[PATCH 1/3] Documentation:spi:fsl-dspi:add DSPI dma transfer support

[PATCH 1/3] Documentation:spi:fsl-dspi:add DSPI dma transfer support

[Chao Fu]

From: Chao Fu <B44548@freescale.com>

Add bool value use-dma.
The bool will determine whether DSPI use dma channel transfer data
in a platform.

Add dmas and dma-names for describing dma channels of DSPI.

Signed-off-by: Chao Fu      <b44548@freescale.com>
---
 Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt b/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
index 5376de4..76a1039 100644
--- a/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
+++ b/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
@@ -11,6 +11,11 @@ Required properties:
 - spi-num-chipselects : the number of the chipselect signals.
 - bus-num : the slave chip chipselect signal number.
 - big-endian : if DSPI modudle is big endian, the bool will be set in node.
+- use-dma: the bool decide if use dma method in DSPI transfering.
+- dmas: List of DMA specifiers with the controller specific format
+	as described in the generic DMA client binding. A tx and rx
+	specifier is required for each chip select.
+- dma-names: Should be named "tx" and "rx".
 Example:
 
 dspi0@4002c000 {
@@ -26,6 +31,10 @@ dspi0@4002c000 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_dspi0_1>;
 	big-endian;
+	use-dma;
+	dmas = <&edma0 0 12>,
+		<&edma0 0 13>;
+	dma-names = "rx", "tx";
 	status = "okay";
 
 	sflash: at26df081a@0 {
-- 
1.8.4

[PATCH 1/3] Documentation:spi:fsl-dspi:add DSPI dma transfer support

[Chao Fu]

From: Chao Fu <B44548@freescale.com>

Add bool value use-dma.
The bool will determine whether DSPI use dma channel transfer data
in a platform.

Add dmas and dma-names for describing dma channels of DSPI.

Signed-off-by: Chao Fu      <b44548@freescale.com>
---
 Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt b/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
index 5376de4..76a1039 100644
--- a/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
+++ b/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
@@ -11,6 +11,11 @@ Required properties:
 - spi-num-chipselects : the number of the chipselect signals.
 - bus-num : the slave chip chipselect signal number.
 - big-endian : if DSPI modudle is big endian, the bool will be set in node.
+- use-dma: the bool decide if use dma method in DSPI transfering.
+- dmas: List of DMA specifiers with the controller specific format
+	as described in the generic DMA client binding. A tx and rx
+	specifier is required for each chip select.
+- dma-names: Should be named "tx" and "rx".
 Example:
 
 dspi0 at 4002c000 {
@@ -26,6 +31,10 @@ dspi0 at 4002c000 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_dspi0_1>;
 	big-endian;
+	use-dma;
+	dmas = <&edma0 0 12>,
+		<&edma0 0 13>;
+	dma-names = "rx", "tx";
 	status = "okay";
 
 	sflash: at26df081a at 0 {
-- 
1.8.4

[PATCH 2/3] arm:dts:vf-610:add vybrid DSPI DMA transfer support

[Chao Fu]

From: Chao Fu <B44548@freescale.com>

DSPI can transfer data in DMA mode or PIO mode.
The ajudgement of using DMA method(use-dma) will be read from dtb.
And add DMA channels info of DSPI.

Signed-off-by: Chao Fu      <b44548@freescale.com>
---
 arch/arm/boot/dts/vf610.dtsi | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/boot/dts/vf610.dtsi b/arch/arm/boot/dts/vf610.dtsi
index e1e1e51..2fe53c1 100644
--- a/arch/arm/boot/dts/vf610.dtsi
+++ b/arch/arm/boot/dts/vf610.dtsi
@@ -148,6 +148,10 @@
 				clocks = <&clks VF610_CLK_DSPI0>;
 				clock-names = "dspi";
 				spi-num-chipselects = <5>;
+				use-dma;
+				dmas = <&edma0 0 12>,
+					<&edma0 0 13>;
+				dma-names = "rx", "tx";
 				status = "disabled";
 			};
 
-- 
1.8.4

[PATCH 2/3] arm:dts:vf-610:add vybrid DSPI DMA transfer support

[Chao Fu]

From: Chao Fu <B44548@freescale.com>

DSPI can transfer data in DMA mode or PIO mode.
The ajudgement of using DMA method(use-dma) will be read from dtb.
And add DMA channels info of DSPI.

Signed-off-by: Chao Fu      <b44548@freescale.com>
---
 arch/arm/boot/dts/vf610.dtsi | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/boot/dts/vf610.dtsi b/arch/arm/boot/dts/vf610.dtsi
index e1e1e51..2fe53c1 100644
--- a/arch/arm/boot/dts/vf610.dtsi
+++ b/arch/arm/boot/dts/vf610.dtsi
@@ -148,6 +148,10 @@
 				clocks = <&clks VF610_CLK_DSPI0>;
 				clock-names = "dspi";
 				spi-num-chipselects = <5>;
+				use-dma;
+				dmas = <&edma0 0 12>,
+					<&edma0 0 13>;
+				dma-names = "rx", "tx";
 				status = "disabled";
 			};
 
-- 
1.8.4

[PATCH 3/3] spi:fsl-dspi:add dspi dma transfer support

[Chao Fu]

From: Chao Fu <B44548-KZfg59tc24xl57MIdRCFDg@public.gmane.org>

DSPI can transfer data in DMA mode or PIO mode.This patch will add the DMA
transfer driver support. Add DMA reference functions and variables to form DMA
transfer process.
DSPI DMA mode need work with Freescale eDMA module together.

The software will be changed in two transfer methods as followwing:
		 DMA			PIO
trigger write:	 dspi_tx_dma		dspi_tx_pio
write complete:	 dspi_dma_tx_complete   irq_handle
trigger read:	 dspi_receive_dma	dspi_rx_pio
read complete:	 dspi_rx_dma		none

Remove bitbang:
Add DMA funtions, DSPI module need get cs change information in a spi transfer.
According cs change, DSPI will give last data the right flag. Bitbang provide
cs change behind the last data in a transfer. DSPI can not deal the last data in
every transfer properly, so remove the bitbang in driver.

Signed-off-by: Chao Fu      <b44548-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
---
 drivers/spi/Kconfig        |   1 -
 drivers/spi/spi-fsl-dspi.c | 425 ++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 360 insertions(+), 66 deletions(-)

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 6554bd0..c9240e9 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -269,7 +269,6 @@ config SPI_FSL_SPI
 
 config SPI_FSL_DSPI
 	tristate "Freescale DSPI controller"
-	select SPI_BITBANG
 	select REGMAP_MMIO
 	depends on SOC_VF610 || COMPILE_TEST
 	help
diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index 42ede0d..a22061f 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -25,7 +25,8 @@
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/spi/spi.h>
-#include <linux/spi/spi_bitbang.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
 #include <linux/pm_runtime.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
@@ -37,6 +38,7 @@
 #define TRAN_STATE_WORD_ODD_NUM	0x04
 
 #define DSPI_FIFO_SIZE			4
+#define DSPI_DMA_BUFSIZE		(DSPI_FIFO_SIZE * 4)
 
 #define SPI_MCR		0x00
 #define SPI_MCR_MASTER		(1 << 31)
@@ -67,6 +69,10 @@
 
 #define SPI_RSER		0x30
 #define SPI_RSER_EOQFE		0x10000000
+#define SPI_RSER_TFFFE		0x02000000
+#define SPI_RSER_TFFFD		0x01000000
+#define SPI_RSER_RFDFE		0x00020000
+#define SPI_RSER_RFDFD		0x00010000
 
 #define SPI_PUSHR		0x34
 #define SPI_PUSHR_CONT		(1 << 31)
@@ -106,7 +112,7 @@ struct chip_data {
 };
 
 struct fsl_dspi {
-	struct spi_bitbang	bitbang;
+	struct spi_master	*master;
 	struct platform_device	*pdev;
 
 	struct regmap		*regmap;
@@ -114,6 +120,7 @@ struct fsl_dspi {
 	struct clk		*clk;
 
 	struct spi_transfer	*cur_transfer;
+	struct spi_message	*cur_msg;
 	struct chip_data	*cur_chip;
 	size_t			len;
 	void			*tx;
@@ -123,11 +130,31 @@ struct fsl_dspi {
 	char			dataflags;
 	u8			cs;
 	u16			void_write_data;
+	u32			cs_change;
 
 	wait_queue_head_t	waitq;
 	u32			waitflags;
+
+	/*For DMA Support*/
+	bool			use_dma;
+	struct dma_chan		*chan_tx;
+	struct dma_chan		*chan_rx;
+	u32			*dma_tx_buf;
+	u32			*dma_rx_buf;
+	dma_addr_t		dma_tx_bufphy;
+	dma_addr_t		dma_rx_bufphy;
+	struct dma_async_tx_descriptor *tx_desc;
+	struct dma_async_tx_descriptor *rx_desc;
+	size_t			dma_count;
+	dma_addr_t		phybase;
 };
 
