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Subject[PATCH] dma: mmp_pdma: support for getting residual bytes
Date
From: Xiang Wang <wangx@marvell.com>

In some of our drivers (e.g. UART) we may stop a running DMA
before it finishes. So we need to know how many bytes have
been transferred.

Signed-off-by: Xiang Wang <wangx@marvell.com>
---
drivers/dma/mmp_pdma.c | 77 +++++++++++++++++++++++++++++++++++++++++++-----
1 files changed, 69 insertions(+), 8 deletions(-)

diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
index 76a8dcf..0c623cc 100644
--- a/drivers/dma/mmp_pdma.c
+++ b/drivers/dma/mmp_pdma.c
@@ -104,7 +104,8 @@ struct mmp_pdma_chan {
spinlock_t desc_lock; /* Descriptor list lock */
struct list_head chain_pending; /* Link descriptors queue for pending */
struct list_head chain_running; /* Link descriptors queue for running */
- bool idle; /* channel statue machine */
+ enum dma_status status; /* channel status machine */
+ u32 bytes_residue;

struct dma_pool *desc_pool; /* Descriptors pool */
};
@@ -270,7 +271,7 @@ static void start_pending_queue(struct mmp_pdma_chan *chan)
struct mmp_pdma_desc_sw *desc;

/* still in running, irq will start the pending list */
- if (!chan->idle) {
+ if (chan->status == DMA_IN_PROGRESS) {
dev_dbg(chan->dev, "DMA controller still busy\n");
return;
}
@@ -307,7 +308,55 @@ static void start_pending_queue(struct mmp_pdma_chan *chan)
*/
set_desc(chan->phy, desc->async_tx.phys);
enable_chan(chan->phy);
- chan->idle = false;
+ chan->status = DMA_IN_PROGRESS;
+ chan->bytes_residue = 0;
+}
+
+/*
+ * Get the number of bytes untransferred by DMA.
+ */
+static u32 mmp_pdma_get_bytes_residue(struct mmp_pdma_chan *chan)
+{
+ u32 reg, orig_pos, cur_pos, residue = 0;
+ struct mmp_pdma_desc_sw *desc_sw;
+ struct list_head *list_chain = NULL;
+
+ /*
+ * When a phy channel is unavailable, maybe its destroied, return last
+ * stored value for safe.
+ */
+ if (!chan || !chan->phy)
+ return chan->bytes_residue;
+
+ if (!list_empty(&chan->chain_running))
+ list_chain = &chan->chain_running;
+ else
+ return 0;
+
+ desc_sw = list_first_entry(list_chain, struct mmp_pdma_desc_sw, node);
+
+ switch (chan->dir) {
+ case DMA_DEV_TO_MEM:
+ reg = (chan->phy->idx << 4) + DTADR;
+ cur_pos = readl_relaxed(chan->phy->base + reg);
+ orig_pos = desc_sw->desc.dtadr;
+ break;
+ case DMA_MEM_TO_DEV:
+ reg = (chan->phy->idx << 4) + DSADR;
+ cur_pos = readl_relaxed(chan->phy->base + reg);
+ orig_pos = desc_sw->desc.dsadr;
+ break;
+ case DMA_MEM_TO_MEM:
+ reg = (chan->phy->idx << 4) + DTADR;
+ cur_pos = readl_relaxed(chan->phy->base + reg);
+ orig_pos = desc_sw->desc.dtadr;
+ break;
+ default:
+ return 0;
+ }
+
+ residue = (u32)(desc_sw->desc.dcmd & DCMD_LENGTH) + orig_pos - cur_pos;
+ return residue;
}


@@ -381,7 +430,7 @@ static int mmp_pdma_alloc_chan_resources(struct dma_chan *dchan)
chan->phy->vchan = NULL;
chan->phy = NULL;
}
- chan->idle = true;
+ chan->status = DMA_SUCCESS;
chan->dev_addr = 0;
return 1;
}
@@ -409,7 +458,7 @@ static void mmp_pdma_free_chan_resources(struct dma_chan *dchan)

dma_pool_destroy(chan->desc_pool);
chan->desc_pool = NULL;
- chan->idle = true;
+ chan->status = DMA_SUCCESS;
chan->dev_addr = 0;
if (chan->phy) {
chan->phy->vchan = NULL;
@@ -589,7 +638,13 @@ static int mmp_pdma_control(struct dma_chan *dchan, enum dma_ctrl_cmd cmd,
mmp_pdma_free_desc_list(chan, &chan->chain_pending);
mmp_pdma_free_desc_list(chan, &chan->chain_running);
spin_unlock_irqrestore(&chan->desc_lock, flags);
- chan->idle = true;
+ chan->status = DMA_SUCCESS;
+ chan->bytes_residue = 0;
+ break;
+ case DMA_PAUSE:
+ disable_chan(chan->phy);
+ chan->status = DMA_PAUSED;
+ chan->bytes_residue = mmp_pdma_get_bytes_residue(chan);
break;
case DMA_SLAVE_CONFIG:
if (cfg->direction == DMA_DEV_TO_MEM) {
@@ -637,7 +692,8 @@ static enum dma_status mmp_pdma_tx_status(struct dma_chan *dchan,
unsigned long flags;

spin_lock_irqsave(&chan->desc_lock, flags);
- ret = dma_cookie_status(dchan, cookie, txstate);
+ ret = chan->status;
+ dma_set_residue(txstate, chan->bytes_residue);
spin_unlock_irqrestore(&chan->desc_lock, flags);

return ret;
@@ -684,6 +740,8 @@ static void dma_do_tasklet(unsigned long data)
dev_dbg(chan->dev, "completed_cookie=%d\n", cookie);
}

+ /* update bytes_residue so that the user can query later on */
+ chan->bytes_residue = mmp_pdma_get_bytes_residue(chan);
/*
* move the descriptors to a temporary list so we can drop the lock
* during the entire cleanup operation
@@ -691,7 +749,7 @@ static void dma_do_tasklet(unsigned long data)
list_splice_tail_init(&chan->chain_running, &chain_cleanup);

/* the hardware is now idle and ready for more */
- chan->idle = true;
+ chan->status = DMA_SUCCESS;

/* Start any pending transactions automatically */
start_pending_queue(chan);
@@ -750,6 +808,9 @@ static int mmp_pdma_chan_init(struct mmp_pdma_device *pdev,
INIT_LIST_HEAD(&chan->chain_pending);
INIT_LIST_HEAD(&chan->chain_running);

+ chan->status = DMA_SUCCESS;
+ chan->bytes_residue = 0;
+
/* register virt channel to dma engine */
list_add_tail(&chan->chan.device_node,
&pdev->device.channels);
--
1.7.5.4


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