spi: rspi: Use SPI core DMA mapping framework

Use the SPI core DMA mapping framework instead of our own.
If available, DMA is used for transfers larger than the FIFO size
(8 or 32 bytes).
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NMark Brown <broonie@linaro.org>

drivers/spi/spi-rspi.c

@@ -195,10 +195,6 @@ struct rspi_data {
 	int rx_irq, tx_irq;
 	const struct spi_ops *ops;
 
-	/* for dmaengine */
-	struct dma_chan *chan_tx;
-	struct dma_chan *chan_rx;
-
 	unsigned dma_callbacked:1;
 	unsigned byte_access:1;
 };
@@ -251,6 +247,7 @@ struct spi_ops {
 			    struct spi_transfer *xfer);
 	u16 mode_bits;
 	u16 flags;
+	u16 fifo_size;
 };
 
 /*
@@ -466,39 +463,16 @@ static void rspi_dma_complete(void *arg)
 	wake_up_interruptible(&rspi->wait);
 }
 
-static int rspi_dma_map_sg(struct scatterlist *sg, const void *buf,
-			   unsigned len, struct dma_chan *chan,
-			   enum dma_transfer_direction dir)
-{
-	sg_init_table(sg, 1);
-	sg_set_buf(sg, buf, len);
-	sg_dma_len(sg) = len;
-	return dma_map_sg(chan->device->dev, sg, 1, dir);
-}
-
-static void rspi_dma_unmap_sg(struct scatterlist *sg, struct dma_chan *chan,
-			      enum dma_transfer_direction dir)
-{
-	dma_unmap_sg(chan->device->dev, sg, 1, dir);
-}
-
 static int rspi_send_dma(struct rspi_data *rspi, struct spi_transfer *t)
 {
-	struct scatterlist sg;
-	const void *buf = t->tx_buf;
 	struct dma_async_tx_descriptor *desc;
-	unsigned int len = t->len;
-	int ret = 0;
-
-	if (!rspi_dma_map_sg(&sg, buf, len, rspi->chan_tx, DMA_TO_DEVICE))
-		return -EFAULT;
+	int ret;
 
-	desc = dmaengine_prep_slave_sg(rspi->chan_tx, &sg, 1, DMA_TO_DEVICE,
+	desc = dmaengine_prep_slave_sg(rspi->master->dma_tx, t->tx_sg.sgl,
+				       t->tx_sg.nents, DMA_TO_DEVICE,
 				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
-	if (!desc) {
-		ret = -EIO;
-		goto end;
-	}
+	if (!desc)
+		return -EIO;
 
 	/*
 	 * DMAC needs SPTIE, but if SPTIE is set, this IRQ routine will be
@@ -513,7 +487,7 @@ static int rspi_send_dma(struct rspi_data *rspi, struct spi_transfer *t)
 	desc->callback = rspi_dma_complete;
 	desc->callback_param = rspi;
 	dmaengine_submit(desc);
-	dma_async_issue_pending(rspi->chan_tx);
+	dma_async_issue_pending(rspi->master->dma_tx);
 
 	ret = wait_event_interruptible_timeout(rspi->wait,
 					       rspi->dma_callbacked, HZ);
@@ -524,9 +498,6 @@ static int rspi_send_dma(struct rspi_data *rspi, struct spi_transfer *t)
 	rspi_disable_irq(rspi, SPCR_SPTIE);
 
 	enable_irq(rspi->tx_irq);
-
-end:
-	rspi_dma_unmap_sg(&sg, rspi->chan_tx, DMA_TO_DEVICE);
 	return ret;
 }
 
@@ -562,39 +533,22 @@ static void qspi_receive_init(const struct rspi_data *rspi)
 
 static int rspi_send_receive_dma(struct rspi_data *rspi, struct spi_transfer *t)
 {
-	struct scatterlist sg_rx, sg_tx;
-	const void *tx_buf = t->tx_buf;
-	void *rx_buf = t->rx_buf;
 	struct dma_async_tx_descriptor *desc_tx, *desc_rx;
-	unsigned int len = t->len;
-	int ret = 0;
+	int ret;
 