+static int dspi_send_dma(struct fsl_dspi *dspi, size_t count);
+static int dspi_receive_dma(struct fsl_dspi *dspi, size_t count);
+void dspi_rx_dma(void *arg);
+static int dspi_tx_dma(struct fsl_dspi *dspi);
+static void dspi_release_dma(struct fsl_dspi *dspi);
+
 static inline int is_double_byte_mode(struct fsl_dspi *dspi)
 {
 	unsigned int val;
@@ -165,7 +192,249 @@ static void hz_to_spi_baud(char *pbr, char *br, int speed_hz,
 	*br =  ARRAY_SIZE(brs) - 1;
 }
 
-static int dspi_transfer_write(struct fsl_dspi *dspi)
+static void dspi_dma_tx_complete(void *arg)
+{
+	struct fsl_dspi *dspi = arg;
+	struct spi_message *msg = dspi->cur_msg;
+
+	dspi_receive_dma(dspi, dspi->dma_count);
+
+	if (dspi->len > 0)
+		msg->actual_length += dspi_tx_dma(dspi);
+}
+
+static int dspi_send_dma(struct fsl_dspi *dspi, size_t count)
+{
+	dspi->tx_desc = dmaengine_prep_slave_single(
+			dspi->chan_tx, dspi->dma_tx_bufphy,
+			count * DMA_SLAVE_BUSWIDTH_4_BYTES,
+			DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+
+	if (!dspi->tx_desc) {
+		dev_err(&dspi->pdev->dev, "dma prepare tx desc fail!\n");
+		dspi->use_dma = 0;
+		dspi_release_dma(dspi);
+		dspi->waitflags = 1;
+		wake_up_interruptible(&dspi->waitq);
+
+		return -EINVAL;
+	}
+
+	dspi->tx_desc->callback = dspi_dma_tx_complete;
+	dspi->tx_desc->callback_param = dspi;
+
+	dmaengine_submit(dspi->tx_desc);
+	dma_async_issue_pending(dspi->chan_tx);
+
+	return 0;
+}
+
+static int dspi_receive_dma(struct fsl_dspi *dspi, size_t count)
+{
+
+	dspi->rx_desc = dmaengine_prep_slave_single(
+			dspi->chan_rx, dspi->dma_rx_bufphy,
+			count * DMA_SLAVE_BUSWIDTH_4_BYTES,
+			DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+
+	if (!dspi->rx_desc) {
+		dev_err(&dspi->pdev->dev, "dma prepare rx desc fail!\n");
+		dspi->use_dma = 0;
+		dspi_release_dma(dspi);
+		dspi->waitflags = 1;
+		wake_up_interruptible(&dspi->waitq);
+
+		return -EINVAL;
+	}
+
+	dspi->rx_desc->callback = dspi_rx_dma;
+	dspi->rx_desc->callback_param = dspi;
+	dma_sync_single_for_device(&dspi->pdev->dev,
+				dspi->dma_rx_bufphy,
+				DSPI_DMA_BUFSIZE, DMA_FROM_DEVICE);
+
+	dmaengine_submit(dspi->rx_desc);
+	dma_async_issue_pending(dspi->chan_rx);
+
+	return 0;
+}
+
+static int dspi_request_dma(struct fsl_dspi *dspi)
+{
+	struct dma_slave_config cfg;
+	int ret = -EINVAL;
+
+	dspi->chan_rx = dma_request_slave_channel(&dspi->pdev->dev, "rx");
+	if (dspi->chan_rx) {
+		cfg.direction = DMA_DEV_TO_MEM;
+		cfg.dst_addr = 0;
+		cfg.src_addr = dspi->phybase + SPI_POPR;
+		cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+		cfg.src_maxburst = 1;
+		ret = dmaengine_slave_config(dspi->chan_rx, &cfg);
+		if (!ret)
+			dev_info(&dspi->pdev->dev, "Configed DSPI rx channel");
+		else
+			return ret;
+	}
+
+	dspi->chan_tx = dma_request_slave_channel(&dspi->pdev->dev, "tx");
+	if (dspi->chan_tx) {
+		cfg.direction = DMA_MEM_TO_DEV;
+		cfg.dst_addr = dspi->phybase + SPI_PUSHR;
+		cfg.src_addr = 0;
+		cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+		cfg.dst_maxburst = 1;
+		ret = dmaengine_slave_config(dspi->chan_tx, &cfg);
+		if (!ret)
+			dev_info(&dspi->pdev->dev, "Configed DSPI tx channel");
+		else
+			return ret;
+	}
+
+	dspi->dma_tx_buf = devm_kzalloc(&dspi->pdev->dev,
+					DSPI_DMA_BUFSIZE, GFP_DMA);
+	if (!dspi->dma_tx_buf)
+		return -ENOMEM;
+	dspi->dma_rx_buf = devm_kzalloc(&dspi->pdev->dev,
+					DSPI_DMA_BUFSIZE, GFP_DMA);
+	if (!dspi->dma_rx_buf)
+		return -ENOMEM;
+
+	dspi->dma_tx_bufphy = dma_map_single(dspi->chan_tx->device->dev,
+						dspi->dma_tx_buf,
+						DSPI_DMA_BUFSIZE,
+						DMA_TO_DEVICE);
+	dspi->dma_rx_bufphy = dma_map_single(dspi->chan_rx->device->dev,
+						dspi->dma_rx_buf,
+						DSPI_DMA_BUFSIZE,
+						DMA_FROM_DEVICE);
+
+	return ret;
+}
+
+static void dspi_release_dma(struct fsl_dspi *dspi)
+{
+	if (dspi->dma_tx_buf)
+		devm_kfree(&dspi->pdev->dev, dspi->dma_tx_buf);
+	if (dspi->dma_rx_buf)
+		devm_kfree(&dspi->pdev->dev, dspi->dma_rx_buf);
+	if (dspi->chan_tx)
+		dma_release_channel(dspi->chan_tx);
+	if (dspi->chan_rx)
+		dma_release_channel(dspi->chan_rx);
+}
+
+void dspi_rx_dma(void *arg)
+{
+	struct fsl_dspi *dspi = arg;
+	int rx_count = 0;
+	int rx_word = is_double_byte_mode(dspi);
+	u16 d;
+
+	dma_sync_single_for_cpu(&dspi->pdev->dev, dspi->dma_rx_bufphy,
+					DSPI_DMA_BUFSIZE, DMA_FROM_DEVICE);
+
+	while ((dspi->rx < dspi->rx_end)
+			&& (rx_count < DSPI_FIFO_SIZE)) {
+		if (rx_word) {
+			if ((dspi->rx_end - dspi->rx) == 1)
+				break;
+
+			d = SPI_POPR_RXDATA(*(dspi->dma_rx_buf + rx_count));
+
+			if (!(dspi->dataflags & TRAN_STATE_RX_VOID))
+				*(u16 *)dspi->rx = d;
+			dspi->rx += 2;
+
+		} else {
+			d = SPI_POPR_RXDATA(*(dspi->dma_rx_buf + rx_count));
+			if (!(dspi->dataflags & TRAN_STATE_RX_VOID))
+				*(u8 *)dspi->rx = d;
+			dspi->rx++;
+		}
+
+		rx_count++;
+	}
+
+	if (dspi->len == 0) {
+		dspi->waitflags = 1;
+		wake_up_interruptible(&dspi->waitq);
+	}
+}
+
+static int dspi_tx_dma(struct fsl_dspi *dspi)
+{
+	int tx_count = 0;
+	int tx_word;
+	u16 d16;
+	u8  d8;
+	u32 *dma_buf = (u32 *)dspi->dma_tx_buf;
+
+	dma_sync_single_for_cpu(&dspi->pdev->dev, dspi->dma_tx_bufphy,
+					DSPI_DMA_BUFSIZE, DMA_TO_DEVICE);
+
+	tx_word = is_double_byte_mode(dspi);
+
+	if (tx_word && (dspi->len == 1)) {
+		dspi->dataflags |= TRAN_STATE_WORD_ODD_NUM;
+		regmap_update_bits(dspi->regmap, SPI_CTAR(dspi->cs),
+			SPI_FRAME_BITS_MASK, SPI_FRAME_BITS(8));
+		tx_word = 0;
+	}
+
+	while (dspi->len && (tx_count < DSPI_FIFO_SIZE)) {
+		if (tx_word) {
+			if (dspi->len == 1)
+				break;
+
+			if (!(dspi->dataflags & TRAN_STATE_TX_VOID)) {
+				d16 = *(u16 *)dspi->tx;
+				dspi->tx += 2;
+			} else {
+				d16 = dspi->void_write_data;
+			}
+
+			*(dma_buf + tx_count) =
+					SPI_PUSHR_TXDATA(d16) |
+					SPI_PUSHR_PCS(dspi->cs) |
+					SPI_PUSHR_CTAS(dspi->cs) |
+					SPI_PUSHR_CONT;
+			dspi->len -= 2;
+		} else {
+			if (!(dspi->dataflags & TRAN_STATE_TX_VOID)) {
+				d8 = *(u8 *)dspi->tx;
+				dspi->tx++;
+			} else {
+				d8 = (u8)dspi->void_write_data;
+			}
+
+			*(dma_buf + tx_count) =
+					SPI_PUSHR_TXDATA(d8) |
+					SPI_PUSHR_PCS(dspi->cs) |
+					SPI_PUSHR_CTAS(dspi->cs) |
+					SPI_PUSHR_CONT;
+			dspi->len--;
+		}
+
+		if ((dspi->cs_change) && (!dspi->len))
+			*(dma_buf + tx_count) &= ~SPI_PUSHR_CONT;
+
+		tx_count++;
+	}
+
+	*(dma_buf) |= SPI_PUSHR_CTCNT; /*first clear fifo count*/
+	dspi->dma_count = tx_count;
+
+	dma_sync_single_for_device(&dspi->pdev->dev, dspi->dma_tx_bufphy,
+					DSPI_DMA_BUFSIZE, DMA_TO_DEVICE);
+	dspi_send_dma(dspi, dspi->dma_count);
+
+	return tx_count * (tx_word + 1);
+}
+
+
+static int dspi_tx_pio(struct fsl_dspi *dspi)
 {
 	int tx_count = 0;
 	int tx_word;
@@ -225,6 +494,9 @@ static int dspi_transfer_write(struct fsl_dspi *dspi)
 		if (dspi->len == 0 || tx_count == DSPI_FIFO_SIZE - 1) {
 			/* last transfer in the transfer */
 			dspi_pushr |= SPI_PUSHR_EOQ;
+			if ((dspi->cs_change) && (!dspi->len))
+				dspi_pushr &= ~SPI_PUSHR_CONT;
+
 		} else if (tx_word && (dspi->len == 1))
 			dspi_pushr |= SPI_PUSHR_EOQ;
 
