1 files changed, 69 insertions, 76 deletions

diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index 1d237e93a289..d5157b2222ce 100644
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -419,16 +419,13 @@ static void omap2_mcspi_tx_dma(struct spi_device *spi,
 
 	if (mcspi_dma->dma_tx) {
 		struct dma_async_tx_descriptor *tx;
-		struct scatterlist sg;
 
 		dmaengine_slave_config(mcspi_dma->dma_tx, &cfg);
 
-		sg_init_table(&sg, 1);
-		sg_dma_address(&sg) = xfer->tx_dma;
-		sg_dma_len(&sg) = xfer->len;
-
-		tx = dmaengine_prep_slave_sg(mcspi_dma->dma_tx, &sg, 1,
-		DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+		tx = dmaengine_prep_slave_sg(mcspi_dma->dma_tx, xfer->tx_sg.sgl,
+					     xfer->tx_sg.nents,
+					     DMA_MEM_TO_DEV,
+					     DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 		if (tx) {
 			tx->callback = omap2_mcspi_tx_callback;
 			tx->callback_param = spi;
@@ -449,7 +446,10 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer,
 {
 	struct omap2_mcspi	*mcspi;
 	struct omap2_mcspi_dma  *mcspi_dma;
-	unsigned int		count, dma_count;
+	unsigned int		count, transfer_reduction = 0;
+	struct scatterlist	*sg_out[2];
+	int			nb_sizes = 0, out_mapped_nents[2], ret, x;
+	size_t			sizes[2];
 	u32			l;
 	int			elements = 0;
 	int			word_len, element_count;
@@ -457,10 +457,14 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer,
 	mcspi = spi_master_get_devdata(spi->master);
 	mcspi_dma = &mcspi->dma_channels[spi->chip_select];
 	count = xfer->len;
-	dma_count = xfer->len;
 
+	/*
+	 *  In the "End-of-Transfer Procedure" section for DMA RX in OMAP35x TRM
+	 *  it mentions reducing DMA transfer length by one element in master
+	 *  normal mode.
+	 */
 	if (mcspi->fifo_depth == 0)
-		dma_count -= es;
+		transfer_reduction = es;
 
 	word_len = cs->word_len;
 	l = mcspi_cached_chconf0(spi);
@@ -474,20 +478,46 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer,
 
 	if (mcspi_dma->dma_rx) {
 		struct dma_async_tx_descriptor *tx;
-		struct scatterlist sg;
 
 		dmaengine_slave_config(mcspi_dma->dma_rx, &cfg);
 
+		/*
+		 *  Reduce DMA transfer length by one more if McSPI is
+		 *  configured in turbo mode.
+		 */
 		if ((l & OMAP2_MCSPI_CHCONF_TURBO) && mcspi->fifo_depth == 0)
-			dma_count -= es;
+			transfer_reduction += es;
+
+		if (transfer_reduction) {
+			/* Split sgl into two. The second sgl won't be used. */
+			sizes[0] = count - transfer_reduction;
+			sizes[1] = transfer_reduction;
+			nb_sizes = 2;
+		} else {
+			/*
+			 * Don't bother splitting the sgl. This essentially
+			 * clones the original sgl.
+			 */
+			sizes[0] = count;
+			nb_sizes = 1;
+		}
+
+		ret = sg_split(xfer->rx_sg.sgl, xfer->rx_sg.nents,
+			       0, nb_sizes,
+			       sizes,
+			       sg_out, out_mapped_nents,
+			       GFP_KERNEL);
 
-		sg_init_table(&sg, 1);
-		sg_dma_address(&sg) = xfer->rx_dma;
-		sg_dma_len(&sg) = dma_count;
+		if (ret < 0) {
+			dev_err(&spi->dev, "sg_split failed\n");
+			return 0;
+		}
 
-		tx = dmaengine_prep_slave_sg(mcspi_dma->dma_rx, &sg, 1,
-				DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT |
-				DMA_CTRL_ACK);
+		tx = dmaengine_prep_slave_sg(mcspi_dma->dma_rx,
+					     sg_out[0],
+					     out_mapped_nents[0],
+					     DMA_DEV_TO_MEM,
+					     DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 		if (tx) {
 			tx->callback = omap2_mcspi_rx_callback;
 			tx->callback_param = spi;
@@ -501,12 +531,17 @@ omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer,
 	omap2_mcspi_set_dma_req(spi, 1, 1);
 
 	wait_for_completion(&mcspi_dma->dma_rx_completion);
-	dma_unmap_single(mcspi->dev, xfer->rx_dma, count,
-			 DMA_FROM_DEVICE);
+
+	for (x = 0; x < nb_sizes; x++)
+		kfree(sg_out[x]);
 
 	if (mcspi->fifo_depth > 0)
 		return count;
 
+	/*
+	 *  Due to the DMA transfer length reduction the missing bytes must
+	 *  be read manually to receive all of the expected data.
+	 */
 	omap2_mcspi_set_enable(spi, 0);
 
 	elements = element_count - 1;
@@ -615,8 +650,6 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
 
 	if (tx != NULL) {
 		wait_for_completion(&mcspi_dma->dma_tx_completion);
-		dma_unmap_single(mcspi->dev, xfer->tx_dma, xfer->len,
-				 DMA_TO_DEVICE);
 
 		if (mcspi->fifo_depth > 0) {
 			irqstat_reg = mcspi->base + OMAP2_MCSPI_IRQSTATUS;
@@ -1074,8 +1107,9 @@ static void omap2_mcspi_cleanup(struct spi_device *spi)
 		gpio_free(spi->cs_gpio);
 }
 