 	/* prepare transmit transfer */
-	if (!rspi_dma_map_sg(&sg_tx, tx_buf, len, rspi->chan_tx,
-			     DMA_TO_DEVICE))
-		return -EFAULT;
-
-	desc_tx = dmaengine_prep_slave_sg(rspi->chan_tx, &sg_tx, 1,
-			DMA_TO_DEVICE, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
-	if (!desc_tx) {
-		ret = -EIO;
-		goto end_tx_mapped;
-	}
+	desc_tx = dmaengine_prep_slave_sg(rspi->master->dma_tx, t->tx_sg.sgl,
+					  t->tx_sg.nents, DMA_TO_DEVICE,
+					  DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!desc_tx)
+		return -EIO;
 
 	/* prepare receive transfer */
-	if (!rspi_dma_map_sg(&sg_rx, rx_buf, len, rspi->chan_rx,
-			     DMA_FROM_DEVICE)) {
-		ret = -EFAULT;
-		goto end_tx_mapped;
-
-	}
-	desc_rx = dmaengine_prep_slave_sg(rspi->chan_rx, &sg_rx, 1,
-					  DMA_FROM_DEVICE,
+	desc_rx = dmaengine_prep_slave_sg(rspi->master->dma_rx, t->rx_sg.sgl,
+					  t->rx_sg.nents, DMA_FROM_DEVICE,
 					  DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
-	if (!desc_rx) {
-		ret = -EIO;
-		goto end;
-	}
+	if (!desc_rx)
+		return -EIO;
 
 	rspi_receive_init(rspi);
 
@@ -613,11 +567,11 @@ static int rspi_send_receive_dma(struct rspi_data *rspi, struct spi_transfer *t)
 	desc_rx->callback = rspi_dma_complete;
 	desc_rx->callback_param = rspi;
 	dmaengine_submit(desc_rx);
-	dma_async_issue_pending(rspi->chan_rx);
+	dma_async_issue_pending(rspi->master->dma_rx);
 
 	desc_tx->callback = NULL;	/* No callback */
 	dmaengine_submit(desc_tx);
-	dma_async_issue_pending(rspi->chan_tx);
+	dma_async_issue_pending(rspi->master->dma_tx);
 
 	ret = wait_event_interruptible_timeout(rspi->wait,
 					       rspi->dma_callbacked, HZ);
@@ -631,19 +585,21 @@ static int rspi_send_receive_dma(struct rspi_data *rspi, struct spi_transfer *t)
 	if (rspi->rx_irq != rspi->tx_irq)
 		enable_irq(rspi->rx_irq);
 
-end:
-	rspi_dma_unmap_sg(&sg_rx, rspi->chan_rx, DMA_FROM_DEVICE);
-end_tx_mapped:
-	rspi_dma_unmap_sg(&sg_tx, rspi->chan_tx, DMA_TO_DEVICE);
 	return ret;
 }
 
-static int rspi_is_dma(const struct rspi_data *rspi, struct spi_transfer *t)
+static bool __rspi_can_dma(const struct rspi_data *rspi,
+			   const struct spi_transfer *xfer)
 {
-	if (rspi->chan_tx)
-		return 1;
+	return xfer->len > rspi->ops->fifo_size;
+}
 
-	return 0;
+static bool rspi_can_dma(struct spi_master *master, struct spi_device *spi,
+			 struct spi_transfer *xfer)
+{
+	struct rspi_data *rspi = spi_master_get_devdata(master);
+
+	return __rspi_can_dma(rspi, xfer);
 }
 
 static int rspi_transfer_out_in(struct rspi_data *rspi,
@@ -676,7 +632,7 @@ static int rspi_transfer_one(struct spi_master *master, struct spi_device *spi,
 {
 	struct rspi_data *rspi = spi_master_get_devdata(master);
 
-	if (!rspi_is_dma(rspi, xfer))
+	if (!master->can_dma || !__rspi_can_dma(rspi, xfer))
 		return rspi_transfer_out_in(rspi, xfer);
 
 	if (xfer->rx_buf)
@@ -976,7 +932,7 @@ static struct dma_chan *rspi_request_dma_chan(struct device *dev,
 	return chan;
 }
 
