Re: [PATCH] atmel_serial: Atmel RS485 support v2

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Philippe De Muyter]

On Wed, Feb 13, 2008 at 08:28:49AM +0000, Alan Cox wrote:
> 
> > Thank you for the feedback.
> >
> > Let me know if this new version solves the above problems.
> 
> Looks good to me. Thanks for the quick clean up.

Could someone add somewhere (Documentation, or usr/include/linux/serial.h)
a precise documentation of how this is to be used from user-space,
and implemented in other drivers ?

Philippe

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Claudio Scordino]

Philippe De Muyter ha scritto:
> On Wed, Feb 13, 2008 at 08:28:49AM +0000, Alan Cox wrote:
>   
>>> Thank you for the feedback.
>>>
>>> Let me know if this new version solves the above problems.
>>>       
>> Looks good to me. Thanks for the quick clean up.
>>     
>
> Could someone add somewhere (Documentation, or usr/include/linux/serial.h)
> a precise documentation of how this is to be used from user-space,
> and implemented in other drivers ?
>   

I can add a short Documention/ file containing information about how to
use ioctls with this driver.

I'll add the document when I'll submit the final patch.

Regards,

            Claudio

[PATCH] atmel_serial: Atmel RS485 support v2

[Claudio Scordino]

Hi all,

   this is the new version of the patch to add RS485 support to the
   atmel_serial driver. It's been changed according to Ryan Mallon's
   comments.

This new patch has been tested again (with and without DMA) by Sebastian
Heutling (CC:-ed).

Many thanks to all,

           Claudio


atmel_serial: Atmel RS485 support

Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
Signed-off-by: Michael Trimarchi <michael@evidence.eu.com>
Signed-off-by: Rick Bronson <rick@efn.org>
Signed-off-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
---
 arch/arm/include/asm/ioctls.h           |    2 +
 arch/arm/mach-at91/include/mach/board.h |    2 +
 drivers/serial/atmel_serial.c           |  244 ++++++++++++++++++++++++++-----
 3 files changed, 212 insertions(+), 36 deletions(-)

diff --git a/arch/arm/include/asm/ioctls.h b/arch/arm/include/asm/ioctls.h
index a91d8a1..82f2177 100644
--- a/arch/arm/include/asm/ioctls.h
+++ b/arch/arm/include/asm/ioctls.h
@@ -70,6 +70,8 @@
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
 #define FIOQSIZE	0x545E
 
+#define TIOCSRS485	0x5461
+
 /* Used for packet mode */
 #define TIOCPKT_DATA		 0
 #define TIOCPKT_FLUSHREAD	 1
diff --git a/arch/arm/mach-at91/include/mach/board.h b/arch/arm/mach-at91/include/mach/board.h
index ceaec6c..fd8a385 100644
--- a/arch/arm/mach-at91/include/mach/board.h
+++ b/arch/arm/mach-at91/include/mach/board.h
@@ -39,6 +39,7 @@
 #include <linux/usb/atmel_usba_udc.h>
 #include <linux/atmel-mci.h>
 #include <sound/atmel-ac97c.h>
+#include <linux/serial.h>
 
  /* USB Device */
 struct at91_udc_data {
@@ -146,6 +147,7 @@ struct atmel_uart_data {
 	short		use_dma_tx;	/* use transmit DMA? */
 	short		use_dma_rx;	/* use receive DMA? */
 	void __iomem	*regs;		/* virtual base address, if any */
+	struct serial_rs485	rs485;	/* rs485 settings */
 };
 extern void __init at91_add_device_serial(void);
 
diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index 2c9bf9b..826a885 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -38,6 +38,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/atmel_pdc.h>
 #include <linux/atmel_serial.h>
+#include <linux/uaccess.h>
 
 #include <asm/io.h>
 
@@ -59,6 +60,9 @@
 
 #include <linux/serial_core.h>
 
+static void atmel_start_rx(struct uart_port *port);
+static void atmel_stop_rx(struct uart_port *port);
+
 #ifdef CONFIG_SERIAL_ATMEL_TTYAT
 
 /* Use device name ttyAT, major 204 and minor 154-169.  This is necessary if we
@@ -93,6 +97,7 @@
 #define UART_GET_BRGR(port)	__raw_readl((port)->membase + ATMEL_US_BRGR)
 #define UART_PUT_BRGR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_BRGR)
 #define UART_PUT_RTOR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_RTOR)
+#define UART_PUT_TTGR(port, v)	__raw_writel(v, (port)->membase + ATMEL_US_TTGR)
 
  /* PDC registers */
 #define UART_PUT_PTCR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_PTCR)
@@ -147,6 +152,10 @@ struct atmel_uart_port {
 	unsigned int		irq_status_prev;
 
 	struct circ_buf		rx_ring;
+
+	struct serial_rs485	rs485;		/* rs485 settings */
+
+	unsigned int		tx_done_mask;
 };
 
 static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
@@ -187,6 +196,81 @@ static bool atmel_use_dma_tx(struct uart_port *port)
 }
 #endif
 
+/* Enable or disable the rs485 support */
+void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	unsigned long flags;
+	unsigned int mode;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	mode = UART_GET_MR(port);
+
+	/* Resetting serial mode to RS232 (0x0) */
+	mode &= ~ATMEL_US_USMODE;
+
+	atmel_port->rs485 = *rs485conf;
+
+	if (rs485conf->flags & SER_RS485_ENABLED) {
+		dev_dbg(port->dev, "Setting UART to RS485\n");
+		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
+		UART_PUT_TTGR(port, rs485conf->delay_rts_before_send);
+		mode |= ATMEL_US_USMODE_RS485;
+	} else {
+		dev_dbg(port->dev, "Setting UART to RS232\n");
+		if (atmel_use_dma_tx(port))
+			atmel_port->tx_done_mask = ATMEL_US_ENDTX | \
+				ATMEL_US_TXBUFE;
+		else
+			atmel_port->tx_done_mask = ATMEL_US_TXRDY;
+	}
+	UART_PUT_MR(port, mode);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+
+static ssize_t show_rs485(struct device *dev, struct device_attribute *attr, \
+			   char *buf)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct uart_port *port = platform_get_drvdata(pdev);
+	unsigned int current_mode;
+
+	current_mode = UART_GET_MR(port) & ATMEL_US_USMODE;
+	return snprintf(buf, PAGE_SIZE, "%u\n", current_mode);
+}
+
+static ssize_t set_rs485(struct device *dev, struct device_attribute *attr, \
+			  const char *buf, size_t len)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct uart_port *port = platform_get_drvdata(pdev);
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	struct serial_rs485 rs485conf = atmel_port->rs485;
+	unsigned int value;
+
+	if (!buf)
+		return -EINVAL;
+
+	value = !!(simple_strtoul(buf, NULL, 0));
+
+	if (value) {
+		rs485conf.flags |= SER_RS485_ENABLED;
+		/* 0x4 is the normal reset value. */
+		rs485conf.delay_rts_before_send = 0x00000004;
+	} else {
+		rs485conf.flags &= ~(SER_RS485_ENABLED);
+	}
+
+	atmel_config_rs485(port, &rs485conf);
+
+	return strnlen(buf, PAGE_SIZE);
+}
+
+static DEVICE_ATTR(rs485, 0644, show_rs485, set_rs485);
+
 /*
  * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
  */
@@ -202,6 +286,7 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
 {
 	unsigned int control = 0;
 	unsigned int mode;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
 #ifdef CONFIG_ARCH_AT91RM9200
 	if (cpu_is_at91rm9200()) {
@@ -236,6 +321,17 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
 		mode |= ATMEL_US_CHMODE_LOC_LOOP;
 	else
 		mode |= ATMEL_US_CHMODE_NORMAL;
+
+	/* Resetting serial mode to RS232 (0x0) */
+	mode &= ~ATMEL_US_USMODE;
+
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+		dev_dbg(port->dev, "Keeping UART to RS485\n");
+		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
+		mode |= ATMEL_US_USMODE_RS485;
+	} else {
+		dev_dbg(port->dev, "Keeping UART to RS232\n");
+	}
 	UART_PUT_MR(port, mode);
 }
 
@@ -268,12 +364,17 @@ static u_int atmel_get_mctrl(struct uart_port *port)
  */
 static void atmel_stop_tx(struct uart_port *port)
 {
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
 	if (atmel_use_dma_tx(port)) {
 		/* disable PDC transmit */
 		UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
-		UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
-	} else
-		UART_PUT_IDR(port, ATMEL_US_TXRDY);
+	}
+	/* Disable interrupts */
+	UART_PUT_IDR(port, atmel_port->tx_done_mask);
+
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+		atmel_start_rx(port);
 }
 
 /*
@@ -281,17 +382,39 @@ static void atmel_stop_tx(struct uart_port *port)
  */
 static void atmel_start_tx(struct uart_port *port)
 {
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
 	if (atmel_use_dma_tx(port)) {
 		if (UART_GET_PTSR(port) & ATMEL_PDC_TXTEN)
 			/* The transmitter is already running.  Yes, we
 			   really need this.*/
 			return;
 
-		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
+		if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+			atmel_stop_rx(port);
+
 		/* re-enable PDC transmit */
 		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
-	} else
-		UART_PUT_IER(port, ATMEL_US_TXRDY);
+	}
+	/* Enable interrupts */
+	UART_PUT_IER(port, atmel_port->tx_done_mask);
+}
+
+/*
+ * start receiving - port is in process of being opened.
+ */
+static void atmel_start_rx(struct uart_port *port)
+{
+	UART_PUT_CR(port, ATMEL_US_RSTSTA);  /* reset status and receiver */
+
+	if (atmel_use_dma_rx(port)) {
+		/* enable PDC controller */
+		UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT | \
+			port->read_status_mask);
+		UART_PUT_PTCR(port, ATMEL_PDC_RXTEN);
+	} else {
+		UART_PUT_IER(port, ATMEL_US_RXRDY);
+	}
 }
 
 /*
@@ -302,9 +425,11 @@ static void atmel_stop_rx(struct uart_port *port)
 	if (atmel_use_dma_rx(port)) {
 		/* disable PDC receive */
 		UART_PUT_PTCR(port, ATMEL_PDC_RXTDIS);
-		UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
-	} else
+		UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT | \
+			port->read_status_mask);
+	} else {
 		UART_PUT_IDR(port, ATMEL_US_RXRDY);
+	}
 }
 
 /*
@@ -428,8 +553,9 @@ static void atmel_rx_chars(struct uart_port *port)
 static void atmel_tx_chars(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->state->xmit;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
-	if (port->x_char && UART_GET_CSR(port) & ATMEL_US_TXRDY) {
+	if (port->x_char && UART_GET_CSR(port) & atmel_port->tx_done_mask) {
 		UART_PUT_CHAR(port, port->x_char);
 		port->icount.tx++;
 		port->x_char = 0;
@@ -437,7 +563,7 @@ static void atmel_tx_chars(struct uart_port *port)
 	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 		return;
 
-	while (UART_GET_CSR(port) & ATMEL_US_TXRDY) {
+	while (UART_GET_CSR(port) & atmel_port->tx_done_mask) {
 		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 		port->icount.tx++;
@@ -449,7 +575,8 @@ static void atmel_tx_chars(struct uart_port *port)
 		uart_write_wakeup(port);
 
 	if (!uart_circ_empty(xmit))
-		UART_PUT_IER(port, ATMEL_US_TXRDY);
+		/* Enable interrupts */
+		UART_PUT_IER(port, atmel_port->tx_done_mask);
 }
 
 /*
@@ -501,18 +628,10 @@ atmel_handle_transmit(struct uart_port *port, unsigned int pending)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
-	if (atmel_use_dma_tx(port)) {
-		/* PDC transmit */
-		if (pending & (ATMEL_US_ENDTX | ATMEL_US_TXBUFE)) {
-			UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
-			tasklet_schedule(&atmel_port->tasklet);
-		}
-	} else {
-		/* Interrupt transmit */
-		if (pending & ATMEL_US_TXRDY) {
-			UART_PUT_IDR(port, ATMEL_US_TXRDY);
-			tasklet_schedule(&atmel_port->tasklet);
-		}
+	if (pending & atmel_port->tx_done_mask) {
+		/* Either PDC or interrupt transmission */
+		UART_PUT_IDR(port, atmel_port->tx_done_mask);
+		tasklet_schedule(&atmel_port->tasklet);
 	}
 }
 
@@ -590,9 +709,15 @@ static void atmel_tx_dma(struct uart_port *port)
 
 		UART_PUT_TPR(port, pdc->dma_addr + xmit->tail);
 		UART_PUT_TCR(port, count);
-		/* re-enable PDC transmit and interrupts */
+		/* re-enable PDC transmit */
 		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
-		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
+		/* Enable interrupts */
+		UART_PUT_IER(port, atmel_port->tx_done_mask);
+	} else {
+		if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+			/* DMA done, stop TX, start RX for RS485 */
+			atmel_start_rx(port);
+		}
 	}
 
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
@@ -1017,6 +1142,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 {
 	unsigned long flags;
 	unsigned int mode, imr, quot, baud;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
 	/* Get current mode register */
 	mode = UART_GET_MR(port) & ~(ATMEL_US_USCLKS | ATMEL_US_CHRL
@@ -1115,6 +1241,17 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 	/* disable receiver and transmitter */
 	UART_PUT_CR(port, ATMEL_US_TXDIS | ATMEL_US_RXDIS);
 
+	/* Resetting serial mode to RS232 (0x0) */
+	mode &= ~ATMEL_US_USMODE;
+
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+		dev_dbg(port->dev, "Keeping UART to RS485\n");
+		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
+		mode |= ATMEL_US_USMODE_RS485;
+	} else {
+		dev_dbg(port->dev, "Keeping UART to RS232\n");
+	}
+
 	/* set the parity, stop bits and data size */
 	UART_PUT_MR(port, mode);
 
@@ -1231,6 +1368,30 @@ static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
 }
 #endif
 
+static int
+atmel_ioctl(struct uart_port *port, unsigned int cmd, unsigned long arg)
+{
+	struct serial_rs485 rs485conf;
+
+	switch (cmd) {
+	case TIOCSRS485:
+		if (copy_from_user(&rs485conf, (struct serial_rs485 *) arg, \
+					sizeof(rs485conf)))
+			return -EFAULT;
+
+		dev_dbg(port->dev, "enable e/o disable rs485\n");
+
+		atmel_config_rs485(port, &rs485conf);
+		break;
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+	return 0;
+}
+
+
+
 static struct uart_ops atmel_pops = {
 	.tx_empty	= atmel_tx_empty,
 	.set_mctrl	= atmel_set_mctrl,
@@ -1250,6 +1411,7 @@ static struct uart_ops atmel_pops = {
 	.config_port	= atmel_config_port,
 	.verify_port	= atmel_verify_port,
 	.pm		= atmel_serial_pm,
+	.ioctl		= atmel_ioctl,
 #ifdef CONFIG_CONSOLE_POLL
 	.poll_get_char	= atmel_poll_get_char,
 	.poll_put_char	= atmel_poll_put_char,
@@ -1265,13 +1427,12 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
 	struct uart_port *port = &atmel_port->uart;
 	struct atmel_uart_data *data = pdev->dev.platform_data;
 
