[PATCH v3 0/3] serial: mxs-auart: add DMA support for auart in mx28

[PATCH v3 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:
	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.


To Lauri: Please try this patch set. thanks.


v2 --> v3:
	[1] fix a multi-open issue found by Lauri.

v1 --> v2:
	[1] use the inline function, not a macro, to distinguish the SOCs.
	[2] remove the "inline" for mxs_auart_tx_chars().
	[3] use the `pio`, not the `pio[1]` to fill the DMA descriptor.
	[4] use bit operation to serialize the DMA TX.
	[5] use the RX/TX DMA channel to enable the DMA support, remove the
	    "fsl,auart-enable-dma".

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          |    8 +
 arch/arm/boot/dts/imx28.dtsi                       |    1 +
 drivers/tty/serial/mxs-auart.c                     |  364 +++++++++++++++++++-
 3 files changed, 362 insertions(+), 11 deletions(-)

[PATCH v3 1/3] serial: mxs-auart: distinguish the different SOCs

[Huang Shijie]

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
distinguish the distinguish SOCs.

This patch adds a new platform_device_id table and a inline function
is_imx28_auart() to distinguish the mx23 and mx28.

Signed-off-by: Huang Shijie <b32955@freescale.com>
---
 drivers/tty/serial/mxs-auart.c |   42 ++++++++++++++++++++++++++++++++++-----
 1 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 6db3baa..06d7271 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -114,11 +114,17 @@
 
 static struct uart_driver auart_driver;
 
+enum mxs_auart_type {
+	IMX23_AUART,
+	IMX28_AUART,
+};
+
 struct mxs_auart_port {
 	struct uart_port port;
 
 	unsigned int flags;
 	unsigned int ctrl;
+	enum mxs_auart_type devtype;
 
 	unsigned int irq;
 
@@ -126,6 +132,29 @@ struct mxs_auart_port {
 	struct device *dev;
 };
 
+static struct platform_device_id mxs_auart_devtype[] = {
+	{ .name = "mxs-auart-imx23", .driver_data = IMX23_AUART },
+	{ .name = "mxs-auart-imx28", .driver_data = IMX28_AUART },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, mxs_auart_devtype);
+
+static struct of_device_id mxs_auart_dt_ids[] = {
+	{
+		.compatible = "fsl,imx28-auart",
+		.data = &mxs_auart_devtype[IMX28_AUART]
+	}, {
+		.compatible = "fsl,imx23-auart",
+		.data = &mxs_auart_devtype[IMX23_AUART]
+	}, { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mxs_auart_dt_ids);
+
+static inline int is_imx28_auart(struct mxs_auart_port *s)
+{
+	return s->devtype == IMX28_AUART;
+}
+
 static void mxs_auart_stop_tx(struct uart_port *u);
 
 #define to_auart_port(u) container_of(u, struct mxs_auart_port, port)
@@ -706,6 +735,8 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s,
 
 static int __devinit mxs_auart_probe(struct platform_device *pdev)
 {
+	const struct of_device_id *of_id =
+			of_match_device(mxs_auart_dt_ids, &pdev->dev);
 	struct mxs_auart_port *s;
 	u32 version;
 	int ret = 0;
@@ -730,6 +761,11 @@ static int __devinit mxs_auart_probe(struct platform_device *pdev)
 		goto out_free;
 	}
 
+	if (of_id) {
+		pdev->id_entry = of_id->data;
+		s->devtype = pdev->id_entry->driver_data;
+	}
+
 	s->clk = clk_get(&pdev->dev, NULL);
 	if (IS_ERR(s->clk)) {
 		ret = PTR_ERR(s->clk);
@@ -805,12 +841,6 @@ 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 v3 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          |    8 +
 drivers/tty/serial/mxs-auart.c                     |  322 +++++++++++++++++++-
 2 files changed, 325 insertions(+), 5 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..273a8d5 100644
--- a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
+++ b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
@@ -6,11 +6,19 @@ 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. If you add this property, it also means that you
+		will enable the DMA support for the auart.
+		Note: due to the hardware bug in imx23(see errata : 2836),
+		only the imx28 can enable the DMA support for the auart.
+
 Example:
 auart0: serial at 8006a000 {
 	compatible = "fsl,imx28-auart", "fsl,imx23-auart";
 	reg = <0x8006a000 0x2000>;
 	interrupts = <112 70 71>;
+	fsl,auart-dma-channel = <8 9>;
 };
 
