[PATCH 0/3] serial: mxs-auart: add DMA support for auart in mx28

[PATCH 0/3] serial: mxs-auart: add DMA support for auart in mx28

[Huang Shijie]

This patch set adds the DMA support for auart in mx28.
patch 1:
	But in mx23, the DMA has a bug(see errata:2836). We can not add the
	DMA support in mx23, but we can add DMA support to auart in mx28.
	So in order to add the DMA support for the auart in mx28, we should add
	the platform_device_id to distinguish the distinguish SOCs.

patch 2: add the DMA support for mx28
	Only we meet the following conditions, we can enable the DMA support
	for auart:
        (1) We enable the DMA support in the dts file, such as
            arch/arm/boot/dts/imx28.dtsi.
        (2) We enable the hardware flow control.
        (3) We use the mx28, not the mx23. Due to hardware bug(see errata: 2836),
            we can not add the DMA support to mx23.

patch 3: enable the DMA support in dts for mx28 
	You can use the /ttyAPP0 to test this patch set. 
	I tested this patch in mx28-evk board.


Huang Shijie (3):
  serial: mxs-auart: distinguish the different SOCs
  serial: mxs-auart: add the DMA support for mx28
  ARM: dts: enable dma support for auart0 in mx28

 .../bindings/tty/serial/fsl-mxs-auart.txt          |    9 +-
 arch/arm/boot/dts/imx28.dtsi                       |   12 +-
 drivers/tty/serial/mxs-auart.c                     |  335 +++++++++++++++++++-
 3 files changed, 341 insertions(+), 15 deletions(-)

[PATCH 1/3] serial: mxs-auart: distinguish the different SOCs

[Huang Shijie]

From: Huang Shijie <shijie8@gmail.com>

The current mxs-auart driver is used for both mx23 and mx28.

But in mx23, the DMA has a bug(see errata:2836). We can not add the
DMA support in mx23, but we can add DMA support to auart in mx28.

So in order to add the DMA support for the auart in mx28, we should add
the platform_device_id to distinguish the distinguish SOCs.

Signed-off-by: Huang Shijie <b32955@freescale.com>
---
 .../bindings/tty/serial/fsl-mxs-auart.txt          |    2 +-
 arch/arm/boot/dts/imx28.dtsi                       |   10 +++---
 drivers/tty/serial/mxs-auart.c                     |   28 +++++++++++++++----
 3 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
index 2ee903f..a154bf1 100644
--- a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
+++ b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
@@ -8,7 +8,7 @@ Required properties:
 
 Example:
 auart0: serial at 8006a000 {
-	compatible = "fsl,imx28-auart", "fsl,imx23-auart";
+	compatible = "fsl,imx28-auart";
 	reg = <0x8006a000 0x2000>;
 	interrupts = <112 70 71>;
 };
diff --git a/arch/arm/boot/dts/imx28.dtsi b/arch/arm/boot/dts/imx28.dtsi
index e16d631..6ed9215 100644
--- a/arch/arm/boot/dts/imx28.dtsi
+++ b/arch/arm/boot/dts/imx28.dtsi
@@ -795,7 +795,7 @@
 			};
 
 			auart0: serial at 8006a000 {
-				compatible = "fsl,imx28-auart", "fsl,imx23-auart";
+				compatible = "fsl,imx28-auart";
 				reg = <0x8006a000 0x2000>;
 				interrupts = <112 70 71>;
 				clocks = <&clks 45>;
@@ -803,7 +803,7 @@
 			};
 
 			auart1: serial at 8006c000 {
-				compatible = "fsl,imx28-auart", "fsl,imx23-auart";
+				compatible = "fsl,imx28-auart";
 				reg = <0x8006c000 0x2000>;
 				interrupts = <113 72 73>;
 				clocks = <&clks 45>;
@@ -811,7 +811,7 @@
 			};
 
 			auart2: serial at 8006e000 {
-				compatible = "fsl,imx28-auart", "fsl,imx23-auart";
+				compatible = "fsl,imx28-auart";
 				reg = <0x8006e000 0x2000>;
 				interrupts = <114 74 75>;
 				clocks = <&clks 45>;
@@ -819,7 +819,7 @@
 			};
 
 			auart3: serial at 80070000 {
-				compatible = "fsl,imx28-auart", "fsl,imx23-auart";
+				compatible = "fsl,imx28-auart";
 				reg = <0x80070000 0x2000>;
 				interrupts = <115 76 77>;
 				clocks = <&clks 45>;
@@ -827,7 +827,7 @@
 			};
 
 			auart4: serial at 80072000 {
-				compatible = "fsl,imx28-auart", "fsl,imx23-auart";
+				compatible = "fsl,imx28-auart";
 				reg = <0x80072000 0x2000>;
 				interrupts = <116 78 79>;
 				clocks = <&clks 45>;
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 6db3baa..cd9ec1d 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -37,6 +37,11 @@
 
 #include <asm/cacheflush.h>
 
+/* Use the platform_id to distinguish different Archs. */
+#define IS_MX23			0x0
+#define IS_MX28			0x1
+#define AUART_IS_MX23(x)	((x)->pdev->id_entry->driver_data == IS_MX23)
+
 #define MXS_AUART_PORTS 5
 
 #define AUART_CTRL0			0x00000000
@@ -124,6 +129,7 @@ struct mxs_auart_port {
 
 	struct clk *clk;
 	struct device *dev;
+	struct platform_device *pdev;
 };
 
 static void mxs_auart_stop_tx(struct uart_port *u);
@@ -680,6 +686,19 @@ static struct uart_driver auart_driver = {
 #endif
 };
 
+static const struct platform_device_id auart_ids[] = {
+	{ .name = "imx23-auart", .driver_data = IS_MX23, },
+	{ .name = "imx28-auart", .driver_data = IS_MX28, },
+	{},
+};
+
+static struct of_device_id mxs_auart_dt_ids[] = {
+	{ .compatible = "fsl,imx23-auart", .data = (void *)&auart_ids[0] },
+	{ .compatible = "fsl,imx28-auart", .data = (void *)&auart_ids[1] },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mxs_auart_dt_ids);
+
 /*
  * This function returns 1 if pdev isn't a device instatiated by dt, 0 if it
  * could successfully get all information from dt or a negative errno.
@@ -701,6 +720,8 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s,
 	}
 	s->port.line = ret;
 
+	pdev->id_entry = of_match_device(mxs_auart_dt_ids, &pdev->dev)->data;
+
 	return 0;
 }
 
@@ -753,6 +774,7 @@ static int __devinit mxs_auart_probe(struct platform_device *pdev)
 
 	s->flags = 0;
 	s->ctrl = 0;
+	s->pdev = pdev;
 
 	s->irq = platform_get_irq(pdev, 0);
 	s->port.irq = s->irq;
@@ -805,12 +827,6 @@ static int __devexit mxs_auart_remove(struct platform_device *pdev)
 	return 0;
 }
 
-static struct of_device_id mxs_auart_dt_ids[] = {
-	{ .compatible = "fsl,imx23-auart", },
-	{ /* sentinel */ }
-};
-MODULE_DEVICE_TABLE(of, mxs_auart_dt_ids);
-
 static struct platform_driver mxs_auart_driver = {
 	.probe = mxs_auart_probe,
 	.remove = __devexit_p(mxs_auart_remove),
-- 
1.7.0.4

[PATCH 2/3] serial: mxs-auart: add the DMA support for mx28

[Huang Shijie]

Only we meet the following conditions, we can enable the DMA support for
auart:

  (1) We enable the DMA support in the dts file, such as
      arch/arm/boot/dts/imx28.dtsi.