-	port->iotype	= UPIO_MEM;
-	port->flags	= UPF_BOOT_AUTOCONF;
-	port->ops	= &atmel_pops;
-	port->fifosize	= 1;
-	port->line	= pdev->id;
-	port->dev	= &pdev->dev;
-
+	port->iotype		= UPIO_MEM;
+	port->flags		= UPF_BOOT_AUTOCONF;
+	port->ops		= &atmel_pops;
+	port->fifosize		= 1;
+	port->line		= pdev->id;
+	port->dev		= &pdev->dev;
 	port->mapbase	= pdev->resource[0].start;
 	port->irq	= pdev->resource[1].start;
 
@@ -1299,8 +1460,16 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
 
 	atmel_port->use_dma_rx = data->use_dma_rx;
 	atmel_port->use_dma_tx = data->use_dma_tx;
-	if (atmel_use_dma_tx(port))
+	atmel_port->rs485	= data->rs485;
+	/* Use TXEMPTY for interrupt when rs485 else TXRDY or ENDTX|TXBUFE */
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
+	else if (atmel_use_dma_tx(port)) {
 		port->fifosize = PDC_BUFFER_SIZE;
+		atmel_port->tx_done_mask = ATMEL_US_ENDTX | ATMEL_US_TXBUFE;
+	} else {
+		atmel_port->tx_done_mask = ATMEL_US_TXRDY;
+	}
 }
 
 /*
@@ -1334,6 +1503,7 @@ static void atmel_console_putchar(struct uart_port *port, int ch)
 static void atmel_console_write(struct console *co, const char *s, u_int count)
 {
 	struct uart_port *port = &atmel_ports[co->index].uart;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 	unsigned int status, imr;
 	unsigned int pdc_tx;
 
@@ -1341,7 +1511,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
 	 * First, save IMR and then disable interrupts
 	 */
 	imr = UART_GET_IMR(port);
-	UART_PUT_IDR(port, ATMEL_US_RXRDY | ATMEL_US_TXRDY);
+	UART_PUT_IDR(port, ATMEL_US_RXRDY | atmel_port->tx_done_mask);
 
 	/* Store PDC transmit status and disable it */
 	pdc_tx = UART_GET_PTSR(port) & ATMEL_PDC_TXTEN;
@@ -1355,7 +1525,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
 	 */
 	do {
 		status = UART_GET_CSR(port);
-	} while (!(status & ATMEL_US_TXRDY));
+	} while (!(status & atmel_port->tx_done_mask));
 
 	/* Restore PDC transmit status */
 	if (pdc_tx)
@@ -1587,7 +1757,7 @@ static int __devinit atmel_serial_probe(struct platform_device *pdev)
 	device_init_wakeup(&pdev->dev, 1);
 	platform_set_drvdata(pdev, port);
 
-	return 0;
+	return device_create_file(&(pdev->dev), &dev_attr_rs485);
 
 err_add_port:
 	kfree(port->rx_ring.buf);
@@ -1619,6 +1789,8 @@ static int __devexit atmel_serial_remove(struct platform_device *pdev)
 
 	clk_put(atmel_port->clk);
 
+	device_remove_file(&(pdev->dev), &dev_attr_rs485);
+
 	return ret;
 }
 
-- 
1.6.0.4

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Ryan Mallon]

Claudio Scordino wrote:
> Hi all,
> 
>    this is the new version of the patch to add RS485 support to the
>    atmel_serial driver. It's been changed according to Ryan Mallon's
>    comments.
> 
> This new patch has been tested again (with and without DMA) by Sebastian
> Heutling (CC:-ed).

A few more, mostly nitpicky, comments below.

> Many thanks to all,
> 
>            Claudio
> 
> 
> atmel_serial: Atmel RS485 support
> 
> Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
> Signed-off-by: Michael Trimarchi <michael@evidence.eu.com>
> Signed-off-by: Rick Bronson <rick@efn.org>
> Signed-off-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
> ---
>  arch/arm/include/asm/ioctls.h           |    2 +
>  arch/arm/mach-at91/include/mach/board.h |    2 +
>  drivers/serial/atmel_serial.c           |  244 ++++++++++++++++++++++++++-----
>  3 files changed, 212 insertions(+), 36 deletions(-)
> 
> diff --git a/arch/arm/include/asm/ioctls.h b/arch/arm/include/asm/ioctls.h
> index a91d8a1..82f2177 100644
> --- a/arch/arm/include/asm/ioctls.h
> +++ b/arch/arm/include/asm/ioctls.h
> @@ -70,6 +70,8 @@
>  #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
>  #define FIOQSIZE	0x545E
>  
> +#define TIOCSRS485	0x5461
> +
>  /* Used for packet mode */
>  #define TIOCPKT_DATA		 0
>  #define TIOCPKT_FLUSHREAD	 1
> diff --git a/arch/arm/mach-at91/include/mach/board.h b/arch/arm/mach-at91/include/mach/board.h
> index ceaec6c..fd8a385 100644
> --- a/arch/arm/mach-at91/include/mach/board.h
> +++ b/arch/arm/mach-at91/include/mach/board.h
> @@ -39,6 +39,7 @@
>  #include <linux/usb/atmel_usba_udc.h>
>  #include <linux/atmel-mci.h>
>  #include <sound/atmel-ac97c.h>
> +#include <linux/serial.h>
>  
>   /* USB Device */
>  struct at91_udc_data {
> @@ -146,6 +147,7 @@ struct atmel_uart_data {
>  	short		use_dma_tx;	/* use transmit DMA? */
>  	short		use_dma_rx;	/* use receive DMA? */
>  	void __iomem	*regs;		/* virtual base address, if any */
> +	struct serial_rs485	rs485;	/* rs485 settings */
>  };

Can you re-indent this structure so the rest of the members line up with
the new rs485 one.

>  extern void __init at91_add_device_serial(void);
>  
> diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
> index 2c9bf9b..826a885 100644
> --- a/drivers/serial/atmel_serial.c
> +++ b/drivers/serial/atmel_serial.c
> @@ -38,6 +38,7 @@
>  #include <linux/dma-mapping.h>
>  #include <linux/atmel_pdc.h>
>  #include <linux/atmel_serial.h>
> +#include <linux/uaccess.h>
>  
>  #include <asm/io.h>
>  
> @@ -59,6 +60,9 @@
>  
>  #include <linux/serial_core.h>
>  
> +static void atmel_start_rx(struct uart_port *port);
> +static void atmel_stop_rx(struct uart_port *port);
> +
>  #ifdef CONFIG_SERIAL_ATMEL_TTYAT
>  
>  /* Use device name ttyAT, major 204 and minor 154-169.  This is necessary if we
> @@ -93,6 +97,7 @@
>  #define UART_GET_BRGR(port)	__raw_readl((port)->membase + ATMEL_US_BRGR)
>  #define UART_PUT_BRGR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_BRGR)
>  #define UART_PUT_RTOR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_RTOR)
> +#define UART_PUT_TTGR(port, v)	__raw_writel(v, (port)->membase + ATMEL_US_TTGR)
>  
>   /* PDC registers */
>  #define UART_PUT_PTCR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_PTCR)
> @@ -147,6 +152,10 @@ struct atmel_uart_port {
>  	unsigned int		irq_status_prev;
>  
>  	struct circ_buf		rx_ring;
> +
> +	struct serial_rs485	rs485;		/* rs485 settings */
> +
> +	unsigned int		tx_done_mask;
>  };

Do we need all the whitespace here?

>  static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
> @@ -187,6 +196,81 @@ static bool atmel_use_dma_tx(struct uart_port *port)
>  }
>  #endif
>  
> +/* Enable or disable the rs485 support */
> +void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
> +{
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> +	unsigned long flags;
> +	unsigned int mode;
> +
> +	spin_lock_irqsave(&port->lock, flags);
> +
> +	mode = UART_GET_MR(port);
> +
> +	/* Resetting serial mode to RS232 (0x0) */
> +	mode &= ~ATMEL_US_USMODE;
> +
> +	atmel_port->rs485 = *rs485conf;
> +
> +	if (rs485conf->flags & SER_RS485_ENABLED) {
> +		dev_dbg(port->dev, "Setting UART to RS485\n");
> +		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
> +		UART_PUT_TTGR(port, rs485conf->delay_rts_before_send);
> +		mode |= ATMEL_US_USMODE_RS485;
> +	} else {
> +		dev_dbg(port->dev, "Setting UART to RS232\n");
> +		if (atmel_use_dma_tx(port))
> +			atmel_port->tx_done_mask = ATMEL_US_ENDTX | \
> +				ATMEL_US_TXBUFE;

You only need to use backslashes on split lines in macro definitions.

> +		else
> +			atmel_port->tx_done_mask = ATMEL_US_TXRDY;
> +	}
> +	UART_PUT_MR(port, mode);
> +
> +	spin_unlock_irqrestore(&port->lock, flags);
> +}
> +
> +
> +static ssize_t show_rs485(struct device *dev, struct device_attribute *attr, \
> +			   char *buf)
> +{

Same here, and a couple more places.

> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct uart_port *port = platform_get_drvdata(pdev);
> +	unsigned int current_mode;
> +
> +	current_mode = UART_GET_MR(port) & ATMEL_US_USMODE;
> +	return snprintf(buf, PAGE_SIZE, "%u\n", current_mode);
> +}
> +
> +static ssize_t set_rs485(struct device *dev, struct device_attribute *attr, \
> +			  const char *buf, size_t len)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct uart_port *port = platform_get_drvdata(pdev);
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> +	struct serial_rs485 rs485conf = atmel_port->rs485;
> +	unsigned int value;
> +
> +	if (!buf)
> +		return -EINVAL;
> +
> +	value = !!(simple_strtoul(buf, NULL, 0));
> +
> +	if (value) {
> +		rs485conf.flags |= SER_RS485_ENABLED;
> +		/* 0x4 is the normal reset value. */
> +		rs485conf.delay_rts_before_send = 0x00000004;
> +	} else {
> +		rs485conf.flags &= ~(SER_RS485_ENABLED);

Don't need the parenthesis here.

> +	}
> +
> +	atmel_config_rs485(port, &rs485conf);
> +
> +	return strnlen(buf, PAGE_SIZE);
> +}
> +
> +static DEVICE_ATTR(rs485, 0644, show_rs485, set_rs485);
> +
>  /*
>   * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
>   */
> @@ -202,6 +286,7 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
>  {
>  	unsigned int control = 0;
>  	unsigned int mode;
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
>  
>  #ifdef CONFIG_ARCH_AT91RM9200
>  	if (cpu_is_at91rm9200()) {
> @@ -236,6 +321,17 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
>  		mode |= ATMEL_US_CHMODE_LOC_LOOP;
>  	else
>  		mode |= ATMEL_US_CHMODE_NORMAL;
> +
> +	/* Resetting serial mode to RS232 (0x0) */
> +	mode &= ~ATMEL_US_USMODE;
> +
> +	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
> +		dev_dbg(port->dev, "Keeping UART to RS485\n");

"Setting" UART to RS485 probably makes more sense here (and couple of
other places).

> +		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
> +		mode |= ATMEL_US_USMODE_RS485;
> +	} else {
> +		dev_dbg(port->dev, "Keeping UART to RS232\n");
> +	}
>  	UART_PUT_MR(port, mode);
>  }
>  
> @@ -268,12 +364,17 @@ static u_int atmel_get_mctrl(struct uart_port *port)
>   */
>  static void atmel_stop_tx(struct uart_port *port)
>  {
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> +
>  	if (atmel_use_dma_tx(port)) {
>  		/* disable PDC transmit */
>  		UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
> -		UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
> -	} else
> -		UART_PUT_IDR(port, ATMEL_US_TXRDY);
> +	}
> +	/* Disable interrupts */
> +	UART_PUT_IDR(port, atmel_port->tx_done_mask);
> +
> +	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
> +		atmel_start_rx(port);
>  }
>  
>  /*
> @@ -281,17 +382,39 @@ static void atmel_stop_tx(struct uart_port *port)
>   */
>  static void atmel_start_tx(struct uart_port *port)
>  {
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> +
>  	if (atmel_use_dma_tx(port)) {
>  		if (UART_GET_PTSR(port) & ATMEL_PDC_TXTEN)
>  			/* The transmitter is already running.  Yes, we
>  			   really need this.*/
>  			return;
>  
> -		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
> +		if (atmel_port->rs485.flags & SER_RS485_ENABLED)
> +			atmel_stop_rx(port);
> +
>  		/* re-enable PDC transmit */
>  		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
> -	} else
> -		UART_PUT_IER(port, ATMEL_US_TXRDY);
> +	}
> +	/* Enable interrupts */
> +	UART_PUT_IER(port, atmel_port->tx_done_mask);
> +}
> +
> +/*
> + * start receiving - port is in process of being opened.
> + */
> +static void atmel_start_rx(struct uart_port *port)
> +{
> +	UART_PUT_CR(port, ATMEL_US_RSTSTA);  /* reset status and receiver */
> +
> +	if (atmel_use_dma_rx(port)) {
> +		/* enable PDC controller */
> +		UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT | \
> +			port->read_status_mask);
> +		UART_PUT_PTCR(port, ATMEL_PDC_RXTEN);
> +	} else {
> +		UART_PUT_IER(port, ATMEL_US_RXRDY);
> +	}
>  }
>  
>  /*
> @@ -302,9 +425,11 @@ static void atmel_stop_rx(struct uart_port *port)
>  	if (atmel_use_dma_rx(port)) {
>  		/* disable PDC receive */
>  		UART_PUT_PTCR(port, ATMEL_PDC_RXTDIS);
> -		UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
> -	} else
> +		UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT | \
> +			port->read_status_mask);
> +	} else {
>  		UART_PUT_IDR(port, ATMEL_US_RXRDY);
> +	}
>  }
>  
>  /*
> @@ -428,8 +553,9 @@ static void atmel_rx_chars(struct uart_port *port)
>  static void atmel_tx_chars(struct uart_port *port)
>  {
>  	struct circ_buf *xmit = &port->state->xmit;
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
>  
> -	if (port->x_char && UART_GET_CSR(port) & ATMEL_US_TXRDY) {
> +	if (port->x_char && UART_GET_CSR(port) & atmel_port->tx_done_mask) {
>  		UART_PUT_CHAR(port, port->x_char);
>  		port->icount.tx++;
>  		port->x_char = 0;
> @@ -437,7 +563,7 @@ static void atmel_tx_chars(struct uart_port *port)
>  	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
>  		return;
>  
> -	while (UART_GET_CSR(port) & ATMEL_US_TXRDY) {
> +	while (UART_GET_CSR(port) & atmel_port->tx_done_mask) {
>  		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
>  		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
>  		port->icount.tx++;
> @@ -449,7 +575,8 @@ static void atmel_tx_chars(struct uart_port *port)
>  		uart_write_wakeup(port);
>  
>  	if (!uart_circ_empty(xmit))
> -		UART_PUT_IER(port, ATMEL_US_TXRDY);
> +		/* Enable interrupts */
> +		UART_PUT_IER(port, atmel_port->tx_done_mask);
>  }
>  
>  /*
> @@ -501,18 +628,10 @@ atmel_handle_transmit(struct uart_port *port, unsigned int pending)
>  {
>  	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
>  
> -	if (atmel_use_dma_tx(port)) {
> -		/* PDC transmit */
> -		if (pending & (ATMEL_US_ENDTX | ATMEL_US_TXBUFE)) {
> -			UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
> -			tasklet_schedule(&atmel_port->tasklet);
> -		}
> -	} else {
> -		/* Interrupt transmit */
> -		if (pending & ATMEL_US_TXRDY) {
> -			UART_PUT_IDR(port, ATMEL_US_TXRDY);
> -			tasklet_schedule(&atmel_port->tasklet);
> -		}
> +	if (pending & atmel_port->tx_done_mask) {
> +		/* Either PDC or interrupt transmission */
> +		UART_PUT_IDR(port, atmel_port->tx_done_mask);
> +		tasklet_schedule(&atmel_port->tasklet);
>  	}
>  }
>  
> @@ -590,9 +709,15 @@ static void atmel_tx_dma(struct uart_port *port)
>  
>  		UART_PUT_TPR(port, pdc->dma_addr + xmit->tail);
>  		UART_PUT_TCR(port, count);
> -		/* re-enable PDC transmit and interrupts */
> +		/* re-enable PDC transmit */
>  		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
> -		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
> +		/* Enable interrupts */
> +		UART_PUT_IER(port, atmel_port->tx_done_mask);
> +	} else {
> +		if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
> +			/* DMA done, stop TX, start RX for RS485 */
> +			atmel_start_rx(port);
> +		}
>  	}
>  
>  	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
> @@ -1017,6 +1142,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
>  {
>  	unsigned long flags;
>  	unsigned int mode, imr, quot, baud;
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
>  
>  	/* Get current mode register */
>  	mode = UART_GET_MR(port) & ~(ATMEL_US_USCLKS | ATMEL_US_CHRL
> @@ -1115,6 +1241,17 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
>  	/* disable receiver and transmitter */
>  	UART_PUT_CR(port, ATMEL_US_TXDIS | ATMEL_US_RXDIS);
>  
> +	/* Resetting serial mode to RS232 (0x0) */
> +	mode &= ~ATMEL_US_USMODE;
> +
> +	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
> +		dev_dbg(port->dev, "Keeping UART to RS485\n");
> +		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
> +		mode |= ATMEL_US_USMODE_RS485;
> +	} else {
> +		dev_dbg(port->dev, "Keeping UART to RS232\n");
> +	}
> +
>  	/* set the parity, stop bits and data size */
>  	UART_PUT_MR(port, mode);
>  
> @@ -1231,6 +1368,30 @@ static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
>  }
>  #endif
>  
> +static int
> +atmel_ioctl(struct uart_port *port, unsigned int cmd, unsigned long arg)
> +{
> +	struct serial_rs485 rs485conf;
> +
> +	switch (cmd) {
> +	case TIOCSRS485:
> +		if (copy_from_user(&rs485conf, (struct serial_rs485 *) arg, \
> +					sizeof(rs485conf)))
> +			return -EFAULT;
> +
> +		dev_dbg(port->dev, "enable e/o disable rs485\n");