@@ -241,7 +513,7 @@ static int dspi_transfer_write(struct fsl_dspi *dspi)
 	return tx_count * (tx_word + 1);
 }
 
-static int dspi_transfer_read(struct fsl_dspi *dspi)
+static int dspi_rx_pio(struct fsl_dspi *dspi)
 {
 	int rx_count = 0;
 	int rx_word = is_double_byte_mode(dspi);
@@ -276,64 +548,74 @@ static int dspi_transfer_read(struct fsl_dspi *dspi)
 	return rx_count;
 }
 
-static int dspi_txrx_transfer(struct spi_device *spi, struct spi_transfer *t)
+static int dspi_transfer_one_message(struct spi_master *master,
+		struct spi_message *message)
 {
-	struct fsl_dspi *dspi = spi_master_get_devdata(spi->master);
-	dspi->cur_transfer = t;
-	dspi->cur_chip = spi_get_ctldata(spi);
-	dspi->cs = spi->chip_select;
-	dspi->void_write_data = dspi->cur_chip->void_write_data;
-
-	dspi->dataflags = 0;
-	dspi->tx = (void *)t->tx_buf;
-	dspi->tx_end = dspi->tx + t->len;
-	dspi->rx = t->rx_buf;
-	dspi->rx_end = dspi->rx + t->len;
-	dspi->len = t->len;
-
-	if (!dspi->rx)
-		dspi->dataflags |= TRAN_STATE_RX_VOID;
-
-	if (!dspi->tx)
-		dspi->dataflags |= TRAN_STATE_TX_VOID;
-
-	regmap_write(dspi->regmap, SPI_MCR, dspi->cur_chip->mcr_val);
-	regmap_write(dspi->regmap, SPI_CTAR(dspi->cs), dspi->cur_chip->ctar_val);
-	regmap_write(dspi->regmap, SPI_RSER, SPI_RSER_EOQFE);
-
-	if (t->speed_hz)
+	struct fsl_dspi *dspi = spi_master_get_devdata(master);
+	struct spi_device *spi = message->spi;
+	struct spi_transfer *transfer;
+	int status = 0;
+	message->actual_length = 0;
+
+	list_for_each_entry(transfer, &message->transfers, transfer_list) {
+		dspi->cur_transfer = transfer;
+		dspi->cur_msg = message;
+		dspi->cur_chip = spi_get_ctldata(spi);
+		dspi->cs = spi->chip_select;
+		if (dspi->cur_transfer->transfer_list.next
+				== &dspi->cur_msg->transfers)
+			transfer->cs_change = 1;
+		dspi->cs_change = transfer->cs_change;
+		dspi->void_write_data = dspi->cur_chip->void_write_data;
+
+		dspi->dataflags = 0;
+		dspi->tx = (void *)transfer->tx_buf;
+		dspi->tx_end = dspi->tx + transfer->len;
+		dspi->rx = transfer->rx_buf;
+		dspi->rx_end = dspi->rx + transfer->len;
+		dspi->len = transfer->len;
+
+		if (!dspi->rx)
+			dspi->dataflags |= TRAN_STATE_RX_VOID;
+
+		if (!dspi->tx)
+			dspi->dataflags |= TRAN_STATE_TX_VOID;
+
+		regmap_write(dspi->regmap, SPI_MCR, dspi->cur_chip->mcr_val);
 		regmap_write(dspi->regmap, SPI_CTAR(dspi->cs),
 				dspi->cur_chip->ctar_val);
+		if (dspi->use_dma)
+			regmap_write(dspi->regmap, SPI_RSER,
+					SPI_RSER_TFFFE | SPI_RSER_TFFFD
+					| SPI_RSER_RFDFE | SPI_RSER_RFDFD);
+		else
+			regmap_write(dspi->regmap, SPI_RSER, SPI_RSER_EOQFE);
 
-	dspi_transfer_write(dspi);
-
-	if (wait_event_interruptible(dspi->waitq, dspi->waitflags))
-		dev_err(&dspi->pdev->dev, "wait transfer complete fail!\n");
-	dspi->waitflags = 0;
+		if (transfer->speed_hz)
+			regmap_write(dspi->regmap, SPI_CTAR(dspi->cs),
+					dspi->cur_chip->ctar_val);
 
-	return t->len - dspi->len;
-}
+		if (dspi->use_dma)
+			message->actual_length += dspi_tx_dma(dspi);
+		else
+			message->actual_length += dspi_tx_pio(dspi);
 
-static void dspi_chipselect(struct spi_device *spi, int value)
-{
-	struct fsl_dspi *dspi = spi_master_get_devdata(spi->master);
-	unsigned int pushr;
+		if (wait_event_interruptible(dspi->waitq, dspi->waitflags))
+			dev_err(&dspi->pdev->dev, "wait transfer complete fail!\n");
+		dspi->waitflags = 0;
 
-	regmap_read(dspi->regmap, SPI_PUSHR, &pushr);
+		if (transfer->delay_usecs)
+			udelay(transfer->delay_usecs);
 
-	switch (value) {
-	case BITBANG_CS_ACTIVE:
-		pushr |= SPI_PUSHR_CONT;
-		break;
-	case BITBANG_CS_INACTIVE:
-		pushr &= ~SPI_PUSHR_CONT;
-		break;
 	}
 
-	regmap_write(dspi->regmap, SPI_PUSHR, pushr);
+	message->status = status;
+	spi_finalize_current_message(master);
+
+	return status;
 }
 
-static int dspi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
+static int dspi_setup(struct spi_device *spi)
 {
 	struct chip_data *chip;
 	struct fsl_dspi *dspi = spi_master_get_devdata(spi->master);
@@ -374,21 +656,24 @@ static int dspi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
 	return 0;
 }
 
-static int dspi_setup(struct spi_device *spi)
+static void dspi_cleanup(struct spi_device *spi)
 {
-	if (!spi->max_speed_hz)
-		return -EINVAL;
+	struct chip_data *chip = spi_get_ctldata((struct spi_device *)spi);
 
-	return dspi_setup_transfer(spi, NULL);
+	dev_dbg(&spi->dev, "spi_device %u.%u cleanup\n",
+			spi->master->bus_num, spi->chip_select);
+
+	kfree(chip);
 }
 
 static irqreturn_t dspi_interrupt(int irq, void *dev_id)
 {
 	struct fsl_dspi *dspi = (struct fsl_dspi *)dev_id;
+	struct spi_message *msg = dspi->cur_msg;
 
 	regmap_write(dspi->regmap, SPI_SR, SPI_SR_EOQF);
 
