[PATCHv9 6/6] dmaengine: rcar-dmac: add iommu support for slave transfers

Enable slave transfers to a device behind a IPMMU by mapping the slave
addresses using the dma-mapping API.

Signed-off-by: Niklas S?derlund <niklas.soderlund+renesas@ragnatech.se>
---
drivers/dma/sh/rcar-dmac.c | 82 ++++++++++++++++++++++++++++++++++++++-----
1 file changed, 74 insertions(+), 8 deletions(-)

diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index cf983a9..22a5e40 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c

@@ -128,6 +128,18 @@ struct rcar_dmac_chan_slave {
 };

 /*
+ * struct rcar_dmac_chan_map - Map of slave device phys to dma address
+ * @addr: slave dma address
+ * @dir: direction of mapping
+ * @slave: slave configuration that is mapped
+ */
+struct rcar_dmac_chan_map {
+	dma_addr_t addr;
+	enum dma_data_direction dir;
+	struct rcar_dmac_chan_slave slave;
+};
+
+/*
  * struct rcar_dmac_chan - R-Car Gen2 DMA Controller Channel
  * @chan: base DMA channel object
  * @iomem: channel I/O memory base

@@ -152,6 +164,7 @@ struct rcar_dmac_chan {

 	struct rcar_dmac_chan_slave src;
 	struct rcar_dmac_chan_slave dst;
+	struct rcar_dmac_chan_map map;
 	int mid_rid;

 	spinlock_t lock;

@@ -1029,13 +1042,65 @@ rcar_dmac_prep_dma_memcpy(struct dma_chan *chan,

dma_addr_t dma_dest, DMA_MEM_TO_MEM, flags, false);
 }

+static int rcar_dmac_map_slave_addr(struct dma_chan *chan,
+				    enum dma_transfer_direction dir)
+{
+	struct rcar_dmac_chan *rchan = to_rcar_dmac_chan(chan);
+	struct rcar_dmac_chan_map *map = &rchan->map;
+	phys_addr_t dev_addr;
+	size_t dev_size;
+	enum dma_data_direction dev_dir;
+
+	if (dir == DMA_DEV_TO_MEM) {
+		dev_addr = rchan->src.slave_addr;
+		dev_size = rchan->src.xfer_size;
+		dev_dir = DMA_TO_DEVICE;

+
+	map->slave.slave_addr = dev_addr;
+	map->slave.xfer_size = dev_size;
+	map->dir = dev_dir;
+
+	return 0;
+}
+
 static struct dma_async_tx_descriptor *
 rcar_dmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 			unsigned int sg_len, enum dma_transfer_direction dir,
 			unsigned long flags, void *context)
 {
 	struct rcar_dmac_chan *rchan = to_rcar_dmac_chan(chan);
-	dma_addr_t dev_addr;

 	/* Someone calling slave DMA on a generic channel? */
 	if (rchan->mid_rid < 0 || !sg_len) {

@@ -1045,9 +1110,10 @@ rcar_dmac_prep_slave_sg(struct dma_chan *chan, struct

scatterlist *sgl, return NULL;
 	}

-	dev_addr = dir == DMA_DEV_TO_MEM
-		 ? rchan->src.slave_addr : rchan->dst.slave_addr;
-	return rcar_dmac_chan_prep_sg(rchan, sgl, sg_len, dev_addr,
+	if (rcar_dmac_map_slave_addr(chan, dir))
+		return NULL;
+
+	return rcar_dmac_chan_prep_sg(rchan, sgl, sg_len, rchan->map.addr,
 				      dir, flags, false);
 }

@@ -1061,7 +1127,6 @@ rcar_dmac_prep_dma_cyclic(struct dma_chan *chan,

dma_addr_t buf_addr, struct rcar_dmac_chan *rchan =
to_rcar_dmac_chan(chan);
 	struct dma_async_tx_descriptor *desc;
 	struct scatterlist *sgl;
-	dma_addr_t dev_addr;
 	unsigned int sg_len;
 	unsigned int i;

@@ -1073,6 +1138,9 @@ rcar_dmac_prep_dma_cyclic(struct dma_chan *chan,

dma_addr_t buf_addr, return NULL;
 	}

+	if (rcar_dmac_map_slave_addr(chan, dir))
+		return NULL;
+
 	sg_len = buf_len / period_len;
 	if (sg_len > RCAR_DMAC_MAX_SG_LEN) {
 		dev_err(chan->device->dev,

@@ -1100,9 +1168,7 @@ rcar_dmac_prep_dma_cyclic(struct dma_chan *chan,

dma_addr_t buf_addr, sg_dma_len(&sgl[i]) = period_len;
 	}

-	dev_addr = dir == DMA_DEV_TO_MEM
-		 ? rchan->src.slave_addr : rchan->dst.slave_addr;
-	desc = rcar_dmac_chan_prep_sg(rchan, sgl, sg_len, dev_addr,
+	desc = rcar_dmac_chan_prep_sg(rchan, sgl, sg_len, rchan->map.addr,
 				      dir, flags, true);

 	kfree(sgl);