 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 06d7271..d5b9e30 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>
 
@@ -71,6 +73,15 @@
 
 #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)
@@ -111,6 +122,7 @@
 #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;
 
@@ -122,7 +134,11 @@ enum mxs_auart_type {
 struct mxs_auart_port {
 	struct uart_port port;
 
-	unsigned int flags;
+#define MXS_AUART_DMA_CONFIG	0x1
+#define MXS_AUART_DMA_ENABLED	0x2
+#define MXS_AUART_DMA_TX_SYNC	2  /* bit 2 */
+#define MXS_AUART_DMA_RX_READY	3  /* bit 3 */
+	unsigned long flags;
 	unsigned int ctrl;
 	enum mxs_auart_type devtype;
 
@@ -130,6 +146,20 @@ struct mxs_auart_port {
 
 	struct clk *clk;
 	struct device *dev;
+
+	/* 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 struct platform_device_id mxs_auart_devtype[] = {
@@ -155,14 +185,107 @@ static inline int is_imx28_auart(struct mxs_auart_port *s)
 	return s->devtype == IMX28_AUART;
 }
 
+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 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);
+
+	/* clear the bit used to serialize the DMA tx. */
+	clear_bit(MXS_AUART_DMA_TX_SYNC, &s->flags);
+	smp_mb__after_clear_bit();
+
+	/* 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] : send PIO. Note, the first pio word is CTRL1. */
+	pio = 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 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;
+
+		if (test_and_set_bit(MXS_AUART_DMA_TX_SYNC, &s->flags))
+			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);
+		} else {
+			clear_bit(MXS_AUART_DMA_TX_SYNC, &s->flags);
+			smp_mb__after_clear_bit();
+		}
+		return;
+	}
+
+
 	while (!(readl(s->port.membase + AUART_STAT) &
 		 AUART_STAT_TXFF)) {
 		if (s->port.x_char) {
@@ -316,10 +439,157 @@ 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;
+	clear_bit(MXS_AUART_DMA_TX_SYNC, &s->flags);
+	clear_bit(MXS_AUART_DMA_RX_READY, &s->flags);
+}
+
+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;
 
@@ -391,10 +661,23 @@ 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 (is_imx28_auart(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);
@@ -406,6 +689,18 @@ 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) &&
+		!test_and_set_bit(MXS_AUART_DMA_RX_READY, &s->flags)) {
+		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)
@@ -484,6 +779,9 @@ 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,
@@ -717,6 +1015,7 @@ 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)
@@ -730,6 +1029,20 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s,
 	}
 	s->port.line = ret;
 
+	s->dma_irq_rx = platform_get_irq(pdev, 1);
+	s->dma_irq_tx = platform_get_irq(pdev, 2);
+
+	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];
+
+		s->flags |= MXS_AUART_DMA_CONFIG;
+	} else {
+		s->dma_channel_rx = -1;
+		s->dma_channel_tx = -1;
+	}
 	return 0;
 }
 
@@ -787,7 +1100,6 @@ 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->irq = platform_get_irq(pdev, 0);
-- 
1.7.0.4

[PATCH v3 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 |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/arch/arm/boot/dts/imx28.dtsi b/arch/arm/boot/dts/imx28.dtsi
index 55c57ea..b4587b2 100644
--- a/arch/arm/boot/dts/imx28.dtsi
+++ b/arch/arm/boot/dts/imx28.dtsi
@@ -799,6 +799,7 @@
 				compatible = "fsl,imx28-auart", "fsl,imx23-auart";
 				reg = <0x8006a000 0x2000>;
 				interrupts = <112 70 71>;
+				fsl,auart-dma-channel = <8 9>;
 				clocks = <&clks 45>;
 				status = "disabled";
 			};
-- 
1.7.0.4