-	dspi_transfer_read(dspi);
+	dspi_rx_pio(dspi);
 
 	if (!dspi->len) {
 		if (dspi->dataflags & TRAN_STATE_WORD_ODD_NUM)
@@ -398,7 +683,7 @@ static irqreturn_t dspi_interrupt(int irq, void *dev_id)
 		dspi->waitflags = 1;
 		wake_up_interruptible(&dspi->waitq);
 	} else {
-		dspi_transfer_write(dspi);
+		msg->actual_length += dspi_tx_pio(dspi);
 
 		return IRQ_HANDLED;
 	}
@@ -463,13 +748,14 @@ static int dspi_probe(struct platform_device *pdev)
 
 	dspi = spi_master_get_devdata(master);
 	dspi->pdev = pdev;
-	dspi->bitbang.master = master;
-	dspi->bitbang.chipselect = dspi_chipselect;
-	dspi->bitbang.setup_transfer = dspi_setup_transfer;
-	dspi->bitbang.txrx_bufs = dspi_txrx_transfer;
-	dspi->bitbang.master->setup = dspi_setup;
-	dspi->bitbang.master->dev.of_node = pdev->dev.of_node;
+	dspi->master = master;
+
+	master->transfer = NULL;
+	master->cleanup = dspi_cleanup;
+	master->setup = dspi_setup;
+	master->transfer_one_message = dspi_transfer_one_message;
 
+	master->dev.of_node = pdev->dev.of_node;
 	master->mode_bits = SPI_CPOL | SPI_CPHA;
 	master->bits_per_word_mask = SPI_BPW_MASK(4) | SPI_BPW_MASK(8) |
 					SPI_BPW_MASK(16);
@@ -490,6 +776,7 @@ static int dspi_probe(struct platform_device *pdev)
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	base = devm_ioremap_resource(&pdev->dev, res);
+	dspi->phybase = res->start;
 	if (IS_ERR(base)) {
 		ret = PTR_ERR(base);
 		goto out_master_put;
@@ -529,10 +816,18 @@ static int dspi_probe(struct platform_device *pdev)
 	}
 	clk_prepare_enable(dspi->clk);
 
+	dspi->use_dma = of_property_read_bool(np, "use-dma");
+	if (dspi->use_dma)
+		if (dspi_request_dma(dspi)) {
+			dspi->use_dma = 0;
+			dev_err(&pdev->dev, "request dma channel fail\n");
+			dspi_release_dma(dspi);
+		}
+
 	init_waitqueue_head(&dspi->waitq);
 	platform_set_drvdata(pdev, dspi);
 
-	ret = spi_bitbang_start(&dspi->bitbang);
+	ret = spi_register_master(master);
 	if (ret != 0) {
 		dev_err(&pdev->dev, "Problem registering DSPI master\n");
 		goto out_clk_put;
@@ -554,9 +849,9 @@ static int dspi_remove(struct platform_device *pdev)
 	struct fsl_dspi *dspi = platform_get_drvdata(pdev);
 
 	/* Disconnect from the SPI framework */
-	spi_bitbang_stop(&dspi->bitbang);
 	clk_disable_unprepare(dspi->clk);
-	spi_master_put(dspi->bitbang.master);
+	spi_unregister_master(dspi->master);
+	spi_master_put(dspi->master);
 
 	return 0;
 }
-- 
1.8.4


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[PATCH 3/3] spi:fsl-dspi:add dspi dma transfer support

[Chao Fu]

From: Chao Fu <B44548@freescale.com>

DSPI can transfer data in DMA mode or PIO mode.This patch will add the DMA
transfer driver support. Add DMA reference functions and variables to form DMA
transfer process.
DSPI DMA mode need work with Freescale eDMA module together.

The software will be changed in two transfer methods as followwing:
		 DMA			PIO
trigger write:	 dspi_tx_dma		dspi_tx_pio
write complete:	 dspi_dma_tx_complete   irq_handle
trigger read:	 dspi_receive_dma	dspi_rx_pio
read complete:	 dspi_rx_dma		none

Remove bitbang:
Add DMA funtions, DSPI module need get cs change information in a spi transfer.
According cs change, DSPI will give last data the right flag. Bitbang provide
cs change behind the last data in a transfer. DSPI can not deal the last data in
every transfer properly, so remove the bitbang in driver.

Signed-off-by: Chao Fu      <b44548@freescale.com>
---
 drivers/spi/Kconfig        |   1 -
 drivers/spi/spi-fsl-dspi.c | 425 ++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 360 insertions(+), 66 deletions(-)

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 6554bd0..c9240e9 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -269,7 +269,6 @@ config SPI_FSL_SPI
 
 config SPI_FSL_DSPI
 	tristate "Freescale DSPI controller"
-	select SPI_BITBANG
 	select REGMAP_MMIO
 	depends on SOC_VF610 || COMPILE_TEST
 	help
diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index 42ede0d..a22061f 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -25,7 +25,8 @@
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/spi/spi.h>
-#include <linux/spi/spi_bitbang.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
 #include <linux/pm_runtime.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
@@ -37,6 +38,7 @@
 #define TRAN_STATE_WORD_ODD_NUM	0x04
 
 #define DSPI_FIFO_SIZE			4
+#define DSPI_DMA_BUFSIZE		(DSPI_FIFO_SIZE * 4)
 
 #define SPI_MCR		0x00
 #define SPI_MCR_MASTER		(1 << 31)
@@ -67,6 +69,10 @@
 
 #define SPI_RSER		0x30
 #define SPI_RSER_EOQFE		0x10000000
+#define SPI_RSER_TFFFE		0x02000000
+#define SPI_RSER_TFFFD		0x01000000
+#define SPI_RSER_RFDFE		0x00020000
+#define SPI_RSER_RFDFD		0x00010000
 
 #define SPI_PUSHR		0x34
 #define SPI_PUSHR_CONT		(1 << 31)
@@ -106,7 +112,7 @@ struct chip_data {
 };
 
 struct fsl_dspi {
-	struct spi_bitbang	bitbang;
+	struct spi_master	*master;
 	struct platform_device	*pdev;
 
 	struct regmap		*regmap;
@@ -114,6 +120,7 @@ struct fsl_dspi {
 	struct clk		*clk;
 
 	struct spi_transfer	*cur_transfer;
+	struct spi_message	*cur_msg;
 	struct chip_data	*cur_chip;
 	size_t			len;
 	void			*tx;
@@ -123,11 +130,31 @@ struct fsl_dspi {
 	char			dataflags;
 	u8			cs;
 	u16			void_write_data;
+	u32			cs_change;
 
 	wait_queue_head_t	waitq;
 	u32			waitflags;
+
+	/*For DMA Support*/
+	bool			use_dma;
+	struct dma_chan		*chan_tx;
+	struct dma_chan		*chan_rx;
+	u32			*dma_tx_buf;
+	u32			*dma_rx_buf;
+	dma_addr_t		dma_tx_bufphy;
+	dma_addr_t		dma_rx_bufphy;
+	struct dma_async_tx_descriptor *tx_desc;
+	struct dma_async_tx_descriptor *rx_desc;
+	size_t			dma_count;
+	dma_addr_t		phybase;
 };
 
+static int dspi_send_dma(struct fsl_dspi *dspi, size_t count);
+static int dspi_receive_dma(struct fsl_dspi *dspi, size_t count);
+void dspi_rx_dma(void *arg);
+static int dspi_tx_dma(struct fsl_dspi *dspi);
+static void dspi_release_dma(struct fsl_dspi *dspi);
+
 static inline int is_double_byte_mode(struct fsl_dspi *dspi)
 {
 	unsigned int val;
@@ -165,7 +192,249 @@ static void hz_to_spi_baud(char *pbr, char *br, int speed_hz,
 	*br =  ARRAY_SIZE(brs) - 1;
 }
 