  (2) We enable the hardware flow control.

  (3) We use the mx28, not the mx23. Due to hardware bug(see errata: 2836),
      we can not add the DMA support to mx23.

Signed-off-by: Huang Shijie <b32955@freescale.com>
---
 .../bindings/tty/serial/fsl-mxs-auart.txt          |    7 +
 drivers/tty/serial/mxs-auart.c                     |  307 +++++++++++++++++++-
 2 files changed, 311 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
index a154bf1..67e54b4 100644
--- a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
+++ b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
@@ -6,11 +6,18 @@ Required properties:
 - reg : Address and length of the register set for the device
 - interrupts : Should contain the auart interrupt numbers
 
+Optional properties:
+- fsl,auart-dma-channel : The DMA channels, the first is for RX, the other
+			is for TX.
+- fsl,auart-enable-dma : Enable the DMA support for the auart.
+
 Example:
 auart0: serial at 8006a000 {
 	compatible = "fsl,imx28-auart";
 	reg = <0x8006a000 0x2000>;
 	interrupts = <112 70 71>;
+	fsl,auart-dma-channel = <8 9>;
+	fsl,auart-enable-dma;
 };
 
 Note: Each auart port should have an alias correctly numbered in "aliases"
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index cd9ec1d..2271330 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -34,6 +34,8 @@
 #include <linux/io.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/of_device.h>
+#include <linux/dma-mapping.h>
+#include <linux/fsl/mxs-dma.h>
 
 #include <asm/cacheflush.h>
 
@@ -76,7 +78,15 @@
 
 #define AUART_CTRL0_SFTRST			(1 << 31)
 #define AUART_CTRL0_CLKGATE			(1 << 30)
+#define AUART_CTRL0_RXTO_ENABLE			(1 << 27)
+#define AUART_CTRL0_RXTIMEOUT(v)		(((v) & 0x7ff) << 16)
+#define AUART_CTRL0_XFER_COUNT(v)		((v) & 0xffff)
 
+#define AUART_CTRL1_XFER_COUNT(v)		((v) & 0xffff)
+
+#define AUART_CTRL2_DMAONERR			(1 << 26)
+#define AUART_CTRL2_TXDMAE			(1 << 25)
+#define AUART_CTRL2_RXDMAE			(1 << 24)
 #define AUART_CTRL2_CTSEN			(1 << 15)
 #define AUART_CTRL2_RTSEN			(1 << 14)
 #define AUART_CTRL2_RTS				(1 << 11)
@@ -116,12 +126,15 @@
 #define AUART_STAT_BERR				(1 << 18)
 #define AUART_STAT_PERR				(1 << 17)
 #define AUART_STAT_FERR				(1 << 16)
+#define AUART_STAT_RXCOUNT_MASK			0xffff
 
 static struct uart_driver auart_driver;
 
 struct mxs_auart_port {
 	struct uart_port port;
 
+#define MXS_AUART_DMA_CONFIG	0x1
+#define MXS_AUART_DMA_ENABLED	0x2
 	unsigned int flags;
 	unsigned int ctrl;
 
@@ -130,16 +143,116 @@ struct mxs_auart_port {
 	struct clk *clk;
 	struct device *dev;
 	struct platform_device *pdev;
+
+	/* for DMA */
+	struct mxs_dma_data dma_data;
+	int dma_channel_rx, dma_channel_tx;
+	int dma_irq_rx, dma_irq_tx;
+	int dma_channel;
+
+	struct scatterlist tx_sgl;
+	struct dma_chan	*tx_dma_chan;
+	void *tx_dma_buf;
+
+	struct scatterlist rx_sgl;
+	struct dma_chan	*rx_dma_chan;
+	void *rx_dma_buf;
 };
 
+static inline bool auart_dma_enabled(struct mxs_auart_port *s)
+{
+	return s->flags & MXS_AUART_DMA_ENABLED;
+}
+
 static void mxs_auart_stop_tx(struct uart_port *u);
 
 #define to_auart_port(u) container_of(u, struct mxs_auart_port, port)
 
+static inline void mxs_auart_tx_chars(struct mxs_auart_port *s);
+
+static void dma_tx_callback(void *param)
+{
+	struct mxs_auart_port *s = param;
+	struct circ_buf *xmit = &s->port.state->xmit;
+
+	dma_unmap_sg(s->dev, &s->tx_sgl, 1, DMA_TO_DEVICE);
+
+	/* wake up the possible processes. */
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&s->port);
+
+	mxs_auart_tx_chars(s);
+}
+
+static int mxs_auart_dma_tx(struct mxs_auart_port *s, int size)
+{
+	struct dma_async_tx_descriptor *desc;
+	struct scatterlist *sgl = &s->tx_sgl;
+	struct dma_chan *channel = s->tx_dma_chan;
+	u32 pio[1];
+
+	/* [1] : send PIO. Note, the first pio word is CTRL1. */
+	pio[0] = AUART_CTRL1_XFER_COUNT(size);
+	desc = dmaengine_prep_slave_sg(channel, (struct scatterlist *)pio,
+					1, DMA_TRANS_NONE, 0);
+	if (!desc) {
+		dev_err(s->dev, "step 1 error\n");
+		return -EINVAL;
+	}
+
+	/* [2] : set DMA buffer. */
+	sg_init_one(sgl, s->tx_dma_buf, size);
+	dma_map_sg(s->dev, sgl, 1, DMA_TO_DEVICE);
+	desc = dmaengine_prep_slave_sg(channel, sgl,
+			1, DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!desc) {
+		dev_err(s->dev, "step 2 error\n");
+		return -EINVAL;
+	}
+
+	/* [3] : submit the DMA */
+	desc->callback = dma_tx_callback;
+	desc->callback_param = s;
+	dmaengine_submit(desc);
+	dma_async_issue_pending(channel);
+	return 0;
+}
+
 static inline void mxs_auart_tx_chars(struct mxs_auart_port *s)
 {
 	struct circ_buf *xmit = &s->port.state->xmit;
 
+	if (auart_dma_enabled(s)) {
+		int i = 0;
+		int size;
+		void *buffer = s->tx_dma_buf;
+		enum dma_status status;
+
+		/* Check whether there is pending DMA operations. */
+		status = dmaengine_tx_status(s->tx_dma_chan, 0, NULL);
+		if (status != DMA_SUCCESS)
+			return;
+
+		while (!uart_circ_empty(xmit) && !uart_tx_stopped(&s->port)) {
+			size = min_t(u32, UART_XMIT_SIZE - i,
+				     CIRC_CNT_TO_END(xmit->head,
+						     xmit->tail,
+						     UART_XMIT_SIZE));
+			memcpy(buffer + i, xmit->buf + xmit->tail, size);
+			xmit->tail = (xmit->tail + size) & (UART_XMIT_SIZE - 1);
+
+			i += size;
+			if (i >= UART_XMIT_SIZE)
+				break;
+		}
+
+		if (uart_tx_stopped(&s->port))
+			mxs_auart_stop_tx(&s->port);
+		if (i)
+			mxs_auart_dma_tx(s, i);
+		return;
+	}
+
 	while (!(readl(s->port.membase + AUART_STAT) &
 		 AUART_STAT_TXFF)) {
 		if (s->port.x_char) {
@@ -293,10 +406,155 @@ static u32 mxs_auart_get_mctrl(struct uart_port *u)
 	return mctrl;
 }
 
