via_dmablit.c

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	/*
	 * Allow for handle wraparounds.
	 */

	active = ((blitq->done_blit_handle - handle) > (1 << 23)) &&
		((blitq->cur_blit_handle - handle) <= (1 << 23));

	if (queue && active) {
		slot = handle - blitq->done_blit_handle + blitq->cur -1;
		if (slot >= VIA_NUM_BLIT_SLOTS) {
			slot -= VIA_NUM_BLIT_SLOTS;
		}
		*queue = blitq->blit_queue + slot;
	}

	spin_unlock_irqrestore(&blitq->blit_lock, irqsave);

	return active;
}
	
/*
 * Sync. Wait for at least three seconds for the blit to be performed.
 */

static int
via_dmablit_sync(struct drm_device *dev, uint32_t handle, int engine) 
{

	drm_via_private_t *dev_priv = (drm_via_private_t *)dev->dev_private;
	drm_via_blitq_t *blitq = dev_priv->blit_queues + engine;
	wait_queue_head_t *queue;
	int ret = 0;

	if (via_dmablit_active(blitq, engine, handle, &queue)) {
		DRM_WAIT_ON(ret, *queue, 3 * DRM_HZ, 
			    !via_dmablit_active(blitq, engine, handle, NULL));
	}
	DRM_DEBUG("DMA blit sync handle 0x%x engine %d returned %d\n",
		  handle, engine, ret);
	
	return ret;
}


/*
 * A timer that regularly polls the blit engine in cases where we don't have interrupts:
 * a) Broken hardware (typically those that don't have any video capture facility).
 * b) Blit abort. The hardware doesn't send an interrupt when a blit is aborted.
 * The timer and hardware IRQ's can and do work in parallel. If the hardware has
 * irqs, it will shorten the latency somewhat.
 */



static void
via_dmablit_timer(unsigned long data)
{
	drm_via_blitq_t *blitq = (drm_via_blitq_t *) data;
	struct drm_device *dev = blitq->dev;
	int engine = (int)
		(blitq - ((drm_via_private_t *)dev->dev_private)->blit_queues);
		
	DRM_DEBUG("Polling timer called for engine %d, jiffies %lu\n", engine, 
		  (unsigned long) jiffies);

	via_dmablit_handler(dev, engine, 0);
	
	if (!timer_pending(&blitq->poll_timer)) {
		mod_timer(&blitq->poll_timer, jiffies + 1);

	       /*
		* Rerun handler to delete timer if engines are off, and
		* to shorten abort latency. This is a little nasty.
		*/

	       via_dmablit_handler(dev, engine, 0);

	}
}




/*
 * Workqueue task that frees data and mappings associated with a blit.
 * Also wakes up waiting processes. Each of these tasks handles one
 * blit engine only and may not be called on each interrupt.
 */


static void 
via_dmablit_workqueue(struct work_struct *work)
{
	drm_via_blitq_t *blitq = container_of(work, drm_via_blitq_t, wq);
	struct drm_device *dev = blitq->dev;
	unsigned long irqsave;
	drm_via_sg_info_t *cur_sg;
	int cur_released;
	
	
	DRM_DEBUG("Workqueue task called for blit engine %ld\n",(unsigned long) 
		  (blitq - ((drm_via_private_t *)dev->dev_private)->blit_queues));

	spin_lock_irqsave(&blitq->blit_lock, irqsave);
	
	while(blitq->serviced != blitq->cur) {

		cur_released = blitq->serviced++;

		DRM_DEBUG("Releasing blit slot %d\n", cur_released);

		if (blitq->serviced >= VIA_NUM_BLIT_SLOTS) 
			blitq->serviced = 0;
		
		cur_sg = blitq->blits[cur_released];
		blitq->num_free++;
				
		spin_unlock_irqrestore(&blitq->blit_lock, irqsave);
		
		DRM_WAKEUP(&blitq->busy_queue);
		
		via_free_sg_info(dev->pdev, cur_sg);
		kfree(cur_sg);
		
		spin_lock_irqsave(&blitq->blit_lock, irqsave);
	}

	spin_unlock_irqrestore(&blitq->blit_lock, irqsave);
}
	

/*
 * Init all blit engines. Currently we use two, but some hardware have 4.
 */


void
via_init_dmablit(struct drm_device *dev)
{
	int i,j;
	drm_via_private_t *dev_priv = (drm_via_private_t *)dev->dev_private;
	drm_via_blitq_t *blitq;

	pci_set_master(dev->pdev);	
	
