| 1 | |
| 2 | * linux/include/linux/console.h
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| 3 | *
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| 4 | * Copyright (C) 1993 Hamish Macdonald
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| 5 | *
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| 6 | * This file is subject to the terms and conditions of the GNU General Public
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| 7 | * License. See the file COPYING in the main directory of this archive
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| 8 | * for more details.
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| 9 | *
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| 10 | * Changed:
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| 11 | * 10-Mar-94: Arno Griffioen: Conversion for vt100 emulator port from PC LINUX
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| 12 |
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| 13 |
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| 14 | #ifndef _LINUX_CONSOLE_H_
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| 15 | #define _LINUX_CONSOLE_H_ 1
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| 16 |
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| 17 | #include <linux/atomic.h>
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| 18 | #include <linux/bits.h>
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| 19 | #include <linux/irq_work.h>
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| 20 | #include <linux/rculist.h>
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| 21 | #include <linux/rcuwait.h>
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| 22 | #include <linux/smp.h>
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| 23 | #include <linux/types.h>
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| 24 | #include <linux/vesa.h>
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| 25 |
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| 26 | struct vc_data;
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| 27 | struct console_font_op;
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| 28 | struct console_font;
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| 29 | struct module;
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| 30 | struct tty_struct;
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| 31 | struct notifier_block;
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| 32 |
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| 33 | enum con_scroll {
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| 34 | SM_UP,
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| 35 | SM_DOWN,
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| 36 | };
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| 37 |
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| 38 | enum vc_intensity;
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| 39 |
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| 40 | |
| 41 | * struct consw - callbacks for consoles
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| 42 | *
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| 43 | * @owner: the module to get references of when this console is used
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| 44 | * @con_startup: set up the console and return its name (like VGA, EGA, ...)
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| 45 | * @con_init: initialize the console on @vc. @init is true for the very first
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| 46 | * call on this @vc.
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| 47 | * @con_deinit: deinitialize the console from @vc.
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| 48 | * @con_clear: erase @count characters at [@x, @y] on @vc. @count >= 1.
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| 49 | * @con_putc: emit one character with attributes @ca to [@x, @y] on @vc.
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| 50 | * (optional -- @con_putcs would be called instead)
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| 51 | * @con_putcs: emit @count characters with attributes @s to [@x, @y] on @vc.
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| 52 | * @con_cursor: enable/disable cursor depending on @enable
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| 53 | * @con_scroll: move lines from @top to @bottom in direction @dir by @lines.
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| 54 | * Return true if no generic handling should be done.
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| 55 | * Invoked by csi_M and printing to the console.
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| 56 | * @con_switch: notifier about the console switch; it is supposed to return
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| 57 | * true if a redraw is needed.
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| 58 | * @con_blank: blank/unblank the console. The target mode is passed in @blank.
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| 59 | * @mode_switch is set if changing from/to text/graphics. The hook
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| 60 | * is supposed to return true if a redraw is needed.
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| 61 | * @con_font_set: set console @vc font to @font with height @vpitch. @flags can
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| 62 | * be %KD_FONT_FLAG_DONT_RECALC. (optional)
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| 63 | * @con_font_get: fetch the current font on @vc of height @vpitch into @font.
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| 64 | * (optional)
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| 65 | * @con_font_default: set default font on @vc. @name can be %NULL or font name
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| 66 | * to search for. @font can be filled back. (optional)
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| 67 | * @con_resize: resize the @vc console to @width x @height. @from_user is true
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| 68 | * when this change comes from the user space.
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| 69 | * @con_set_palette: sets the palette of the console @vc to @table (optional)
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| 70 | * @con_scrolldelta: the contents of the console should be scrolled by @lines.
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| 71 | * Invoked by user. (optional)
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| 72 | * @con_set_origin: set origin (see &vc_data::vc_origin) of the @vc. If not
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| 73 | * provided or returns false, the origin is set to
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| 74 | * @vc->vc_screenbuf. (optional)
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| 75 | * @con_save_screen: save screen content into @vc->vc_screenbuf. Called e.g.
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| 76 | * upon entering graphics. (optional)
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| 77 | * @con_build_attr: build attributes based on @color, @intensity and other
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| 78 | * parameters. The result is used for both normal and erase
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| 79 | * characters. (optional)
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| 80 | * @con_invert_region: invert a region of length @count on @vc starting at @p.