You could remove this dev_dbg since amtel_config_rs485 already prints
debug information.

> +
> +		atmel_config_rs485(port, &rs485conf);
> +		break;
> +
> +	default:
> +		return -ENOIOCTLCMD;
> +	}
> +	return 0;
> +}
> +
> +
> +
>  static struct uart_ops atmel_pops = {
>  	.tx_empty	= atmel_tx_empty,
>  	.set_mctrl	= atmel_set_mctrl,
> @@ -1250,6 +1411,7 @@ static struct uart_ops atmel_pops = {
>  	.config_port	= atmel_config_port,
>  	.verify_port	= atmel_verify_port,
>  	.pm		= atmel_serial_pm,
> +	.ioctl		= atmel_ioctl,
>  #ifdef CONFIG_CONSOLE_POLL
>  	.poll_get_char	= atmel_poll_get_char,
>  	.poll_put_char	= atmel_poll_put_char,
> @@ -1265,13 +1427,12 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
>  	struct uart_port *port = &atmel_port->uart;
>  	struct atmel_uart_data *data = pdev->dev.platform_data;
>  
> -	port->iotype	= UPIO_MEM;
> -	port->flags	= UPF_BOOT_AUTOCONF;
> -	port->ops	= &atmel_pops;
> -	port->fifosize	= 1;
> -	port->line	= pdev->id;
> -	port->dev	= &pdev->dev;
> -
> +	port->iotype		= UPIO_MEM;
> +	port->flags		= UPF_BOOT_AUTOCONF;
> +	port->ops		= &atmel_pops;
> +	port->fifosize		= 1;
> +	port->line		= pdev->id;
> +	port->dev		= &pdev->dev;
>  	port->mapbase	= pdev->resource[0].start;
>  	port->irq	= pdev->resource[1].start;
>  
> @@ -1299,8 +1460,16 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
>  
>  	atmel_port->use_dma_rx = data->use_dma_rx;
>  	atmel_port->use_dma_tx = data->use_dma_tx;
> -	if (atmel_use_dma_tx(port))
> +	atmel_port->rs485	= data->rs485;
> +	/* Use TXEMPTY for interrupt when rs485 else TXRDY or ENDTX|TXBUFE */
> +	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
> +		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
> +	else if (atmel_use_dma_tx(port)) {
>  		port->fifosize = PDC_BUFFER_SIZE;
> +		atmel_port->tx_done_mask = ATMEL_US_ENDTX | ATMEL_US_TXBUFE;
> +	} else {
> +		atmel_port->tx_done_mask = ATMEL_US_TXRDY;
> +	}
>  }
>  
>  /*
> @@ -1334,6 +1503,7 @@ static void atmel_console_putchar(struct uart_port *port, int ch)
>  static void atmel_console_write(struct console *co, const char *s, u_int count)
>  {
>  	struct uart_port *port = &atmel_ports[co->index].uart;
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
>  	unsigned int status, imr;
>  	unsigned int pdc_tx;
>  
> @@ -1341,7 +1511,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
>  	 * First, save IMR and then disable interrupts
>  	 */
>  	imr = UART_GET_IMR(port);
> -	UART_PUT_IDR(port, ATMEL_US_RXRDY | ATMEL_US_TXRDY);
> +	UART_PUT_IDR(port, ATMEL_US_RXRDY | atmel_port->tx_done_mask);
>  
>  	/* Store PDC transmit status and disable it */
>  	pdc_tx = UART_GET_PTSR(port) & ATMEL_PDC_TXTEN;
> @@ -1355,7 +1525,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
>  	 */
>  	do {
>  		status = UART_GET_CSR(port);
> -	} while (!(status & ATMEL_US_TXRDY));
> +	} while (!(status & atmel_port->tx_done_mask));
>  
>  	/* Restore PDC transmit status */
>  	if (pdc_tx)
> @@ -1587,7 +1757,7 @@ static int __devinit atmel_serial_probe(struct platform_device *pdev)
>  	device_init_wakeup(&pdev->dev, 1);
>  	platform_set_drvdata(pdev, port);
>  
> -	return 0;
> +	return device_create_file(&(pdev->dev), &dev_attr_rs485);
>  
>  err_add_port:
>  	kfree(port->rx_ring.buf);
> @@ -1619,6 +1789,8 @@ static int __devexit atmel_serial_remove(struct platform_device *pdev)
>  
>  	clk_put(atmel_port->clk);
>  
> +	device_remove_file(&(pdev->dev), &dev_attr_rs485);
> +
>  	return ret;
>  }
>  

~Ryan

-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Claudio Scordino]

Ryan Mallon ha scritto:
> Claudio Scordino wrote:
>> Hi all,
>>
>>    this is the new version of the patch to add RS485 support to the
>>    atmel_serial driver. It's been changed according to Ryan Mallon's
>>    comments.
>>
>> This new patch has been tested again (with and without DMA) by Sebastian
>> Heutling (CC:-ed).
> 
> A few more, mostly nitpicky, comments below.

Hi Ryan,

   many thanks for your feedback.

Please find attached a new version of the patch, modified according to
your comments.

Regards,

         Claudio


atmel_serial: Atmel RS485 support

Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
Signed-off-by: Michael Trimarchi <michael@evidence.eu.com>
Signed-off-by: Rick Bronson <rick@efn.org>
Signed-off-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
---
 arch/arm/include/asm/ioctls.h           |    2 +
 arch/arm/mach-at91/include/mach/board.h |    8 +-
 drivers/serial/atmel_serial.c           |  241 ++++++++++++++++++++++++++-----
 3 files changed, 212 insertions(+), 39 deletions(-)

diff --git a/arch/arm/include/asm/ioctls.h b/arch/arm/include/asm/ioctls.h
index a91d8a1..82f2177 100644
--- a/arch/arm/include/asm/ioctls.h
+++ b/arch/arm/include/asm/ioctls.h
@@ -70,6 +70,8 @@
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
 #define FIOQSIZE	0x545E
 
+#define TIOCSRS485	0x5461
+
 /* Used for packet mode */
 #define TIOCPKT_DATA		 0
 #define TIOCPKT_FLUSHREAD	 1
diff --git a/arch/arm/mach-at91/include/mach/board.h b/arch/arm/mach-at91/include/mach/board.h
index ceaec6c..df2ed84 100644
--- a/arch/arm/mach-at91/include/mach/board.h
+++ b/arch/arm/mach-at91/include/mach/board.h
@@ -39,6 +39,7 @@
 #include <linux/usb/atmel_usba_udc.h>
 #include <linux/atmel-mci.h>
 #include <sound/atmel-ac97c.h>
+#include <linux/serial.h>
 
  /* USB Device */
 struct at91_udc_data {
@@ -143,9 +144,10 @@ extern struct platform_device *atmel_default_console_device;
 extern void __init __deprecated at91_init_serial(struct at91_uart_config *config);
 
 struct atmel_uart_data {
-	short		use_dma_tx;	/* use transmit DMA? */
-	short		use_dma_rx;	/* use receive DMA? */
-	void __iomem	*regs;		/* virtual base address, if any */
+	short			use_dma_tx;	/* use transmit DMA? */
+	short			use_dma_rx;	/* use receive DMA? */
+	void __iomem		*regs;		/* virt. base address, if any */
+	struct serial_rs485	rs485;		/* rs485 settings */
 };
 extern void __init at91_add_device_serial(void);
 
diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index 2c9bf9b..039cd65 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -38,6 +38,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/atmel_pdc.h>
 #include <linux/atmel_serial.h>
+#include <linux/uaccess.h>
 
 #include <asm/io.h>
 
@@ -59,6 +60,9 @@
 
 #include <linux/serial_core.h>
 
+static void atmel_start_rx(struct uart_port *port);
+static void atmel_stop_rx(struct uart_port *port);
+
 #ifdef CONFIG_SERIAL_ATMEL_TTYAT
 
 /* Use device name ttyAT, major 204 and minor 154-169.  This is necessary if we
@@ -93,6 +97,7 @@
 #define UART_GET_BRGR(port)	__raw_readl((port)->membase + ATMEL_US_BRGR)
 #define UART_PUT_BRGR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_BRGR)
 #define UART_PUT_RTOR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_RTOR)
+#define UART_PUT_TTGR(port, v)	__raw_writel(v, (port)->membase + ATMEL_US_TTGR)
 
  /* PDC registers */
 #define UART_PUT_PTCR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_PTCR)
@@ -147,6 +152,9 @@ struct atmel_uart_port {
 	unsigned int		irq_status_prev;
 
 	struct circ_buf		rx_ring;
+
+	struct serial_rs485	rs485;		/* rs485 settings */
+	unsigned int		tx_done_mask;
 };
 
 static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
@@ -187,6 +195,81 @@ static bool atmel_use_dma_tx(struct uart_port *port)
 }
 #endif
 
+/* Enable or disable the rs485 support */
+void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	unsigned long flags;
+	unsigned int mode;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	mode = UART_GET_MR(port);
+
+	/* Resetting serial mode to RS232 (0x0) */
+	mode &= ~ATMEL_US_USMODE;
+
+	atmel_port->rs485 = *rs485conf;
+
+	if (rs485conf->flags & SER_RS485_ENABLED) {
+		dev_dbg(port->dev, "Setting UART to RS485\n");
+		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
+		UART_PUT_TTGR(port, rs485conf->delay_rts_before_send);
+		mode |= ATMEL_US_USMODE_RS485;
+	} else {
+		dev_dbg(port->dev, "Setting UART to RS232\n");
+		if (atmel_use_dma_tx(port))
+			atmel_port->tx_done_mask = ATMEL_US_ENDTX |
+				ATMEL_US_TXBUFE;
+		else
+			atmel_port->tx_done_mask = ATMEL_US_TXRDY;
+	}
+	UART_PUT_MR(port, mode);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+
+static ssize_t show_rs485(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct uart_port *port = platform_get_drvdata(pdev);
+	unsigned int current_mode;
+
+	current_mode = UART_GET_MR(port) & ATMEL_US_USMODE;
+	return snprintf(buf, PAGE_SIZE, "%u\n", current_mode);
+}
+
+static ssize_t set_rs485(struct device *dev, struct device_attribute *attr,
+			  const char *buf, size_t len)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct uart_port *port = platform_get_drvdata(pdev);
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	struct serial_rs485 rs485conf = atmel_port->rs485;
+	unsigned int value;
+
+	if (!buf)
+		return -EINVAL;
+
+	value = !!(simple_strtoul(buf, NULL, 0));
+
+	if (value) {
+		rs485conf.flags |= SER_RS485_ENABLED;
+		/* 0x4 is the normal reset value. */
+		rs485conf.delay_rts_before_send = 0x00000004;
+	} else {
+		rs485conf.flags &= ~SER_RS485_ENABLED;
+	}
+
+	atmel_config_rs485(port, &rs485conf);
+
+	return strnlen(buf, PAGE_SIZE);
+}
+
+static DEVICE_ATTR(rs485, 0644, show_rs485, set_rs485);
+
 /*
  * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
  */
@@ -202,6 +285,7 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
 {
 	unsigned int control = 0;
 	unsigned int mode;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
 #ifdef CONFIG_ARCH_AT91RM9200
 	if (cpu_is_at91rm9200()) {
@@ -236,6 +320,17 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
 		mode |= ATMEL_US_CHMODE_LOC_LOOP;
 	else
 		mode |= ATMEL_US_CHMODE_NORMAL;
+
+	/* Resetting serial mode to RS232 (0x0) */
+	mode &= ~ATMEL_US_USMODE;
+
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+		dev_dbg(port->dev, "Setting UART to RS485\n");
+		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
+		mode |= ATMEL_US_USMODE_RS485;
+	} else {
+		dev_dbg(port->dev, "Setting UART to RS232\n");
+	}
 	UART_PUT_MR(port, mode);
 }
 
@@ -268,12 +363,17 @@ static u_int atmel_get_mctrl(struct uart_port *port)
  */
 static void atmel_stop_tx(struct uart_port *port)
 {
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
 	if (atmel_use_dma_tx(port)) {
 		/* disable PDC transmit */
 		UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
-		UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
-	} else
-		UART_PUT_IDR(port, ATMEL_US_TXRDY);
+	}
+	/* Disable interrupts */
+	UART_PUT_IDR(port, atmel_port->tx_done_mask);
+
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+		atmel_start_rx(port);
 }
 
 /*
@@ -281,17 +381,39 @@ static void atmel_stop_tx(struct uart_port *port)
  */
 static void atmel_start_tx(struct uart_port *port)
 {
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
 	if (atmel_use_dma_tx(port)) {
 		if (UART_GET_PTSR(port) & ATMEL_PDC_TXTEN)
 			/* The transmitter is already running.  Yes, we
 			   really need this.*/
 			return;
 