	for (i=0; i< VIA_NUM_BLIT_ENGINES; ++i) {
		blitq = dev_priv->blit_queues + i;
		blitq->dev = dev;
		blitq->cur_blit_handle = 0;
		blitq->done_blit_handle = 0;
		blitq->head = 0;
		blitq->cur = 0;
		blitq->serviced = 0;
		blitq->num_free = VIA_NUM_BLIT_SLOTS - 1;
		blitq->num_outstanding = 0;
		blitq->is_active = 0;
		blitq->aborting = 0;
		spin_lock_init(&blitq->blit_lock);
		for (j=0; j<VIA_NUM_BLIT_SLOTS; ++j) {
			DRM_INIT_WAITQUEUE(blitq->blit_queue + j);
		}
		DRM_INIT_WAITQUEUE(&blitq->busy_queue);
		INIT_WORK(&blitq->wq, via_dmablit_workqueue);
		setup_timer(&blitq->poll_timer, via_dmablit_timer,
				(unsigned long)blitq);
	}	
}

/*
 * Build all info and do all mappings required for a blit.
 */
		

static int
via_build_sg_info(struct drm_device *dev, drm_via_sg_info_t *vsg, drm_via_dmablit_t *xfer)
{
	int draw = xfer->to_fb;
	int ret = 0;
	
	vsg->direction = (draw) ? DMA_TO_DEVICE : DMA_FROM_DEVICE;
	vsg->bounce_buffer = NULL;

	vsg->state = dr_via_sg_init;

	if (xfer->num_lines <= 0 || xfer->line_length <= 0) {
		DRM_ERROR("Zero size bitblt.\n");
		return -EINVAL;
	}

	/*
	 * Below check is a driver limitation, not a hardware one. We
	 * don't want to lock unused pages, and don't want to incoporate the
	 * extra logic of avoiding them. Make sure there are no. 
	 * (Not a big limitation anyway.)
	 */

	if ((xfer->mem_stride - xfer->line_length) >= PAGE_SIZE) {
		DRM_ERROR("Too large system memory stride. Stride: %d, "
			  "Length: %d\n", xfer->mem_stride, xfer->line_length);
		return -EINVAL;
	}

	if ((xfer->mem_stride == xfer->line_length) &&
	   (xfer->fb_stride == xfer->line_length)) {
		xfer->mem_stride *= xfer->num_lines;
		xfer->line_length = xfer->mem_stride;
		xfer->fb_stride = xfer->mem_stride;
		xfer->num_lines = 1;
	}

	/*
	 * Don't lock an arbitrary large number of pages, since that causes a
	 * DOS security hole.
	 */

	if (xfer->num_lines > 2048 || (xfer->num_lines*xfer->mem_stride > (2048*2048*4))) {
		DRM_ERROR("Too large PCI DMA bitblt.\n");
		return -EINVAL;
	}		

	/* 
	 * we allow a negative fb stride to allow flipping of images in
	 * transfer. 
	 */

	if (xfer->mem_stride < xfer->line_length ||
		abs(xfer->fb_stride) < xfer->line_length) {
		DRM_ERROR("Invalid frame-buffer / memory stride.\n");
		return -EINVAL;
	}

	/*
	 * A hardware bug seems to be worked around if system memory addresses start on
	 * 16 byte boundaries. This seems a bit restrictive however. VIA is contacted
	 * about this. Meanwhile, impose the following restrictions:
	 */

#ifdef VIA_BUGFREE
	if ((((unsigned long)xfer->mem_addr & 3) != ((unsigned long)xfer->fb_addr & 3)) ||
	    ((xfer->num_lines > 1) && ((xfer->mem_stride & 3) != (xfer->fb_stride & 3)))) {
		DRM_ERROR("Invalid DRM bitblt alignment.\n");
		return -EINVAL;
	}
#else
	if ((((unsigned long)xfer->mem_addr & 15) ||
	      ((unsigned long)xfer->fb_addr & 3)) ||
	   ((xfer->num_lines > 1) && 
	   ((xfer->mem_stride & 15) || (xfer->fb_stride & 3)))) {
		DRM_ERROR("Invalid DRM bitblt alignment.\n");
		return -EINVAL;
	}	
#endif

	if (0 != (ret = via_lock_all_dma_pages(vsg, xfer))) {
		DRM_ERROR("Could not lock DMA pages.\n");
		via_free_sg_info(dev->pdev, vsg);
		return ret;
	}

	via_map_blit_for_device(dev->pdev, xfer, vsg, 0);
	if (0 != (ret = via_alloc_desc_pages(vsg))) {
		DRM_ERROR("Could not allocate DMA descriptor pages.\n");
		via_free_sg_info(dev->pdev, vsg);
		return ret;
	}
	via_map_blit_for_device(dev->pdev, xfer, vsg, 1);
	
	return 0;
}
	

/*
 * Reserve one free slot in the blit queue. Will wait for one second for one
 * to become available. Otherwise -EBUSY is returned.
 */

static int 
via_dmablit_grab_slot(drm_via_blitq_t *blitq, int engine)
{
	int ret=0;
	unsigned long irqsave;