-static int dspi_transfer_write(struct fsl_dspi *dspi)
+static void dspi_dma_tx_complete(void *arg)
+{
+	struct fsl_dspi *dspi = arg;
+	struct spi_message *msg = dspi->cur_msg;
+
+	dspi_receive_dma(dspi, dspi->dma_count);
+
+	if (dspi->len > 0)
+		msg->actual_length += dspi_tx_dma(dspi);
+}
+
+static int dspi_send_dma(struct fsl_dspi *dspi, size_t count)
+{
+	dspi->tx_desc = dmaengine_prep_slave_single(
+			dspi->chan_tx, dspi->dma_tx_bufphy,
+			count * DMA_SLAVE_BUSWIDTH_4_BYTES,
+			DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+
+	if (!dspi->tx_desc) {
+		dev_err(&dspi->pdev->dev, "dma prepare tx desc fail!\n");
+		dspi->use_dma = 0;
+		dspi_release_dma(dspi);
+		dspi->waitflags = 1;
+		wake_up_interruptible(&dspi->waitq);
+
+		return -EINVAL;
+	}
+
+	dspi->tx_desc->callback = dspi_dma_tx_complete;
+	dspi->tx_desc->callback_param = dspi;
+
+	dmaengine_submit(dspi->tx_desc);
+	dma_async_issue_pending(dspi->chan_tx);
+
+	return 0;
+}
+
+static int dspi_receive_dma(struct fsl_dspi *dspi, size_t count)
+{
+
+	dspi->rx_desc = dmaengine_prep_slave_single(
+			dspi->chan_rx, dspi->dma_rx_bufphy,
+			count * DMA_SLAVE_BUSWIDTH_4_BYTES,
+			DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+
+	if (!dspi->rx_desc) {
+		dev_err(&dspi->pdev->dev, "dma prepare rx desc fail!\n");
+		dspi->use_dma = 0;
+		dspi_release_dma(dspi);
+		dspi->waitflags = 1;
+		wake_up_interruptible(&dspi->waitq);
+
+		return -EINVAL;
+	}
+
+	dspi->rx_desc->callback = dspi_rx_dma;
+	dspi->rx_desc->callback_param = dspi;
+	dma_sync_single_for_device(&dspi->pdev->dev,
+				dspi->dma_rx_bufphy,
+				DSPI_DMA_BUFSIZE, DMA_FROM_DEVICE);
+
+	dmaengine_submit(dspi->rx_desc);
+	dma_async_issue_pending(dspi->chan_rx);
+
+	return 0;
+}
+
+static int dspi_request_dma(struct fsl_dspi *dspi)
+{
+	struct dma_slave_config cfg;
+	int ret = -EINVAL;
+
+	dspi->chan_rx = dma_request_slave_channel(&dspi->pdev->dev, "rx");
+	if (dspi->chan_rx) {
+		cfg.direction = DMA_DEV_TO_MEM;
+		cfg.dst_addr = 0;
+		cfg.src_addr = dspi->phybase + SPI_POPR;
+		cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+		cfg.src_maxburst = 1;
+		ret = dmaengine_slave_config(dspi->chan_rx, &cfg);
+		if (!ret)
+			dev_info(&dspi->pdev->dev, "Configed DSPI rx channel");
+		else
+			return ret;
+	}
+
+	dspi->chan_tx = dma_request_slave_channel(&dspi->pdev->dev, "tx");
+	if (dspi->chan_tx) {
+		cfg.direction = DMA_MEM_TO_DEV;
+		cfg.dst_addr = dspi->phybase + SPI_PUSHR;
+		cfg.src_addr = 0;
+		cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+		cfg.dst_maxburst = 1;
+		ret = dmaengine_slave_config(dspi->chan_tx, &cfg);
+		if (!ret)
+			dev_info(&dspi->pdev->dev, "Configed DSPI tx channel");
+		else
+			return ret;
+	}
+
+	dspi->dma_tx_buf = devm_kzalloc(&dspi->pdev->dev,
+					DSPI_DMA_BUFSIZE, GFP_DMA);
+	if (!dspi->dma_tx_buf)
+		return -ENOMEM;
+	dspi->dma_rx_buf = devm_kzalloc(&dspi->pdev->dev,
+					DSPI_DMA_BUFSIZE, GFP_DMA);
+	if (!dspi->dma_rx_buf)
+		return -ENOMEM;
+
+	dspi->dma_tx_bufphy = dma_map_single(dspi->chan_tx->device->dev,
+						dspi->dma_tx_buf,
+						DSPI_DMA_BUFSIZE,
+						DMA_TO_DEVICE);
+	dspi->dma_rx_bufphy = dma_map_single(dspi->chan_rx->device->dev,
+						dspi->dma_rx_buf,
+						DSPI_DMA_BUFSIZE,
+						DMA_FROM_DEVICE);
+
+	return ret;
+}
+
+static void dspi_release_dma(struct fsl_dspi *dspi)
+{
+	if (dspi->dma_tx_buf)
+		devm_kfree(&dspi->pdev->dev, dspi->dma_tx_buf);
+	if (dspi->dma_rx_buf)
+		devm_kfree(&dspi->pdev->dev, dspi->dma_rx_buf);
+	if (dspi->chan_tx)
+		dma_release_channel(dspi->chan_tx);
+	if (dspi->chan_rx)
+		dma_release_channel(dspi->chan_rx);
+}
+
+void dspi_rx_dma(void *arg)
+{
+	struct fsl_dspi *dspi = arg;
+	int rx_count = 0;
+	int rx_word = is_double_byte_mode(dspi);
+	u16 d;
+
+	dma_sync_single_for_cpu(&dspi->pdev->dev, dspi->dma_rx_bufphy,
+					DSPI_DMA_BUFSIZE, DMA_FROM_DEVICE);
+
+	while ((dspi->rx < dspi->rx_end)
+			&& (rx_count < DSPI_FIFO_SIZE)) {
+		if (rx_word) {
+			if ((dspi->rx_end - dspi->rx) == 1)
+				break;
+
+			d = SPI_POPR_RXDATA(*(dspi->dma_rx_buf + rx_count));
+
+			if (!(dspi->dataflags & TRAN_STATE_RX_VOID))
+				*(u16 *)dspi->rx = d;
+			dspi->rx += 2;
+
+		} else {
+			d = SPI_POPR_RXDATA(*(dspi->dma_rx_buf + rx_count));
+			if (!(dspi->dataflags & TRAN_STATE_RX_VOID))
+				*(u8 *)dspi->rx = d;
+			dspi->rx++;
+		}
+
+		rx_count++;
+	}
+
+	if (dspi->len == 0) {
+		dspi->waitflags = 1;
+		wake_up_interruptible(&dspi->waitq);
+	}
+}
+
+static int dspi_tx_dma(struct fsl_dspi *dspi)
+{
+	int tx_count = 0;
+	int tx_word;
+	u16 d16;
+	u8  d8;
+	u32 *dma_buf = (u32 *)dspi->dma_tx_buf;
+
+	dma_sync_single_for_cpu(&dspi->pdev->dev, dspi->dma_tx_bufphy,
+					DSPI_DMA_BUFSIZE, DMA_TO_DEVICE);
+
+	tx_word = is_double_byte_mode(dspi);
+
+	if (tx_word && (dspi->len == 1)) {
+		dspi->dataflags |= TRAN_STATE_WORD_ODD_NUM;
+		regmap_update_bits(dspi->regmap, SPI_CTAR(dspi->cs),
+			SPI_FRAME_BITS_MASK, SPI_FRAME_BITS(8));
+		tx_word = 0;
+	}
+
+	while (dspi->len && (tx_count < DSPI_FIFO_SIZE)) {
+		if (tx_word) {
+			if (dspi->len == 1)
+				break;
+
+			if (!(dspi->dataflags & TRAN_STATE_TX_VOID)) {
+				d16 = *(u16 *)dspi->tx;
+				dspi->tx += 2;
+			} else {
+				d16 = dspi->void_write_data;
+			}
+
+			*(dma_buf + tx_count) =
+					SPI_PUSHR_TXDATA(d16) |
+					SPI_PUSHR_PCS(dspi->cs) |
+					SPI_PUSHR_CTAS(dspi->cs) |
+					SPI_PUSHR_CONT;
+			dspi->len -= 2;
+		} else {
+			if (!(dspi->dataflags & TRAN_STATE_TX_VOID)) {
+				d8 = *(u8 *)dspi->tx;
+				dspi->tx++;
+			} else {
+				d8 = (u8)dspi->void_write_data;
+			}
+
+			*(dma_buf + tx_count) =
+					SPI_PUSHR_TXDATA(d8) |
+					SPI_PUSHR_PCS(dspi->cs) |
+					SPI_PUSHR_CTAS(dspi->cs) |
+					SPI_PUSHR_CONT;
+			dspi->len--;
+		}
+
+		if ((dspi->cs_change) && (!dspi->len))
+			*(dma_buf + tx_count) &= ~SPI_PUSHR_CONT;
+
+		tx_count++;
+	}
+
+	*(dma_buf) |= SPI_PUSHR_CTCNT; /*first clear fifo count*/
+	dspi->dma_count = tx_count;
+
+	dma_sync_single_for_device(&dspi->pdev->dev, dspi->dma_tx_bufphy,
+					DSPI_DMA_BUFSIZE, DMA_TO_DEVICE);
+	dspi_send_dma(dspi, dspi->dma_count);
+
+	return tx_count * (tx_word + 1);
+}
+
+
+static int dspi_tx_pio(struct fsl_dspi *dspi)
 {
 	int tx_count = 0;
 	int tx_word;
@@ -225,6 +494,9 @@ static int dspi_transfer_write(struct fsl_dspi *dspi)
 		if (dspi->len == 0 || tx_count == DSPI_FIFO_SIZE - 1) {
 			/* last transfer in the transfer */
 			dspi_pushr |= SPI_PUSHR_EOQ;
+			if ((dspi->cs_change) && (!dspi->len))
+				dspi_pushr &= ~SPI_PUSHR_CONT;
+
 		} else if (tx_word && (dspi->len == 1))
 			dspi_pushr |= SPI_PUSHR_EOQ;
 
