fsldma: implement support for scatterlist to scatterlist copy
Ira Snyder [Thu, 30 Sep 2010 11:46:45 +0000 (11:46 +0000)]
Now that the DMAEngine API has support for scatterlist to scatterlist
copy, implement support for the Freescale DMA controller.

Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dma/fsldma.c

index cea08be..1ed29d1 100644 (file)
@@ -38,6 +38,8 @@
 #include <asm/fsldma.h>
 #include "fsldma.h"
 
+static const char msg_ld_oom[] = "No free memory for link descriptor\n";
+
 static void dma_init(struct fsldma_chan *chan)
 {
        /* Reset the channel */
@@ -499,7 +501,7 @@ fsl_dma_prep_interrupt(struct dma_chan *dchan, unsigned long flags)
 
        new = fsl_dma_alloc_descriptor(chan);
        if (!new) {
-               dev_err(chan->dev, "No free memory for link descriptor\n");
+               dev_err(chan->dev, msg_ld_oom);
                return NULL;
        }
 
@@ -536,8 +538,7 @@ static struct dma_async_tx_descriptor *fsl_dma_prep_memcpy(
                /* Allocate the link descriptor from DMA pool */
                new = fsl_dma_alloc_descriptor(chan);
                if (!new) {
-                       dev_err(chan->dev,
-                                       "No free memory for link descriptor\n");
+                       dev_err(chan->dev, msg_ld_oom);
                        goto fail;
                }
 #ifdef FSL_DMA_LD_DEBUG
@@ -583,6 +584,125 @@ fail:
        return NULL;
 }
 
+static struct dma_async_tx_descriptor *fsl_dma_prep_sg(struct dma_chan *dchan,
+       struct scatterlist *dst_sg, unsigned int dst_nents,
+       struct scatterlist *src_sg, unsigned int src_nents,
+       unsigned long flags)
+{
+       struct fsl_desc_sw *first = NULL, *prev = NULL, *new = NULL;
+       struct fsldma_chan *chan = to_fsl_chan(dchan);
+       size_t dst_avail, src_avail;
+       dma_addr_t dst, src;
+       size_t len;
+
+       /* basic sanity checks */
+       if (dst_nents == 0 || src_nents == 0)
+               return NULL;
+
+       if (dst_sg == NULL || src_sg == NULL)
+               return NULL;
+
+       /*
+        * TODO: should we check that both scatterlists have the same
+        * TODO: number of bytes in total? Is that really an error?
+        */
+
+       /* get prepared for the loop */
+       dst_avail = sg_dma_len(dst_sg);
+       src_avail = sg_dma_len(src_sg);
+
+       /* run until we are out of scatterlist entries */
+       while (true) {
+
+               /* create the largest transaction possible */
+               len = min_t(size_t, src_avail, dst_avail);
+               len = min_t(size_t, len, FSL_DMA_BCR_MAX_CNT);
+               if (len == 0)
+                       goto fetch;
+
+               dst = sg_dma_address(dst_sg) + sg_dma_len(dst_sg) - dst_avail;
+               src = sg_dma_address(src_sg) + sg_dma_len(src_sg) - src_avail;
+
+               /* allocate and populate the descriptor */
+               new = fsl_dma_alloc_descriptor(chan);
+               if (!new) {
+                       dev_err(chan->dev, msg_ld_oom);
+                       goto fail;
+               }
+#ifdef FSL_DMA_LD_DEBUG
+               dev_dbg(chan->dev, "new link desc alloc %p\n", new);
+#endif
+
+               set_desc_cnt(chan, &new->hw, len);
+               set_desc_src(chan, &new->hw, src);
+               set_desc_dst(chan, &new->hw, dst);
+
+               if (!first)
+                       first = new;
+               else
+                       set_desc_next(chan, &prev->hw, new->async_tx.phys);
+
+               new->async_tx.cookie = 0;
+               async_tx_ack(&new->async_tx);
+               prev = new;
+
+               /* Insert the link descriptor to the LD ring */
+               list_add_tail(&new->node, &first->tx_list);
+
+               /* update metadata */
+               dst_avail -= len;
+               src_avail -= len;
+
+fetch:
+               /* fetch the next dst scatterlist entry */
+               if (dst_avail == 0) {
+
+                       /* no more entries: we're done */
+                       if (dst_nents == 0)
+                               break;
+
+                       /* fetch the next entry: if there are no more: done */
+                       dst_sg = sg_next(dst_sg);
+                       if (dst_sg == NULL)
+                               break;
+
+                       dst_nents--;
+                       dst_avail = sg_dma_len(dst_sg);
+               }
+
+               /* fetch the next src scatterlist entry */
+               if (src_avail == 0) {
+
+                       /* no more entries: we're done */
+                       if (src_nents == 0)
+                               break;
+
+                       /* fetch the next entry: if there are no more: done */
+                       src_sg = sg_next(src_sg);
+                       if (src_sg == NULL)
+                               break;
+
+                       src_nents--;
+                       src_avail = sg_dma_len(src_sg);
+               }
+       }
+
+       new->async_tx.flags = flags; /* client is in control of this ack */
+       new->async_tx.cookie = -EBUSY;
+
+       /* Set End-of-link to the last link descriptor of new list */
+       set_ld_eol(chan, new);
+
+       return &first->async_tx;
+
+fail:
+       if (!first)
+               return NULL;
+
+       fsldma_free_desc_list_reverse(chan, &first->tx_list);
+       return NULL;
+}
+
 /**
  * fsl_dma_prep_slave_sg - prepare descriptors for a DMA_SLAVE transaction
  * @chan: DMA channel
@@ -1327,11 +1447,13 @@ static int __devinit fsldma_of_probe(struct platform_device *op,
 
        dma_cap_set(DMA_MEMCPY, fdev->common.cap_mask);
        dma_cap_set(DMA_INTERRUPT, fdev->common.cap_mask);
+       dma_cap_set(DMA_SG, fdev->common.cap_mask);
        dma_cap_set(DMA_SLAVE, fdev->common.cap_mask);
        fdev->common.device_alloc_chan_resources = fsl_dma_alloc_chan_resources;
        fdev->common.device_free_chan_resources = fsl_dma_free_chan_resources;
        fdev->common.device_prep_dma_interrupt = fsl_dma_prep_interrupt;
        fdev->common.device_prep_dma_memcpy = fsl_dma_prep_memcpy;
+       fdev->common.device_prep_dma_sg = fsl_dma_prep_sg;
        fdev->common.device_tx_status = fsl_tx_status;
        fdev->common.device_issue_pending = fsl_dma_memcpy_issue_pending;
        fdev->common.device_prep_slave_sg = fsl_dma_prep_slave_sg;