From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS3215 2.6.0.0/16 X-Spam-Status: No, score=-4.3 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server2.sourceware.org [IPv6:2620:52:3:1:0:246e:9693:128c]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id 22FA51F8C6 for ; Tue, 31 Aug 2021 20:35:01 +0000 (UTC) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 1FBCE385841D for ; Tue, 31 Aug 2021 20:35:00 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 1FBCE385841D DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1630442100; bh=gE3ETN3pOHuuYF93MWu9zN6hR3S8ZluZLEeExDowIjk=; h=Date:To:Subject:References:In-Reply-To:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=BO2F8G/adZKI9Zoznxh6OxlNBSFSyEiqPTGust3qg182vrkpFY7ZvtwsyiMi1/UC+ dmIQDr9/ojDfnFOxsED6j4u/GSdQKCGsRkHiIbggTLG5mqQEwm3MkN4/LMNdjjMvIB rfCp7Yu1T/XnplKcrXHrfWC9krTKE8Wi/5dIMH48= Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by sourceware.org (Postfix) with ESMTPS id 421AE3858C27 for ; Tue, 31 Aug 2021 20:34:40 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 421AE3858C27 Received: by mail.kernel.org (Postfix) with ESMTPSA id D965460ED4; Tue, 31 Aug 2021 20:34:38 +0000 (UTC) Received: by pali.im (Postfix) id 810E5EF2; Tue, 31 Aug 2021 22:34:36 +0200 (CEST) Date: Tue, 31 Aug 2021 22:34:36 +0200 To: linux-man@vger.kernel.org, Alejandro Colomar , Michael Kerrisk Subject: Re: [PATCH v4] ioctl_tty.2: Add example how to get or set baudrate on the serial port Message-ID: <20210831203436.hy52aimer5hozb6r@pali> References: <20210730095333.6118-1-pali@kernel.org> <20210810194928.16408-1-pali@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210810194928.16408-1-pali@kernel.org> User-Agent: NeoMutt/20180716 X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: =?utf-8?q?Pali_Roh=C3=A1r_via_Libc-alpha?= Reply-To: Pali =?utf-8?B?Um9ow6Fy?= Cc: Marek =?utf-8?B?QmVow7pu?= , "G. Branden Robinson" , libc-alpha@sourceware.org Errors-To: libc-alpha-bounces+e=80x24.org@sourceware.org Sender: "Libc-alpha" On Tuesday 10 August 2021 21:49:28 Pali Rohár wrote: > Setting custom baudrate for which is not defined Bnnn constant is possible > via BOTHER flag and then filling speed in c_ospeed and c_ispeed fields. > > These two fields are either in struct termios or struct termios2. Former > belongs to TCGETS/TCSETS ioctls, latter to TCGETS2/TCSETS2 ioctls. > > BOTHER flag with these two fields and new struct termios2 is not supported > by older versions of include header files. > > Some architectures (e.g. amd64) provide both struct termios and struct > termios2, but c_ospeed and c_ispeed are only in struct termios2. > > Some other architectures (e.g. alpha) provide both struct termios and struct > termios2 and both have c_ospeed and c_ispeed fields. > > And some other architectures (e.g. powerpc) provide only struct termios > (no struct termios2) and it has c_ospeed and c_ispeed fields. > > So basically to support all architectures it is needed to use > struct termios2 when TCGETS2/TCSETS2 is supported. Otherwise it is needed > to use struct termios with TCGETS/TCSETS (case for e.g. powerpc). > > Setting input baudrate is done via IBSHIFT macro. > > Signed-off-by: Pali Rohár Hello! Do you have any comments on this patch? > --- > Changes in v4: > * Add SPDX-License-Identifier > * Correctly process split baudrates (separate output and input) via IBSHIFT > * Update commit message > > Changes in v3: > * Check support for custom baudrate only based on BOTHER macro > * Use TCGETS/TCSETS/termios when TCGETS2/TCSETS2/termios2 is not available > > Changes in v2: > * Use \e for backslash > * Use exit(EXIT_*) instead of return num > * Sort includes > * Add comment about possible fallback > --- > man2/ioctl_tty.2 | 100 +++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 100 insertions(+) > > diff --git a/man2/ioctl_tty.2 b/man2/ioctl_tty.2 > index abfdc1e21fe9..7b2b03ff6757 100644 > --- a/man2/ioctl_tty.2 > +++ b/man2/ioctl_tty.2 > @@ -796,6 +796,106 @@ main(void) > close(fd); > } > .EE > +.PP > +Get or set arbitrary baudrate on the serial port. > +.PP > +.EX > +/* SPDX-License-Identifier: GPL-2.0-or-later */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +int > +main(int argc, char *argv[]) > +{ > +#ifndef BOTHER > + fprintf(stderr, "BOTHER is unsupported\en"); > + /* Program may fallback to TCGETS/TCSETS with Bnnn constants */ > + exit(EXIT_FAILURE); > +#else > + /* Declare tio structure, its type depends on supported ioctl */ > +#ifdef TCGETS2 > + struct termios2 tio; > +#else > + struct termios tio; > +#endif > + int fd, rc; > + > + if (argc != 2 && argc != 3 && argc != 4) { > + fprintf(stderr, "Usage: %s device [output [input] ]\en", argv[0]); > + exit(EXIT_FAILURE); > + } > + > + fd = open(argv[1], O_RDWR | O_NONBLOCK | O_NOCTTY); > + if (fd < 0) { > + perror("open"); > + exit(EXIT_FAILURE); > + } > + > + /* Get the current serial port settings via supported ioctl */ > +#ifdef TCGETS2 > + rc = ioctl(fd, TCGETS2, &tio); > +#else > + rc = ioctl(fd, TCGETS, &tio); > +#endif > + if (rc) { > + perror("TCGETS"); > + close(fd); > + exit(EXIT_FAILURE); > + } > + > + /* Change baud rate when more arguments were provided */ > + if (argc == 3 || argc == 4) { > + /* Clear the current output baud rate and fill a new value */ > + tio.c_cflag &= ~CBAUD; > + tio.c_cflag |= BOTHER; > + tio.c_ospeed = atoi(argv[2]); > + > + /* Clear the current input baud rate and fill a new value */ > + tio.c_cflag &= ~(CBAUD << IBSHIFT); > + tio.c_cflag |= BOTHER << IBSHIFT; > + /* When 4th argument is not provided reuse output baud rate */ > + tio.c_ispeed = (argc == 4) ? atoi(argv[3]) : atoi(argv[2]); > + > + /* Set new serial port settings via supported ioctl */ > +#ifdef TCSETS2 > + rc = ioctl(fd, TCSETS2, &tio); > +#else > + rc = ioctl(fd, TCSETS, &tio); > +#endif > + if (rc) { > + perror("TCSETS"); > + close(fd); > + exit(EXIT_FAILURE); > + } > + > + /* And get new values which were really configured */ > +#ifdef TCGETS2 > + rc = ioctl(fd, TCGETS2, &tio); > +#else > + rc = ioctl(fd, TCGETS, &tio); > +#endif > + if (rc) { > + perror("TCGETS"); > + close(fd); > + exit(EXIT_FAILURE); > + } > + } > + > + close(fd); > + > + printf("output baud rate: %u\en", tio.c_ospeed); > + printf("input baud rate: %u\en", tio.c_ispeed); > + > + exit(EXIT_SUCCESS); > +#endif > +} > +.EE > .SH SEE ALSO > .BR ldattach (1), > .BR ioctl (2), > -- > 2.20.1 >