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| 81 | * (optional)
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| 82 |
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| 83 | struct consw {
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| 84 | struct module *owner;
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| 85 | const char *(*con_startup)(void);
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| 86 | void (*con_init)(struct vc_data *vc, bool init);
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| 87 | void (*con_deinit)(struct vc_data *vc);
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| 88 | void (*con_clear)(struct vc_data *vc, unsigned int y,
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| 89 | unsigned int x, unsigned int count);
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| 90 | void (*con_putc)(struct vc_data *vc, u16 ca, unsigned int y,
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| 91 | unsigned int x);
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| 92 | void (*con_putcs)(struct vc_data *vc, const u16 *s,
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| 93 | unsigned int count, unsigned int ypos,
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| 94 | unsigned int xpos);
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| 95 | void (*con_cursor)(struct vc_data *vc, bool enable);
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| 96 | bool (*con_scroll)(struct vc_data *vc, unsigned int top,
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| 97 | unsigned int bottom, enum con_scroll dir,
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| 98 | unsigned int lines);
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| 99 | bool (*con_switch)(struct vc_data *vc);
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| 100 | bool (*con_blank)(struct vc_data *vc, enum vesa_blank_mode blank,
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| 101 | bool mode_switch);
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| 102 | int (*con_font_set)(struct vc_data *vc,
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| 103 | const struct console_font *font,
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| 104 | unsigned int vpitch, unsigned int flags);
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| 105 | int (*con_font_get)(struct vc_data *vc, struct console_font *font,
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| 106 | unsigned int vpitch);
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| 107 | int (*con_font_default)(struct vc_data *vc,
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| 108 | struct console_font *font, const char *name);
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| 109 | int (*con_resize)(struct vc_data *vc, unsigned int width,
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| 110 | unsigned int height, bool from_user);
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| 111 | void (*con_set_palette)(struct vc_data *vc,
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| 112 | const unsigned char *table);
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| 113 | void (*con_scrolldelta)(struct vc_data *vc, int lines);
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| 114 | bool (*con_set_origin)(struct vc_data *vc);
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| 115 | void (*con_save_screen)(struct vc_data *vc);
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| 116 | u8 (*con_build_attr)(struct vc_data *vc, u8 color,
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| 117 | enum vc_intensity intensity,
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| 118 | bool blink, bool underline, bool reverse, bool italic);
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| 119 | void (*con_invert_region)(struct vc_data *vc, u16 *p, int count);
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| 120 | };
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| 121 |
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| 122 | extern const struct consw *conswitchp;
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| 123 |
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| 124 | extern const struct consw dummy_con;
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| 125 | extern const struct consw vga_con;
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| 126 | extern const struct consw newport_con;
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| 127 |
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| 128 | struct screen_info;
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| 129 | #ifdef CONFIG_VGA_CONSOLE
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| 130 | void vgacon_register_screen(struct screen_info *si);
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| 131 | #else
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| 132 | static inline void vgacon_register_screen(struct screen_info *si) { }
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| 133 | #endif
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| 134 |
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| 135 | int con_is_bound(const struct consw *csw);
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| 136 | int do_unregister_con_driver(const struct consw *csw);
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| 137 | int do_take_over_console(const struct consw *sw, int first, int last, int deflt);
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| 138 | void give_up_console(const struct consw *sw);
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| 139 | #ifdef CONFIG_VT
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| 140 | void con_debug_enter(struct vc_data *vc);
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| 141 | void con_debug_leave(void);
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| 142 | #else
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| 143 | static inline void con_debug_enter(struct vc_data *vc) { }
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| 144 | static inline void con_debug_leave(void) { }
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| 145 | #endif
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| 146 |
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| 147 | |
| 148 | * The interface for a console, or any other device that wants to capture
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| 149 | * console messages (printer driver?)
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| 150 |
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| 151 |
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| 152 | |
| 153 | * enum cons_flags - General console flags
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| 154 | * @CON_PRINTBUFFER: Used by newly registered consoles to avoid duplicate
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| 155 | * output of messages that were already shown by boot
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| 156 | * consoles or read by userspace via syslog() syscall.
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| 157 | * @CON_CONSDEV: Indicates that the console driver is backing
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| 158 | * /dev/console.
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| 159 | * @CON_ENABLED: Indicates if a console is allowed to print records. If
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| 160 | * false, the console also will not advance to later
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| 161 | * records.
