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Commit e8faff73 authored by Claudio Scordino's avatar Claudio Scordino Committed by Russell King
Browse files

ARM: 6092/1: atmel_serial: support for RS485 communications 



Final version of the patch that adds support for RS485 communications to the atmel_serial driver.

The patch has been already sent and discussed on both linux-kernel and linux-arm-kernel mailing lists several times.

Many people collaborated to improve and test the code:

Tested-by: default avatarSebastian Heutling <Sebastian.Heutling@who-ing.de>
Tested-by: default avatarBernhard Roth <br@pwrnet.de>
Reviewed-by: default avatarRyan Mallon <ryan@bluewatersys.com>
Signed-off-by: default avatarClaudio Scordino <claudio@evidence.eu.com>
Signed-off-by: default avatarMichael Trimarchi <michael@evidence.eu.com>
Signed-off-by: default avatarRick Bronson <rick@efn.org>
Signed-off-by: default avatarSebastian Heutling <Sebastian.Heutling@who-ing.de>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent aec9562f

arch/arm/include/asm/ioctls.h

+3 −0
Original line number Diff line number Diff line
@@ -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

arch/arm/mach-at91/include/mach/board.h

+5 −3
Original line number Diff line number Diff line
@@ -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 {
@@ -145,7 +146,8 @@ 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 */

	void __iomem		*regs;		/* virt. base address, if any */

	struct serial_rs485	rs485;		/* rs485 settings */

};

extern void __init at91_add_device_serial(void);

drivers/serial/atmel_serial.c

+173 −34
Original line number Diff line number Diff line
@@ -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 +195,46 @@ 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 int mode;



	spin_lock(&port->lock);



	/* Disable interrupts */

	UART_PUT_IDR(port, atmel_port->tx_done_mask);



	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);



	/* Enable interrupts */

	UART_PUT_IER(port, atmel_port->tx_done_mask);



	spin_unlock(&port->lock);



}



/*

 * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.

 */
@@ -202,6 +250,7 @@ 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 +285,17 @@ 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 +328,17 @@ 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 +346,39 @@ 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);

	}

}



/*
@@ -302,10 +389,12 @@ 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);

	}

}



/*

 * Enable modem status interrupts
@@ -428,8 +517,9 @@ 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 +527,7 @@ 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 +539,8 @@ 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);

}



/*
@@ -501,20 +592,12 @@ 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);

	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);

	}

}

}



/*

 * status flags interrupt handler.
@@ -590,9 +673,15 @@ 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 +1106,7 @@ 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 +1205,17 @@ 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 +1332,35 @@ 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 +1380,7 @@ 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,
@@ -1271,7 +1402,6 @@ static void __devinit atmel_init_port(struct atmel_uart_port *atmel_port, 
	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 +1429,16 @@ 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 +1472,7 @@ 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 +1480,7 @@ 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;