@@ -241,7 +513,7 @@ static int dspi_transfer_write(struct fsl_dspi *dspi)
 	return tx_count * (tx_word + 1);
 }
 
-static int dspi_transfer_read(struct fsl_dspi *dspi)
+static int dspi_rx_pio(struct fsl_dspi *dspi)
 {
 	int rx_count = 0;
 	int rx_word = is_double_byte_mode(dspi);
@@ -276,64 +548,74 @@ static int dspi_transfer_read(struct fsl_dspi *dspi)
 	return rx_count;
 }
 
-static int dspi_txrx_transfer(struct spi_device *spi, struct spi_transfer *t)
+static int dspi_transfer_one_message(struct spi_master *master,
+		struct spi_message *message)
 {
-	struct fsl_dspi *dspi = spi_master_get_devdata(spi->master);
-	dspi->cur_transfer = t;
-	dspi->cur_chip = spi_get_ctldata(spi);
-	dspi->cs = spi->chip_select;
-	dspi->void_write_data = dspi->cur_chip->void_write_data;
-
-	dspi->dataflags = 0;
-	dspi->tx = (void *)t->tx_buf;
-	dspi->tx_end = dspi->tx + t->len;
-	dspi->rx = t->rx_buf;
-	dspi->rx_end = dspi->rx + t->len;
-	dspi->len = t->len;
-
-	if (!dspi->rx)
-		dspi->dataflags |= TRAN_STATE_RX_VOID;
-
-	if (!dspi->tx)
-		dspi->dataflags |= TRAN_STATE_TX_VOID;
-
-	regmap_write(dspi->regmap, SPI_MCR, dspi->cur_chip->mcr_val);
-	regmap_write(dspi->regmap, SPI_CTAR(dspi->cs), dspi->cur_chip->ctar_val);
-	regmap_write(dspi->regmap, SPI_RSER, SPI_RSER_EOQFE);
-
-	if (t->speed_hz)
+	struct fsl_dspi *dspi = spi_master_get_devdata(master);
+	struct spi_device *spi = message->spi;
+	struct spi_transfer *transfer;
+	int status = 0;
+	message->actual_length = 0;
+
+	list_for_each_entry(transfer, &message->transfers, transfer_list) {
+		dspi->cur_transfer = transfer;
+		dspi->cur_msg = message;
+		dspi->cur_chip = spi_get_ctldata(spi);
+		dspi->cs = spi->chip_select;
+		if (dspi->cur_transfer->transfer_list.next
+				== &dspi->cur_msg->transfers)
+			transfer->cs_change = 1;
+		dspi->cs_change = transfer->cs_change;
+		dspi->void_write_data = dspi->cur_chip->void_write_data;
+
+		dspi->dataflags = 0;
+		dspi->tx = (void *)transfer->tx_buf;
+		dspi->tx_end = dspi->tx + transfer->len;
+		dspi->rx = transfer->rx_buf;
+		dspi->rx_end = dspi->rx + transfer->len;
+		dspi->len = transfer->len;
+
+		if (!dspi->rx)
+			dspi->dataflags |= TRAN_STATE_RX_VOID;
+
+		if (!dspi->tx)
+			dspi->dataflags |= TRAN_STATE_TX_VOID;
+
+		regmap_write(dspi->regmap, SPI_MCR, dspi->cur_chip->mcr_val);
 		regmap_write(dspi->regmap, SPI_CTAR(dspi->cs),
 				dspi->cur_chip->ctar_val);
+		if (dspi->use_dma)
+			regmap_write(dspi->regmap, SPI_RSER,
+					SPI_RSER_TFFFE | SPI_RSER_TFFFD
+					| SPI_RSER_RFDFE | SPI_RSER_RFDFD);
+		else
+			regmap_write(dspi->regmap, SPI_RSER, SPI_RSER_EOQFE);
 
-	dspi_transfer_write(dspi);
-
-	if (wait_event_interruptible(dspi->waitq, dspi->waitflags))
-		dev_err(&dspi->pdev->dev, "wait transfer complete fail!\n");
-	dspi->waitflags = 0;
+		if (transfer->speed_hz)
+			regmap_write(dspi->regmap, SPI_CTAR(dspi->cs),
+					dspi->cur_chip->ctar_val);
 
-	return t->len - dspi->len;
-}
+		if (dspi->use_dma)
+			message->actual_length += dspi_tx_dma(dspi);
+		else
+			message->actual_length += dspi_tx_pio(dspi);
 
-static void dspi_chipselect(struct spi_device *spi, int value)
-{
-	struct fsl_dspi *dspi = spi_master_get_devdata(spi->master);
-	unsigned int pushr;
+		if (wait_event_interruptible(dspi->waitq, dspi->waitflags))
+			dev_err(&dspi->pdev->dev, "wait transfer complete fail!\n");
+		dspi->waitflags = 0;
 
-	regmap_read(dspi->regmap, SPI_PUSHR, &pushr);
+		if (transfer->delay_usecs)
+			udelay(transfer->delay_usecs);
 
-	switch (value) {
-	case BITBANG_CS_ACTIVE:
-		pushr |= SPI_PUSHR_CONT;
-		break;
-	case BITBANG_CS_INACTIVE:
-		pushr &= ~SPI_PUSHR_CONT;
-		break;
 	}
 
-	regmap_write(dspi->regmap, SPI_PUSHR, pushr);
+	message->status = status;
+	spi_finalize_current_message(master);
+
+	return status;
 }
 
-static int dspi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
+static int dspi_setup(struct spi_device *spi)
 {
 	struct chip_data *chip;
 	struct fsl_dspi *dspi = spi_master_get_devdata(spi->master);
@@ -374,21 +656,24 @@ static int dspi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
 	return 0;
 }
 
-static int dspi_setup(struct spi_device *spi)
+static void dspi_cleanup(struct spi_device *spi)
 {
-	if (!spi->max_speed_hz)
-		return -EINVAL;
+	struct chip_data *chip = spi_get_ctldata((struct spi_device *)spi);
 
-	return dspi_setup_transfer(spi, NULL);
+	dev_dbg(&spi->dev, "spi_device %u.%u cleanup\n",
+			spi->master->bus_num, spi->chip_select);
+
+	kfree(chip);
 }
 
 static irqreturn_t dspi_interrupt(int irq, void *dev_id)
 {
 	struct fsl_dspi *dspi = (struct fsl_dspi *)dev_id;
+	struct spi_message *msg = dspi->cur_msg;
 
 	regmap_write(dspi->regmap, SPI_SR, SPI_SR_EOQF);
 
-	dspi_transfer_read(dspi);
+	dspi_rx_pio(dspi);
 
 	if (!dspi->len) {
 		if (dspi->dataflags & TRAN_STATE_WORD_ODD_NUM)
@@ -398,7 +683,7 @@ static irqreturn_t dspi_interrupt(int irq, void *dev_id)
 		dspi->waitflags = 1;
 		wake_up_interruptible(&dspi->waitq);
 	} else {
-		dspi_transfer_write(dspi);
+		msg->actual_length += dspi_tx_pio(dspi);
 
 		return IRQ_HANDLED;
 	}
@@ -463,13 +748,14 @@ static int dspi_probe(struct platform_device *pdev)
 
 	dspi = spi_master_get_devdata(master);
 	dspi->pdev = pdev;
-	dspi->bitbang.master = master;
-	dspi->bitbang.chipselect = dspi_chipselect;
-	dspi->bitbang.setup_transfer = dspi_setup_transfer;
-	dspi->bitbang.txrx_bufs = dspi_txrx_transfer;
-	dspi->bitbang.master->setup = dspi_setup;
-	dspi->bitbang.master->dev.of_node = pdev->dev.of_node;
+	dspi->master = master;
+
+	master->transfer = NULL;
+	master->cleanup = dspi_cleanup;
+	master->setup = dspi_setup;
+	master->transfer_one_message = dspi_transfer_one_message;
 