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| 162 | * @CON_BOOT: Marks the console driver as early console driver which
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| 163 | * is used during boot before the real driver becomes
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| 164 | * available. It will be automatically unregistered
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| 165 | * when the real console driver is registered unless
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| 166 | * "keep_bootcon" parameter is used.
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| 167 | * @CON_ANYTIME: A misnomed historical flag which tells the core code
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| 168 | * that the legacy @console::write callback can be invoked
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| 169 | * on a CPU which is marked OFFLINE. That is misleading as
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| 170 | * it suggests that there is no contextual limit for
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| 171 | * invoking the callback. The original motivation was
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| 172 | * readiness of the per-CPU areas.
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| 173 | * @CON_BRL: Indicates a braille device which is exempt from
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| 174 | * receiving the printk spam for obvious reasons.
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| 175 | * @CON_EXTENDED: The console supports the extended output format of
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| 176 | * /dev/kmesg which requires a larger output buffer.
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| 177 | * @CON_SUSPENDED: Indicates if a console is suspended. If true, the
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| 178 | * printing callbacks must not be called.
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| 179 | * @CON_NBCON: Console can operate outside of the legacy style console_lock
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| 180 | * constraints.
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| 181 | * @CON_NBCON_ATOMIC_UNSAFE: The write_atomic() callback is not safe and is
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| 182 | * therefore only used by nbcon_atomic_flush_unsafe().
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| 183 |
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| 184 | enum cons_flags {
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| 185 | CON_PRINTBUFFER = BIT(0),
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| 186 | CON_CONSDEV = BIT(1),
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| 187 | CON_ENABLED = BIT(2),
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| 188 | CON_BOOT = BIT(3),
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| 189 | CON_ANYTIME = BIT(4),
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| 190 | CON_BRL = BIT(5),
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| 191 | CON_EXTENDED = BIT(6),
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| 192 | CON_SUSPENDED = BIT(7),
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| 193 | CON_NBCON = BIT(8),
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| 194 | CON_NBCON_ATOMIC_UNSAFE = BIT(9),
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| 195 | };
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| 196 |
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| 197 | |
| 198 | * struct nbcon_state - console state for nbcon consoles
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| 199 | * @atom: Compound of the state fields for atomic operations
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| 200 | *
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| 201 | * @req_prio: The priority of a handover request
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| 202 | * @prio: The priority of the current owner
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| 203 | * @unsafe: Console is busy in a non takeover region
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| 204 | * @unsafe_takeover: A hostile takeover in an unsafe state happened in the
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| 205 | * past. The console cannot be safe until re-initialized.
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| 206 | * @cpu: The CPU on which the owner runs
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| 207 | *
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| 208 | * To be used for reading and preparing of the value stored in the nbcon
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| 209 | * state variable @console::nbcon_state.
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| 210 | *
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| 211 | * The @prio and @req_prio fields are particularly important to allow
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| 212 | * spin-waiting to timeout and give up without the risk of a waiter being
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| 213 | * assigned the lock after giving up.
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| 214 |
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| 215 | struct nbcon_state {
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| 216 | union {
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| 217 | unsigned int atom;
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| 218 | struct {
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| 219 | unsigned int prio : 2;
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| 220 | unsigned int req_prio : 2;
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| 221 | unsigned int unsafe : 1;
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| 222 | unsigned int unsafe_takeover : 1;
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| 223 | unsigned int cpu : 24;
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| 224 | };
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| 225 | };
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| 226 | };
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| 227 |
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| 228 | |
| 229 | * The nbcon_state struct is used to easily create and interpret values that
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| 230 | * are stored in the @console::nbcon_state variable. Ensure this struct stays
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| 231 | * within the size boundaries of the atomic variable's underlying type in
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| 232 | * order to avoid any accidental truncation.
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| 233 |
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| 234 | static_assert(sizeof(struct nbcon_state) <= sizeof(int));
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| 235 |
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| 236 | |
| 237 | * enum nbcon_prio - console owner priority for nbcon consoles
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| 238 | * @NBCON_PRIO_NONE: Unused
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| 239 | * @NBCON_PRIO_NORMAL: Normal (non-emergency) usage
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| 240 | * @NBCON_PRIO_EMERGENCY: Emergency output (WARN/OOPS...)
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| 241 | * @NBCON_PRIO_PANIC: Panic output
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| 242 | * @NBCON_PRIO_MAX: The number of priority levels
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| 243 | *
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| 244 | * A higher priority context can takeover the console when it is
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| 245 | * in the safe state. The final attempt to flush consoles in panic()
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| 246 | * can be allowed to do so even in an unsafe state (Hope and pray).
