From nobody Thu Dec 18 08:09:26 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ABAFFC54FB9 for ; Tue, 21 Nov 2023 11:32:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234111AbjKULc7 (ORCPT ); Tue, 21 Nov 2023 06:32:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59040 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234198AbjKULcz (ORCPT ); Tue, 21 Nov 2023 06:32:55 -0500 Received: from muru.com (muru.com [72.249.23.125]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 2A79CD1; Tue, 21 Nov 2023 03:32:50 -0800 (PST) Received: from hillo.muru.com (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTP id D5C8380E2; Tue, 21 Nov 2023 11:32:47 +0000 (UTC) From: Tony Lindgren To: Greg Kroah-Hartman , Jiri Slaby , Petr Mladek , Steven Rostedt , John Ogness , Sergey Senozhatsky Cc: "David S . Miller" , Andy Shevchenko , Dhruva Gole , =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , Johan Hovold , Sebastian Andrzej Siewior , Vignesh Raghavendra , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org Subject: [PATCH v3 1/3] printk: Save console options for add_preferred_console_match() Date: Tue, 21 Nov 2023 13:31:55 +0200 Message-ID: <20231121113203.61341-2-tony@atomide.com> X-Mailer: git-send-email 2.42.1 In-Reply-To: <20231121113203.61341-1-tony@atomide.com> References: <20231121113203.61341-1-tony@atomide.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Driver subsystems may need to translate the preferred console name to the character device name used. We already do some of this in console_setup() with a few hardcoded names, but that does not scale well. The console options are parsed early in console_setup(), and the consoles are added with __add_preferred_console(). At this point we don't know much about the character device names and device drivers getting probed. To allow drivers subsystems to set up a preferred console, let's save the kernel command line console options. To add a preferred console, let's add a new function add_preferred_console_match(). This allows the serial core layer to support console=3DDEVNAME:0.0 style hardware based addressing in addition to the current console=3DttyS0 style naming. And we can start moving console_setup() character device parsing to the driver subsystem specific code. We use a separate array from the console_cmdline array as the character device name and index may be unknown at the console_setup() time. And we do not want to call __add_preferred_console() until the character device name and index are known. Adding the console name in addition to the character device name, and a flag for an added console, could be added to the struct console_cmdline. And the console_cmdline array handling modified accordingly. But that complicates things compared saving the console options, and then adding the consoles when the subsystems handling the consoles are ready. Signed-off-by: Tony Lindgren --- include/linux/printk.h | 3 + kernel/printk/Makefile | 2 +- kernel/printk/conopt.c | 115 ++++++++++++++++++++++++++++++++ kernel/printk/console_cmdline.h | 4 ++ kernel/printk/printk.c | 11 ++- 5 files changed, 131 insertions(+), 4 deletions(-) create mode 100644 kernel/printk/conopt.c diff --git a/include/linux/printk.h b/include/linux/printk.h --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -60,6 +60,9 @@ static inline const char *printk_skip_headers(const char = *buffer) #define CONSOLE_LOGLEVEL_DEFAULT CONFIG_CONSOLE_LOGLEVEL_DEFAULT #define CONSOLE_LOGLEVEL_QUIET CONFIG_CONSOLE_LOGLEVEL_QUIET =20 +int add_preferred_console_match(const char *match, const char *name, + const short idx); + extern int console_printk[]; =20 #define console_loglevel (console_printk[0]) diff --git a/kernel/printk/Makefile b/kernel/printk/Makefile --- a/kernel/printk/Makefile +++ b/kernel/printk/Makefile @@ -1,5 +1,5 @@ # SPDX-License-Identifier: GPL-2.0-only -obj-y =3D printk.o +obj-y =3D printk.o conopt.o obj-$(CONFIG_PRINTK) +=3D printk_safe.o nbcon.o obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) +=3D braille.o obj-$(CONFIG_PRINTK_INDEX) +=3D index.o diff --git a/kernel/printk/conopt.c