-		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
+		if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+			atmel_stop_rx(port);
+
 		/* re-enable PDC transmit */
 		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
-	} else
-		UART_PUT_IER(port, ATMEL_US_TXRDY);
+	}
+	/* Enable interrupts */
+	UART_PUT_IER(port, atmel_port->tx_done_mask);
+}
+
+/*
+ * start receiving - port is in process of being opened.
+ */
+static void atmel_start_rx(struct uart_port *port)
+{
+	UART_PUT_CR(port, ATMEL_US_RSTSTA);  /* reset status and receiver */
+
+	if (atmel_use_dma_rx(port)) {
+		/* enable PDC controller */
+		UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
+			port->read_status_mask);
+		UART_PUT_PTCR(port, ATMEL_PDC_RXTEN);
+	} else {
+		UART_PUT_IER(port, ATMEL_US_RXRDY);
+	}
 }
 
 /*
@@ -302,9 +424,11 @@ static void atmel_stop_rx(struct uart_port *port)
 	if (atmel_use_dma_rx(port)) {
 		/* disable PDC receive */
 		UART_PUT_PTCR(port, ATMEL_PDC_RXTDIS);
-		UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
-	} else
+		UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
+			port->read_status_mask);
+	} else {
 		UART_PUT_IDR(port, ATMEL_US_RXRDY);
+	}
 }
 
 /*
@@ -428,8 +552,9 @@ static void atmel_rx_chars(struct uart_port *port)
 static void atmel_tx_chars(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->state->xmit;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
-	if (port->x_char && UART_GET_CSR(port) & ATMEL_US_TXRDY) {
+	if (port->x_char && UART_GET_CSR(port) & atmel_port->tx_done_mask) {
 		UART_PUT_CHAR(port, port->x_char);
 		port->icount.tx++;
 		port->x_char = 0;
@@ -437,7 +562,7 @@ static void atmel_tx_chars(struct uart_port *port)
 	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 		return;
 
-	while (UART_GET_CSR(port) & ATMEL_US_TXRDY) {
+	while (UART_GET_CSR(port) & atmel_port->tx_done_mask) {
 		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 		port->icount.tx++;
@@ -449,7 +574,8 @@ static void atmel_tx_chars(struct uart_port *port)
 		uart_write_wakeup(port);
 
 	if (!uart_circ_empty(xmit))
-		UART_PUT_IER(port, ATMEL_US_TXRDY);
+		/* Enable interrupts */
+		UART_PUT_IER(port, atmel_port->tx_done_mask);
 }
 
 /*
@@ -501,18 +627,10 @@ atmel_handle_transmit(struct uart_port *port, unsigned int pending)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
-	if (atmel_use_dma_tx(port)) {
-		/* PDC transmit */
-		if (pending & (ATMEL_US_ENDTX | ATMEL_US_TXBUFE)) {
-			UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
-			tasklet_schedule(&atmel_port->tasklet);
-		}
-	} else {
-		/* Interrupt transmit */
-		if (pending & ATMEL_US_TXRDY) {
-			UART_PUT_IDR(port, ATMEL_US_TXRDY);
-			tasklet_schedule(&atmel_port->tasklet);
-		}
+	if (pending & atmel_port->tx_done_mask) {
+		/* Either PDC or interrupt transmission */
+		UART_PUT_IDR(port, atmel_port->tx_done_mask);
+		tasklet_schedule(&atmel_port->tasklet);
 	}
 }
 
@@ -590,9 +708,15 @@ static void atmel_tx_dma(struct uart_port *port)
 
 		UART_PUT_TPR(port, pdc->dma_addr + xmit->tail);
 		UART_PUT_TCR(port, count);
-		/* re-enable PDC transmit and interrupts */
+		/* re-enable PDC transmit */
 		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
-		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
+		/* Enable interrupts */
+		UART_PUT_IER(port, atmel_port->tx_done_mask);
+	} else {
+		if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+			/* DMA done, stop TX, start RX for RS485 */
+			atmel_start_rx(port);
+		}
 	}
 
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
@@ -1017,6 +1141,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 {
 	unsigned long flags;
 	unsigned int mode, imr, quot, baud;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
 	/* Get current mode register */
 	mode = UART_GET_MR(port) & ~(ATMEL_US_USCLKS | ATMEL_US_CHRL
@@ -1115,6 +1240,17 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 	/* disable receiver and transmitter */
 	UART_PUT_CR(port, ATMEL_US_TXDIS | ATMEL_US_RXDIS);
 
+	/* Resetting serial mode to RS232 (0x0) */
+	mode &= ~ATMEL_US_USMODE;
+
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+		dev_dbg(port->dev, "Setting UART to RS485\n");
+		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
+		mode |= ATMEL_US_USMODE_RS485;
+	} else {
+		dev_dbg(port->dev, "Setting UART to RS232\n");
+	}
+
 	/* set the parity, stop bits and data size */
 	UART_PUT_MR(port, mode);
 
@@ -1231,6 +1367,28 @@ static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
 }
 #endif
 
+static int
+atmel_ioctl(struct uart_port *port, unsigned int cmd, unsigned long arg)
+{
+	struct serial_rs485 rs485conf;
+
+	switch (cmd) {
+	case TIOCSRS485:
+		if (copy_from_user(&rs485conf, (struct serial_rs485 *) arg,
+					sizeof(rs485conf)))
+			return -EFAULT;
+
+		atmel_config_rs485(port, &rs485conf);
+		break;
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+	return 0;
+}
+
+
+
 static struct uart_ops atmel_pops = {
 	.tx_empty	= atmel_tx_empty,
 	.set_mctrl	= atmel_set_mctrl,
@@ -1250,6 +1408,7 @@ static struct uart_ops atmel_pops = {
 	.config_port	= atmel_config_port,
 	.verify_port	= atmel_verify_port,
 	.pm		= atmel_serial_pm,
+	.ioctl		= atmel_ioctl,
 #ifdef CONFIG_CONSOLE_POLL
 	.poll_get_char	= atmel_poll_get_char,
 	.poll_put_char	= atmel_poll_put_char,
@@ -1265,13 +1424,12 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
 	struct uart_port *port = &atmel_port->uart;
 	struct atmel_uart_data *data = pdev->dev.platform_data;
 
-	port->iotype	= UPIO_MEM;
-	port->flags	= UPF_BOOT_AUTOCONF;
-	port->ops	= &atmel_pops;
-	port->fifosize	= 1;
-	port->line	= pdev->id;
-	port->dev	= &pdev->dev;
-
+	port->iotype		= UPIO_MEM;
+	port->flags		= UPF_BOOT_AUTOCONF;
+	port->ops		= &atmel_pops;
+	port->fifosize		= 1;
+	port->line		= pdev->id;
+	port->dev		= &pdev->dev;
 	port->mapbase	= pdev->resource[0].start;
 	port->irq	= pdev->resource[1].start;
 
@@ -1299,8 +1457,16 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
 
 	atmel_port->use_dma_rx = data->use_dma_rx;
 	atmel_port->use_dma_tx = data->use_dma_tx;
-	if (atmel_use_dma_tx(port))
+	atmel_port->rs485	= data->rs485;
+	/* Use TXEMPTY for interrupt when rs485 else TXRDY or ENDTX|TXBUFE */
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
+	else if (atmel_use_dma_tx(port)) {
 		port->fifosize = PDC_BUFFER_SIZE;
+		atmel_port->tx_done_mask = ATMEL_US_ENDTX | ATMEL_US_TXBUFE;
+	} else {
+		atmel_port->tx_done_mask = ATMEL_US_TXRDY;
+	}
 }
 
 /*
@@ -1334,6 +1500,7 @@ static void atmel_console_putchar(struct uart_port *port, int ch)
 static void atmel_console_write(struct console *co, const char *s, u_int count)
 {
 	struct uart_port *port = &atmel_ports[co->index].uart;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 	unsigned int status, imr;
 	unsigned int pdc_tx;
 
@@ -1341,7 +1508,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
 	 * First, save IMR and then disable interrupts
 	 */
 	imr = UART_GET_IMR(port);
-	UART_PUT_IDR(port, ATMEL_US_RXRDY | ATMEL_US_TXRDY);
+	UART_PUT_IDR(port, ATMEL_US_RXRDY | atmel_port->tx_done_mask);
 
 	/* Store PDC transmit status and disable it */
 	pdc_tx = UART_GET_PTSR(port) & ATMEL_PDC_TXTEN;
@@ -1355,7 +1522,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
 	 */
 	do {
 		status = UART_GET_CSR(port);
-	} while (!(status & ATMEL_US_TXRDY));
+	} while (!(status & atmel_port->tx_done_mask));
 
 	/* Restore PDC transmit status */
 	if (pdc_tx)
@@ -1587,7 +1754,7 @@ static int __devinit atmel_serial_probe(struct platform_device *pdev)
 	device_init_wakeup(&pdev->dev, 1);
 	platform_set_drvdata(pdev, port);
 
-	return 0;
+	return device_create_file(&(pdev->dev), &dev_attr_rs485);
 
 err_add_port:
 	kfree(port->rx_ring.buf);
@@ -1619,6 +1786,8 @@ static int __devexit atmel_serial_remove(struct platform_device *pdev)
 
 	clk_put(atmel_port->clk);
 
+	device_remove_file(&(pdev->dev), &dev_attr_rs485);
+
 	return ret;
 }
 
-- 
1.6.0.4

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Ryan Mallon]

Claudio Scordino wrote:
> Ryan Mallon ha scritto:
>> Claudio Scordino wrote:
>>> Hi all,
>>>
>>>    this is the new version of the patch to add RS485 support to the
>>>    atmel_serial driver. It's been changed according to Ryan Mallon's
>>>    comments.
>>>
>>> This new patch has been tested again (with and without DMA) by Sebastian
>>> Heutling (CC:-ed).
>> A few more, mostly nitpicky, comments below.
> 
> Hi Ryan,
> 
>    many thanks for your feedback.
> 
> Please find attached a new version of the patch, modified according to
> your comments.

Looks good. You should add a Tested-by for Sebastian, and you can add:

Reviewed-by: Ryan Mallon <ryan@bluewatersys.com>

~Ryan

> Regards,
> 
>          Claudio
> 
> 
> atmel_serial: Atmel RS485 support
> 
> Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
> Signed-off-by: Michael Trimarchi <michael@evidence.eu.com>
> Signed-off-by: Rick Bronson <rick@efn.org>
> Signed-off-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
> ---
>  arch/arm/include/asm/ioctls.h           |    2 +
>  arch/arm/mach-at91/include/mach/board.h |    8 +-
>  drivers/serial/atmel_serial.c           |  241 ++++++++++++++++++++++++++-----
>  3 files changed, 212 insertions(+), 39 deletions(-)
> 
> diff --git a/arch/arm/include/asm/ioctls.h b/arch/arm/include/asm/ioctls.h
> index a91d8a1..82f2177 100644
> --- a/arch/arm/include/asm/ioctls.h
> +++ b/arch/arm/include/asm/ioctls.h
> @@ -70,6 +70,8 @@
>  #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
>  #define FIOQSIZE	0x545E
>  
> +#define TIOCSRS485	0x5461
> +
>  /* Used for packet mode */
>  #define TIOCPKT_DATA		 0
>  #define TIOCPKT_FLUSHREAD	 1
> diff --git a/arch/arm/mach-at91/include/mach/board.h b/arch/arm/mach-at91/include/mach/board.h
> index ceaec6c..df2ed84 100644
> --- a/arch/arm/mach-at91/include/mach/board.h
> +++ b/arch/arm/mach-at91/include/mach/board.h
> @@ -39,6 +39,7 @@
>  #include <linux/usb/atmel_usba_udc.h>
>  #include <linux/atmel-mci.h>
>  #include <sound/atmel-ac97c.h>
> +#include <linux/serial.h>
>  
>   /* USB Device */
>  struct at91_udc_data {
> @@ -143,9 +144,10 @@ extern struct platform_device *atmel_default_console_device;
>  extern void __init __deprecated at91_init_serial(struct at91_uart_config *config);
>  
>  struct atmel_uart_data {
> -	short		use_dma_tx;	/* use transmit DMA? */
> -	short		use_dma_rx;	/* use receive DMA? */
> -	void __iomem	*regs;		/* virtual base address, if any */
> +	short			use_dma_tx;	/* use transmit DMA? */
> +	short			use_dma_rx;	/* use receive DMA? */
> +	void __iomem		*regs;		/* virt. base address, if any */
> +	struct serial_rs485	rs485;		/* rs485 settings */
>  };
>  extern void __init at91_add_device_serial(void);
>  
> diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
> index 2c9bf9b..039cd65 100644
> --- a/drivers/serial/atmel_serial.c
> +++ b/drivers/serial/atmel_serial.c
> @@ -38,6 +38,7 @@
>  #include <linux/dma-mapping.h>
>  #include <linux/atmel_pdc.h>
>  #include <linux/atmel_serial.h>
> +#include <linux/uaccess.h>
>  
>  #include <asm/io.h>
>  
> @@ -59,6 +60,9 @@
>  
>  #include <linux/serial_core.h>
>  
> +static void atmel_start_rx(struct uart_port *port);
> +static void atmel_stop_rx(struct uart_port *port);
> +
>  #ifdef CONFIG_SERIAL_ATMEL_TTYAT
>  
>  /* Use device name ttyAT, major 204 and minor 154-169.  This is necessary if we
> @@ -93,6 +97,7 @@
>  #define UART_GET_BRGR(port)	__raw_readl((port)->membase + ATMEL_US_BRGR)
>  #define UART_PUT_BRGR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_BRGR)
>  #define UART_PUT_RTOR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_RTOR)
> +#define UART_PUT_TTGR(port, v)	__raw_writel(v, (port)->membase + ATMEL_US_TTGR)
>  
>   /* PDC registers */
>  #define UART_PUT_PTCR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_PTCR)
> @@ -147,6 +152,9 @@ struct atmel_uart_port {
>  	unsigned int		irq_status_prev;
>  
>  	struct circ_buf		rx_ring;
> +
> +	struct serial_rs485	rs485;		/* rs485 settings */
> +	unsigned int		tx_done_mask;
>  };
>  
>  static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
> @@ -187,6 +195,81 @@ static bool atmel_use_dma_tx(struct uart_port *port)
>  }
>  #endif
>  
> +/* Enable or disable the rs485 support */
> +void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
> +{
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> +	unsigned long flags;
> +	unsigned int mode;
> +
> +	spin_lock_irqsave(&port->lock, flags);
> +
> +	mode = UART_GET_MR(port);
> +
> +	/* Resetting serial mode to RS232 (0x0) */
> +	mode &= ~ATMEL_US_USMODE;
> +
> +	atmel_port->rs485 = *rs485conf;
> +
> +	if (rs485conf->flags & SER_RS485_ENABLED) {
> +		dev_dbg(port->dev, "Setting UART to RS485\n");
> +		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
> +		UART_PUT_TTGR(port, rs485conf->delay_rts_before_send);
> +		mode |= ATMEL_US_USMODE_RS485;
> +	} else {
> +		dev_dbg(port->dev, "Setting UART to RS232\n");
> +		if (atmel_use_dma_tx(port))
> +			atmel_port->tx_done_mask = ATMEL_US_ENDTX |
> +				ATMEL_US_TXBUFE;
> +		else
> +			atmel_port->tx_done_mask = ATMEL_US_TXRDY;
> +	}
> +	UART_PUT_MR(port, mode);
> +
> +	spin_unlock_irqrestore(&port->lock, flags);
> +}
> +
> +
> +static ssize_t show_rs485(struct device *dev, struct device_attribute *attr,
> +			   char *buf)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct uart_port *port = platform_get_drvdata(pdev);
> +	unsigned int current_mode;
> +
> +	current_mode = UART_GET_MR(port) & ATMEL_US_USMODE;
> +	return snprintf(buf, PAGE_SIZE, "%u\n", current_mode);
> +}
> +
> +static ssize_t set_rs485(struct device *dev, struct device_attribute *attr,
> +			  const char *buf, size_t len)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct uart_port *port = platform_get_drvdata(pdev);
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> +	struct serial_rs485 rs485conf = atmel_port->rs485;
> +	unsigned int value;
> +
> +	if (!buf)
> +		return -EINVAL;
> +
> +	value = !!(simple_strtoul(buf, NULL, 0));
> +
> +	if (value) {
> +		rs485conf.flags |= SER_RS485_ENABLED;
> +		/* 0x4 is the normal reset value. */
> +		rs485conf.delay_rts_before_send = 0x00000004;
> +	} else {
> +		rs485conf.flags &= ~SER_RS485_ENABLED;
> +	}
> +
> +	atmel_config_rs485(port, &rs485conf);
> +
> +	return strnlen(buf, PAGE_SIZE);
> +}
> +
> +static DEVICE_ATTR(rs485, 0644, show_rs485, set_rs485);
> +
>  /*
>   * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
>   */
> @@ -202,6 +285,7 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
>  {
>  	unsigned int control = 0;
>  	unsigned int mode;
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
>  
>  #ifdef CONFIG_ARCH_AT91RM9200
>  	if (cpu_is_at91rm9200()) {
> @@ -236,6 +320,17 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
>  		mode |= ATMEL_US_CHMODE_LOC_LOOP;
>  	else
>  		mode |= ATMEL_US_CHMODE_NORMAL;
> +
> +	/* Resetting serial mode to RS232 (0x0) */
> +	mode &= ~ATMEL_US_USMODE;
> +
> +	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
> +		dev_dbg(port->dev, "Setting UART to RS485\n");
> +		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
> +		mode |= ATMEL_US_USMODE_RS485;
> +	} else {
> +		dev_dbg(port->dev, "Setting UART to RS232\n");
> +	}
>  	UART_PUT_MR(port, mode);
>  }
>  
> @@ -268,12 +363,17 @@ static u_int atmel_get_mctrl(struct uart_port *port)
>   */
>  static void atmel_stop_tx(struct uart_port *port)
>  {
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> +
>  	if (atmel_use_dma_tx(port)) {
>  		/* disable PDC transmit */
>  		UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
> -		UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
> -	} else
> -		UART_PUT_IDR(port, ATMEL_US_TXRDY);
> +	}
> +	/* Disable interrupts */
> +	UART_PUT_IDR(port, atmel_port->tx_done_mask);
> +
> +	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
> +		atmel_start_rx(port);
>  }
>  
>  /*
> @@ -281,17 +381,39 @@ static void atmel_stop_tx(struct uart_port *port)
>   */
>  static void atmel_start_tx(struct uart_port *port)
>  {
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> +
>  	if (atmel_use_dma_tx(port)) {
>  		if (UART_GET_PTSR(port) & ATMEL_PDC_TXTEN)
>  			/* The transmitter is already running.  Yes, we
>  			   really need this.*/
>  			return;
>  
> -		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
> +		if (atmel_port->rs485.flags & SER_RS485_ENABLED)
> +			atmel_stop_rx(port);
> +
>  		/* re-enable PDC transmit */
>  		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
> -	} else
> -		UART_PUT_IER(port, ATMEL_US_TXRDY);
> +	}
> +	/* Enable interrupts */
> +	UART_PUT_IER(port, atmel_port->tx_done_mask);
> +}
> +
> +/*
> + * start receiving - port is in process of being opened.
> + */
> +static void atmel_start_rx(struct uart_port *port)
> +{
> +	UART_PUT_CR(port, ATMEL_US_RSTSTA);  /* reset status and receiver */
> +
> +	if (atmel_use_dma_rx(port)) {
> +		/* enable PDC controller */
> +		UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
> +			port->read_status_mask);
> +		UART_PUT_PTCR(port, ATMEL_PDC_RXTEN);
> +	} else {
> +		UART_PUT_IER(port, ATMEL_US_RXRDY);
> +	}
>  }
>  
>  /*
> @@ -302,9 +424,11 @@ static void atmel_stop_rx(struct uart_port *port)
>  	if (atmel_use_dma_rx(port)) {
>  		/* disable PDC receive */
>  		UART_PUT_PTCR(port, ATMEL_PDC_RXTDIS);
> -		UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
> -	} else
> +		UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
> +			port->read_status_mask);
> +	} else {
>  		UART_PUT_IDR(port, ATMEL_US_RXRDY);
> +	}
>  }
>  
>  /*
> @@ -428,8 +552,9 @@ static void atmel_rx_chars(struct uart_port *port)
>  static void atmel_tx_chars(struct uart_port *port)
>  {
>  	struct circ_buf *xmit = &port->state->xmit;
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
>  
> -	if (port->x_char && UART_GET_CSR(port) & ATMEL_US_TXRDY) {
> +	if (port->x_char && UART_GET_CSR(port) & atmel_port->tx_done_mask) {
>  		UART_PUT_CHAR(port, port->x_char);
>  		port->icount.tx++;
>  		port->x_char = 0;
> @@ -437,7 +562,7 @@ static void atmel_tx_chars(struct uart_port *port)
>  	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
>  		return;
>  
> -	while (UART_GET_CSR(port) & ATMEL_US_TXRDY) {
> +	while (UART_GET_CSR(port) & atmel_port->tx_done_mask) {
>  		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
>  		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
>  		port->icount.tx++;
> @@ -449,7 +574,8 @@ static void atmel_tx_chars(struct uart_port *port)
>  		uart_write_wakeup(port);
>  
>  	if (!uart_circ_empty(xmit))
> -		UART_PUT_IER(port, ATMEL_US_TXRDY);
> +		/* Enable interrupts */
> +		UART_PUT_IER(port, atmel_port->tx_done_mask);
>  }
>  
>  /*
> @@ -501,18 +627,10 @@ atmel_handle_transmit(struct uart_port *port, unsigned int pending)
>  {
>  	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
>  
> -	if (atmel_use_dma_tx(port)) {
> -		/* PDC transmit */
> -		if (pending & (ATMEL_US_ENDTX | ATMEL_US_TXBUFE)) {
> -			UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
> -			tasklet_schedule(&atmel_port->tasklet);
> -		}
> -	} else {
> -		/* Interrupt transmit */
> -		if (pending & ATMEL_US_TXRDY) {
> -			UART_PUT_IDR(port, ATMEL_US_TXRDY);
> -			tasklet_schedule(&atmel_port->tasklet);
> -		}
> +	if (pending & atmel_port->tx_done_mask) {
> +		/* Either PDC or interrupt transmission */
> +		UART_PUT_IDR(port, atmel_port->tx_done_mask);
> +		tasklet_schedule(&atmel_port->tasklet);
>  	}
>  }
>  
> @@ -590,9 +708,15 @@ static void atmel_tx_dma(struct uart_port *port)
>  
>  		UART_PUT_TPR(port, pdc->dma_addr + xmit->tail);
>  		UART_PUT_TCR(port, count);
> -		/* re-enable PDC transmit and interrupts */
> +		/* re-enable PDC transmit */
>  		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
> -		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
> +		/* Enable interrupts */
> +		UART_PUT_IER(port, atmel_port->tx_done_mask);
> +	} else {
> +		if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
> +			/* DMA done, stop TX, start RX for RS485 */
> +			atmel_start_rx(port);
> +		}
>  	}
>  
>  	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
> @@ -1017,6 +1141,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
>  {
>  	unsigned long flags;
>  	unsigned int mode, imr, quot, baud;
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
>  
>  	/* Get current mode register */
>  	mode = UART_GET_MR(port) & ~(ATMEL_US_USCLKS | ATMEL_US_CHRL
> @@ -1115,6 +1240,17 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
>  	/* disable receiver and transmitter */
>  	UART_PUT_CR(port, ATMEL_US_TXDIS | ATMEL_US_RXDIS);
>  
> +	/* Resetting serial mode to RS232 (0x0) */
> +	mode &= ~ATMEL_US_USMODE;
> +
> +	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
> +		dev_dbg(port->dev, "Setting UART to RS485\n");
> +		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
> +		mode |= ATMEL_US_USMODE_RS485;
> +	} else {
> +		dev_dbg(port->dev, "Setting UART to RS232\n");
> +	}
> +
>  	/* set the parity, stop bits and data size */
>  	UART_PUT_MR(port, mode);
>  
> @@ -1231,6 +1367,28 @@ static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
>  }
>  #endif
>  
> +static int
> +atmel_ioctl(struct uart_port *port, unsigned int cmd, unsigned long arg)
> +{
> +	struct serial_rs485 rs485conf;
> +
> +	switch (cmd) {
> +	case TIOCSRS485:
> +		if (copy_from_user(&rs485conf, (struct serial_rs485 *) arg,
> +					sizeof(rs485conf)))
> +			return -EFAULT;
> +
> +		atmel_config_rs485(port, &rs485conf);
> +		break;
> +
> +	default:
> +		return -ENOIOCTLCMD;
> +	}
> +	return 0;
> +}
> +
> +
> +
>  static struct uart_ops atmel_pops = {
>  	.tx_empty	= atmel_tx_empty,
>  	.set_mctrl	= atmel_set_mctrl,
> @@ -1250,6 +1408,7 @@ static struct uart_ops atmel_pops = {
>  	.config_port	= atmel_config_port,
>  	.verify_port	= atmel_verify_port,
>  	.pm		= atmel_serial_pm,
> +	.ioctl		= atmel_ioctl,
>  #ifdef CONFIG_CONSOLE_POLL
>  	.poll_get_char	= atmel_poll_get_char,
>  	.poll_put_char	= atmel_poll_put_char,
> @@ -1265,13 +1424,12 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
>  	struct uart_port *port = &atmel_port->uart;
>  	struct atmel_uart_data *data = pdev->dev.platform_data;
>  
> -	port->iotype	= UPIO_MEM;
> -	port->flags	= UPF_BOOT_AUTOCONF;
> -	port->ops	= &atmel_pops;
> -	port->fifosize	= 1;
> -	port->line	= pdev->id;
> -	port->dev	= &pdev->dev;
> -
> +	port->iotype		= UPIO_MEM;
> +	port->flags		= UPF_BOOT_AUTOCONF;
> +	port->ops		= &atmel_pops;
> +	port->fifosize		= 1;
> +	port->line		= pdev->id;
> +	port->dev		= &pdev->dev;
>  	port->mapbase	= pdev->resource[0].start;
>  	port->irq	= pdev->resource[1].start;
>  
> @@ -1299,8 +1457,16 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
>  
>  	atmel_port->use_dma_rx = data->use_dma_rx;
>  	atmel_port->use_dma_tx = data->use_dma_tx;
> -	if (atmel_use_dma_tx(port))
> +	atmel_port->rs485	= data->rs485;
> +	/* Use TXEMPTY for interrupt when rs485 else TXRDY or ENDTX|TXBUFE */
> +	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
> +		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
> +	else if (atmel_use_dma_tx(port)) {
>  		port->fifosize = PDC_BUFFER_SIZE;
> +		atmel_port->tx_done_mask = ATMEL_US_ENDTX | ATMEL_US_TXBUFE;
> +	} else {
> +		atmel_port->tx_done_mask = ATMEL_US_TXRDY;
> +	}
>  }
>  
>  /*
> @@ -1334,6 +1500,7 @@ static void atmel_console_putchar(struct uart_port *port, int ch)
>  static void atmel_console_write(struct console *co, const char *s, u_int count)
>  {
>  	struct uart_port *port = &atmel_ports[co->index].uart;
> +	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
>  	unsigned int status, imr;
>  	unsigned int pdc_tx;
>  
> @@ -1341,7 +1508,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
>  	 * First, save IMR and then disable interrupts
>  	 */
>  	imr = UART_GET_IMR(port);
> -	UART_PUT_IDR(port, ATMEL_US_RXRDY | ATMEL_US_TXRDY);
> +	UART_PUT_IDR(port, ATMEL_US_RXRDY | atmel_port->tx_done_mask);
>  
>  	/* Store PDC transmit status and disable it */
>  	pdc_tx = UART_GET_PTSR(port) & ATMEL_PDC_TXTEN;
> @@ -1355,7 +1522,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
>  	 */
>  	do {
>  		status = UART_GET_CSR(port);
> -	} while (!(status & ATMEL_US_TXRDY));
> +	} while (!(status & atmel_port->tx_done_mask));
>  
>  	/* Restore PDC transmit status */
>  	if (pdc_tx)
> @@ -1587,7 +1754,7 @@ static int __devinit atmel_serial_probe(struct platform_device *pdev)
>  	device_init_wakeup(&pdev->dev, 1);
>  	platform_set_drvdata(pdev, port);
>  
> -	return 0;
> +	return device_create_file(&(pdev->dev), &dev_attr_rs485);
>  
>  err_add_port:
>  	kfree(port->rx_ring.buf);
> @@ -1619,6 +1786,8 @@ static int __devexit atmel_serial_remove(struct platform_device *pdev)
>  
>  	clk_put(atmel_port->clk);
>  
> +	device_remove_file(&(pdev->dev), &dev_attr_rs485);
> +
>  	return ret;
>  }
>  


-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@bluewatersys.com         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Claudio Scordino]

Ryan Mallon ha scritto:
> Claudio Scordino wrote:
>> Ryan Mallon ha scritto:
>>> Claudio Scordino wrote:
>>>> Hi all,
>>>>
>>>>    this is the new version of the patch to add RS485 support to the
>>>>    atmel_serial driver. It's been changed according to Ryan Mallon's
>>>>    comments.
>>>>
>>>> This new patch has been tested again (with and without DMA) by Sebastian
>>>> Heutling (CC:-ed).
>>> A few more, mostly nitpicky, comments below.
>> Hi Ryan,
>>
>>    many thanks for your feedback.
>>
>> Please find attached a new version of the patch, modified according to
>> your comments.
> 
> Looks good. You should add a Tested-by for Sebastian, and you can add:
> 
> Reviewed-by: Ryan Mallon <ryan@bluewatersys.com>
> 

Here it is (I just added the Tested-by and Reviewed-by fields).

