block: implement drain buffers

[linux-2.6-omap-h63xx.git] / block / ll_rw_blk.c

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 8054b7d8e07ca362582a14a7c5df48dcc1fecd53..768987dc2697501921a606e22078b879a24f8fd3 100644 (file)
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -725,6 +725,45 @@ void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
 
 EXPORT_SYMBOL(blk_queue_stack_limits);
 
+/**
+ * blk_queue_dma_drain - Set up a drain buffer for excess dma.
+ *
+ * @q:  the request queue for the device
+ * @buf:       physically contiguous buffer
+ * @size:      size of the buffer in bytes
+ *
+ * Some devices have excess DMA problems and can't simply discard (or
+ * zero fill) the unwanted piece of the transfer.  They have to have a
+ * real area of memory to transfer it into.  The use case for this is
+ * ATAPI devices in DMA mode.  If the packet command causes a transfer
+ * bigger than the transfer size some HBAs will lock up if there
+ * aren't DMA elements to contain the excess transfer.  What this API
+ * does is adjust the queue so that the buf is always appended
+ * silently to the scatterlist.
+ *
+ * Note: This routine adjusts max_hw_segments to make room for
+ * appending the drain buffer.  If you call
+ * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after
+ * calling this routine, you must set the limit to one fewer than your
+ * device can support otherwise there won't be room for the drain
+ * buffer.
+ */
+int blk_queue_dma_drain(struct request_queue *q, void *buf,
+                               unsigned int size)
+{
+       if (q->max_hw_segments < 2 || q->max_phys_segments < 2)
+               return -EINVAL;
+       /* make room for appending the drain */
+       --q->max_hw_segments;
+       --q->max_phys_segments;
+       q->dma_drain_buffer = buf;
+       q->dma_drain_size = size;
+
+       return 0;
+}
+
+EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
+
 /**
  * blk_queue_segment_boundary - set boundary rules for segment merging
  * @q:  the request queue for the device
@@ -759,6 +798,30 @@ void blk_queue_dma_alignment(struct request_queue *q, int mask)
 
 EXPORT_SYMBOL(blk_queue_dma_alignment);
 
+/**
+ * blk_queue_update_dma_alignment - update dma length and memory alignment
+ * @q:     the request queue for the device
+ * @mask:  alignment mask
+ *
+ * description:
+ *    update required memory and length aligment for direct dma transactions.
+ *    If the requested alignment is larger than the current alignment, then
+ *    the current queue alignment is updated to the new value, otherwise it
+ *    is left alone.  The design of this is to allow multiple objects
+ *    (driver, device, transport etc) to set their respective
+ *    alignments without having them interfere.
+ *
+ **/
+void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
+{
+       BUG_ON(mask > PAGE_SIZE);
+
+       if (mask > q->dma_alignment)
+               q->dma_alignment = mask;
+}
+
+EXPORT_SYMBOL(blk_queue_update_dma_alignment);
+
 /**
  * blk_queue_find_tag - find a request by its tag and queue
  * @q:  The request queue for the device
@@ -1355,6 +1418,16 @@ new_segment:
                bvprv = bvec;
        } /* segments in rq */
 
+       if (q->dma_drain_size) {
+               sg->page_link &= ~0x02;
+               sg = sg_next(sg);
+               sg_set_page(sg, virt_to_page(q->dma_drain_buffer),
+                           q->dma_drain_size,
+                           ((unsigned long)q->dma_drain_buffer) &
+                           (PAGE_SIZE - 1));
+               nsegs++;
+       }
+
        if (sg)
                sg_mark_end(sg);
 
@@ -1862,7 +1935,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 
        init_timer(&q->unplug_timer);
 
-       kobject_init_ng(&q->kobj, &queue_ktype);
+       kobject_init(&q->kobj, &queue_ktype);
 
        mutex_init(&q->sysfs_lock);
 
@@ -4180,8 +4253,8 @@ int blk_register_queue(struct gendisk *disk)
        if (!q || !q->request_fn)
                return -ENXIO;
 
-       ret = kobject_add_ng(&q->kobj, kobject_get(&disk->dev.kobj),
-                            "%s", "queue");
+       ret = kobject_add(&q->kobj, kobject_get(&disk->dev.kobj),
+                         "%s", "queue");
        if (ret < 0)
                return ret;