[PATCH 1/2] spi: Provide core support for DMA mapping transfers

[PATCH 1/2] spi: Provide core support for DMA mapping transfers

[Mark Brown]

From: Mark Brown <broonie-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

The process of DMA mapping buffers for SPI transfers does not vary between
devices so in order to save duplication of code in drivers this can be
factored out into the core, allowing it to be integrated with the work that
is being done on factoring out the common elements from the data path
including more sharing of dmaengine code.

In order to use this masters need to provide a can_dma() operation and while
the hardware is prepared they should ensure that DMA channels are provided
in tx_dma and rx_dma. The core will then ensure that the buffers are mapped
for DMA prior to calling transfer_one_message().

Currently the cleanup on error is not complete, this needs to be improved.

Signed-off-by: Mark Brown <broonie-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 drivers/spi/spi.c       | 79 +++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/spi/spi.h | 18 +++++++++++
 2 files changed, 97 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index a86569e1f178..314d326bce9f 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -24,6 +24,8 @@
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/cache.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
 #include <linux/mutex.h>
 #include <linux/of_device.h>
 #include <linux/of_irq.h>
@@ -570,6 +572,74 @@ static void spi_set_cs(struct spi_device *spi, bool enable)
 		spi->master->set_cs(spi, !enable);
 }
 
+static int spi_dma_map_msg(struct spi_master *master, struct spi_message *msg)
+{
+	struct device *dev = master->dev.parent;
+	struct device *tx_dev, *rx_dev;
+	struct spi_transfer *xfer;
+
+	if (msg->is_dma_mapped || !master->can_dma)
+		return 0;
+
+	tx_dev = &master->dma_tx->dev->device;
+	rx_dev = &master->dma_rx->dev->device;
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		if (!master->can_dma(master, msg->spi, xfer))
+			continue;
+
+		if (xfer->tx_buf != NULL) {
+			xfer->tx_dma = dma_map_single(tx_dev,
+						      (void *)xfer->tx_buf,
+						      xfer->len,
+						      DMA_TO_DEVICE);
+			if (dma_mapping_error(dev, xfer->tx_dma)) {
+				dev_err(dev, "dma_map_single Tx failed\n");
+				return -ENOMEM;
+			}
+		}
+
+		if (xfer->rx_buf != NULL) {
+			xfer->rx_dma = dma_map_single(rx_dev,
+						      xfer->rx_buf, xfer->len,
+						      DMA_FROM_DEVICE);
+			if (dma_mapping_error(dev, xfer->rx_dma)) {
+				dev_err(dev, "dma_map_single Rx failed\n");
+				dma_unmap_single(tx_dev, xfer->tx_dma,
+						 xfer->len, DMA_TO_DEVICE);
+				return -ENOMEM;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static int spi_dma_unmap_msg(struct spi_master *master,
+			     struct spi_message *msg)
+{
+	struct spi_transfer *xfer;
+	struct device *tx_dev, *rx_dev;
+
+	if (!master->cur_msg_mapped || msg->is_dma_mapped || !master->can_dma)
+		return 0;
+
+	tx_dev = &master->dma_tx->dev->device;
+	rx_dev = &master->dma_rx->dev->device;
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		if (!master->can_dma(master, msg->spi, xfer))
+			continue;
+
+		dma_unmap_single(rx_dev, xfer->rx_dma, xfer->len,
+				 DMA_FROM_DEVICE);
+		dma_unmap_single(tx_dev, xfer->tx_dma, xfer->len,
+				 DMA_TO_DEVICE);
+	}
+
+	return 0;
+}
+
 /*
  * spi_transfer_one_message - Default implementation of transfer_one_message()
  *
@@ -740,6 +810,13 @@ static void spi_pump_messages(struct kthread_work *work)
 		master->cur_msg_prepared = true;
 	}
 