b/kernel/printk/conopt.c new file mode 100644 --- /dev/null +++ b/kernel/printk/conopt.c @@ -0,0 +1,115 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Kernel command line console options for hardware based addressing + * + * Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/ + * Author: Tony Lindgren + */ + +#include +#include + +#include "console_cmdline.h" + +/* + * Allow longer DEVNAME:0.0 style console naming such as abcd0000.serial:0= .0 + * in addition to the legacy ttyS0 style naming. + */ +#define CONSOLE_NAME_MAX 32 + +#define CONSOLE_OPT_MAX 16 + +struct console_option { + char name[CONSOLE_NAME_MAX]; + char opt[CONSOLE_OPT_MAX]; +}; + +/* Updated only at console_setup() time, no locking needed */ +static struct console_option conopt[MAX_CMDLINECONSOLES]; + +/** + * console_opt_save - Saves kernel command line console option for driver = use + * @str: Kernel command line console name and option + * + * Saves a kernel command line console option for driver subsystems to use= for + * adding a preferred console during init. Called from console_setup() onl= y. + */ +int __init console_opt_save(char *str) +{ + struct console_option *con; + const char *opt =3D NULL; + size_t namelen, optlen; + int i; + + namelen =3D strcspn(str, ","); + if (!namelen) + return -EINVAL; + + optlen =3D strlen(str) - namelen; + if (optlen > 1) + opt =3D str + namelen + 1; + + if (namelen >=3D CONSOLE_NAME_MAX || optlen >=3D CONSOLE_OPT_MAX) + return -EINVAL; + + for (i =3D 0; i < MAX_CMDLINECONSOLES; i++) { + con =3D &conopt[i]; + + if (con->name[0]) { + if (!strncmp(str, con->name, namelen)) + return 0; + continue; + } + + strscpy(con->name, str, namelen + 1); + if (opt) + strscpy(con->opt, opt, optlen + 1); + + return 0; + } + + return -ENOMEM; +} + +static struct console_option *console_opt_find(const char *name) +{ + struct console_option *con; + int i; + + for (i =3D 0; i < MAX_CMDLINECONSOLES; i++) { + con =3D &conopt[i]; + if (!strcmp(name, con->name)) + return con; + } + + return NULL; +} + +/** + * add_preferred_console_match - Adds a preferred console if a match is fo= und + * @match: Expected console on kernel command line, such as console=3DDEVN= AME:0.0 + * @name: Name of the console character device to add such as ttyS + * @idx: Index for the console + * + * Allows driver subsystems to add a console after translating the command + * line name to the character device name used for the console. Options are + * added automatically based on the kernel command line. Duplicate preferr= ed + * consoles are ignored by __add_preferred_console(). + */ +int add_preferred_console_match(const char *match, const char *name, + const short idx) +{ + struct console_option *con; + + if (!match || !strlen(match) || !name || !strlen(name) || + idx < 0) + return -EINVAL; + + con =3D console_opt_find(match); + if (!con) + return -ENOENT; + + add_preferred_console(name, idx, con->opt); + + return 0; +} diff --git a/kernel/printk/console_cmdline.h b/kernel/printk/console_cmdlin= e.h --- a/kernel/printk/console_cmdline.h +++ b/kernel/printk/console_cmdline.h @@ -2,6 +2,10 @@ #ifndef _CONSOLE_CMDLINE_H #define _CONSOLE_CMDLINE_H =20 +#define MAX_CMDLINECONSOLES 8 + +int console_opt_save(char *str); + struct console_cmdline { char name[16]; /* Name of the driver */ diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -360,9 +360,6 @@ static int console_locked; /* * Array of consoles built from command line options (console=3D) */ - -#define MAX_CMDLINECONSOLES 8 - static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; =20 static int preferred_console =3D -1; @@ -2445,6 +2442,14 @@ static int __init console_setup(char *str) char *s, *options, *brl_options =3D NULL; int idx; =20 + /* + * Save the console for possible driver subsystem use. Bail out early + * for DEVICE:0.0 style console names as the character device name is + * be unknown at this point. + */ + if (!console_opt_save(str) && strchr(str, ':')) + return 1; + /* * console=3D"" or console=3Dnull have been suggested as a way to * disable console output. Use ttynull that has been created --=20 2.42.1