Best regards,

            Claudio


atmel_serial: Atmel RS485 support

Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
Signed-off-by: Michael Trimarchi <michael@evidence.eu.com>
Signed-off-by: Rick Bronson <rick@efn.org>
Signed-off-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
Tested-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
Reviewed-by: Ryan Mallon <ryan@bluewatersys.com>
---
 arch/arm/include/asm/ioctls.h           |    2 +
 arch/arm/mach-at91/include/mach/board.h |    8 +-
 drivers/serial/atmel_serial.c           |  241 ++++++++++++++++++++++++++-----
 3 files changed, 212 insertions(+), 39 deletions(-)

diff --git a/arch/arm/include/asm/ioctls.h b/arch/arm/include/asm/ioctls.h
index a91d8a1..82f2177 100644
--- a/arch/arm/include/asm/ioctls.h
+++ b/arch/arm/include/asm/ioctls.h
@@ -70,6 +70,8 @@
 #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
 #define FIOQSIZE	0x545E
 
+#define TIOCSRS485	0x5461
+
 /* Used for packet mode */
 #define TIOCPKT_DATA		 0
 #define TIOCPKT_FLUSHREAD	 1
diff --git a/arch/arm/mach-at91/include/mach/board.h b/arch/arm/mach-at91/include/mach/board.h
index ceaec6c..df2ed84 100644
--- a/arch/arm/mach-at91/include/mach/board.h
+++ b/arch/arm/mach-at91/include/mach/board.h
@@ -39,6 +39,7 @@
 #include <linux/usb/atmel_usba_udc.h>
 #include <linux/atmel-mci.h>
 #include <sound/atmel-ac97c.h>
+#include <linux/serial.h>
 
  /* USB Device */
 struct at91_udc_data {
@@ -143,9 +144,10 @@ extern struct platform_device *atmel_default_console_device;
 extern void __init __deprecated at91_init_serial(struct at91_uart_config *config);
 
 struct atmel_uart_data {
-	short		use_dma_tx;	/* use transmit DMA? */
-	short		use_dma_rx;	/* use receive DMA? */
-	void __iomem	*regs;		/* virtual base address, if any */
+	short			use_dma_tx;	/* use transmit DMA? */
+	short			use_dma_rx;	/* use receive DMA? */
+	void __iomem		*regs;		/* virt. base address, if any */
+	struct serial_rs485	rs485;		/* rs485 settings */
 };
 extern void __init at91_add_device_serial(void);
 
diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index 2c9bf9b..039cd65 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -38,6 +38,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/atmel_pdc.h>
 #include <linux/atmel_serial.h>
+#include <linux/uaccess.h>
 
 #include <asm/io.h>
 
@@ -59,6 +60,9 @@
 
 #include <linux/serial_core.h>
 
+static void atmel_start_rx(struct uart_port *port);
+static void atmel_stop_rx(struct uart_port *port);
+
 #ifdef CONFIG_SERIAL_ATMEL_TTYAT
 
 /* Use device name ttyAT, major 204 and minor 154-169.  This is necessary if we
@@ -93,6 +97,7 @@
 #define UART_GET_BRGR(port)	__raw_readl((port)->membase + ATMEL_US_BRGR)
 #define UART_PUT_BRGR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_BRGR)
 #define UART_PUT_RTOR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_RTOR)
+#define UART_PUT_TTGR(port, v)	__raw_writel(v, (port)->membase + ATMEL_US_TTGR)
 
  /* PDC registers */
 #define UART_PUT_PTCR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_PTCR)
@@ -147,6 +152,9 @@ struct atmel_uart_port {
 	unsigned int		irq_status_prev;
 
 	struct circ_buf		rx_ring;
+
+	struct serial_rs485	rs485;		/* rs485 settings */
+	unsigned int		tx_done_mask;
 };
 
 static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
@@ -187,6 +195,81 @@ static bool atmel_use_dma_tx(struct uart_port *port)
 }
 #endif
 
+/* Enable or disable the rs485 support */
+void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	unsigned long flags;
+	unsigned int mode;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	mode = UART_GET_MR(port);
+
+	/* Resetting serial mode to RS232 (0x0) */
+	mode &= ~ATMEL_US_USMODE;
+
+	atmel_port->rs485 = *rs485conf;
+
+	if (rs485conf->flags & SER_RS485_ENABLED) {
+		dev_dbg(port->dev, "Setting UART to RS485\n");
+		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
+		UART_PUT_TTGR(port, rs485conf->delay_rts_before_send);
+		mode |= ATMEL_US_USMODE_RS485;
+	} else {
+		dev_dbg(port->dev, "Setting UART to RS232\n");
+		if (atmel_use_dma_tx(port))
+			atmel_port->tx_done_mask = ATMEL_US_ENDTX |
+				ATMEL_US_TXBUFE;
+		else
+			atmel_port->tx_done_mask = ATMEL_US_TXRDY;
+	}
+	UART_PUT_MR(port, mode);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+
+static ssize_t show_rs485(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct uart_port *port = platform_get_drvdata(pdev);
+	unsigned int current_mode;
+
+	current_mode = UART_GET_MR(port) & ATMEL_US_USMODE;
+	return snprintf(buf, PAGE_SIZE, "%u\n", current_mode);
+}
+
+static ssize_t set_rs485(struct device *dev, struct device_attribute *attr,
+			  const char *buf, size_t len)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct uart_port *port = platform_get_drvdata(pdev);
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	struct serial_rs485 rs485conf = atmel_port->rs485;
+	unsigned int value;
+
+	if (!buf)
+		return -EINVAL;
+
+	value = !!(simple_strtoul(buf, NULL, 0));
+
+	if (value) {
+		rs485conf.flags |= SER_RS485_ENABLED;
+		/* 0x4 is the normal reset value. */
+		rs485conf.delay_rts_before_send = 0x00000004;
+	} else {
+		rs485conf.flags &= ~SER_RS485_ENABLED;
+	}
+
+	atmel_config_rs485(port, &rs485conf);
+
+	return strnlen(buf, PAGE_SIZE);
+}
+
+static DEVICE_ATTR(rs485, 0644, show_rs485, set_rs485);
+
 /*
  * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
  */
@@ -202,6 +285,7 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
 {
 	unsigned int control = 0;
 	unsigned int mode;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
 #ifdef CONFIG_ARCH_AT91RM9200
 	if (cpu_is_at91rm9200()) {
@@ -236,6 +320,17 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
 		mode |= ATMEL_US_CHMODE_LOC_LOOP;
 	else
 		mode |= ATMEL_US_CHMODE_NORMAL;
+
+	/* Resetting serial mode to RS232 (0x0) */
+	mode &= ~ATMEL_US_USMODE;
+
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+		dev_dbg(port->dev, "Setting UART to RS485\n");
+		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
+		mode |= ATMEL_US_USMODE_RS485;
+	} else {
+		dev_dbg(port->dev, "Setting UART to RS232\n");
+	}
 	UART_PUT_MR(port, mode);
 }
 
@@ -268,12 +363,17 @@ static u_int atmel_get_mctrl(struct uart_port *port)
  */
 static void atmel_stop_tx(struct uart_port *port)
 {
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
 	if (atmel_use_dma_tx(port)) {
 		/* disable PDC transmit */
 		UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
-		UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
-	} else
-		UART_PUT_IDR(port, ATMEL_US_TXRDY);
+	}
+	/* Disable interrupts */
+	UART_PUT_IDR(port, atmel_port->tx_done_mask);
+
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+		atmel_start_rx(port);
 }
 
 /*
@@ -281,17 +381,39 @@ static void atmel_stop_tx(struct uart_port *port)
  */
 static void atmel_start_tx(struct uart_port *port)
 {
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
 	if (atmel_use_dma_tx(port)) {
 		if (UART_GET_PTSR(port) & ATMEL_PDC_TXTEN)
 			/* The transmitter is already running.  Yes, we
 			   really need this.*/
 			return;
 
-		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
+		if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+			atmel_stop_rx(port);
+
 		/* re-enable PDC transmit */
 		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
-	} else
-		UART_PUT_IER(port, ATMEL_US_TXRDY);
+	}
+	/* Enable interrupts */
+	UART_PUT_IER(port, atmel_port->tx_done_mask);
+}
+
+/*
+ * start receiving - port is in process of being opened.
+ */
+static void atmel_start_rx(struct uart_port *port)
+{
+	UART_PUT_CR(port, ATMEL_US_RSTSTA);  /* reset status and receiver */
+
+	if (atmel_use_dma_rx(port)) {
+		/* enable PDC controller */
+		UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
+			port->read_status_mask);
+		UART_PUT_PTCR(port, ATMEL_PDC_RXTEN);
+	} else {
+		UART_PUT_IER(port, ATMEL_US_RXRDY);
+	}
 }
 
 /*
@@ -302,9 +424,11 @@ static void atmel_stop_rx(struct uart_port *port)
 	if (atmel_use_dma_rx(port)) {
 		/* disable PDC receive */
 		UART_PUT_PTCR(port, ATMEL_PDC_RXTDIS);
-		UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
-	} else
+		UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
+			port->read_status_mask);
+	} else {
 		UART_PUT_IDR(port, ATMEL_US_RXRDY);
+	}
 }
 
 /*
@@ -428,8 +552,9 @@ static void atmel_rx_chars(struct uart_port *port)
 static void atmel_tx_chars(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->state->xmit;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
-	if (port->x_char && UART_GET_CSR(port) & ATMEL_US_TXRDY) {
+	if (port->x_char && UART_GET_CSR(port) & atmel_port->tx_done_mask) {
 		UART_PUT_CHAR(port, port->x_char);
 		port->icount.tx++;
 		port->x_char = 0;
@@ -437,7 +562,7 @@ static void atmel_tx_chars(struct uart_port *port)
 	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 		return;
 
-	while (UART_GET_CSR(port) & ATMEL_US_TXRDY) {
+	while (UART_GET_CSR(port) & atmel_port->tx_done_mask) {
 		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 		port->icount.tx++;
@@ -449,7 +574,8 @@ static void atmel_tx_chars(struct uart_port *port)
 		uart_write_wakeup(port);
 
 	if (!uart_circ_empty(xmit))
-		UART_PUT_IER(port, ATMEL_US_TXRDY);
+		/* Enable interrupts */
+		UART_PUT_IER(port, atmel_port->tx_done_mask);
 }
 
 /*
@@ -501,18 +627,10 @@ atmel_handle_transmit(struct uart_port *port, unsigned int pending)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
-	if (atmel_use_dma_tx(port)) {
-		/* PDC transmit */
-		if (pending & (ATMEL_US_ENDTX | ATMEL_US_TXBUFE)) {
-			UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
-			tasklet_schedule(&atmel_port->tasklet);
-		}
-	} else {
-		/* Interrupt transmit */
-		if (pending & ATMEL_US_TXRDY) {
-			UART_PUT_IDR(port, ATMEL_US_TXRDY);
-			tasklet_schedule(&atmel_port->tasklet);
-		}
+	if (pending & atmel_port->tx_done_mask) {
+		/* Either PDC or interrupt transmission */
+		UART_PUT_IDR(port, atmel_port->tx_done_mask);
+		tasklet_schedule(&atmel_port->tasklet);
 	}
 }
 
@@ -590,9 +708,15 @@ static void atmel_tx_dma(struct uart_port *port)
 
 		UART_PUT_TPR(port, pdc->dma_addr + xmit->tail);
 		UART_PUT_TCR(port, count);
-		/* re-enable PDC transmit and interrupts */
+		/* re-enable PDC transmit */
 		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
-		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
+		/* Enable interrupts */
+		UART_PUT_IER(port, atmel_port->tx_done_mask);
+	} else {
+		if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+			/* DMA done, stop TX, start RX for RS485 */
+			atmel_start_rx(port);
+		}
 	}
 
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
@@ -1017,6 +1141,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 {
 	unsigned long flags;
 	unsigned int mode, imr, quot, baud;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
 	/* Get current mode register */
 	mode = UART_GET_MR(port) & ~(ATMEL_US_USCLKS | ATMEL_US_CHRL
@@ -1115,6 +1240,17 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 	/* disable receiver and transmitter */
 	UART_PUT_CR(port, ATMEL_US_TXDIS | ATMEL_US_RXDIS);
 
+	/* Resetting serial mode to RS232 (0x0) */
+	mode &= ~ATMEL_US_USMODE;
+
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+		dev_dbg(port->dev, "Setting UART to RS485\n");
+		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
+		mode |= ATMEL_US_USMODE_RS485;
+	} else {
+		dev_dbg(port->dev, "Setting UART to RS232\n");
+	}
+
 	/* set the parity, stop bits and data size */
 	UART_PUT_MR(port, mode);
 
@@ -1231,6 +1367,28 @@ static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
 }
 #endif
 
+static int
+atmel_ioctl(struct uart_port *port, unsigned int cmd, unsigned long arg)
+{
+	struct serial_rs485 rs485conf;
+
+	switch (cmd) {
+	case TIOCSRS485:
+		if (copy_from_user(&rs485conf, (struct serial_rs485 *) arg,
+					sizeof(rs485conf)))
+			return -EFAULT;
+
+		atmel_config_rs485(port, &rs485conf);
+		break;
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+	return 0;
+}
+
+
+
 static struct uart_ops atmel_pops = {
 	.tx_empty	= atmel_tx_empty,
 	.set_mctrl	= atmel_set_mctrl,
@@ -1250,6 +1408,7 @@ static struct uart_ops atmel_pops = {
 	.config_port	= atmel_config_port,
 	.verify_port	= atmel_verify_port,
 	.pm		= atmel_serial_pm,
+	.ioctl		= atmel_ioctl,
 #ifdef CONFIG_CONSOLE_POLL
 	.poll_get_char	= atmel_poll_get_char,
 	.poll_put_char	= atmel_poll_put_char,
@@ -1265,13 +1424,12 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
 	struct uart_port *port = &atmel_port->uart;
 	struct atmel_uart_data *data = pdev->dev.platform_data;
 
-	port->iotype	= UPIO_MEM;
-	port->flags	= UPF_BOOT_AUTOCONF;
-	port->ops	= &atmel_pops;
-	port->fifosize	= 1;
-	port->line	= pdev->id;
-	port->dev	= &pdev->dev;
-
+	port->iotype		= UPIO_MEM;
+	port->flags		= UPF_BOOT_AUTOCONF;
+	port->ops		= &atmel_pops;
+	port->fifosize		= 1;
+	port->line		= pdev->id;
+	port->dev		= &pdev->dev;
 	port->mapbase	= pdev->resource[0].start;
 	port->irq	= pdev->resource[1].start;
 
@@ -1299,8 +1457,16 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
 
 	atmel_port->use_dma_rx = data->use_dma_rx;
 	atmel_port->use_dma_tx = data->use_dma_tx;
-	if (atmel_use_dma_tx(port))
+	atmel_port->rs485	= data->rs485;
+	/* Use TXEMPTY for interrupt when rs485 else TXRDY or ENDTX|TXBUFE */
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
+	else if (atmel_use_dma_tx(port)) {
 		port->fifosize = PDC_BUFFER_SIZE;
+		atmel_port->tx_done_mask = ATMEL_US_ENDTX | ATMEL_US_TXBUFE;
+	} else {
+		atmel_port->tx_done_mask = ATMEL_US_TXRDY;
+	}
 }
 
 /*
@@ -1334,6 +1500,7 @@ static void atmel_console_putchar(struct uart_port *port, int ch)
 static void atmel_console_write(struct console *co, const char *s, u_int count)
 {
 	struct uart_port *port = &atmel_ports[co->index].uart;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 	unsigned int status, imr;
 	unsigned int pdc_tx;
 
@@ -1341,7 +1508,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
 	 * First, save IMR and then disable interrupts
 	 */
 	imr = UART_GET_IMR(port);
-	UART_PUT_IDR(port, ATMEL_US_RXRDY | ATMEL_US_TXRDY);
+	UART_PUT_IDR(port, ATMEL_US_RXRDY | atmel_port->tx_done_mask);
 
 	/* Store PDC transmit status and disable it */
 	pdc_tx = UART_GET_PTSR(port) & ATMEL_PDC_TXTEN;
@@ -1355,7 +1522,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
 	 */
 	do {
 		status = UART_GET_CSR(port);
-	} while (!(status & ATMEL_US_TXRDY));
+	} while (!(status & atmel_port->tx_done_mask));
 
 	/* Restore PDC transmit status */
 	if (pdc_tx)
@@ -1587,7 +1754,7 @@ static int __devinit atmel_serial_probe(struct platform_device *pdev)
 	device_init_wakeup(&pdev->dev, 1);
 	platform_set_drvdata(pdev, port);
 
-	return 0;
+	return device_create_file(&(pdev->dev), &dev_attr_rs485);
 
 err_add_port:
 	kfree(port->rx_ring.buf);
@@ -1619,6 +1786,8 @@ static int __devexit atmel_serial_remove(struct platform_device *pdev)
 
 	clk_put(atmel_port->clk);
 
+	device_remove_file(&(pdev->dev), &dev_attr_rs485);
+
 	return ret;
 }
 
-- 
1.6.0.4

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Russell King - ARM Linux]

On Thu, Apr 08, 2010 at 09:58:21AM +0200, Claudio Scordino wrote:
> diff --git a/arch/arm/include/asm/ioctls.h b/arch/arm/include/asm/ioctls.h
> index a91d8a1..82f2177 100644
> --- a/arch/arm/include/asm/ioctls.h
> +++ b/arch/arm/include/asm/ioctls.h
> @@ -70,6 +70,8 @@
>  #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
>  #define FIOQSIZE	0x545E
>  
> +#define TIOCSRS485	0x5461

Why are you only supporting half the interface?