+	ret = spi_dma_map_msg(master, master->cur_msg);
+	if (ret) {
+		master->cur_msg->status = ret;
+		spi_finalize_current_message(master);
+		return;
+	}
+
 	ret = master->transfer_one_message(master, master->cur_msg);
 	if (ret) {
 		dev_err(&master->dev,
@@ -829,6 +906,8 @@ void spi_finalize_current_message(struct spi_master *master)
 	queue_kthread_work(&master->kworker, &master->pump_messages);
 	spin_unlock_irqrestore(&master->queue_lock, flags);
 
+	spi_dma_unmap_msg(master, mesg);
+
 	if (master->cur_msg_prepared && master->unprepare_message) {
 		ret = master->unprepare_message(master, mesg);
 		if (ret) {
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 21a7251d85ee..14380043491b 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -25,6 +25,8 @@
 #include <linux/kthread.h>
 #include <linux/completion.h>
 
+struct dma_chan;
+
 /*
  * INTERFACES between SPI master-side drivers and SPI infrastructure.
  * (There's no SPI slave support for Linux yet...)
@@ -385,6 +387,17 @@ struct spi_master {
 	void			(*cleanup)(struct spi_device *spi);
 
 	/*
+	 * Used to enable core support for DMA handling, if can_dma()
+	 * exists and returns true then the transfer will be mapped
+	 * prior to transfer_one() being called.  The driver should
+	 * not modify or store xfer and dma_tx and dma_rx must be set
+	 * while the device is prepared.
+	 */
+	bool			(*can_dma)(struct spi_master *master,
+					   struct spi_device *spi,
+					   struct spi_transfer *xfer);
+
+	/*
 	 * These hooks are for drivers that want to use the generic
 	 * master transfer queueing mechanism. If these are used, the
 	 * transfer() function above must NOT be specified by the driver.
@@ -402,6 +415,7 @@ struct spi_master {
 	bool				rt;
 	bool				auto_runtime_pm;
 	bool                            cur_msg_prepared;
+	bool				cur_msg_mapped;
 	struct completion               xfer_completion;
 
 	int (*prepare_transfer_hardware)(struct spi_master *master);
@@ -423,6 +437,10 @@ struct spi_master {
 
 	/* gpio chip select */
 	int			*cs_gpios;
+
+	/* DMA channels for use with core dmaengine helpers */
+	struct dma_chan		*dma_tx;
+	struct dma_chan		*dma_rx;
 };
 
 static inline void *spi_master_get_devdata(struct spi_master *master)
-- 
1.8.5.2

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[PATCH 2/2] spi/s3c64xx: Use core DMA mapping code with dmaengine

[Mark Brown]

From: Mark Brown <broonie-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

When using dmaengine allow the core to do the DMA mapping. We still need
local mapping code for the non-dmaengine case so this doesn't save us
anything for now.

Signed-off-by: Mark Brown <broonie-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 drivers/spi/spi-s3c64xx.c | 178 +++++++++++++++++++++++++++-------------------
 1 file changed, 103 insertions(+), 75 deletions(-)

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index ae907dde1371..e7620f299777 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -291,6 +291,81 @@ static struct s3c2410_dma_client s3c64xx_spi_dma_client = {
 	.name = "samsung-spi-dma",
 };
 