-static int omap2_mcspi_work_one(struct omap2_mcspi *mcspi,
-		struct spi_device *spi, struct spi_transfer *t)
+static int omap2_mcspi_transfer_one(struct spi_master *master,
+				    struct spi_device *spi,
+				    struct spi_transfer *t)
 {
 
 	/* We only enable one channel at a time -- the one whose message is
@@ -1085,7 +1119,7 @@ static int omap2_mcspi_work_one(struct omap2_mcspi *mcspi,
 	 * chipselect with the FORCE bit ... CS != channel enable.
 	 */
 
-	struct spi_master		*master;
+	struct omap2_mcspi		*mcspi;
 	struct omap2_mcspi_dma		*mcspi_dma;
 	struct omap2_mcspi_cs		*cs;
 	struct omap2_mcspi_device_config *cd;
@@ -1093,7 +1127,7 @@ static int omap2_mcspi_work_one(struct omap2_mcspi *mcspi,
 	int				status = 0;
 	u32				chconf;
 
-	master = spi->master;
+	mcspi = spi_master_get_devdata(master);
 	mcspi_dma = mcspi->dma_channels + spi->chip_select;
 	cs = spi->controller_state;
 	cd = spi->controller_data;
@@ -1153,7 +1187,8 @@ static int omap2_mcspi_work_one(struct omap2_mcspi *mcspi,
 		unsigned	count;
 
 		if ((mcspi_dma->dma_rx && mcspi_dma->dma_tx) &&
-		    (t->len >= DMA_MIN_BYTES))
+		    master->cur_msg_mapped &&
+		    master->can_dma(master, spi, t))
 			omap2_mcspi_set_fifo(spi, t, 1);
 
 		omap2_mcspi_set_enable(spi, 1);
@@ -1164,7 +1199,8 @@ static int omap2_mcspi_work_one(struct omap2_mcspi *mcspi,
 					+ OMAP2_MCSPI_TX0);
 
 		if ((mcspi_dma->dma_rx && mcspi_dma->dma_tx) &&
-		    (t->len >= DMA_MIN_BYTES))
+		    master->cur_msg_mapped &&
+		    master->can_dma(master, spi, t))
 			count = omap2_mcspi_txrx_dma(spi, t);
 		else
 			count = omap2_mcspi_txrx_pio(spi, t);
@@ -1233,55 +1269,11 @@ static int omap2_mcspi_prepare_message(struct spi_master *master,
 	return 0;
 }
 
-static int omap2_mcspi_transfer_one(struct spi_master *master,
-		struct spi_device *spi, struct spi_transfer *t)
+static bool omap2_mcspi_can_dma(struct spi_master *master,
+				struct spi_device *spi,
+				struct spi_transfer *xfer)
 {
-	struct omap2_mcspi	*mcspi;
-	struct omap2_mcspi_dma	*mcspi_dma;
-	const void	*tx_buf = t->tx_buf;
-	void		*rx_buf = t->rx_buf;
-	unsigned	len = t->len;
-
-	mcspi = spi_master_get_devdata(master);
-	mcspi_dma = mcspi->dma_channels + spi->chip_select;
-
-	if ((len && !(rx_buf || tx_buf))) {
-		dev_dbg(mcspi->dev, "transfer: %d Hz, %d %s%s, %d bpw\n",
-				t->speed_hz,
-				len,
-				tx_buf ? "tx" : "",
-				rx_buf ? "rx" : "",
-				t->bits_per_word);
-		return -EINVAL;
-	}
-
-	if (len < DMA_MIN_BYTES)
-		goto skip_dma_map;
-
-	if (mcspi_dma->dma_tx && tx_buf != NULL) {
-		t->tx_dma = dma_map_single(mcspi->dev, (void *) tx_buf,
-				len, DMA_TO_DEVICE);
-		if (dma_mapping_error(mcspi->dev, t->tx_dma)) {
-			dev_dbg(mcspi->dev, "dma %cX %d bytes error\n",
-					'T', len);
-			return -EINVAL;
-		}
-	}
-	if (mcspi_dma->dma_rx && rx_buf != NULL) {
-		t->rx_dma = dma_map_single(mcspi->dev, rx_buf, t->len,
-				DMA_FROM_DEVICE);
-		if (dma_mapping_error(mcspi->dev, t->rx_dma)) {
-			dev_dbg(mcspi->dev, "dma %cX %d bytes error\n",
-					'R', len);
-			if (tx_buf != NULL)
-				dma_unmap_single(mcspi->dev, t->tx_dma,
-						len, DMA_TO_DEVICE);
-			return -EINVAL;
-		}
-	}
-
-skip_dma_map:
-	return omap2_mcspi_work_one(mcspi, spi, t);
+	return (xfer->len >= DMA_MIN_BYTES);
 }
 
 static int omap2_mcspi_master_setup(struct omap2_mcspi *mcspi)
@@ -1361,6 +1353,7 @@ static int omap2_mcspi_probe(struct platform_device *pdev)
 	master->setup = omap2_mcspi_setup;
 	master->auto_runtime_pm = true;
 	master->prepare_message = omap2_mcspi_prepare_message;
+	master->can_dma = omap2_mcspi_can_dma;
 	master->transfer_one = omap2_mcspi_transfer_one;
 	master->set_cs = omap2_mcspi_set_cs;
 	master->cleanup = omap2_mcspi_cleanup;