#define TIOCGRS485      0x542E
#define TIOCSRS485      0x542F

is what is in include/asm-generic/ioctls.h - and it would be a good idea
to use the same numbering as the generic file rather than creating yet
more divergence.

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Alan Cox]

NAK - assorted problems, notably locking ones caused by the sysfs stuff
which should probably be dropped.

> +#define TIOCSRS485	0x5461

Please provide TIOCGRS485 as well



> +static ssize_t show_rs485(struct device *dev, struct device_attribute *attr,
> +			   char *buf)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct uart_port *port = platform_get_drvdata(pdev);
> +	unsigned int current_mode;
> +
> +	current_mode = UART_GET_MR(port) & ATMEL_US_USMODE;
> +	return snprintf(buf, PAGE_SIZE, "%u\n", current_mode);
> +}

You should have TIOCGRS485 for providing the info back as part of the API

> +
> +static ssize_t set_rs485(struct device *dev, struct device_attribute *attr,
> +			  const char *buf, size_t len)

Expain the locking on this could you - I don't see what protects against
parallel ioctl and sysfs stuff ?

> +static DEVICE_ATTR(rs485, 0644, show_rs485, set_rs485);

Why should this be public read ?

> +	/* Resetting serial mode to RS232 (0x0) */
> +	mode &= ~ATMEL_US_USMODE;
> +
> +	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
> +		dev_dbg(port->dev, "Setting UART to RS485\n");
> +		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
> +		mode |= ATMEL_US_USMODE_RS485;
> +	} else {
> +		dev_dbg(port->dev, "Setting UART to RS232\n");

Locking versus sysfs ?

> +	UART_PUT_IDR(port, atmel_port->tx_done_mask);
> +
> +	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
> +		atmel_start_rx(port);
>  }

Ditto

> -		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
> +		if (atmel_port->rs485.flags & SER_RS485_ENABLED)
> +			atmel_stop_rx(port);
> +

Ditto


Given the locking mess you are going to create I would suggest dropping
the sysfs stuff.

Alan

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Claudio Scordino]

Alan Cox ha scritto:
> NAK - assorted problems, notably locking ones caused by the sysfs stuff
> which should probably be dropped.
> 
>> +#define TIOCSRS485	0x5461
> 
> Please provide TIOCGRS485 as well
> 
> 
> 
>> +static ssize_t show_rs485(struct device *dev, struct device_attribute *attr,
>> +			   char *buf)
>> +{
>> +	struct platform_device *pdev = to_platform_device(dev);
>> +	struct uart_port *port = platform_get_drvdata(pdev);
>> +	unsigned int current_mode;
>> +
>> +	current_mode = UART_GET_MR(port) & ATMEL_US_USMODE;
>> +	return snprintf(buf, PAGE_SIZE, "%u\n", current_mode);
>> +}
> 
> You should have TIOCGRS485 for providing the info back as part of the API
> 
>> +
>> +static ssize_t set_rs485(struct device *dev, struct device_attribute *attr,
>> +			  const char *buf, size_t len)
> 
> Expain the locking on this could you - I don't see what protects against
> parallel ioctl and sysfs stuff ?
> 
>> +static DEVICE_ATTR(rs485, 0644, show_rs485, set_rs485);
> 
> Why should this be public read ?
> 
>> +	/* Resetting serial mode to RS232 (0x0) */
>> +	mode &= ~ATMEL_US_USMODE;
>> +
>> +	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
>> +		dev_dbg(port->dev, "Setting UART to RS485\n");
>> +		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
>> +		mode |= ATMEL_US_USMODE_RS485;
>> +	} else {
>> +		dev_dbg(port->dev, "Setting UART to RS232\n");
> 
> Locking versus sysfs ?
> 
>> +	UART_PUT_IDR(port, atmel_port->tx_done_mask);
>> +
>> +	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
>> +		atmel_start_rx(port);
>>  }
> 
> Ditto
> 
>> -		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
>> +		if (atmel_port->rs485.flags & SER_RS485_ENABLED)
>> +			atmel_stop_rx(port);
>> +
> 
> Ditto
> 
> 
> Given the locking mess you are going to create I would suggest dropping
> the sysfs stuff.
> 
> Alan


Thank you for the feedback.

Let me know if this new version solves the above problems.

	Claudio


atmel_serial: Atmel RS485 support

Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
Signed-off-by: Michael Trimarchi <michael@evidence.eu.com>
Signed-off-by: Rick Bronson <rick@efn.org>
Signed-off-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
Tested-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
Reviewed-by: Ryan Mallon <ryan@bluewatersys.com>
---
 arch/arm/include/asm/ioctls.h           |    3 +
 arch/arm/mach-at91/include/mach/board.h |    8 +-
 drivers/serial/atmel_serial.c           |  203 +++++++++++++++++++++++++------
 3 files changed, 176 insertions(+), 38 deletions(-)

diff --git a/arch/arm/include/asm/ioctls.h b/arch/arm/include/asm/ioctls.h
index a91d8a1..7f0b6d1 100644
--- a/arch/arm/include/asm/ioctls.h
+++ b/arch/arm/include/asm/ioctls.h
@@ -53,6 +53,9 @@
 #define TIOCGPTN	_IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux device) */
 #define TIOCSPTLCK	_IOW('T',0x31, int)  /* Lock/unlock Pty */
 
+#define TIOCGRS485      0x542E
+#define TIOCSRS485      0x542F
+
 #define FIONCLEX	0x5450  /* these numbers need to be adjusted. */
 #define FIOCLEX		0x5451
 #define FIOASYNC	0x5452
diff --git a/arch/arm/mach-at91/include/mach/board.h b/arch/arm/mach-at91/include/mach/board.h
index ceaec6c..df2ed84 100644
--- a/arch/arm/mach-at91/include/mach/board.h
+++ b/arch/arm/mach-at91/include/mach/board.h
@@ -39,6 +39,7 @@
 #include <linux/usb/atmel_usba_udc.h>
 #include <linux/atmel-mci.h>
 #include <sound/atmel-ac97c.h>
+#include <linux/serial.h>
 
  /* USB Device */
 struct at91_udc_data {
@@ -143,9 +144,10 @@ extern struct platform_device *atmel_default_console_device;
 extern void __init __deprecated at91_init_serial(struct at91_uart_config *config);
 
 struct atmel_uart_data {
-	short		use_dma_tx;	/* use transmit DMA? */
-	short		use_dma_rx;	/* use receive DMA? */
-	void __iomem	*regs;		/* virtual base address, if any */
+	short			use_dma_tx;	/* use transmit DMA? */
+	short			use_dma_rx;	/* use receive DMA? */
+	void __iomem		*regs;		/* virt. base address, if any */
+	struct serial_rs485	rs485;		/* rs485 settings */
 };
 extern void __init at91_add_device_serial(void);
 
diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index 2c9bf9b..4f4b0b9 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -38,6 +38,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/atmel_pdc.h>
 #include <linux/atmel_serial.h>
+#include <linux/uaccess.h>
 
 #include <asm/io.h>
 
@@ -59,6 +60,9 @@
 
 #include <linux/serial_core.h>
 
+static void atmel_start_rx(struct uart_port *port);
+static void atmel_stop_rx(struct uart_port *port);
+
 #ifdef CONFIG_SERIAL_ATMEL_TTYAT
 
 /* Use device name ttyAT, major 204 and minor 154-169.  This is necessary if we
@@ -93,6 +97,7 @@
 #define UART_GET_BRGR(port)	__raw_readl((port)->membase + ATMEL_US_BRGR)
 #define UART_PUT_BRGR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_BRGR)
 #define UART_PUT_RTOR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_RTOR)
+#define UART_PUT_TTGR(port, v)	__raw_writel(v, (port)->membase + ATMEL_US_TTGR)
 
  /* PDC registers */
 #define UART_PUT_PTCR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_PTCR)
@@ -147,6 +152,9 @@ struct atmel_uart_port {
 	unsigned int		irq_status_prev;
 
 	struct circ_buf		rx_ring;
+
+	struct serial_rs485	rs485;		/* rs485 settings */
+	unsigned int		tx_done_mask;
 };
 
 static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
@@ -187,6 +195,40 @@ static bool atmel_use_dma_tx(struct uart_port *port)
 }
 #endif
 
+/* Enable or disable the rs485 support */
+void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	unsigned long flags;
+	unsigned int mode;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	mode = UART_GET_MR(port);
+
+	/* Resetting serial mode to RS232 (0x0) */
+	mode &= ~ATMEL_US_USMODE;
+
+	atmel_port->rs485 = *rs485conf;
+
+	if (rs485conf->flags & SER_RS485_ENABLED) {
+		dev_dbg(port->dev, "Setting UART to RS485\n");
+		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
+		UART_PUT_TTGR(port, rs485conf->delay_rts_before_send);
+		mode |= ATMEL_US_USMODE_RS485;
+	} else {
+		dev_dbg(port->dev, "Setting UART to RS232\n");
+		if (atmel_use_dma_tx(port))
+			atmel_port->tx_done_mask = ATMEL_US_ENDTX |
+				ATMEL_US_TXBUFE;
+		else
+			atmel_port->tx_done_mask = ATMEL_US_TXRDY;
+	}
+	UART_PUT_MR(port, mode);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
 /*
  * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
  */
@@ -202,6 +244,7 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
 {
 	unsigned int control = 0;
 	unsigned int mode;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
 #ifdef CONFIG_ARCH_AT91RM9200
 	if (cpu_is_at91rm9200()) {
@@ -236,6 +279,17 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
 		mode |= ATMEL_US_CHMODE_LOC_LOOP;
 	else
 		mode |= ATMEL_US_CHMODE_NORMAL;
+
+	/* Resetting serial mode to RS232 (0x0) */
+	mode &= ~ATMEL_US_USMODE;
+
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+		dev_dbg(port->dev, "Setting UART to RS485\n");
+		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
+		mode |= ATMEL_US_USMODE_RS485;
+	} else {
+		dev_dbg(port->dev, "Setting UART to RS232\n");
+	}
 	UART_PUT_MR(port, mode);
 }
 
@@ -268,12 +322,17 @@ static u_int atmel_get_mctrl(struct uart_port *port)
  */
 static void atmel_stop_tx(struct uart_port *port)
 {
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
 	if (atmel_use_dma_tx(port)) {
 		/* disable PDC transmit */
 		UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
-		UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
-	} else
-		UART_PUT_IDR(port, ATMEL_US_TXRDY);
+	}
+	/* Disable interrupts */
+	UART_PUT_IDR(port, atmel_port->tx_done_mask);
+
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+		atmel_start_rx(port);
 }
 
 /*
@@ -281,17 +340,39 @@ static void atmel_stop_tx(struct uart_port *port)
  */
 static void atmel_start_tx(struct uart_port *port)
 {
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
 	if (atmel_use_dma_tx(port)) {
 		if (UART_GET_PTSR(port) & ATMEL_PDC_TXTEN)
 			/* The transmitter is already running.  Yes, we
 			   really need this.*/
 			return;
 
-		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
+		if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+			atmel_stop_rx(port);
+
 		/* re-enable PDC transmit */
 		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
-	} else
-		UART_PUT_IER(port, ATMEL_US_TXRDY);
+	}
+	/* Enable interrupts */
+	UART_PUT_IER(port, atmel_port->tx_done_mask);
+}
+
+/*
+ * start receiving - port is in process of being opened.
+ */
+static void atmel_start_rx(struct uart_port *port)
+{
+	UART_PUT_CR(port, ATMEL_US_RSTSTA);  /* reset status and receiver */
+
+	if (atmel_use_dma_rx(port)) {
+		/* enable PDC controller */
+		UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
+			port->read_status_mask);
+		UART_PUT_PTCR(port, ATMEL_PDC_RXTEN);
+	} else {
+		UART_PUT_IER(port, ATMEL_US_RXRDY);
+	}
 }
 
 /*
@@ -302,9 +383,11 @@ static void atmel_stop_rx(struct uart_port *port)
 	if (atmel_use_dma_rx(port)) {
 		/* disable PDC receive */
 		UART_PUT_PTCR(port, ATMEL_PDC_RXTDIS);
-		UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
-	} else
+		UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
+			port->read_status_mask);
+	} else {
 		UART_PUT_IDR(port, ATMEL_US_RXRDY);
+	}
 }
 
 /*
@@ -428,8 +511,9 @@ static void atmel_rx_chars(struct uart_port *port)
 static void atmel_tx_chars(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->state->xmit;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
-	if (port->x_char && UART_GET_CSR(port) & ATMEL_US_TXRDY) {
+	if (port->x_char && UART_GET_CSR(port) & atmel_port->tx_done_mask) {
 		UART_PUT_CHAR(port, port->x_char);
 		port->icount.tx++;
 		port->x_char = 0;
@@ -437,7 +521,7 @@ static void atmel_tx_chars(struct uart_port *port)
 	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
 		return;
 
-	while (UART_GET_CSR(port) & ATMEL_US_TXRDY) {
+	while (UART_GET_CSR(port) & atmel_port->tx_done_mask) {
 		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 		port->icount.tx++;
@@ -449,7 +533,8 @@ static void atmel_tx_chars(struct uart_port *port)
 		uart_write_wakeup(port);
 
 	if (!uart_circ_empty(xmit))
-		UART_PUT_IER(port, ATMEL_US_TXRDY);
+		/* Enable interrupts */
+		UART_PUT_IER(port, atmel_port->tx_done_mask);
 }
 
 /*
@@ -501,18 +586,10 @@ atmel_handle_transmit(struct uart_port *port, unsigned int pending)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
-	if (atmel_use_dma_tx(port)) {
-		/* PDC transmit */
-		if (pending & (ATMEL_US_ENDTX | ATMEL_US_TXBUFE)) {
-			UART_PUT_IDR(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
-			tasklet_schedule(&atmel_port->tasklet);
-		}
-	} else {
-		/* Interrupt transmit */
-		if (pending & ATMEL_US_TXRDY) {
-			UART_PUT_IDR(port, ATMEL_US_TXRDY);
-			tasklet_schedule(&atmel_port->tasklet);
-		}
+	if (pending & atmel_port->tx_done_mask) {
+		/* Either PDC or interrupt transmission */
+		UART_PUT_IDR(port, atmel_port->tx_done_mask);
+		tasklet_schedule(&atmel_port->tasklet);
 	}
 }
 
@@ -590,9 +667,15 @@ static void atmel_tx_dma(struct uart_port *port)
 
