dma: mmp_pdma: add support for cyclic DMA descriptors

Provide a callback to prepare cyclic DMA transfers.
This is for instance needed for audio channel transport.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

1 files changed, 111 insertions, 1 deletions

diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
index 3676fdeac96d..f0e6d7d49b06 100644
--- a/drivers/dma/mmp_pdma.c
+++ b/drivers/dma/mmp_pdma.c
@@ -98,6 +98,9 @@ struct mmp_pdma_chan {
         struct mmp_pdma_phy *phy;
         enum dma_transfer_direction dir;
 
+        struct mmp_pdma_desc_sw *cyclic_first;  /* first desc_sw if channel
+                                                 * is in cyclic mode */
+
         /* channel's basic info */
         struct tasklet_struct tasklet;
         u32 dcmd;
@@ -500,6 +503,8 @@ mmp_pdma_prep_memcpy(struct dma_chan *dchan,
         new->desc.ddadr = DDADR_STOP;
         new->desc.dcmd |= DCMD_ENDIRQEN;
 
+        chan->cyclic_first = NULL;
+
         return &first->async_tx;
 
 fail:
@@ -575,6 +580,94 @@ mmp_pdma_prep_slave_sg(struct dma_chan *dchan, struct scatterlist *sgl,
         new->desc.ddadr = DDADR_STOP;
         new->desc.dcmd |= DCMD_ENDIRQEN;
 
+        chan->dir = dir;
+        chan->cyclic_first = NULL;
+
+        return &first->async_tx;
+
+fail:
+        if (first)
+                mmp_pdma_free_desc_list(chan, &first->tx_list);
+        return NULL;
+}
+
+static struct dma_async_tx_descriptor *mmp_pdma_prep_dma_cyclic(
+        struct dma_chan *dchan, dma_addr_t buf_addr, size_t len,
+        size_t period_len, enum dma_transfer_direction direction,
+        unsigned long flags, void *context)
+{
+        struct mmp_pdma_chan *chan;
+        struct mmp_pdma_desc_sw *first = NULL, *prev = NULL, *new;
+        dma_addr_t dma_src, dma_dst;
+
+        if (!dchan || !len || !period_len)
+                return NULL;
+
+        /* the buffer length must be a multiple of period_len */
+        if (len % period_len != 0)
+                return NULL;
+
+        if (period_len > PDMA_MAX_DESC_BYTES)
+                return NULL;
+
+        chan = to_mmp_pdma_chan(dchan);
+
+        switch (direction) {
+        case DMA_MEM_TO_DEV:
+                dma_src = buf_addr;
+                dma_dst = chan->dev_addr;
+                break;
+        case DMA_DEV_TO_MEM:
+                dma_dst = buf_addr;
+                dma_src = chan->dev_addr;
+                break;
+        default:
+                dev_err(chan->dev, "Unsupported direction for cyclic DMA\n");
+                return NULL;
+        }
+
+        chan->dir = direction;
+
+        do {
+                /* Allocate the link descriptor from DMA pool */
+                new = mmp_pdma_alloc_descriptor(chan);
+                if (!new) {
+                        dev_err(chan->dev, "no memory for desc\n");
+                        goto fail;
+                }
+
+                new->desc.dcmd = chan->dcmd | DCMD_ENDIRQEN |
+                                        (DCMD_LENGTH & period_len);
+                new->desc.dsadr = dma_src;
+                new->desc.dtadr = dma_dst;
+
+                if (!first)
+                        first = new;
+                else
+                        prev->desc.ddadr = new->async_tx.phys;
+
+                new->async_tx.cookie = 0;
+                async_tx_ack(&new->async_tx);
+
+                prev = new;
+                len -= period_len;
+
+                if (chan->dir == DMA_MEM_TO_DEV)
+                        dma_src += period_len;
+                else
+                        dma_dst += period_len;
+
+                /* Insert the link descriptor to the LD ring */
+                list_add_tail(&new->node, &first->tx_list);
+        } while (len);
+
+        first->async_tx.flags = flags; /* client is in control of this ack */
+        first->async_tx.cookie = -EBUSY;
+
+        /* make the cyclic link */
+        new->desc.ddadr = first->async_tx.phys;
+        chan->cyclic_first = first;
+
         return &first->async_tx;
 
 fail:
@@ -681,8 +774,23 @@ static void dma_do_tasklet(unsigned long data)
         LIST_HEAD(chain_cleanup);
         unsigned long flags;
 
-        /* submit pending list; callback for each desc; free desc */
+        if (chan->cyclic_first) {
+                dma_async_tx_callback cb = NULL;
+                void *cb_data = NULL;
 
+                spin_lock_irqsave(&chan->desc_lock, flags);
+                desc = chan->cyclic_first;
+                cb = desc->async_tx.callback;
+                cb_data = desc->async_tx.callback_param;
+                spin_unlock_irqrestore(&chan->desc_lock, flags);
+
+                if (cb)
+                        cb(cb_data);
+
+                return;
+        }
+
+        /* submit pending list; callback for each desc; free desc */
         spin_lock_irqsave(&chan->desc_lock, flags);
 
         list_for_each_entry_safe(desc, _desc, &chan->chain_running, node) {
@@ -876,12 +984,14 @@ static int mmp_pdma_probe(struct platform_device *op)
 
         dma_cap_set(DMA_SLAVE, pdev->device.cap_mask);
         dma_cap_set(DMA_MEMCPY, pdev->device.cap_mask);
+        dma_cap_set(DMA_CYCLIC, pdev->device.cap_mask);
         pdev->device.dev = &op->dev;
         pdev->device.device_alloc_chan_resources = mmp_pdma_alloc_chan_resources;
         pdev->device.device_free_chan_resources = mmp_pdma_free_chan_resources;
         pdev->device.device_tx_status = mmp_pdma_tx_status;
         pdev->device.device_prep_dma_memcpy = mmp_pdma_prep_memcpy;
         pdev->device.device_prep_slave_sg = mmp_pdma_prep_slave_sg;
+        pdev->device.device_prep_dma_cyclic = mmp_pdma_prep_dma_cyclic;
         pdev->device.device_issue_pending = mmp_pdma_issue_pending;
         pdev->device.device_control = mmp_pdma_control;
         pdev->device.copy_align = PDMA_ALIGNMENT;