+static bool mxs_auart_dma_filter(struct dma_chan *chan, void *param)
+{
+	struct mxs_auart_port *s = param;
+
+	if (!mxs_dma_is_apbx(chan))
+		return false;
+
+	if (s->dma_channel == chan->chan_id) {
+		chan->private = &s->dma_data;
+		return true;
+	}
+	return false;
+}
+
+static int mxs_auart_dma_prep_rx(struct mxs_auart_port *s);
+static void dma_rx_callback(void *arg)
+{
+	struct mxs_auart_port *s = (struct mxs_auart_port *) arg;
+	struct tty_struct *tty = s->port.state->port.tty;
+	int count;
+	u32 stat;
+
+	stat = readl(s->port.membase + AUART_STAT);
+	stat &= ~(AUART_STAT_OERR | AUART_STAT_BERR |
+			AUART_STAT_PERR | AUART_STAT_FERR);
+
+	count = stat & AUART_STAT_RXCOUNT_MASK;
+	tty_insert_flip_string(tty, s->rx_dma_buf, count);
+
+	writel(stat, s->port.membase + AUART_STAT);
+	tty_flip_buffer_push(tty);
+
+	/* start the next DMA for RX. */
+	mxs_auart_dma_prep_rx(s);
+}
+
+static int mxs_auart_dma_prep_rx(struct mxs_auart_port *s)
+{
+	struct dma_async_tx_descriptor *desc;
+	struct scatterlist *sgl = &s->rx_sgl;
+	struct dma_chan *channel = s->rx_dma_chan;
+	u32 pio[1];
+
+	/* [1] : send PIO */
+	pio[0] = AUART_CTRL0_RXTO_ENABLE
+		| AUART_CTRL0_RXTIMEOUT(0x80)
+		| AUART_CTRL0_XFER_COUNT(UART_XMIT_SIZE);
+	desc = dmaengine_prep_slave_sg(channel, (struct scatterlist *)pio,
+					1, DMA_TRANS_NONE, 0);
+	if (!desc) {
+		dev_err(s->dev, "step 1 error\n");
+		return -EINVAL;
+	}
+
+	/* [2] : send DMA request */
+	sg_init_one(sgl, s->rx_dma_buf, UART_XMIT_SIZE);
+	dma_map_sg(s->dev, sgl, 1, DMA_FROM_DEVICE);
+	desc = dmaengine_prep_slave_sg(channel, sgl, 1, DMA_DEV_TO_MEM,
+					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!desc) {
+		dev_err(s->dev, "step 2 error\n");
+		return -1;
+	}
+
+	/* [3] : submit the DMA, but do not issue it. */
+	desc->callback = dma_rx_callback;
+	desc->callback_param = s;
+	dmaengine_submit(desc);
+	dma_async_issue_pending(channel);
+	return 0;
+}
+
+static void mxs_auart_dma_exit_channel(struct mxs_auart_port *s)
+{
+	if (s->tx_dma_chan) {
+		dma_release_channel(s->tx_dma_chan);
+		s->tx_dma_chan = NULL;
+	}
+	if (s->rx_dma_chan) {
+		dma_release_channel(s->rx_dma_chan);
+		s->rx_dma_chan = NULL;
+	}
+
+	kfree(s->tx_dma_buf);
+	kfree(s->rx_dma_buf);
+	s->tx_dma_buf = NULL;
+	s->rx_dma_buf = NULL;
+}
+
+static void mxs_auart_dma_exit(struct mxs_auart_port *s)
+{
+
+	writel(AUART_CTRL2_TXDMAE | AUART_CTRL2_RXDMAE | AUART_CTRL2_DMAONERR,
+		s->port.membase + AUART_CTRL2_CLR);
+
+	mxs_auart_dma_exit_channel(s);
+	s->flags &= ~MXS_AUART_DMA_ENABLED;
+}
+
+static int mxs_auart_dma_init(struct mxs_auart_port *s)
+{
+	dma_cap_mask_t mask;
+
+	if (auart_dma_enabled(s))
+		return 0;
+
+	/* We do not get the right DMA channels. */
+	if (s->dma_channel_rx == -1 || s->dma_channel_rx == -1)
+		return -EINVAL;
+
+	/* init for RX */
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_SLAVE, mask);
+	s->dma_channel = s->dma_channel_rx;
+	s->dma_data.chan_irq = s->dma_irq_rx;
+	s->rx_dma_chan = dma_request_channel(mask, mxs_auart_dma_filter, s);
+	if (!s->rx_dma_chan)
+		goto err_out;
+	s->rx_dma_buf = kzalloc(UART_XMIT_SIZE, GFP_KERNEL | GFP_DMA);
+	if (!s->rx_dma_buf)
+		goto err_out;
+
+	/* init for TX */
+	s->dma_channel = s->dma_channel_tx;
+	s->dma_data.chan_irq = s->dma_irq_tx;
+	s->tx_dma_chan = dma_request_channel(mask, mxs_auart_dma_filter, s);
+	if (!s->tx_dma_chan)
+		goto err_out;
+	s->tx_dma_buf = kzalloc(UART_XMIT_SIZE, GFP_KERNEL | GFP_DMA);
+	if (!s->tx_dma_buf)
+		goto err_out;
+
+	/* set the flags */
+	s->flags |= MXS_AUART_DMA_ENABLED;
+	dev_dbg(s->dev, "enabled the DMA support.");
+
+	return 0;
+
+err_out:
+	mxs_auart_dma_exit_channel(s);
+	return -EINVAL;
+
+}
+
 static void mxs_auart_settermios(struct uart_port *u,
 				 struct ktermios *termios,
 				 struct ktermios *old)
 {
+	struct mxs_auart_port *s = to_auart_port(u);
 	u32 bm, ctrl, ctrl2, div;
 	unsigned int cflag, baud;
 
@@ -368,10 +626,23 @@ static void mxs_auart_settermios(struct uart_port *u,
 		ctrl |= AUART_LINECTRL_STP2;
 
 	/* figure out the hardware flow control settings */
-	if (cflag & CRTSCTS)
+	if (cflag & CRTSCTS) {
+		/*
+		 * The DMA has a bug(see errata:2836) in mx23.
+		 * So we can not implement the DMA for auart in mx23,
+		 * we can only implement the DMA support for auart
+		 * in mx28.
+		 */
+		if (!AUART_IS_MX23(s) && (s->flags & MXS_AUART_DMA_CONFIG)) {
+			if (!mxs_auart_dma_init(s))
+				/* enable DMA tranfer */
+				ctrl2 |= AUART_CTRL2_TXDMAE | AUART_CTRL2_RXDMAE
+				       | AUART_CTRL2_DMAONERR;
+		}
 		ctrl2 |= AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN;
-	else
+	} else {
 		ctrl2 &= ~(AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN);
+	}
 