+	master->dev.of_node = pdev->dev.of_node;
 	master->mode_bits = SPI_CPOL | SPI_CPHA;
 	master->bits_per_word_mask = SPI_BPW_MASK(4) | SPI_BPW_MASK(8) |
 					SPI_BPW_MASK(16);
@@ -490,6 +776,7 @@ static int dspi_probe(struct platform_device *pdev)
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	base = devm_ioremap_resource(&pdev->dev, res);
+	dspi->phybase = res->start;
 	if (IS_ERR(base)) {
 		ret = PTR_ERR(base);
 		goto out_master_put;
@@ -529,10 +816,18 @@ static int dspi_probe(struct platform_device *pdev)
 	}
 	clk_prepare_enable(dspi->clk);
 
+	dspi->use_dma = of_property_read_bool(np, "use-dma");
+	if (dspi->use_dma)
+		if (dspi_request_dma(dspi)) {
+			dspi->use_dma = 0;
+			dev_err(&pdev->dev, "request dma channel fail\n");
+			dspi_release_dma(dspi);
+		}
+
 	init_waitqueue_head(&dspi->waitq);
 	platform_set_drvdata(pdev, dspi);
 
-	ret = spi_bitbang_start(&dspi->bitbang);
+	ret = spi_register_master(master);
 	if (ret != 0) {
 		dev_err(&pdev->dev, "Problem registering DSPI master\n");
 		goto out_clk_put;
@@ -554,9 +849,9 @@ static int dspi_remove(struct platform_device *pdev)
 	struct fsl_dspi *dspi = platform_get_drvdata(pdev);
 
 	/* Disconnect from the SPI framework */
-	spi_bitbang_stop(&dspi->bitbang);
 	clk_disable_unprepare(dspi->clk);
-	spi_master_put(dspi->bitbang.master);
+	spi_unregister_master(dspi->master);
+	spi_master_put(dspi->master);
 
 	return 0;
 }
-- 
1.8.4

Re: [PATCH 1/3] Documentation:spi:fsl-dspi:add DSPI dma transfer support

[Mark Rutland]

On Tue, Feb 25, 2014 at 06:54:16AM +0000, Chao Fu wrote:
> From: Chao Fu <B44548-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> 
> Add bool value use-dma.
> The bool will determine whether DSPI use dma channel transfer data
> in a platform.
> 
> Add dmas and dma-names for describing dma channels of DSPI.
> 
> Signed-off-by: Chao Fu      <b44548-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> ---
>  Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt b/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
> index 5376de4..76a1039 100644
> --- a/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
> +++ b/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
> @@ -11,6 +11,11 @@ Required properties:
>  - spi-num-chipselects : the number of the chipselect signals.
>  - bus-num : the slave chip chipselect signal number.
>  - big-endian : if DSPI modudle is big endian, the bool will be set in node.
> +- use-dma: the bool decide if use dma method in DSPI transfering.

Why can the OS not decide this based on the presence of dmas which it
can use?

Is there ever a case that there would be dmas present but it would be in
the interests of the OS to not use them?

Mark.

> +- dmas: List of DMA specifiers with the controller specific format
> +	as described in the generic DMA client binding. A tx and rx
> +	specifier is required for each chip select.
> +- dma-names: Should be named "tx" and "rx".
>  Example:
>  
>  dspi0@4002c000 {
> @@ -26,6 +31,10 @@ dspi0@4002c000 {
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&pinctrl_dspi0_1>;
>  	big-endian;
> +	use-dma;
> +	dmas = <&edma0 0 12>,
> +		<&edma0 0 13>;
> +	dma-names = "rx", "tx";
>  	status = "okay";
>  
>  	sflash: at26df081a@0 {
> -- 
> 1.8.4
> 
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 
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[PATCH 1/3] Documentation:spi:fsl-dspi:add DSPI dma transfer support

[Mark Rutland]

On Tue, Feb 25, 2014 at 06:54:16AM +0000, Chao Fu wrote:
> From: Chao Fu <B44548@freescale.com>
> 
> Add bool value use-dma.
> The bool will determine whether DSPI use dma channel transfer data
> in a platform.
> 
> Add dmas and dma-names for describing dma channels of DSPI.
> 
> Signed-off-by: Chao Fu      <b44548@freescale.com>
> ---
>  Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt b/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
> index 5376de4..76a1039 100644
> --- a/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
> +++ b/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
> @@ -11,6 +11,11 @@ Required properties:
>  - spi-num-chipselects : the number of the chipselect signals.
>  - bus-num : the slave chip chipselect signal number.
>  - big-endian : if DSPI modudle is big endian, the bool will be set in node.
> +- use-dma: the bool decide if use dma method in DSPI transfering.

Why can the OS not decide this based on the presence of dmas which it
can use?

Is there ever a case that there would be dmas present but it would be in
the interests of the OS to not use them?

Mark.

> +- dmas: List of DMA specifiers with the controller specific format
> +	as described in the generic DMA client binding. A tx and rx
> +	specifier is required for each chip select.
> +- dma-names: Should be named "tx" and "rx".
>  Example:
>  
>  dspi0 at 4002c000 {
> @@ -26,6 +31,10 @@ dspi0 at 4002c000 {
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&pinctrl_dspi0_1>;
>  	big-endian;
> +	use-dma;
> +	dmas = <&edma0 0 12>,
> +		<&edma0 0 13>;
> +	dma-names = "rx", "tx";
>  	status = "okay";
>  
>  	sflash: at26df081a at 0 {
> -- 
> 1.8.4
> 
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

Re: [PATCH 3/3] spi:fsl-dspi:add dspi dma transfer support

[Mark Rutland]

On Tue, Feb 25, 2014 at 06:54:18AM +0000, Chao Fu wrote:
> From: Chao Fu <B44548-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> 
> DSPI can transfer data in DMA mode or PIO mode.This patch will add the DMA
> transfer driver support. Add DMA reference functions and variables to form DMA
> transfer process.
> DSPI DMA mode need work with Freescale eDMA module together.
> 
> The software will be changed in two transfer methods as followwing:
>                  DMA                    PIO
> trigger write:   dspi_tx_dma            dspi_tx_pio
> write complete:  dspi_dma_tx_complete   irq_handle
> trigger read:    dspi_receive_dma       dspi_rx_pio
> read complete:   dspi_rx_dma            none
> 
> Remove bitbang:
> Add DMA funtions, DSPI module need get cs change information in a spi transfer.
> According cs change, DSPI will give last data the right flag. Bitbang provide
> cs change behind the last data in a transfer. DSPI can not deal the last data in
> every transfer properly, so remove the bitbang in driver.
> 
> Signed-off-by: Chao Fu      <b44548-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> ---
>  drivers/spi/Kconfig        |   1 -
>  drivers/spi/spi-fsl-dspi.c | 425 ++++++++++++++++++++++++++++++++++++++-------
>  2 files changed, 360 insertions(+), 66 deletions(-)

[...]

> @@ -529,10 +816,18 @@ static int dspi_probe(struct platform_device *pdev)
>         }
>         clk_prepare_enable(dspi->clk);
> 
> +       dspi->use_dma = of_property_read_bool(np, "use-dma");
> +       if (dspi->use_dma)
> +               if (dspi_request_dma(dspi)) {
> +                       dspi->use_dma = 0;
> +                       dev_err(&pdev->dev, "request dma channel fail\n");
> +                       dspi_release_dma(dspi);
> +               }

Why have the use-dma property at all? You already fall back to PIO mode
if the DMAs are not present, so it's clearly not a requirement to use
DMA.

Why not always try to request he dmas you need? You already have the
fallback logic, the only difference would be changing the dev_err to
better describe the situation:

dev_info(&pdev->dev, "No 'tx' and/or 'rx' DMA(s), using PIO mode\n");

Cheers,
Mark.
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[PATCH 3/3] spi:fsl-dspi:add dspi dma transfer support

[Mark Rutland]

On Tue, Feb 25, 2014 at 06:54:18AM +0000, Chao Fu wrote:
> From: Chao Fu <B44548@freescale.com>
> 
> DSPI can transfer data in DMA mode or PIO mode.This patch will add the DMA
> transfer driver support. Add DMA reference functions and variables to form DMA
> transfer process.
> DSPI DMA mode need work with Freescale eDMA module together.
> 
> The software will be changed in two transfer methods as followwing:
>                  DMA                    PIO
> trigger write:   dspi_tx_dma            dspi_tx_pio
> write complete:  dspi_dma_tx_complete   irq_handle
> trigger read:    dspi_receive_dma       dspi_rx_pio
> read complete:   dspi_rx_dma            none
> 
> Remove bitbang:
> Add DMA funtions, DSPI module need get cs change information in a spi transfer.
> According cs change, DSPI will give last data the right flag. Bitbang provide
> cs change behind the last data in a transfer. DSPI can not deal the last data in
> every transfer properly, so remove the bitbang in driver.
> 
> Signed-off-by: Chao Fu      <b44548@freescale.com>
> ---
>  drivers/spi/Kconfig        |   1 -
>  drivers/spi/spi-fsl-dspi.c | 425 ++++++++++++++++++++++++++++++++++++++-------
>  2 files changed, 360 insertions(+), 66 deletions(-)

[...]

