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Message-Id: <1285883207-13761-3-git-send-email-iws@ovro.caltech.edu>
Date: Thu, 30 Sep 2010 14:46:45 -0700
From: "Ira W. Snyder" <iws@...o.caltech.edu>
To: linux-kernel@...r.kernel.org
Cc: Dan Williams <dan.j.williams@...el.com>,
linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v4 2/4] 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@...o.caltech.edu>
---
drivers/dma/fsldma.c | 128 ++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 125 insertions(+), 3 deletions(-)
diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index cea08be..1ed29d1 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;
--
1.7.1
--
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