 	/* set baud rate */
 	baud = uart_get_baud_rate(u, termios, old, 0, u->uartclk);
@@ -383,6 +654,17 @@ static void mxs_auart_settermios(struct uart_port *u,
 	writel(ctrl2, u->membase + AUART_CTRL2);
 
 	uart_update_timeout(u, termios->c_cflag, baud);
+
+	/* prepare for the DMA RX. */
+	if (auart_dma_enabled(s)) {
+		if (!mxs_auart_dma_prep_rx(s)) {
+			/* Disable the normal RX interrupt. */
+			writel(AUART_INTR_RXIEN, u->membase + AUART_INTR_CLR);
+		} else {
+			mxs_auart_dma_exit(s);
+			dev_err(s->dev, "We can not start up the DMA.\n");
+		}
+	}
 }
 
 static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
@@ -461,6 +743,9 @@ static void mxs_auart_shutdown(struct uart_port *u)
 {
 	struct mxs_auart_port *s = to_auart_port(u);
 
+	if (auart_dma_enabled(s))
+		mxs_auart_dma_exit(s);
+
 	writel(AUART_CTRL2_UARTEN, u->membase + AUART_CTRL2_CLR);
 
 	writel(AUART_INTR_RXIEN | AUART_INTR_RTIEN | AUART_INTR_CTSMIEN,
@@ -707,6 +992,7 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s,
 		struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
+	u32 dma_channel[2];
 	int ret;
 
 	if (!np)
@@ -722,6 +1008,22 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s,
 
 	pdev->id_entry = of_match_device(mxs_auart_dt_ids, &pdev->dev)->data;
 
+	ret = of_property_read_u32_array(np, "fsl,auart-dma-channel",
+					dma_channel, 2);
+	if (ret == 0) {
+		s->dma_channel_rx = dma_channel[0];
+		s->dma_channel_tx = dma_channel[1];
+	} else {
+		s->dma_channel_rx = -1;
+		s->dma_channel_tx = -1;
+	}
+
+	s->dma_irq_rx = platform_get_irq(pdev, 1);
+	s->dma_irq_tx = platform_get_irq(pdev, 2);
+
+	if (of_property_read_bool(np, "fsl,auart-enable-dma"))
+		s->flags |= MXS_AUART_DMA_CONFIG;
+
 	return 0;
 }
 
@@ -772,7 +1074,6 @@ static int __devinit mxs_auart_probe(struct platform_device *pdev)
 	s->port.type = PORT_IMX;
 	s->port.dev = s->dev = get_device(&pdev->dev);
 
-	s->flags = 0;
 	s->ctrl = 0;
 	s->pdev = pdev;
 
-- 
1.7.0.4

[PATCH 3/3] ARM: dts: enable dma support for auart0 in mx28

[Huang Shijie]

enable the dma support for auart0 in mx28.

Signed-off-by: Huang Shijie <b32955@freescale.com>
---
 arch/arm/boot/dts/imx28.dtsi |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/arm/boot/dts/imx28.dtsi b/arch/arm/boot/dts/imx28.dtsi
index 6ed9215..738e023 100644
--- a/arch/arm/boot/dts/imx28.dtsi
+++ b/arch/arm/boot/dts/imx28.dtsi
@@ -798,6 +798,8 @@
 				compatible = "fsl,imx28-auart";
 				reg = <0x8006a000 0x2000>;
 				interrupts = <112 70 71>;
+				fsl,auart-dma-channel = <8 9>;
+				fsl,auart-enable-dma;
 				clocks = <&clks 45>;
 				status = "disabled";
 			};
-- 
1.7.0.4

[PATCH 1/3] serial: mxs-auart: distinguish the different SOCs

[Shawn Guo]

On Tue, Oct 16, 2012 at 02:03:04PM +0800, Huang Shijie wrote:
> From: Huang Shijie <shijie8@gmail.com>
> 
> The current mxs-auart driver is used for both mx23 and mx28.
> 
> But in mx23, the DMA has a bug(see errata:2836). We can not add the
> DMA support in mx23, but we can add DMA support to auart in mx28.
> 
> So in order to add the DMA support for the auart in mx28, we should add
> the platform_device_id to distinguish the distinguish SOCs.
> 
> Signed-off-by: Huang Shijie <b32955@freescale.com>
> ---
>  .../bindings/tty/serial/fsl-mxs-auart.txt          |    2 +-
>  arch/arm/boot/dts/imx28.dtsi                       |   10 +++---
>  drivers/tty/serial/mxs-auart.c                     |   28 +++++++++++++++----
>  3 files changed, 28 insertions(+), 12 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
> index 2ee903f..a154bf1 100644
> --- a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
> +++ b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
> @@ -8,7 +8,7 @@ Required properties:
>  
>  Example:
>  auart0: serial at 8006a000 {
> -	compatible = "fsl,imx28-auart", "fsl,imx23-auart";
> +	compatible = "fsl,imx28-auart";
>  	reg = <0x8006a000 0x2000>;
>  	interrupts = <112 70 71>;
>  };
> diff --git a/arch/arm/boot/dts/imx28.dtsi b/arch/arm/boot/dts/imx28.dtsi
> index e16d631..6ed9215 100644
> --- a/arch/arm/boot/dts/imx28.dtsi
> +++ b/arch/arm/boot/dts/imx28.dtsi
> @@ -795,7 +795,7 @@
>  			};
>  
>  			auart0: serial at 8006a000 {
> -				compatible = "fsl,imx28-auart", "fsl,imx23-auart";
> +				compatible = "fsl,imx28-auart";
>  				reg = <0x8006a000 0x2000>;
>  				interrupts = <112 70 71>;
>  				clocks = <&clks 45>;
> @@ -803,7 +803,7 @@
>  			};
>  
>  			auart1: serial at 8006c000 {
> -				compatible = "fsl,imx28-auart", "fsl,imx23-auart";
> +				compatible = "fsl,imx28-auart";
>  				reg = <0x8006c000 0x2000>;
>  				interrupts = <113 72 73>;
>  				clocks = <&clks 45>;
> @@ -811,7 +811,7 @@
>  			};
>  
>  			auart2: serial at 8006e000 {
> -				compatible = "fsl,imx28-auart", "fsl,imx23-auart";
> +				compatible = "fsl,imx28-auart";
>  				reg = <0x8006e000 0x2000>;
>  				interrupts = <114 74 75>;
>  				clocks = <&clks 45>;
> @@ -819,7 +819,7 @@
>  			};
>  
>  			auart3: serial at 80070000 {
> -				compatible = "fsl,imx28-auart", "fsl,imx23-auart";
> +				compatible = "fsl,imx28-auart";
>  				reg = <0x80070000 0x2000>;
>  				interrupts = <115 76 77>;
>  				clocks = <&clks 45>;
> @@ -827,7 +827,7 @@
>  			};
>  
>  			auart4: serial at 80072000 {
> -				compatible = "fsl,imx28-auart", "fsl,imx23-auart";
> +				compatible = "fsl,imx28-auart";
>  				reg = <0x80072000 0x2000>;
>  				interrupts = <116 78 79>;
>  				clocks = <&clks 45>;

All changes above are unnecessary.  With "fsl,imx28-auart" added to
driver's compatible, driver will match it first.

> diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
> index 6db3baa..cd9ec1d 100644
> --- a/drivers/tty/serial/mxs-auart.c
> +++ b/drivers/tty/serial/mxs-auart.c
> @@ -37,6 +37,11 @@
>  
>  #include <asm/cacheflush.h>
>  
> +/* Use the platform_id to distinguish different Archs. */
> +#define IS_MX23			0x0
> +#define IS_MX28			0x1

I do not like the name.  We are distinguishing the IP not SoC, but just
happen to use SoC to identify the version.

You can look at drivers/mmc/host/sdhci-esdhc-imx.c for example.

> +#define AUART_IS_MX23(x)	((x)->pdev->id_entry->driver_data == IS_MX23)
> +

Use inline function.

>  #define MXS_AUART_PORTS 5
>  
>  #define AUART_CTRL0			0x00000000
> @@ -124,6 +129,7 @@ struct mxs_auart_port {
>  
>  	struct clk *clk;
>  	struct device *dev;
> +	struct platform_device *pdev;
>  };
>  
>  static void mxs_auart_stop_tx(struct uart_port *u);
> @@ -680,6 +686,19 @@ static struct uart_driver auart_driver = {
>  #endif
>  };
>  
> +static const struct platform_device_id auart_ids[] = {
> +	{ .name = "imx23-auart", .driver_data = IS_MX23, },
> +	{ .name = "imx28-auart", .driver_data = IS_MX28, },
> +	{},
> +};
> +

The driver is only used on mach-mxs.  Since mach-mxs becomes a DT only
platform, auart_ids is not really needed.  Look, you do not use it in
mxs_auart_driver for probing at all.

> +static struct of_device_id mxs_auart_dt_ids[] = {
> +	{ .compatible = "fsl,imx23-auart", .data = (void *)&auart_ids[0] },
> +	{ .compatible = "fsl,imx28-auart", .data = (void *)&auart_ids[1] },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, mxs_auart_dt_ids);
> +
>  /*
>   * This function returns 1 if pdev isn't a device instatiated by dt, 0 if it
>   * could successfully get all information from dt or a negative errno.
> @@ -701,6 +720,8 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s,
>  	}
>  	s->port.line = ret;
>  
> +	pdev->id_entry = of_match_device(mxs_auart_dt_ids, &pdev->dev)->data;
> +
>  	return 0;
>  }
>  
> @@ -753,6 +774,7 @@ static int __devinit mxs_auart_probe(struct platform_device *pdev)
>  
>  	s->flags = 0;
>  	s->ctrl = 0;
> +	s->pdev = pdev;

What is this for?

Shawn

>  
>  	s->irq = platform_get_irq(pdev, 0);
>  	s->port.irq = s->irq;
> @@ -805,12 +827,6 @@ static int __devexit mxs_auart_remove(struct platform_device *pdev)
>  	return 0;
>  }
>  
> -static struct of_device_id mxs_auart_dt_ids[] = {
> -	{ .compatible = "fsl,imx23-auart", },
> -	{ /* sentinel */ }
> -};
> -MODULE_DEVICE_TABLE(of, mxs_auart_dt_ids);
> -
>  static struct platform_driver mxs_auart_driver = {
>  	.probe = mxs_auart_probe,
>  	.remove = __devexit_p(mxs_auart_remove),
> -- 
> 1.7.0.4
> 
> 

[PATCH 2/3] serial: mxs-auart: add the DMA support for mx28

[Shawn Guo]

On Tue, Oct 16, 2012 at 02:03:05PM +0800, Huang Shijie wrote:
> Only we meet the following conditions, we can enable the DMA support for
> auart:
> 
>   (1) We enable the DMA support in the dts file, such as
>       arch/arm/boot/dts/imx28.dtsi.
> 
>   (2) We enable the hardware flow control.
> 
>   (3) We use the mx28, not the mx23. Due to hardware bug(see errata: 2836),
>       we can not add the DMA support to mx23.
> 
> Signed-off-by: Huang Shijie <b32955@freescale.com>
> ---
>  .../bindings/tty/serial/fsl-mxs-auart.txt          |    7 +
>  drivers/tty/serial/mxs-auart.c                     |  307 +++++++++++++++++++-
>  2 files changed, 311 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
> index a154bf1..67e54b4 100644
> --- a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
> +++ b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
> @@ -6,11 +6,18 @@ Required properties:
>  - reg : Address and length of the register set for the device
>  - interrupts : Should contain the auart interrupt numbers
>  
> +Optional properties:
> +- fsl,auart-dma-channel : The DMA channels, the first is for RX, the other
> +			is for TX.
> +- fsl,auart-enable-dma : Enable the DMA support for the auart.
> +

If we want to have it decided by device tree, can we drop the property
and simply check if "fsl,auart-dma-channel" presents?

>  Example:
>  auart0: serial at 8006a000 {
>  	compatible = "fsl,imx28-auart";
>  	reg = <0x8006a000 0x2000>;
>  	interrupts = <112 70 71>;
> +	fsl,auart-dma-channel = <8 9>;
> +	fsl,auart-enable-dma;
>  };
>  
>  Note: Each auart port should have an alias correctly numbered in "aliases"
> diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
> index cd9ec1d..2271330 100644
> --- a/drivers/tty/serial/mxs-auart.c
> +++ b/drivers/tty/serial/mxs-auart.c
> @@ -34,6 +34,8 @@
>  #include <linux/io.h>
>  #include <linux/pinctrl/consumer.h>
>  #include <linux/of_device.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/fsl/mxs-dma.h>
>  
>  #include <asm/cacheflush.h>
>  
> @@ -76,7 +78,15 @@
>  
>  #define AUART_CTRL0_SFTRST			(1 << 31)
>  #define AUART_CTRL0_CLKGATE			(1 << 30)
> +#define AUART_CTRL0_RXTO_ENABLE			(1 << 27)
> +#define AUART_CTRL0_RXTIMEOUT(v)		(((v) & 0x7ff) << 16)
> +#define AUART_CTRL0_XFER_COUNT(v)		((v) & 0xffff)
>  
> +#define AUART_CTRL1_XFER_COUNT(v)		((v) & 0xffff)
> +
> +#define AUART_CTRL2_DMAONERR			(1 << 26)
> +#define AUART_CTRL2_TXDMAE			(1 << 25)
> +#define AUART_CTRL2_RXDMAE			(1 << 24)
>  #define AUART_CTRL2_CTSEN			(1 << 15)
>  #define AUART_CTRL2_RTSEN			(1 << 14)
>  #define AUART_CTRL2_RTS				(1 << 11)
> @@ -116,12 +126,15 @@
>  #define AUART_STAT_BERR				(1 << 18)
>  #define AUART_STAT_PERR				(1 << 17)
>  #define AUART_STAT_FERR				(1 << 16)
> +#define AUART_STAT_RXCOUNT_MASK			0xffff
>  
>  static struct uart_driver auart_driver;
>  
>  struct mxs_auart_port {
>  	struct uart_port port;
>  
> +#define MXS_AUART_DMA_CONFIG	0x1
> +#define MXS_AUART_DMA_ENABLED	0x2
>  	unsigned int flags;
>  	unsigned int ctrl;
>  
> @@ -130,16 +143,116 @@ struct mxs_auart_port {
>  	struct clk *clk;
>  	struct device *dev;
>  	struct platform_device *pdev;
> +
> +	/* for DMA */
> +	struct mxs_dma_data dma_data;
> +	int dma_channel_rx, dma_channel_tx;
> +	int dma_irq_rx, dma_irq_tx;
> +	int dma_channel;
> +
> +	struct scatterlist tx_sgl;
> +	struct dma_chan	*tx_dma_chan;
> +	void *tx_dma_buf;
> +
> +	struct scatterlist rx_sgl;
> +	struct dma_chan	*rx_dma_chan;
> +	void *rx_dma_buf;
>  };
>  
> +static inline bool auart_dma_enabled(struct mxs_auart_port *s)
> +{
> +	return s->flags & MXS_AUART_DMA_ENABLED;
> +}
> +
>  static void mxs_auart_stop_tx(struct uart_port *u);
>  
>  #define to_auart_port(u) container_of(u, struct mxs_auart_port, port)
>  
> +static inline void mxs_auart_tx_chars(struct mxs_auart_port *s);
> +
> +static void dma_tx_callback(void *param)
> +{
> +	struct mxs_auart_port *s = param;
> +	struct circ_buf *xmit = &s->port.state->xmit;
> +
> +	dma_unmap_sg(s->dev, &s->tx_sgl, 1, DMA_TO_DEVICE);
> +
> +	/* wake up the possible processes. */
> +	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
> +		uart_write_wakeup(&s->port);
> +
> +	mxs_auart_tx_chars(s);
> +}
> +
> +static int mxs_auart_dma_tx(struct mxs_auart_port *s, int size)
> +{
> +	struct dma_async_tx_descriptor *desc;
> +	struct scatterlist *sgl = &s->tx_sgl;
> +	struct dma_chan *channel = s->tx_dma_chan;
> +	u32 pio[1];