> @@ -529,10 +816,18 @@ static int dspi_probe(struct platform_device *pdev)
>         }
>         clk_prepare_enable(dspi->clk);
> 
> +       dspi->use_dma = of_property_read_bool(np, "use-dma");
> +       if (dspi->use_dma)
> +               if (dspi_request_dma(dspi)) {
> +                       dspi->use_dma = 0;
> +                       dev_err(&pdev->dev, "request dma channel fail\n");
> +                       dspi_release_dma(dspi);
> +               }

Why have the use-dma property at all? You already fall back to PIO mode
if the DMAs are not present, so it's clearly not a requirement to use
DMA.

Why not always try to request he dmas you need? You already have the
fallback logic, the only difference would be changing the dev_err to
better describe the situation:

dev_info(&pdev->dev, "No 'tx' and/or 'rx' DMA(s), using PIO mode\n");

Cheers,
Mark.

Re: [PATCH 1/3] Documentation:spi:fsl-dspi:add DSPI dma transfer support

[Shawn Guo]

On Tue, Feb 25, 2014 at 09:08:30AM +0000, Mark Rutland wrote:
> On Tue, Feb 25, 2014 at 06:54:16AM +0000, Chao Fu wrote:
> > From: Chao Fu <B44548-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> > 
> > Add bool value use-dma.
> > The bool will determine whether DSPI use dma channel transfer data
> > in a platform.
> > 
> > Add dmas and dma-names for describing dma channels of DSPI.
> > 
> > Signed-off-by: Chao Fu      <b44548-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> > ---
> >  Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt b/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
> > index 5376de4..76a1039 100644
> > --- a/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
> > +++ b/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
> > @@ -11,6 +11,11 @@ Required properties:
> >  - spi-num-chipselects : the number of the chipselect signals.
> >  - bus-num : the slave chip chipselect signal number.
> >  - big-endian : if DSPI modudle is big endian, the bool will be set in node.
> > +- use-dma: the bool decide if use dma method in DSPI transfering.
> 
> Why can the OS not decide this based on the presence of dmas which it
> can use?

Yes, OS/driver should decide to use DMA or not, but it shouldn't be
based on the presence of 'dmas' property.  The DMA is a hardware
resource just like IRQ.  It should be just there in client device's node
as long as the SoC design assigns the channel to the device.  The device
driver should make the decision when DMA should be used, e.g. big amount
data transfer, and when PIO should be used, e.g. small data.

Shawn

> 
> Is there ever a case that there would be dmas present but it would be in
> the interests of the OS to not use them?

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[PATCH 1/3] Documentation:spi:fsl-dspi:add DSPI dma transfer support

[Shawn Guo]

On Tue, Feb 25, 2014 at 09:08:30AM +0000, Mark Rutland wrote:
> On Tue, Feb 25, 2014 at 06:54:16AM +0000, Chao Fu wrote:
> > From: Chao Fu <B44548@freescale.com>
> > 
> > Add bool value use-dma.
> > The bool will determine whether DSPI use dma channel transfer data
> > in a platform.
> > 
> > Add dmas and dma-names for describing dma channels of DSPI.
> > 
> > Signed-off-by: Chao Fu      <b44548@freescale.com>
> > ---
> >  Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt b/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
> > index 5376de4..76a1039 100644
> > --- a/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
> > +++ b/Documentation/devicetree/bindings/spi/spi-fsl-dspi.txt
> > @@ -11,6 +11,11 @@ Required properties:
> >  - spi-num-chipselects : the number of the chipselect signals.
> >  - bus-num : the slave chip chipselect signal number.
> >  - big-endian : if DSPI modudle is big endian, the bool will be set in node.
> > +- use-dma: the bool decide if use dma method in DSPI transfering.
> 
> Why can the OS not decide this based on the presence of dmas which it
> can use?

Yes, OS/driver should decide to use DMA or not, but it shouldn't be
based on the presence of 'dmas' property.  The DMA is a hardware
resource just like IRQ.  It should be just there in client device's node
as long as the SoC design assigns the channel to the device.  The device
driver should make the decision when DMA should be used, e.g. big amount
data transfer, and when PIO should be used, e.g. small data.

Shawn

> 
> Is there ever a case that there would be dmas present but it would be in
> the interests of the OS to not use them?

Re: [PATCH 1/3] Documentation:spi:fsl-dspi:add DSPI dma transfer support

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 866 bytes --]

On Wed, Feb 26, 2014 at 10:19:49PM +0800, Shawn Guo wrote:
> On Tue, Feb 25, 2014 at 09:08:30AM +0000, Mark Rutland wrote:

> > > +- use-dma: the bool decide if use dma method in DSPI transfering.

> > Why can the OS not decide this based on the presence of dmas which it
> > can use?

> Yes, OS/driver should decide to use DMA or not, but it shouldn't be
> based on the presence of 'dmas' property.  The DMA is a hardware
> resource just like IRQ.  It should be just there in client device's node
> as long as the SoC design assigns the channel to the device.  The device
> driver should make the decision when DMA should be used, e.g. big amount
> data transfer, and when PIO should be used, e.g. small data.

Right, that's very common - but that decision is usually taken on a per
transfer basis so a DT property would seem odd, especially just a simple
boolean.

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]

[PATCH 1/3] Documentation:spi:fsl-dspi:add DSPI dma transfer support

[Mark Brown]

On Wed, Feb 26, 2014 at 10:19:49PM +0800, Shawn Guo wrote:
> On Tue, Feb 25, 2014 at 09:08:30AM +0000, Mark Rutland wrote:

> > > +- use-dma: the bool decide if use dma method in DSPI transfering.

> > Why can the OS not decide this based on the presence of dmas which it
> > can use?

> Yes, OS/driver should decide to use DMA or not, but it shouldn't be
> based on the presence of 'dmas' property.  The DMA is a hardware
> resource just like IRQ.  It should be just there in client device's node
> as long as the SoC design assigns the channel to the device.  The device
> driver should make the decision when DMA should be used, e.g. big amount
> data transfer, and when PIO should be used, e.g. small data.

Right, that's very common - but that decision is usually taken on a per
transfer basis so a DT property would seem odd, especially just a simple
boolean.
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Re: [PATCH 1/3] Documentation:spi:fsl-dspi:add DSPI dma transfer support

[Shawn Guo]

On Thu, Feb 27, 2014 at 12:38:22AM +0900, Mark Brown wrote:
> On Wed, Feb 26, 2014 at 10:19:49PM +0800, Shawn Guo wrote:
> > On Tue, Feb 25, 2014 at 09:08:30AM +0000, Mark Rutland wrote:
> 
> > > > +- use-dma: the bool decide if use dma method in DSPI transfering.
> 
> > > Why can the OS not decide this based on the presence of dmas which it
> > > can use?
> 
> > Yes, OS/driver should decide to use DMA or not, but it shouldn't be
> > based on the presence of 'dmas' property.  The DMA is a hardware
> > resource just like IRQ.  It should be just there in client device's node
> > as long as the SoC design assigns the channel to the device.  The device
> > driver should make the decision when DMA should be used, e.g. big amount
> > data transfer, and when PIO should be used, e.g. small data.
> 
> Right, that's very common - but that decision is usually taken on a per
> transfer basis so a DT property would seem odd, especially just a simple
> boolean.

Yea, I guess we're on the same page - the decision should be made by
the device driver on its own not the device tree.

Shawn

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[PATCH 1/3] Documentation:spi:fsl-dspi:add DSPI dma transfer support

[Shawn Guo]

On Thu, Feb 27, 2014 at 12:38:22AM +0900, Mark Brown wrote:
> On Wed, Feb 26, 2014 at 10:19:49PM +0800, Shawn Guo wrote:
> > On Tue, Feb 25, 2014 at 09:08:30AM +0000, Mark Rutland wrote:
> 
> > > > +- use-dma: the bool decide if use dma method in DSPI transfering.
> 
> > > Why can the OS not decide this based on the presence of dmas which it
> > > can use?
> 
> > Yes, OS/driver should decide to use DMA or not, but it shouldn't be
> > based on the presence of 'dmas' property.  The DMA is a hardware
> > resource just like IRQ.  It should be just there in client device's node
> > as long as the SoC design assigns the channel to the device.  The device
> > driver should make the decision when DMA should be used, e.g. big amount
> > data transfer, and when PIO should be used, e.g. small data.
> 
> Right, that's very common - but that decision is usually taken on a per
> transfer basis so a DT property would seem odd, especially just a simple
> boolean.

Yea, I guess we're on the same page - the decision should be made by
the device driver on its own not the device tree.

Shawn