RE: [PATCH v1] 8250: add support for DTR/DSR hardware flow control

["Tosoni" <jp.tosoni@acksys.fr>]

[-- Attachment #1: Type: text/plain, Size: 1985 bytes --]

In my opinion, DSR/DTR is another (wrong) way to do RTS/CTS flow control, so
I would have it implemented in setserial as a modifier to the CRTSCTS flag.

About a RS485 ioctl: could you consider the attached files which are already
in the Linux kernel (in include/asm-cris).
They define a TIOCSERSETRS485 (ioctl.h), and the data structure (rs485.h)
with allows to specify timings. Sounds just like what we want ?

JP Tosoni

> -----Original Message-----
> From: linux-serial-owner@vger.kernel.org
> [mailto:linux-serial-owner@vger.kernel.org]On Behalf Of
> Laurent Pinchart
> Sent: Thursday, August 07, 2008 10:32 AM
> To: Aristeu Rozanski
> Cc: linux-serial@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v1] 8250: add support for DTR/DSR hardware flow
> control
>
>
> Hi,
>
> On Wednesday 06 August 2008, Aristeu Rozanski wrote:
> > This patch adds support for DTR/DSR hardware flow control
> on 8250 driver on
> > x86 machines. It's done by adding a CDTRDSR flag to work
> just like CRTSCTS,
> > which is not done on other architectures on purpose (so
> each maintainer can
> > allocate it).
>
> It's funny, serial flow control hasn't been discussed for a
> long time, and you're the third person to start a flow
> control related thread on this mailing list in a few days.
>
> > This patch was tested with success with a serial printer
> configured with a
> > small buffer and DTR/DSR flow control.
> >
> > This is based on the work of Michael Westermann
> > (http://lkml.org/lkml/2007/8/31/133)
> >
> > Comments more than welcome.
>
> Please read the '[PATCH/RFC] 8250: Auto RS485 direction
> control' thread for background information. In a nutshell we
> need more than just CTS/RTS and DTR/DSR, and we don't have
> enough c_cflags bits. We will probably have to create a new ioctl.
>
> Best regards,
>
> --
> Laurent Pinchart
> CSE Semaphore Belgium
>
> Chaussee de Bruxelles, 732A
> B-1410 Waterloo
> Belgium
>
> T +32 (2) 387 42 59
> F +32 (2) 387 42 75
>

[-- Attachment #2: ioctls.h --]
[-- Type: text/plain, Size: 2955 bytes --]

#ifndef __ARCH_CRIS_IOCTLS_H__
#define __ARCH_CRIS_IOCTLS_H__

/* verbatim copy of asm-i386/ioctls.h */

#include <asm/ioctl.h>

/* 0x54 is just a magic number to make these relatively unique ('T') */

#define TCGETS		0x5401
#define TCSETS		0x5402
#define TCSETSW		0x5403
#define TCSETSF		0x5404
#define TCGETA		0x5405
#define TCSETA		0x5406
#define TCSETAW		0x5407
#define TCSETAF		0x5408
#define TCSBRK		0x5409
#define TCXONC		0x540A
#define TCFLSH		0x540B
#define TIOCEXCL	0x540C
#define TIOCNXCL	0x540D
#define TIOCSCTTY	0x540E
#define TIOCGPGRP	0x540F
#define TIOCSPGRP	0x5410
#define TIOCOUTQ	0x5411
#define TIOCSTI		0x5412
#define TIOCGWINSZ	0x5413
#define TIOCSWINSZ	0x5414
#define TIOCMGET	0x5415
#define TIOCMBIS	0x5416
#define TIOCMBIC	0x5417
#define TIOCMSET	0x5418
#define TIOCGSOFTCAR	0x5419
#define TIOCSSOFTCAR	0x541A
#define FIONREAD	0x541B
#define TIOCINQ		FIONREAD
#define TIOCLINUX	0x541C
#define TIOCCONS	0x541D
#define TIOCGSERIAL	0x541E
#define TIOCSSERIAL	0x541F
#define TIOCPKT		0x5420
#define FIONBIO		0x5421
#define TIOCNOTTY	0x5422
#define TIOCSETD	0x5423
#define TIOCGETD	0x5424
#define TCSBRKP		0x5425	/* Needed for POSIX tcsendbreak() */
#define TIOCSBRK	0x5427  /* BSD compatibility */
#define TIOCCBRK	0x5428  /* BSD compatibility */
#define TIOCGSID	0x5429  /* Return the session ID of FD */
#define TCGETS2		_IOR('T',0x2A, struct termios2)
#define TCSETS2		_IOW('T',0x2B, struct termios2)
#define TCSETSW2	_IOW('T',0x2C, struct termios2)
#define TCSETSF2	_IOW('T',0x2D, struct termios2)
#define TIOCGPTN	_IOR('T',0x30, unsigned int) /* Get Pty Number (of pty-mux device) */
#define TIOCSPTLCK	_IOW('T',0x31, int)  /* Lock/unlock Pty */

#define FIONCLEX	0x5450  /* these numbers need to be adjusted. */
#define FIOCLEX		0x5451
#define FIOASYNC	0x5452
#define TIOCSERCONFIG	0x5453
#define TIOCSERGWILD	0x5454
#define TIOCSERSWILD	0x5455
#define TIOCGLCKTRMIOS	0x5456
#define TIOCSLCKTRMIOS	0x5457
#define TIOCSERGSTRUCT	0x5458 /* For debugging only */
#define TIOCSERGETLSR   0x5459 /* Get line status register */
#define TIOCSERGETMULTI 0x545A /* Get multiport config  */
#define TIOCSERSETMULTI 0x545B /* Set multiport config */

#define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
#define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
#define TIOCGHAYESESP   0x545E  /* Get Hayes ESP configuration */
#define TIOCSHAYESESP   0x545F  /* Set Hayes ESP configuration */
#define FIOQSIZE	0x5460

#define TIOCSERSETRS485 0x5461  /* enable rs-485 */
#define TIOCSERWRRS485  0x5462  /* write rs-485 */

/* Used for packet mode */
#define TIOCPKT_DATA		 0
#define TIOCPKT_FLUSHREAD	 1
#define TIOCPKT_FLUSHWRITE	 2
#define TIOCPKT_STOP		 4
#define TIOCPKT_START		 8
#define TIOCPKT_NOSTOP		16
#define TIOCPKT_DOSTOP		32

#define TIOCSER_TEMT    0x01	/* Transmitter physically empty */

#endif

[-- Attachment #3: rs485.h --]
[-- Type: text/plain, Size: 474 bytes --]

/* RS-485 structures */

/* RS-485 support */
/* Used with ioctl() TIOCSERSETRS485 */
struct rs485_control {
        unsigned short rts_on_send;
        unsigned short rts_after_sent;
        unsigned long delay_rts_before_send;
        unsigned short enabled;
#ifdef __KERNEL__
        int disable_serial_loopback;
#endif
};

/* Used with ioctl() TIOCSERWRRS485 */
struct rs485_write {
        unsigned short outc_size;
        unsigned char *outc;
};