-static int rspi_request_dma(struct device *dev, struct rspi_data *rspi,
+static int rspi_request_dma(struct device *dev, struct spi_master *master,
 			    const struct resource *res)
 {
 	const struct rspi_plat_data *rspi_pd = dev_get_platdata(dev);
@@ -984,31 +940,32 @@ static int rspi_request_dma(struct device *dev, struct rspi_data *rspi,
 	if (!rspi_pd || !rspi_pd->dma_rx_id || !rspi_pd->dma_tx_id)
 		return 0;	/* The driver assumes no error. */
 
-	rspi->chan_rx = rspi_request_dma_chan(dev, DMA_DEV_TO_MEM,
-					      rspi_pd->dma_rx_id,
-					      res->start + RSPI_SPDR);
-	if (!rspi->chan_rx)
+	master->dma_rx = rspi_request_dma_chan(dev, DMA_DEV_TO_MEM,
+					       rspi_pd->dma_rx_id,
+					       res->start + RSPI_SPDR);
+	if (!master->dma_rx)
 		return -ENODEV;
 
-	rspi->chan_tx = rspi_request_dma_chan(dev, DMA_MEM_TO_DEV,
-					      rspi_pd->dma_tx_id,
-					      res->start + RSPI_SPDR);
-	if (!rspi->chan_tx) {
-		dma_release_channel(rspi->chan_rx);
-		rspi->chan_rx = NULL;
+	master->dma_tx = rspi_request_dma_chan(dev, DMA_MEM_TO_DEV,
+					       rspi_pd->dma_tx_id,
+					       res->start + RSPI_SPDR);
+	if (!master->dma_tx) {
+		dma_release_channel(master->dma_rx);
+		master->dma_rx = NULL;
 		return -ENODEV;
 	}
 
+	master->can_dma = rspi_can_dma;
 	dev_info(dev, "DMA available");
 	return 0;
 }
 
 static void rspi_release_dma(struct rspi_data *rspi)
 {
-	if (rspi->chan_tx)
-		dma_release_channel(rspi->chan_tx);
-	if (rspi->chan_rx)
-		dma_release_channel(rspi->chan_rx);
+	if (rspi->master->dma_tx)
+		dma_release_channel(rspi->master->dma_tx);
+	if (rspi->master->dma_rx)
+		dma_release_channel(rspi->master->dma_rx);
 }
 
 static int rspi_remove(struct platform_device *pdev)
@@ -1026,6 +983,7 @@ static const struct spi_ops rspi_ops = {
 	.transfer_one =		rspi_transfer_one,
 	.mode_bits =		SPI_CPHA | SPI_CPOL | SPI_LOOP,
 	.flags =		SPI_MASTER_MUST_TX,
+	.fifo_size =		8,
 };
 
 static const struct spi_ops rspi_rz_ops = {
@@ -1033,6 +991,7 @@ static const struct spi_ops rspi_rz_ops = {
 	.transfer_one =		rspi_rz_transfer_one,
 	.mode_bits =		SPI_CPHA | SPI_CPOL | SPI_LOOP,
 	.flags =		SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX,
+	.fifo_size =		8,	/* 8 for TX, 32 for RX */
 };
 
 static const struct spi_ops qspi_ops = {
@@ -1042,6 +1001,7 @@ static const struct spi_ops qspi_ops = {
 				SPI_TX_DUAL | SPI_TX_QUAD |
 				SPI_RX_DUAL | SPI_RX_QUAD,
 	.flags =		SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX,
+	.fifo_size =		32,
 };
 
 #ifdef CONFIG_OF
@@ -1199,7 +1159,7 @@ static int rspi_probe(struct platform_device *pdev)
 		goto error2;
 	}
 
-	ret = rspi_request_dma(&pdev->dev, rspi, res);
+	ret = rspi_request_dma(&pdev->dev, master, res);
 	if (ret < 0)
 		dev_warn(&pdev->dev, "DMA not available, using PIO\n");