	DRM_DEBUG("Num free is %d\n", blitq->num_free);
	spin_lock_irqsave(&blitq->blit_lock, irqsave);
	while(blitq->num_free == 0) {
		spin_unlock_irqrestore(&blitq->blit_lock, irqsave);

		DRM_WAIT_ON(ret, blitq->busy_queue, DRM_HZ, blitq->num_free > 0);
		if (ret) {
			return (-EINTR == ret) ? -EAGAIN : ret;
		}
		
		spin_lock_irqsave(&blitq->blit_lock, irqsave);
	}
	
	blitq->num_free--;
	spin_unlock_irqrestore(&blitq->blit_lock, irqsave);

	return 0;
}

/*
 * Hand back a free slot if we changed our mind.
 */

static void 
via_dmablit_release_slot(drm_via_blitq_t *blitq)
{
	unsigned long irqsave;

	spin_lock_irqsave(&blitq->blit_lock, irqsave);
	blitq->num_free++;
	spin_unlock_irqrestore(&blitq->blit_lock, irqsave);
	DRM_WAKEUP( &blitq->busy_queue );
}

/*
 * Grab a free slot. Build blit info and queue a blit.
 */


static int 
via_dmablit(struct drm_device *dev, drm_via_dmablit_t *xfer)	 
{
	drm_via_private_t *dev_priv = (drm_via_private_t *)dev->dev_private;
	drm_via_sg_info_t *vsg;
	drm_via_blitq_t *blitq;
	int ret;
	int engine;
	unsigned long irqsave;

	if (dev_priv == NULL) {
		DRM_ERROR("Called without initialization.\n");
		return -EINVAL;
	}

	engine = (xfer->to_fb) ? 0 : 1;
	blitq = dev_priv->blit_queues + engine;
	if (0 != (ret = via_dmablit_grab_slot(blitq, engine))) {
		return ret;
	}
	if (NULL == (vsg = kmalloc(sizeof(*vsg), GFP_KERNEL))) {
		via_dmablit_release_slot(blitq);
		return -ENOMEM;
	}
	if (0 != (ret = via_build_sg_info(dev, vsg, xfer))) {
		via_dmablit_release_slot(blitq);
		kfree(vsg);
		return ret;
	}
	spin_lock_irqsave(&blitq->blit_lock, irqsave);

	blitq->blits[blitq->head++] = vsg;
	if (blitq->head >= VIA_NUM_BLIT_SLOTS) 
		blitq->head = 0;
	blitq->num_outstanding++;
	xfer->sync.sync_handle = ++blitq->cur_blit_handle; 

	spin_unlock_irqrestore(&blitq->blit_lock, irqsave);
	xfer->sync.engine = engine;

       	via_dmablit_handler(dev, engine, 0);

	return 0;
}

/*
 * Sync on a previously submitted blit. Note that the X server use signals extensively, and
 * that there is a very big probability that this IOCTL will be interrupted by a signal. In that
 * case it returns with -EAGAIN for the signal to be delivered. 
 * The caller should then reissue the IOCTL. This is similar to what is being done for drmGetLock().
 */

int
via_dma_blit_sync( struct drm_device *dev, void *data, struct drm_file *file_priv )
{
	drm_via_blitsync_t *sync = data;
	int err;

	if (sync->engine >= VIA_NUM_BLIT_ENGINES) 
		return -EINVAL;

	err = via_dmablit_sync(dev, sync->sync_handle, sync->engine);

	if (-EINTR == err)
		err = -EAGAIN;

	return err;
}
	

/*
 * Queue a blit and hand back a handle to be used for sync. This IOCTL may be interrupted by a signal
 * while waiting for a free slot in the blit queue. In that case it returns with -EAGAIN and should 
 * be reissued. See the above IOCTL code.
 */

int 
via_dma_blit( struct drm_device *dev, void *data, struct drm_file *file_priv )
{
	drm_via_dmablit_t *xfer = data;
	int err;

	err = via_dmablit(dev, xfer);

	return err;
}