm_lock_take(__volatile__ unsigned int *lock, unsigned int context)
{
        unsigned int old, new, prev;

        do {
                old = *lock;
                if (old & _DRM_LOCK_HELD) new = old | _DRM_LOCK_CONT;
                else                      new = context | _DRM_LOCK_HELD;
                prev = cmpxchg(lock, old, new);
        } while (prev != old);
        if (_DRM_LOCKING_CONTEXT(old) == context) {
                if (old & _DRM_LOCK_HELD) {
                        if (context != DRM_KERNEL_CONTEXT) {
                                DRM_ERROR("%d holds heavyweight lock\n",
                                          context);
                        }
                        return 0;
                }
        }
        if (new == (context | _DRM_LOCK_HELD)) {
                                /* Have lock */
                return 1;
        }
        return 0;
}

/* This takes a lock forcibly and hands it to context.  Should ONLY be used
   inside *_unlock to give lock to kernel before calling *_dma_schedule. */
int drm_lock_transfer(drm_device_t *dev,
                      __volatile__ unsigned int *lock, unsigned int context)
{
        unsigned int old, new, prev;

        dev->lock.pid = 0;
        do {
                old  = *lock;
                new  = context | _DRM_LOCK_HELD;
                prev = cmpxchg(lock, old, new);
        } while (prev != old);
        return 1;
}

int drm_lock_free(drm_device_t *dev,
                  __volatile__ unsigned int *lock, unsigned int context)
{
        unsigned int old, new, prev;
        pid_t        pid = dev->lock.pid;

        dev->lock.pid = 0;
        do {
                old  = *lock;
                new  = 0;
                prev = cmpxchg(lock, old, new);
        } while (prev != old);
        if (_DRM_LOCK_IS_HELD(old) && _DRM_LOCKING_CONTEXT(old) != context) {
                DRM_ERROR("%d freed heavyweight lock held by %d (pid %d)\n",
                          context,
                          _DRM_LOCKING_CONTEXT(old),
                          pid);
                return 1;
        }
        wake_up_interruptible(&dev->lock.lock_queue);
        return 0;
}

static int drm_flush_queue(drm_device_t *dev, int context)
{
        DECLARE_WAITQUEUE(entry, current);
        int               ret   = 0;
        drm_queue_t       *q    = dev->queuelist[context];
        
        DRM_DEBUG("\n");
        
        atomic_inc(&q->use_count);
        if (atomic_read(&q->use_count) > 1) {
                atomic_inc(&q->block_write);
                add_wait_queue(&q->flush_queue, &entry);
                atomic_inc(&q->block_count);
                for (;;) {
                        current->state = TASK_INTERRUPTIBLE;
                        if (!DRM_BUFCOUNT(&q->waitlist)) break;
                        schedule();
                        if (signal_pending(current)) {
                                ret = -EINTR; /* Can't restart */
                                break;
                        }
                }
                atomic_dec(&q->block_count);
                current->state = TASK_RUNNING;
                remove_wait_queue(&q->flush_queue, &entry);
        }
        atomic_dec(&q->use_count);
        atomic_inc(&q->total_flushed);
                
                                /* NOTE: block_write is still incremented!
                                   Use drm_flush_unlock_queue to decrement. */
        return ret;
}

static int drm_flush_unblock_queue(drm_device_t *dev, int context)
{
        drm_queue_t       *q    = dev->queuelist[context];
        
        DRM_DEBUG("\n");
        
        atomic_inc(&q->use_count);
        if (atomic_read(&q->use_count) > 1) {
                if (atomic_read(&q->block_write)) {
                        atomic_dec(&q->block_write);
                        wake_up_interruptible(&q->write_queue);
                }
        }
        atomic_dec(&q->use_count);
        return 0;
}

int drm_flush_block_and_flush(drm_device_t *dev, int context,
                              drm_lock_flags_t flags)
{
        int ret = 0;
        int i;
        
        DRM_DEBUG("\n");
        
        if (flags & _DRM_LOCK_FLUSH) {
                ret = drm_flush_queue(dev, DRM_KERNEL_CONTEXT);
                if (!ret) ret = drm_flush_queue(dev, context);
        }
        if (flags & _DRM_LOCK_FLUSH_ALL) {
                for (i = 0; !ret && i < dev->queue_count; i++) {
                        ret = drm_flush_queue(dev, i);
                }
        }
        return ret;
}

int drm_flush_unblock(drm_device_t *dev, int context, drm_lock_flags_t flags)
{
        int ret = 0;
        int i;
        
        DRM_DEBUG("\n");
        
        if (flags & _DRM_LOCK_FLUSH) {
                ret = drm_flush_unblock_queue(dev, DRM_KERNEL_CONTEXT);
                if (!ret) ret = drm_flush_unblock_queue(dev, context);
        }
        if (flags & _DRM_LOCK_FLUSH_ALL) {
                for (i = 0; !ret && i < dev->queue_count; i++) {
                        ret = drm_flush_unblock_queue(dev, i);
                }
        }
                
        return ret;
}

int drm_finish(struct inode *inode, struct file *filp, unsigned int cmd,
               unsigned long arg)
{
        drm_file_t        *priv   = filp->private_data;
        drm_device_t      *dev    = priv->dev;
        int               ret     = 0;
        drm_lock_t        lock;

        DRM_DEBUG("\n");

        if (copy_from_user(&lock, (drm_lock_t *)arg, sizeof(lock)))
                return -EFAULT;
        ret = drm_flush_block_and_flush(dev, lock.context, lock.flags);
        drm_flush_unblock(dev, lock.context, lock.flags);
        return ret;
}

/* If we get here, it means that the process has called DRM_IOCTL_LOCK
   without calling DRM_IOCTL_UNLOCK.
   
   If the lock is not held, then let the signal proceed as usual.
   
   If the lock is held, then set the contended flag and keep the signal
   blocked.
   

   Return 1 if the signal should be delivered normally.
   Return 0 if the signal should be blocked.  */

int drm_notifier(void *priv)
{
        drm_sigdata_t *s = (drm_sigdata_t *)priv;
        unsigned int  old, new, prev;


                                /* Allow signal delivery if lock isn't held */
        if (!_DRM_LOCK_IS_HELD(s->lock->lock)
            || _DRM_LOCKING_CONTEXT(s->lock->lock) != s->context) return 1;
        
                                /* Otherwise, set flag to force call to
                                   drmUnlock */
        do {
                old  = s->lock->lock;
                new  = old | _DRM_LOCK_CONT;
                prev = cmpxchg(&s->lock->lock, old, new);
        } while (prev != old);
        return 0;
}