+static int s3c64xx_spi_map_mssg(struct s3c64xx_spi_driver_data *sdd,
+						struct spi_message *msg)
+{
+	struct device *dev = &sdd->pdev->dev;
+	struct spi_transfer *xfer;
+
+	if (is_polling(sdd) || msg->is_dma_mapped)
+		return 0;
+
+	/* First mark all xfer unmapped */
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		xfer->rx_dma = XFER_DMAADDR_INVALID;
+		xfer->tx_dma = XFER_DMAADDR_INVALID;
+	}
+
+	/* Map until end or first fail */
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+
+		if (xfer->len <= ((FIFO_LVL_MASK(sdd) >> 1) + 1))
+			continue;
+
+		if (xfer->tx_buf != NULL) {
+			xfer->tx_dma = dma_map_single(dev,
+					(void *)xfer->tx_buf, xfer->len,
+					DMA_TO_DEVICE);
+			if (dma_mapping_error(dev, xfer->tx_dma)) {
+				dev_err(dev, "dma_map_single Tx failed\n");
+				xfer->tx_dma = XFER_DMAADDR_INVALID;
+				return -ENOMEM;
+			}
+		}
+
+		if (xfer->rx_buf != NULL) {
+			xfer->rx_dma = dma_map_single(dev, xfer->rx_buf,
+						xfer->len, DMA_FROM_DEVICE);
+			if (dma_mapping_error(dev, xfer->rx_dma)) {
+				dev_err(dev, "dma_map_single Rx failed\n");
+				dma_unmap_single(dev, xfer->tx_dma,
+						xfer->len, DMA_TO_DEVICE);
+				xfer->tx_dma = XFER_DMAADDR_INVALID;
+				xfer->rx_dma = XFER_DMAADDR_INVALID;
+				return -ENOMEM;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static void s3c64xx_spi_unmap_mssg(struct s3c64xx_spi_driver_data *sdd,
+						struct spi_message *msg)
+{
+	struct device *dev = &sdd->pdev->dev;
+	struct spi_transfer *xfer;
+
+	if (is_polling(sdd) || msg->is_dma_mapped)
+		return;
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+
+		if (xfer->len <= ((FIFO_LVL_MASK(sdd) >> 1) + 1))
+			continue;
+
+		if (xfer->rx_buf != NULL
+				&& xfer->rx_dma != XFER_DMAADDR_INVALID)
+			dma_unmap_single(dev, xfer->rx_dma,
+						xfer->len, DMA_FROM_DEVICE);
+
+		if (xfer->tx_buf != NULL
+				&& xfer->tx_dma != XFER_DMAADDR_INVALID)
+			dma_unmap_single(dev, xfer->tx_dma,
+						xfer->len, DMA_TO_DEVICE);
+	}
+}
+
 static void prepare_dma(struct s3c64xx_spi_dma_data *dma,
 					unsigned len, dma_addr_t buf)
 {
@@ -378,8 +453,22 @@ static void s3c64xx_spi_dma_stop(struct s3c64xx_spi_driver_data *sdd,
 {
 	sdd->ops->stop((enum dma_ch)dma->ch);
 }
+
+#define s3c64xx_spi_can_dma NULL
+
 #else
 
+static int s3c64xx_spi_map_mssg(struct s3c64xx_spi_driver_data *sdd,
+						struct spi_message *msg)
+{
+	return 0;
+}
+
+static void s3c64xx_spi_unmap_mssg(struct s3c64xx_spi_driver_data *sdd,
+						struct spi_message *msg)
+{
+}
+
 static void prepare_dma(struct s3c64xx_spi_dma_data *dma,
 					unsigned len, dma_addr_t buf)
 {
@@ -437,6 +526,7 @@ static int s3c64xx_spi_prepare_transfer(struct spi_master *spi)
 			ret = -EBUSY;
 			goto out;
 		}
+		spi->dma_rx = sdd->rx_dma.ch;
 
 		sdd->tx_dma.ch = dma_request_slave_channel_compat(mask, filter,
 				   (void *)sdd->tx_dma.dmach, dev, "tx");
@@ -445,6 +535,7 @@ static int s3c64xx_spi_prepare_transfer(struct spi_master *spi)
 			ret = -EBUSY;
 			goto out_rx;
 		}
+		spi->dma_tx = sdd->tx_dma.ch;
 	}
 
 	ret = pm_runtime_get_sync(&sdd->pdev->dev);
@@ -482,6 +573,16 @@ static void s3c64xx_spi_dma_stop(struct s3c64xx_spi_driver_data *sdd,
 {
 	dmaengine_terminate_all(dma->ch);
 }
+
+static bool s3c64xx_spi_can_dma(struct spi_master *master,
+				struct spi_device *spi,
+				struct spi_transfer *xfer)
+{
+	struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(master);
+
+	return xfer->len > (FIFO_LVL_MASK(sdd) >> 1) + 1;
+}
+
 #endif
 
 static void enable_datapath(struct s3c64xx_spi_driver_data *sdd,
@@ -774,81 +875,6 @@ static void s3c64xx_spi_config(struct s3c64xx_spi_driver_data *sdd)
 
