From caf38f4702a75c7ba13d5d80d902812c5faa8501 Mon Sep 17 00:00:00 2001
From: Joel Fernandes <joelf@ti.com>
Date: Thu, 27 Jun 2013 20:18:52 -0500
Subject: [PATCH 10/13] DMA: EDMA: Add support for Cyclic DMA
 
Using the PaRAM configuration function that we split for reuse by the
different DMA types, we implement Cyclic DMA support.
For the cyclic case, we pass different configuration paramters to this
function, and add all the Cyclic-specific code separately.
Callbacks are handled transparently as usual by the virt-dma layer.
Linking is handled the same way as the slave SG case.
 
Signed-off-by: Joel Fernandes <joelf@ti.com>
---
 drivers/dma/edma.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 
diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index 87b7e2b..cec9a12 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -321,6 +321,88 @@ static int edma_config_pset(struct dma_chan *chan, struct edmacc_param *pset,
 	return absync;
 }
 
+static struct dma_async_tx_descriptor *edma_prep_dma_cyclic(
+	struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
+	size_t period_len, enum dma_transfer_direction direction, unsigned long flags,
+	void *context)
+{
+	struct edma_chan *echan = to_edma_chan(chan);
+	struct device *dev = chan->device->dev;
+	struct edma_desc *edesc;
+	dma_addr_t src_addr, dst_addr;
+	enum dma_slave_buswidth dev_width;
+	u32 burst;
+	int i, ret, nr_periods;
+
+	if (unlikely(!echan || !buf_len || !period_len))
+		return NULL;
+
+	if (direction == DMA_DEV_TO_MEM) {
+		src_addr = echan->cfg.src_addr;
+		dst_addr = buf_addr;
+		dev_width = echan->cfg.src_addr_width;
+		burst = echan->cfg.src_maxburst;
+	} else if (direction == DMA_MEM_TO_DEV) {
+		src_addr = buf_addr;
+		dst_addr = echan->cfg.dst_addr;
+		dev_width = echan->cfg.dst_addr_width;
+		burst = echan->cfg.dst_maxburst;
+	} else {
+		dev_err(dev, "%s: bad direction?\n", __func__);
+		return NULL;
+	}
+
+	if (dev_width == DMA_SLAVE_BUSWIDTH_UNDEFINED) {
+		dev_err(dev, "Undefined slave buswidth\n");
+		return NULL;
+	}
+
+	if(unlikely(period_len % buf_len)) {
+		dev_err(dev, "Period should be multiple of Buf length\n");
+		return NULL;
+	}
+
+	nr_periods = period_len / buf_len;
+
+	edesc = kzalloc(sizeof(*edesc) + nr_periods *
+		sizeof(edesc->pset[0]), GFP_ATOMIC);
+	if (!edesc) {
+		dev_dbg(dev, "Failed to allocate a descriptor\n");
+		return NULL;
+	}
+
+	edesc->pset_nr = nr_periods;
+
+	for(i = 0; i < nr_periods; i++) {
+		/* Allocate a PaRAM slot, if needed */
+		if (echan->slot[i] < 0) {
+			echan->slot[i] =
+				edma_alloc_slot(EDMA_CTLR(echan->ch_num),
+						EDMA_SLOT_ANY);
+			if (echan->slot[i] < 0) {
+				dev_err(dev, "Failed to allocate slot\n");
+				return NULL;
+			}
+		}
+
+		if (direction == DMA_DEV_TO_MEM)
+			dst_addr += period_len;
+		else
+			src_addr += period_len;
+
+		ret = edma_config_pset(chan, &edesc->pset[i], src_addr, dst_addr,
+					      burst, dev_width, period_len, direction);
+		if(ret < 0)
+			return NULL;
+
+		edesc->absync = ret;
+		if (i == nr_periods - 1)
+			edesc->pset[i].opt |= TCINTEN;
+	}
+	/* TODO tx_flags (last parameter) needs to be investigated...\n" */
+	return vchan_tx_prep(&echan->vchan, &edesc->vdesc, 0);
+}
+
 static struct dma_async_tx_descriptor *edma_prep_slave_sg(
 	struct dma_chan *chan, struct scatterlist *sgl,
 	unsigned int sg_len, enum dma_transfer_direction direction,
@@ -424,6 +506,8 @@ static void edma_callback(unsigned ch_num, u16 ch_status, void *data)
 		edesc = echan->edesc;
 		if (edesc) {
 			edma_execute(echan);
+			/* Note: that desc->callback must be setup by EDMA users so that
+			the virt-dma layer calls their callback on vchan_cookie_complete() */
 			vchan_cookie_complete(&edesc->vdesc);
 		}
 
@@ -605,6 +689,7 @@ static void edma_dma_init(struct edma_cc *ecc, struct dma_device *dma,
 			  struct device *dev)
 {
 	dma->device_prep_slave_sg = edma_prep_slave_sg;
+	dma->device_prep_dma_cyclic = edma_prep_dma_cyclic;
 	dma->device_alloc_chan_resources = edma_alloc_chan_resources;
 	dma->device_free_chan_resources = edma_free_chan_resources;
 	dma->device_issue_pending = edma_issue_pending;
-- 
1.8.2.1