[PATCH v3 0/3] serial: mxs-auart: add DMA support for auart in mx28

[Lauri Hintsala]

Hi Huang,

Thanks for new version. Now I don't get any errors and the CPU doesn't 
freeze any more but:

1) AUART corrupts data with baudrate over 1Mbits/s

2) We would need DMA support without flow control.

By the way, how do you test drivers? Is there any standard tools for 
uart data and throughput testing?

Lauri

On 11/16/2012 10:03 AM, Huang Shijie wrote:
> This patch set adds the DMA support for auart in mx28.
> patch 1:
> 	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.
>
>
> To Lauri: Please try this patch set. thanks.
>
>
> v2 --> v3:
> 	[1] fix a multi-open issue found by Lauri.
>
> v1 --> v2:
> 	[1] use the inline function, not a macro, to distinguish the SOCs.
> 	[2] remove the "inline" for mxs_auart_tx_chars().
> 	[3] use the `pio`, not the `pio[1]` to fill the DMA descriptor.
> 	[4] use bit operation to serialize the DMA TX.
> 	[5] use the RX/TX DMA channel to enable the DMA support, remove the
> 	    "fsl,auart-enable-dma".
>
> 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          |    8 +
>   arch/arm/boot/dts/imx28.dtsi                       |    1 +
>   drivers/tty/serial/mxs-auart.c                     |  364 +++++++++++++++++++-
>   3 files changed, 362 insertions(+), 11 deletions(-)
>
>

[PATCH v3 0/3] serial: mxs-auart: add DMA support for auart in mx28

[Huang Shijie]

On Fri, Nov 16, 2012 at 11:08 PM, Lauri Hintsala
<lauri.hintsala@bluegiga.com> wrote:
> Hi Huang,
>
> Thanks for new version. Now I don't get any errors and the CPU doesn't
> freeze any more but:
>
> 1) AUART corrupts data with baudrate over 1Mbits/s
The tranceivers, such as MAX3380E, will limit the speed.
i ever removed it, and tested the AUART in 3M bits/s.

>
> 2) We would need DMA support without flow control.
:)
I really think it's not wise to support the DMA withou flow control.
it will losts the data in some case.
Even use the FREESCALE's bsp code, I also recomand to use the flow control.


>
> By the way, how do you test drivers? Is there any standard tools for uart
> data and throughput testing?
I tested the driver with our own small tool.
If you want to test it too, I can send you the resource next monday.
You can use it to test if you have received the right data.

thanks
Huang Shijie


>
> Lauri
>
>
> On 11/16/2012 10:03 AM, Huang Shijie wrote:
>>
>> This patch set adds the DMA support for auart in mx28.
>> patch 1:
>>         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.
>>
>>
>> To Lauri: Please try this patch set. thanks.
>>
>>
>> v2 --> v3:
>>         [1] fix a multi-open issue found by Lauri.
>>
>> v1 --> v2:
>>         [1] use the inline function, not a macro, to distinguish the SOCs.
>>         [2] remove the "inline" for mxs_auart_tx_chars().
>>         [3] use the `pio`, not the `pio[1]` to fill the DMA descriptor.
>>         [4] use bit operation to serialize the DMA TX.
>>         [5] use the RX/TX DMA channel to enable the DMA support, remove
>> the
>>             "fsl,auart-enable-dma".
>>
>> 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          |    8 +
>>   arch/arm/boot/dts/imx28.dtsi                       |    1 +
>>   drivers/tty/serial/mxs-auart.c                     |  364
>> +++++++++++++++++++-
>>   3 files changed, 362 insertions(+), 11 deletions(-)
>>
>>
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