One element array looks strange to me.

> +
> +	/* [1] : send PIO. Note, the first pio word is CTRL1. */
> +	pio[0] = AUART_CTRL1_XFER_COUNT(size);
> +	desc = dmaengine_prep_slave_sg(channel, (struct scatterlist *)pio,
> +					1, DMA_TRANS_NONE, 0);
> +	if (!desc) {
> +		dev_err(s->dev, "step 1 error\n");
> +		return -EINVAL;
> +	}
> +
> +	/* [2] : set DMA buffer. */
> +	sg_init_one(sgl, s->tx_dma_buf, size);
> +	dma_map_sg(s->dev, sgl, 1, DMA_TO_DEVICE);
> +	desc = dmaengine_prep_slave_sg(channel, sgl,
> +			1, DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> +	if (!desc) {
> +		dev_err(s->dev, "step 2 error\n");
> +		return -EINVAL;
> +	}
> +
> +	/* [3] : submit the DMA */
> +	desc->callback = dma_tx_callback;
> +	desc->callback_param = s;
> +	dmaengine_submit(desc);
> +	dma_async_issue_pending(channel);
> +	return 0;
> +}
> +
>  static inline void mxs_auart_tx_chars(struct mxs_auart_port *s)

I'm not sure why this function is inline from the beginning.  It
becomes even more inappropriate after you add more codes below.

