fsldma: implement support for scatterlist to scatterlist copy

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>

1 files changed, 125 insertions, 3 deletions

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index cea08bed9cf9..1ed29d10a5fa 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -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;