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=DEVNAME:0.0 style hardware based addressing in addition to the current console=ttyS0 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 <tony@xxxxxxxxxxx> --- 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 +int add_preferred_console_match(const char *match, const char *name, + const short idx); + extern int console_printk[]; #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 = printk.o +obj-y = printk.o conopt.o obj-$(CONFIG_PRINTK) += printk_safe.o nbcon.o obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) += braille.o obj-$(CONFIG_PRINTK_INDEX) += 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 <tony@xxxxxxxxxxx> + */ + +#include <linux/console.h> +#include <linux/kernel.h> + +#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() only. + */ +int __init console_opt_save(char *str) +{ + struct console_option *con; + const char *opt = NULL; + size_t namelen, optlen; + int i; + + namelen = strcspn(str, ","); + if (!namelen) + return -EINVAL; + + optlen = strlen(str) - namelen; + if (optlen > 1) + opt = str + namelen + 1; + + if (namelen >= CONSOLE_NAME_MAX || optlen >= CONSOLE_OPT_MAX) + return -EINVAL; + + for (i = 0; i < MAX_CMDLINECONSOLES; i++) { + con = &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 = 0; i < MAX_CMDLINECONSOLES; i++) { + con = &conopt[i]; + if (!strcmp(name, con->name)) + return con; + } + + return NULL; +} + +/** + * add_preferred_console_match - Adds a preferred console if a match is found + * @match: Expected console on kernel command line, such as console=DEVNAME: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 preferred + * 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 = 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_cmdline.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 +#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=) */ - -#define MAX_CMDLINECONSOLES 8 - static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; static int preferred_console = -1; @@ -2445,6 +2442,14 @@ static int __init console_setup(char *str) char *s, *options, *brl_options = NULL; int idx; + /* + * 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="" or console=null have been suggested as a way to * disable console output. Use ttynull that has been created -- 2.42.1