Shawn

>  {
>  	struct circ_buf *xmit = &s->port.state->xmit;
>  
> +	if (auart_dma_enabled(s)) {
> +		int i = 0;
> +		int size;
> +		void *buffer = s->tx_dma_buf;
> +		enum dma_status status;
> +
> +		/* Check whether there is pending DMA operations. */
> +		status = dmaengine_tx_status(s->tx_dma_chan, 0, NULL);
> +		if (status != DMA_SUCCESS)
> +			return;
> +
> +		while (!uart_circ_empty(xmit) && !uart_tx_stopped(&s->port)) {
> +			size = min_t(u32, UART_XMIT_SIZE - i,
> +				     CIRC_CNT_TO_END(xmit->head,
> +						     xmit->tail,
> +						     UART_XMIT_SIZE));
> +			memcpy(buffer + i, xmit->buf + xmit->tail, size);
> +			xmit->tail = (xmit->tail + size) & (UART_XMIT_SIZE - 1);
> +
> +			i += size;
> +			if (i >= UART_XMIT_SIZE)
> +				break;
> +		}
> +
> +		if (uart_tx_stopped(&s->port))
> +			mxs_auart_stop_tx(&s->port);
> +		if (i)
> +			mxs_auart_dma_tx(s, i);
> +		return;
> +	}
> +
>  	while (!(readl(s->port.membase + AUART_STAT) &
>  		 AUART_STAT_TXFF)) {
>  		if (s->port.x_char) {
> @@ -293,10 +406,155 @@ static u32 mxs_auart_get_mctrl(struct uart_port *u)
>  	return mctrl;
>  }
>  
> +static bool mxs_auart_dma_filter(struct dma_chan *chan, void *param)
> +{
> +	struct mxs_auart_port *s = param;
> +
> +	if (!mxs_dma_is_apbx(chan))
> +		return false;
> +
> +	if (s->dma_channel == chan->chan_id) {
> +		chan->private = &s->dma_data;
> +		return true;
> +	}
> +	return false;
> +}
> +
> +static int mxs_auart_dma_prep_rx(struct mxs_auart_port *s);
> +static void dma_rx_callback(void *arg)
> +{
> +	struct mxs_auart_port *s = (struct mxs_auart_port *) arg;
> +	struct tty_struct *tty = s->port.state->port.tty;
> +	int count;
> +	u32 stat;
> +
> +	stat = readl(s->port.membase + AUART_STAT);
> +	stat &= ~(AUART_STAT_OERR | AUART_STAT_BERR |
> +			AUART_STAT_PERR | AUART_STAT_FERR);
> +
> +	count = stat & AUART_STAT_RXCOUNT_MASK;
> +	tty_insert_flip_string(tty, s->rx_dma_buf, count);
> +
> +	writel(stat, s->port.membase + AUART_STAT);
> +	tty_flip_buffer_push(tty);
> +
> +	/* start the next DMA for RX. */
> +	mxs_auart_dma_prep_rx(s);
> +}
> +
> +static int mxs_auart_dma_prep_rx(struct mxs_auart_port *s)
> +{
> +	struct dma_async_tx_descriptor *desc;
> +	struct scatterlist *sgl = &s->rx_sgl;
> +	struct dma_chan *channel = s->rx_dma_chan;
> +	u32 pio[1];
> +
> +	/* [1] : send PIO */
> +	pio[0] = AUART_CTRL0_RXTO_ENABLE
> +		| AUART_CTRL0_RXTIMEOUT(0x80)
> +		| AUART_CTRL0_XFER_COUNT(UART_XMIT_SIZE);
> +	desc = dmaengine_prep_slave_sg(channel, (struct scatterlist *)pio,
> +					1, DMA_TRANS_NONE, 0);
> +	if (!desc) {
> +		dev_err(s->dev, "step 1 error\n");
> +		return -EINVAL;
> +	}
> +
> +	/* [2] : send DMA request */
> +	sg_init_one(sgl, s->rx_dma_buf, UART_XMIT_SIZE);
> +	dma_map_sg(s->dev, sgl, 1, DMA_FROM_DEVICE);
> +	desc = dmaengine_prep_slave_sg(channel, sgl, 1, DMA_DEV_TO_MEM,
> +					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> +	if (!desc) {
> +		dev_err(s->dev, "step 2 error\n");
> +		return -1;
> +	}
> +
> +	/* [3] : submit the DMA, but do not issue it. */
> +	desc->callback = dma_rx_callback;
> +	desc->callback_param = s;
> +	dmaengine_submit(desc);
> +	dma_async_issue_pending(channel);
> +	return 0;
> +}
> +
> +static void mxs_auart_dma_exit_channel(struct mxs_auart_port *s)
> +{
> +	if (s->tx_dma_chan) {
> +		dma_release_channel(s->tx_dma_chan);
> +		s->tx_dma_chan = NULL;
> +	}
> +	if (s->rx_dma_chan) {
> +		dma_release_channel(s->rx_dma_chan);
> +		s->rx_dma_chan = NULL;
> +	}
> +
> +	kfree(s->tx_dma_buf);
> +	kfree(s->rx_dma_buf);
> +	s->tx_dma_buf = NULL;
> +	s->rx_dma_buf = NULL;
> +}
> +
> +static void mxs_auart_dma_exit(struct mxs_auart_port *s)
> +{
> +
> +	writel(AUART_CTRL2_TXDMAE | AUART_CTRL2_RXDMAE | AUART_CTRL2_DMAONERR,
> +		s->port.membase + AUART_CTRL2_CLR);
> +
> +	mxs_auart_dma_exit_channel(s);
> +	s->flags &= ~MXS_AUART_DMA_ENABLED;
> +}
> +
> +static int mxs_auart_dma_init(struct mxs_auart_port *s)
> +{
> +	dma_cap_mask_t mask;
> +
> +	if (auart_dma_enabled(s))
> +		return 0;
> +
> +	/* We do not get the right DMA channels. */
> +	if (s->dma_channel_rx == -1 || s->dma_channel_rx == -1)
> +		return -EINVAL;
> +
> +	/* init for RX */
> +	dma_cap_zero(mask);
> +	dma_cap_set(DMA_SLAVE, mask);
> +	s->dma_channel = s->dma_channel_rx;
> +	s->dma_data.chan_irq = s->dma_irq_rx;
> +	s->rx_dma_chan = dma_request_channel(mask, mxs_auart_dma_filter, s);
> +	if (!s->rx_dma_chan)
> +		goto err_out;
> +	s->rx_dma_buf = kzalloc(UART_XMIT_SIZE, GFP_KERNEL | GFP_DMA);
> +	if (!s->rx_dma_buf)
> +		goto err_out;
> +
> +	/* init for TX */
> +	s->dma_channel = s->dma_channel_tx;
> +	s->dma_data.chan_irq = s->dma_irq_tx;
> +	s->tx_dma_chan = dma_request_channel(mask, mxs_auart_dma_filter, s);
> +	if (!s->tx_dma_chan)
> +		goto err_out;
> +	s->tx_dma_buf = kzalloc(UART_XMIT_SIZE, GFP_KERNEL | GFP_DMA);
> +	if (!s->tx_dma_buf)
> +		goto err_out;
> +
> +	/* set the flags */
> +	s->flags |= MXS_AUART_DMA_ENABLED;
> +	dev_dbg(s->dev, "enabled the DMA support.");
> +
> +	return 0;
> +
> +err_out:
> +	mxs_auart_dma_exit_channel(s);
> +	return -EINVAL;
> +
> +}
> +
>  static void mxs_auart_settermios(struct uart_port *u,
>  				 struct ktermios *termios,
>  				 struct ktermios *old)
>  {
> +	struct mxs_auart_port *s = to_auart_port(u);
>  	u32 bm, ctrl, ctrl2, div;
>  	unsigned int cflag, baud;
>  
> @@ -368,10 +626,23 @@ static void mxs_auart_settermios(struct uart_port *u,
>  		ctrl |= AUART_LINECTRL_STP2;
>  
>  	/* figure out the hardware flow control settings */
> -	if (cflag & CRTSCTS)
> +	if (cflag & CRTSCTS) {
> +		/*
> +		 * The DMA has a bug(see errata:2836) in mx23.
> +		 * So we can not implement the DMA for auart in mx23,
> +		 * we can only implement the DMA support for auart
> +		 * in mx28.
> +		 */
> +		if (!AUART_IS_MX23(s) && (s->flags & MXS_AUART_DMA_CONFIG)) {
> +			if (!mxs_auart_dma_init(s))
> +				/* enable DMA tranfer */
> +				ctrl2 |= AUART_CTRL2_TXDMAE | AUART_CTRL2_RXDMAE
> +				       | AUART_CTRL2_DMAONERR;
> +		}
>  		ctrl2 |= AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN;
> -	else
> +	} else {
>  		ctrl2 &= ~(AUART_CTRL2_CTSEN | AUART_CTRL2_RTSEN);
> +	}
>  
>  	/* set baud rate */
>  	baud = uart_get_baud_rate(u, termios, old, 0, u->uartclk);
> @@ -383,6 +654,17 @@ static void mxs_auart_settermios(struct uart_port *u,
>  	writel(ctrl2, u->membase + AUART_CTRL2);
>  
>  	uart_update_timeout(u, termios->c_cflag, baud);
> +
> +	/* prepare for the DMA RX. */
> +	if (auart_dma_enabled(s)) {
> +		if (!mxs_auart_dma_prep_rx(s)) {
> +			/* Disable the normal RX interrupt. */
> +			writel(AUART_INTR_RXIEN, u->membase + AUART_INTR_CLR);
> +		} else {
> +			mxs_auart_dma_exit(s);
> +			dev_err(s->dev, "We can not start up the DMA.\n");
> +		}
> +	}
>  }
>  
>  static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
> @@ -461,6 +743,9 @@ static void mxs_auart_shutdown(struct uart_port *u)
>  {
>  	struct mxs_auart_port *s = to_auart_port(u);
>  
> +	if (auart_dma_enabled(s))
> +		mxs_auart_dma_exit(s);
> +
>  	writel(AUART_CTRL2_UARTEN, u->membase + AUART_CTRL2_CLR);
>  
>  	writel(AUART_INTR_RXIEN | AUART_INTR_RTIEN | AUART_INTR_CTSMIEN,
> @@ -707,6 +992,7 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s,
>  		struct platform_device *pdev)
>  {
>  	struct device_node *np = pdev->dev.of_node;
> +	u32 dma_channel[2];
>  	int ret;
>  
>  	if (!np)
> @@ -722,6 +1008,22 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s,
>  
>  	pdev->id_entry = of_match_device(mxs_auart_dt_ids, &pdev->dev)->data;
>  
> +	ret = of_property_read_u32_array(np, "fsl,auart-dma-channel",
> +					dma_channel, 2);
> +	if (ret == 0) {
> +		s->dma_channel_rx = dma_channel[0];
> +		s->dma_channel_tx = dma_channel[1];
> +	} else {
> +		s->dma_channel_rx = -1;
> +		s->dma_channel_tx = -1;
> +	}
> +
> +	s->dma_irq_rx = platform_get_irq(pdev, 1);
> +	s->dma_irq_tx = platform_get_irq(pdev, 2);
> +
> +	if (of_property_read_bool(np, "fsl,auart-enable-dma"))
> +		s->flags |= MXS_AUART_DMA_CONFIG;
> +
>  	return 0;
>  }
>  
> @@ -772,7 +1074,6 @@ static int __devinit mxs_auart_probe(struct platform_device *pdev)
>  	s->port.type = PORT_IMX;
>  	s->port.dev = s->dev = get_device(&pdev->dev);
>  
> -	s->flags = 0;
>  	s->ctrl = 0;
>  	s->pdev = pdev;
>  
> -- 
> 1.7.0.4
> 
> 