 #define XFER_DMAADDR_INVALID DMA_BIT_MASK(32)
 
-static int s3c64xx_spi_map_mssg(struct s3c64xx_spi_driver_data *sdd,
-						struct spi_message *msg)
-{
-	struct device *dev = &sdd->pdev->dev;
-	struct spi_transfer *xfer;
-
-	if (is_polling(sdd) || msg->is_dma_mapped)
-		return 0;
-
-	/* First mark all xfer unmapped */
-	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
-		xfer->rx_dma = XFER_DMAADDR_INVALID;
-		xfer->tx_dma = XFER_DMAADDR_INVALID;
-	}
-
-	/* Map until end or first fail */
-	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
-
-		if (xfer->len <= ((FIFO_LVL_MASK(sdd) >> 1) + 1))
-			continue;
-
-		if (xfer->tx_buf != NULL) {
-			xfer->tx_dma = dma_map_single(dev,
-					(void *)xfer->tx_buf, xfer->len,
-					DMA_TO_DEVICE);
-			if (dma_mapping_error(dev, xfer->tx_dma)) {
-				dev_err(dev, "dma_map_single Tx failed\n");
-				xfer->tx_dma = XFER_DMAADDR_INVALID;
-				return -ENOMEM;
-			}
-		}
-
-		if (xfer->rx_buf != NULL) {
-			xfer->rx_dma = dma_map_single(dev, xfer->rx_buf,
-						xfer->len, DMA_FROM_DEVICE);
-			if (dma_mapping_error(dev, xfer->rx_dma)) {
-				dev_err(dev, "dma_map_single Rx failed\n");
-				dma_unmap_single(dev, xfer->tx_dma,
-						xfer->len, DMA_TO_DEVICE);
-				xfer->tx_dma = XFER_DMAADDR_INVALID;
-				xfer->rx_dma = XFER_DMAADDR_INVALID;
-				return -ENOMEM;
-			}
-		}
-	}
-
-	return 0;
-}
-
-static void s3c64xx_spi_unmap_mssg(struct s3c64xx_spi_driver_data *sdd,
-						struct spi_message *msg)
-{
-	struct device *dev = &sdd->pdev->dev;
-	struct spi_transfer *xfer;
-
-	if (is_polling(sdd) || msg->is_dma_mapped)
-		return;
-
-	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
-
-		if (xfer->len <= ((FIFO_LVL_MASK(sdd) >> 1) + 1))
-			continue;
-
-		if (xfer->rx_buf != NULL
-				&& xfer->rx_dma != XFER_DMAADDR_INVALID)
-			dma_unmap_single(dev, xfer->rx_dma,
-						xfer->len, DMA_FROM_DEVICE);
-
-		if (xfer->tx_buf != NULL
-				&& xfer->tx_dma != XFER_DMAADDR_INVALID)
-			dma_unmap_single(dev, xfer->tx_dma,
-						xfer->len, DMA_TO_DEVICE);
-	}
-}
-
 static int s3c64xx_spi_prepare_message(struct spi_master *master,
 				       struct spi_message *msg)
 {
@@ -1347,6 +1373,8 @@ static int s3c64xx_spi_probe(struct platform_device *pdev)
 	/* the spi->mode bits understood by this driver: */
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 	master->auto_runtime_pm = true;
+	if (!is_polling(sdd))
+		master->can_dma = s3c64xx_spi_can_dma;
 
 	sdd->regs = devm_ioremap_resource(&pdev->dev, mem_res);
 	if (IS_ERR(sdd->regs)) {
-- 
1.8.5.2

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