[PATCH v3 1/2] dma: pl330: improve pl330_tx_status() function

[Robert Baldyga]

This patch adds possibility to read residue of DMA transfer. It's useful
when we want to know how many bytes have been transferred before we
terminate channel. It can take place, for example, on timeout interrupt.

Signed-off-by: Lukasz Czerwinski <l.czerwinski@xxxxxxxxxxx>
Signed-off-by: Robert Baldyga <r.baldyga@xxxxxxxxxxx>
---
 drivers/dma/pl330.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 66 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index bdf40b5..2f4d561 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -504,6 +504,9 @@ struct dma_pl330_desc {
 
 	enum desc_status status;
 
+	int bytes_requested;
+	bool last;
+
 	/* The channel which currently holds this desc */
 	struct dma_pl330_chan *pchan;
 
@@ -2182,11 +2185,68 @@ static void pl330_free_chan_resources(struct dma_chan *chan)
 	pm_runtime_put_autosuspend(pch->dmac->ddma.dev);
 }
 
+int pl330_get_current_xferred_count(struct dma_pl330_chan *pch,
+		struct dma_pl330_desc *desc)
+{
+	struct pl330_thread *thrd = pch->thread;
+	struct pl330_dmac *pl330 = pch->dmac;
+	void __iomem *regs = thrd->dmac->base;
+	u32 val, addr;
+
+	pm_runtime_get_sync(pl330->ddma.dev);
+	val = addr = 0;
+	if (desc->rqcfg.src_inc) {
+		val = readl(regs + SA(thrd->id));
+		addr = desc->px.src_addr;
+	} else {
+		val = readl(regs + DA(thrd->id));
+		addr = desc->px.dst_addr;
+	}
+	pm_runtime_mark_last_busy(pch->dmac->ddma.dev);
+	pm_runtime_put_autosuspend(pl330->ddma.dev);
+	return val - addr;
+}
+
 static enum dma_status
 pl330_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
 		 struct dma_tx_state *txstate)
 {
-	return dma_cookie_status(chan, cookie, txstate);
+	enum dma_status ret;
+	unsigned long flags;
+	struct dma_pl330_desc *desc, *running = NULL;
+	struct dma_pl330_chan *pch = to_pchan(chan);
+	unsigned int transferred, residual = 0;
+
+	spin_lock_irqsave(&pch->lock, flags);
+
+	if (pch->thread->req_running != -1)
+		running = pch->thread->req[pch->thread->req_running].desc;
+
+	/* Check in pending list */
+	list_for_each_entry(desc, &pch->work_list, node) {
+		if (desc->status == DONE)
+			transferred = desc->bytes_requested;
+		else if (running && desc == running)
+			transferred =
+				pl330_get_current_xferred_count(pch, desc);
+		else
+			transferred = 0;
+		residual += desc->bytes_requested - transferred;
+		if (desc->txd.cookie == cookie) {
+			dma_set_residue(txstate, residual);
+			ret = desc->status;
+			spin_unlock_irqrestore(&pch->lock, flags);
+			return ret;
+		}
+		if (desc->last)
+			residual = 0;
+	}
+	spin_unlock_irqrestore(&pch->lock, flags);
+
+	ret = dma_cookie_status(chan, cookie, txstate);
+	dma_set_residue(txstate, 0);
+
+	return ret;
 }
 
 static void pl330_issue_pending(struct dma_chan *chan)
@@ -2231,12 +2291,14 @@ static dma_cookie_t pl330_tx_submit(struct dma_async_tx_descriptor *tx)
 			desc->txd.callback = last->txd.callback;
 			desc->txd.callback_param = last->txd.callback_param;
 		}
+		last->last = false;
 
 		dma_cookie_assign(&desc->txd);
 
 		list_move_tail(&desc->node, &pch->submitted_list);
 	}
 
+	last->last = true;
 	cookie = dma_cookie_assign(&last->txd);
 	list_add_tail(&last->node, &pch->submitted_list);
 	spin_unlock_irqrestore(&pch->lock, flags);
@@ -2459,6 +2521,7 @@ static struct dma_async_tx_descriptor *pl330_prep_dma_cyclic(
 		desc->rqtype = direction;
 		desc->rqcfg.brst_size = pch->burst_sz;
 		desc->rqcfg.brst_len = 1;
+		desc->bytes_requested = period_len;
 		fill_px(&desc->px, dst, src, period_len);
 
 		if (!first)
@@ -2601,6 +2664,7 @@ pl330_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 		desc->rqcfg.brst_size = pch->burst_sz;
 		desc->rqcfg.brst_len = 1;
 		desc->rqtype = direction;
+		desc->bytes_requested = sg_dma_len(sg);
 	}
 
 	/* Return the last desc in the chain */
@@ -2631,7 +2695,7 @@ static int pl330_dma_device_slave_caps(struct dma_chan *dchan,
 	caps->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
 	caps->cmd_pause = false;
 	caps->cmd_terminate = true;
-	caps->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
+	caps->residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
 
 	return 0;
 }
-- 
1.9.1

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