[PATCH 2/3] serial: mxs-auart: add the DMA support for mx28

[Huang Shijie]

? 2012?10?18? 11:20, Shawn Guo ??:
> On Tue, Oct 16, 2012 at 02:03:05PM +0800, Huang Shijie wrote:
>> Only we meet the following conditions, we can enable the DMA support for
>> auart:
>>
>> @@ -6,11 +6,18 @@ Required properties:
>>   - reg : Address and length of the register set for the device
>>   - interrupts : Should contain the auart interrupt numbers
>>
>> +Optional properties:
>> +- fsl,auart-dma-channel : The DMA channels, the first is for RX, the other
>> +			is for TX.
>> +- fsl,auart-enable-dma : Enable the DMA support for the auart.
>> +
> If we want to have it decided by device tree, can we drop the property
> and simply check if "fsl,auart-dma-channel" presents?
It's ok to me. fix it in next version.
>>   Example:
>>   auart0: serial at 8006a000 {
>>   	compatible = "fsl,imx28-auart";
>>   	reg =<0x8006a000 0x2000>;
>>   	interrupts =<112 70 71>;
>> +	fsl,auart-dma-channel =<8 9>;
>> +	fsl,auart-enable-dma;
>>   };
>>
>>   Note: Each auart port should have an alias correctly numbered in "aliases"
>> diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
>> index cd9ec1d..2271330 100644
>> --- a/drivers/tty/serial/mxs-auart.c
>> +++ b/drivers/tty/serial/mxs-auart.c
>> @@ -34,6 +34,8 @@
>>   #include<linux/io.h>
>>   #include<linux/pinctrl/consumer.h>
>>   #include<linux/of_device.h>
>> +#include<linux/dma-mapping.h>
>> +#include<linux/fsl/mxs-dma.h>
>>
>>   #include<asm/cacheflush.h>
>>
>> @@ -76,7 +78,15 @@
>>
>>   #define AUART_CTRL0_SFTRST			(1<<  31)
>>   #define AUART_CTRL0_CLKGATE			(1<<  30)
>> +#define AUART_CTRL0_RXTO_ENABLE			(1<<  27)
>> +#define AUART_CTRL0_RXTIMEOUT(v)		(((v)&  0x7ff)<<  16)
>> +#define AUART_CTRL0_XFER_COUNT(v)		((v)&  0xffff)
>>
>> +#define AUART_CTRL1_XFER_COUNT(v)		((v)&  0xffff)
>> +
>> +#define AUART_CTRL2_DMAONERR			(1<<  26)
>> +#define AUART_CTRL2_TXDMAE			(1<<  25)
>> +#define AUART_CTRL2_RXDMAE			(1<<  24)
>>   #define AUART_CTRL2_CTSEN			(1<<  15)
>>   #define AUART_CTRL2_RTSEN			(1<<  14)
>>   #define AUART_CTRL2_RTS				(1<<  11)
>> @@ -116,12 +126,15 @@
>>   #define AUART_STAT_BERR				(1<<  18)
>>   #define AUART_STAT_PERR				(1<<  17)
>>   #define AUART_STAT_FERR				(1<<  16)
>> +#define AUART_STAT_RXCOUNT_MASK			0xffff
>>
>>   static struct uart_driver auart_driver;
>>
>>   struct mxs_auart_port {
>>   	struct uart_port port;
>>
>> +#define MXS_AUART_DMA_CONFIG	0x1
>> +#define MXS_AUART_DMA_ENABLED	0x2
>>   	unsigned int flags;
>>   	unsigned int ctrl;
>>
>> @@ -130,16 +143,116 @@ struct mxs_auart_port {
>>   	struct clk *clk;
>>   	struct device *dev;
>>   	struct platform_device *pdev;
>> +
>> +	/* for DMA */
>> +	struct mxs_dma_data dma_data;
>> +	int dma_channel_rx, dma_channel_tx;
>> +	int dma_irq_rx, dma_irq_tx;
>> +	int dma_channel;
>> +
>> +	struct scatterlist tx_sgl;
>> +	struct dma_chan	*tx_dma_chan;
>> +	void *tx_dma_buf;
>> +
>> +	struct scatterlist rx_sgl;
>> +	struct dma_chan	*rx_dma_chan;
>> +	void *rx_dma_buf;
>>   };
>>
>> +static inline bool auart_dma_enabled(struct mxs_auart_port *s)
>> +{
>> +	return s->flags&  MXS_AUART_DMA_ENABLED;
>> +}
>> +
>>   static void mxs_auart_stop_tx(struct uart_port *u);
>>
>>   #define to_auart_port(u) container_of(u, struct mxs_auart_port, port)
>>
>> +static inline void mxs_auart_tx_chars(struct mxs_auart_port *s);
>> +
>> +static void dma_tx_callback(void *param)
>> +{
>> +	struct mxs_auart_port *s = param;
>> +	struct circ_buf *xmit =&s->port.state->xmit;
>> +
>> +	dma_unmap_sg(s->dev,&s->tx_sgl, 1, DMA_TO_DEVICE);
>> +
>> +	/* wake up the possible processes. */
>> +	if (uart_circ_chars_pending(xmit)<  WAKEUP_CHARS)
>> +		uart_write_wakeup(&s->port);
>> +
>> +	mxs_auart_tx_chars(s);
>> +}
>> +
>> +static int mxs_auart_dma_tx(struct mxs_auart_port *s, int size)
>> +{
>> +	struct dma_async_tx_descriptor *desc;
>> +	struct scatterlist *sgl =&s->tx_sgl;
>> +	struct dma_chan *channel = s->tx_dma_chan;
>> +	u32 pio[1];
> One element array looks strange to me.
got it.
>> +
>> +	/* [1] : send PIO. Note, the first pio word is CTRL1. */
>> +	pio[0] = AUART_CTRL1_XFER_COUNT(size);
>> +	desc = dmaengine_prep_slave_sg(channel, (struct scatterlist *)pio,
>> +					1, DMA_TRANS_NONE, 0);
>> +	if (!desc) {
>> +		dev_err(s->dev, "step 1 error\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	/* [2] : set DMA buffer. */
>> +	sg_init_one(sgl, s->tx_dma_buf, size);
>> +	dma_map_sg(s->dev, sgl, 1, DMA_TO_DEVICE);
>> +	desc = dmaengine_prep_slave_sg(channel, sgl,
>> +			1, DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
>> +	if (!desc) {
>> +		dev_err(s->dev, "step 2 error\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	/* [3] : submit the DMA */
>> +	desc->callback = dma_tx_callback;
>> +	desc->callback_param = s;
>> +	dmaengine_submit(desc);
>> +	dma_async_issue_pending(channel);
>> +	return 0;
>> +}
>> +
>>   static inline void mxs_auart_tx_chars(struct mxs_auart_port *s)
> I'm not sure why this function is inline from the beginning.  It
yes. The inline is not proper.

Best Regards
Huang Shijie