 		UART_PUT_TPR(port, pdc->dma_addr + xmit->tail);
 		UART_PUT_TCR(port, count);
-		/* re-enable PDC transmit and interrupts */
+		/* re-enable PDC transmit */
 		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
-		UART_PUT_IER(port, ATMEL_US_ENDTX | ATMEL_US_TXBUFE);
+		/* Enable interrupts */
+		UART_PUT_IER(port, atmel_port->tx_done_mask);
+	} else {
+		if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+			/* DMA done, stop TX, start RX for RS485 */
+			atmel_start_rx(port);
+		}
 	}
 
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
@@ -1017,6 +1100,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 {
 	unsigned long flags;
 	unsigned int mode, imr, quot, baud;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
 	/* Get current mode register */
 	mode = UART_GET_MR(port) & ~(ATMEL_US_USCLKS | ATMEL_US_CHRL
@@ -1115,6 +1199,17 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 	/* disable receiver and transmitter */
 	UART_PUT_CR(port, ATMEL_US_TXDIS | ATMEL_US_RXDIS);
 
+	/* Resetting serial mode to RS232 (0x0) */
+	mode &= ~ATMEL_US_USMODE;
+
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+		dev_dbg(port->dev, "Setting UART to RS485\n");
+		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_before_send);
+		mode |= ATMEL_US_USMODE_RS485;
+	} else {
+		dev_dbg(port->dev, "Setting UART to RS232\n");
+	}
+
 	/* set the parity, stop bits and data size */
 	UART_PUT_MR(port, mode);
 
@@ -1231,6 +1326,35 @@ static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
 }
 #endif
 
+static int
+atmel_ioctl(struct uart_port *port, unsigned int cmd, unsigned long arg)
+{
+	struct serial_rs485 rs485conf;
+
+	switch (cmd) {
+	case TIOCSRS485:
+		if (copy_from_user(&rs485conf, (struct serial_rs485 *) arg,
+					sizeof(rs485conf)))
+			return -EFAULT;
+
+		atmel_config_rs485(port, &rs485conf);
+		break;
+
+	case TIOCGRS485:
+		if (copy_to_user((struct serial_rs485 *) arg,
+					&(to_atmel_uart_port(port)->rs485),
+					sizeof(rs485conf)))
+			return -EFAULT;
+		break;
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+	return 0;
+}
+
+
+
 static struct uart_ops atmel_pops = {
 	.tx_empty	= atmel_tx_empty,
 	.set_mctrl	= atmel_set_mctrl,
@@ -1250,6 +1374,7 @@ static struct uart_ops atmel_pops = {
 	.config_port	= atmel_config_port,
 	.verify_port	= atmel_verify_port,
 	.pm		= atmel_serial_pm,
+	.ioctl		= atmel_ioctl,
 #ifdef CONFIG_CONSOLE_POLL
 	.poll_get_char	= atmel_poll_get_char,
 	.poll_put_char	= atmel_poll_put_char,
@@ -1265,13 +1390,12 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
 	struct uart_port *port = &atmel_port->uart;
 	struct atmel_uart_data *data = pdev->dev.platform_data;
 
-	port->iotype	= UPIO_MEM;
-	port->flags	= UPF_BOOT_AUTOCONF;
-	port->ops	= &atmel_pops;
-	port->fifosize	= 1;
-	port->line	= pdev->id;
-	port->dev	= &pdev->dev;
-
+	port->iotype		= UPIO_MEM;
+	port->flags		= UPF_BOOT_AUTOCONF;
+	port->ops		= &atmel_pops;
+	port->fifosize		= 1;
+	port->line		= pdev->id;
+	port->dev		= &pdev->dev;
 	port->mapbase	= pdev->resource[0].start;
 	port->irq	= pdev->resource[1].start;
 
@@ -1299,8 +1423,16 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port,
 
 	atmel_port->use_dma_rx = data->use_dma_rx;
 	atmel_port->use_dma_tx = data->use_dma_tx;
-	if (atmel_use_dma_tx(port))
+	atmel_port->rs485	= data->rs485;
+	/* Use TXEMPTY for interrupt when rs485 else TXRDY or ENDTX|TXBUFE */
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
+	else if (atmel_use_dma_tx(port)) {
 		port->fifosize = PDC_BUFFER_SIZE;
+		atmel_port->tx_done_mask = ATMEL_US_ENDTX | ATMEL_US_TXBUFE;
+	} else {
+		atmel_port->tx_done_mask = ATMEL_US_TXRDY;
+	}
 }
 
 /*
@@ -1334,6 +1466,7 @@ static void atmel_console_putchar(struct uart_port *port, int ch)
 static void atmel_console_write(struct console *co, const char *s, u_int count)
 {
 	struct uart_port *port = &atmel_ports[co->index].uart;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 	unsigned int status, imr;
 	unsigned int pdc_tx;
 
@@ -1341,7 +1474,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
 	 * First, save IMR and then disable interrupts
 	 */
 	imr = UART_GET_IMR(port);
-	UART_PUT_IDR(port, ATMEL_US_RXRDY | ATMEL_US_TXRDY);
+	UART_PUT_IDR(port, ATMEL_US_RXRDY | atmel_port->tx_done_mask);
 
 	/* Store PDC transmit status and disable it */
 	pdc_tx = UART_GET_PTSR(port) & ATMEL_PDC_TXTEN;
@@ -1355,7 +1488,7 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
 	 */
 	do {
 		status = UART_GET_CSR(port);
-	} while (!(status & ATMEL_US_TXRDY));
+	} while (!(status & atmel_port->tx_done_mask));
 
 	/* Restore PDC transmit status */
 	if (pdc_tx)
-- 
1.6.0.4

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Alan Cox]

> Thank you for the feedback.
> 
> Let me know if this new version solves the above problems.

Looks good to me. Thanks for the quick clean up.

Alan

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Nicolas Ferre]

Le 08/04/2010 15:16, Claudio Scordino :

[..]

> atmel_serial: Atmel RS485 support
> 
> Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
> Signed-off-by: Michael Trimarchi <michael@evidence.eu.com>
> Signed-off-by: Rick Bronson <rick@efn.org>
> Signed-off-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
> Tested-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
> Reviewed-by: Ryan Mallon <ryan@bluewatersys.com>

Even though I personally did not test this patch I think it is time to
go forward with this very good work.

Considering the number of people involved in this testing and review I
think that we can submit this patch for mainline. Who will handle it?
- do we submit to ARM or serial subsystem ?

Best regards,
-- 
Nicolas Ferre

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Claudio Scordino]

Nicolas Ferre ha scritto:
> Le 08/04/2010 15:16, Claudio Scordino :
>
> [..]
>
>   
>> atmel_serial: Atmel RS485 support
>>
>> Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
>> Signed-off-by: Michael Trimarchi <michael@evidence.eu.com>
>> Signed-off-by: Rick Bronson <rick@efn.org>
>> Signed-off-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
>> Tested-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
>> Reviewed-by: Ryan Mallon <ryan@bluewatersys.com>
>>     
>
> Even though I personally did not test this patch I think it is time to
> go forward with this very good work.
>
> Considering the number of people involved in this testing and review I
> think that we can submit this patch for mainline. Who will handle it?
> - do we submit to ARM or serial subsystem ?
>   

Hi Nicolas,

    the latest version of the patch has been already merged in the
latest Linus' git tree through Russell King's patchsystem (the maintainer of the
driver never answered to emails...).

Many thanks,

       Claudio

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Nicolas Ferre]

Le 27/05/2010 10:37, Claudio Scordino :
> Nicolas Ferre ha scritto:
>> Le 08/04/2010 15:16, Claudio Scordino :
>>
>> [..]
>>
>>   
>>> atmel_serial: Atmel RS485 support
>>>
>>> Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
>>> Signed-off-by: Michael Trimarchi <michael@evidence.eu.com>
>>> Signed-off-by: Rick Bronson <rick@efn.org>
>>> Signed-off-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
>>> Tested-by: Sebastian Heutling <Sebastian.Heutling@who-ing.de>
>>> Reviewed-by: Ryan Mallon <ryan@bluewatersys.com>
>>>     
>>
>> Even though I personally did not test this patch I think it is time to
>> go forward with this very good work.
>>
>> Considering the number of people involved in this testing and review I
>> think that we can submit this patch for mainline. Who will handle it?
>> - do we submit to ARM or serial subsystem ?
>>   
> 
> Hi Nicolas,
> 
>     the latest version of the patch has been already merged in the
> latest Linus' git tree through Russell King's patchsystem 

My fault: I use to check Russell patchsystem with "AT91" searching
string and not "atmel" ;-)

> (the maintainer of the driver never answered to emails...).

I was supposed to take over its maintainance one year ago but did not
find time to do it. My fault here also...

Anyway, it was the occasion to tell all of you that this RS485 support
is a nice job and that even if I do not answer, I try to track all
interesting activity in the background.

Best regards,
-- 
Nicolas Ferre

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 488 bytes --]

Hi Claudio,

kudos for getting a RS485-implementation into the kernel! Very useful.

> >     the latest version of the patch has been already merged in the
> > latest Linus' git tree through Russell King's patchsystem 

Nitpick: Wasn't there some documentation promised after the final patch ;)

Regards,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 197 bytes --]

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Claudio Scordino]

Wolfram Sang ha scritto:
> Hi Claudio,
> 
> kudos for getting a RS485-implementation into the kernel! Very useful.

Many thanks!

I hope other people will find it useful too.

> 
>>>     the latest version of the patch has been already merged in the
>>> latest Linus' git tree through Russell King's patchsystem 
> 
> Nitpick: Wasn't there some documentation promised after the final patch ;)

Here is the first attempt.

Best regards,

		Claudio


Documentation about RS485

Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
---
 Documentation/serial/00-INDEX         |    2 +
 Documentation/serial/serial-rs485.txt |  118 +++++++++++++++++++++++++++++++++
 2 files changed, 120 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/serial/serial-rs485.txt

diff --git a/Documentation/serial/00-INDEX b/Documentation/serial/00-INDEX
index 07dcdb0..e09468a 100644
--- a/Documentation/serial/00-INDEX
+++ b/Documentation/serial/00-INDEX
@@ -14,6 +14,8 @@ riscom8.txt
 	- notes on using the RISCom/8 multi-port serial driver.
 rocket.txt
 	- info on the Comtrol RocketPort multiport serial driver.
+serial-rs485.txt
+	- info about RS485 structures and support in the kernel.
 specialix.txt
 	- info on hardware/driver for specialix IO8+ multiport serial card.
 stallion.txt
diff --git a/Documentation/serial/serial-rs485.txt b/Documentation/serial/serial-rs485.txt
new file mode 100644
index 0000000..dac98c3
--- /dev/null
+++ b/Documentation/serial/serial-rs485.txt
@@ -0,0 +1,118 @@
+                        RS485 SERIAL COMMUNICATIONS
+
+1. INTRODUCTION
+
+   EIA-485, also known as TIA/EIA-485 or RS-485, is a standard defining the
+   electrical characteristics of drivers and receivers for use in balanced
+   digital multipoint systems.
+   This standard is widely used for communications in industrial automation
+   because it can be used effectively over long distances and in electrically
+   noisy environments.
+   Even though the data is transmitted over a 2-wire twisted pair bus, all
+   EIA-485 transceivers interpret the voltage levels of the differential
+   signals with respect to a third common voltage. Without this common
+   reference, a set of transceivers may interpret the differential signals
+   incorrectly.
+   See [1] for more information.
+
+
+2. HARDWARE-RELATED CONSIDERATIONS
+
+   Some CPUs (e.g., Atmel AT91) contain a transceiver capable of working both
+   as RS232 and RS485. For these microcontrollers, the Linux driver should be
+   able of working in both modes, and proper ioctls (see later) should be made
+   available at user-level to allow switching from one mode to the other, and
+   viceversa.
+   
+   On some other CPUs (e.g., Freescale imx25) the RS485 transceiver is not
+   integrated inside the microcontroller itself. Therefore, manufacturers who
+   use these microcontrollers to produce embedded boards need to connect an
+   external transceiver to some pin of the CPU.
+   On these architectures, therefore, no assumptions can be done at the
+   CPU-level about the presence of a RS485 transceiver, because the connection
+   (if any) is done outside the microcontroller. Moreover, even in case of
+   RS485 transceiver, the manufacturer is free to choose the CPU pin used for
+   the connection.
+
+
+3. DATA STRUCTURES ALREADY AVAILABLE IN THE KERNEL
+
+   The Linux kernel provides the serial_rs485 structure (inside
+   include/linux/serial.h) to handle RS485 communications. This data structure
+   is used to set and configure RS485 parameters in the platform data and in
+   ioctls.
+
+   Any driver for interfaces capable of working both as RS232 and RS485 should
+   provide at least the following ioctls:
+
+    - TIOCSRS485 (typically associated with number 0x542F). This ioctl is used
+      to enable/disable RS485 mode from user-space
+
+    - TIOCGRS485 (typically associated with number 0x542E). This ioctl is used
+      to get RS485 mode from kernel-space (i.e., driver) to user-space.
+
+   In other words, the serial driver should contain a code similar to the next
+   one:
+
+	static struct uart_ops atmel_pops = {
+		/* ... */
+		.ioctl		= handle_ioctl,
+	};
+
+	static int 
+	handle_ioctl(struct uart_port *port, 
+		unsigned int cmd, 
+		unsigned long arg)
+	{
+	struct serial_rs485 rs485conf;
+
+	switch (cmd) {
+		case TIOCSRS485:
+			if (copy_from_user(&rs485conf, 
+				(struct serial_rs485 *) arg,
+				sizeof(rs485conf)))
+					return -EFAULT;
+
+			/* ... */
+			break;
+
+		case TIOCGRS485:
+			if (copy_to_user((struct serial_rs485 *) arg,
+				...,
+				sizeof(rs485conf)))
+					return -EFAULT;
+			/* ... */
+			break;
+		/* ... */
+	}
+
+
+4. USAGE FROM USER-LEVEL
+
+   From user-level, RS485 configuration can be get/set using the previous
+   ioctls. For instance, to set RS485 you can use the following code:
+
+	#include <linux/serial.h>
+
+	/* Driver-specific ioctls: */
+	#define TIOCGRS485      0x542E
+	#define TIOCSRS485      0x542F
+
+	/* Open specific device: */
+	int fd = open ("/dev/mydevice", O_RDWR); 
+	struct serial_rs485 rs485conf;
+
+	/* Set RS485 mode: */
+	rs485conf.flags |= SER_RS485_ENABLED;
+	
+	/* Set delay: */
+	rs485conf.delay_rts_before_send = 0x00000004;
+	ioctl (fd, TIOCSRS485, &rs485conf);
+	
+	close (fd);
+
+5. REFERENCES
+
+ [1]	http://en.wikipedia.org/wiki/Rs485
+
+
-- 
1.6.0.4

Re: [PATCH] atmel_serial: Atmel RS485 support v2

[Haavard Skinnemoen]

Nicolas Ferre <nicolas.ferre@atmel.com> wrote:
> > (the maintainer of the driver never answered to emails...).  
> 
> I was supposed to take over its maintainance one year ago but did not
> find time to do it. My fault here also...

My fault too...I should really try harder to respond to e-mails. I was
planning to give it a spin and send it upstream, but I never found the
time.

Nicolas, is it ok if I send a patch to update MAINTAINERS? That way,
you'll receive these patches and questions about them by e-mail rather
than me.

Haavard