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| 247 |
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| 248 | enum nbcon_prio {
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| 249 | NBCON_PRIO_NONE = 0,
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| 250 | NBCON_PRIO_NORMAL,
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| 251 | NBCON_PRIO_EMERGENCY,
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| 252 | NBCON_PRIO_PANIC,
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| 253 | NBCON_PRIO_MAX,
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| 254 | };
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| 255 |
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| 256 | struct console;
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| 257 | struct printk_buffers;
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| 258 |
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| 259 | |
| 260 | * struct nbcon_context - Context for console acquire/release
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| 261 | * @console: The associated console
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| 262 | * @spinwait_max_us: Limit for spin-wait acquire
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| 263 | * @prio: Priority of the context
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| 264 | * @allow_unsafe_takeover: Allow performing takeover even if unsafe. Can
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| 265 | * be used only with NBCON_PRIO_PANIC @prio. It
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| 266 | * might cause a system freeze when the console
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| 267 | * is used later.
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| 268 | * @backlog: Ringbuffer has pending records
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| 269 | * @pbufs: Pointer to the text buffer for this context
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| 270 | * @seq: The sequence number to print for this context
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| 271 |
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| 272 | struct nbcon_context {
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| 273 |
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| 274 | struct console *console;
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| 275 | unsigned int spinwait_max_us;
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| 276 | enum nbcon_prio prio;
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| 277 | unsigned int allow_unsafe_takeover : 1;
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| 278 |
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| 279 |
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| 280 | unsigned int backlog : 1;
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| 281 |
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| 282 |
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| 283 | struct printk_buffers *pbufs;
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| 284 | u64 seq;
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| 285 | };
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| 286 |
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| 287 | |
| 288 | * struct nbcon_write_context - Context handed to the nbcon write callbacks
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| 289 | * @ctxt: The core console context
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| 290 | * @outbuf: Pointer to the text buffer for output
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| 291 | * @len: Length to write
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| 292 | * @unsafe_takeover: If a hostile takeover in an unsafe state has occurred
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| 293 | * @cpu: CPU on which the message was generated
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| 294 | * @pid: PID of the task that generated the message
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| 295 | * @comm: Name of the task that generated the message
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| 296 |
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| 297 | struct nbcon_write_context {
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| 298 | struct nbcon_context __private ctxt;
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| 299 | char *outbuf;
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| 300 | unsigned int len;
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| 301 | bool unsafe_takeover;
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| 302 | #ifdef CONFIG_PRINTK_EXECUTION_CTX
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| 303 | int cpu;
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| 304 | pid_t pid;
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| 305 | char comm[TASK_COMM_LEN];
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| 306 | #endif
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| 307 | };
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| 308 |
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| 309 | |
| 310 | * struct console - The console descriptor structure
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| 311 | * @name: The name of the console driver
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| 312 | * @write: Legacy write callback to output messages (Optional)
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| 313 | * @read: Read callback for console input (Optional)
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| 314 | * @device: The underlying TTY device driver (Optional)
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| 315 | * @unblank: Callback to unblank the console (Optional)
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| 316 | * @setup: Callback for initializing the console (Optional)
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| 317 | * @exit: Callback for teardown of the console (Optional)
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| 318 | * @match: Callback for matching a console (Optional)
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| 319 | * @flags: Console flags. See enum cons_flags
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| 320 | * @index: Console index, e.g. port number
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| 321 | * @cflag: TTY control mode flags
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| 322 | * @ispeed: TTY input speed
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| 323 | * @ospeed: TTY output speed
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| 324 | * @seq: Sequence number of the next ringbuffer record to print
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| 325 | * @dropped: Number of unreported dropped ringbuffer records
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| 326 | * @data: Driver private data
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| 327 | * @node: hlist node for the console list
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| 328 | *
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| 329 | * @nbcon_state: State for nbcon consoles
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| 330 | * @nbcon_seq: Sequence number of the next record for nbcon to print
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| 331 | * @nbcon_device_ctxt: Context available for non-printing operations
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| 332 | * @nbcon_prev_seq: Seq num the previous nbcon owner was assigned to print
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| 333 | * @pbufs: Pointer to nbcon private buffer
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| 334 | * @kthread: Printer kthread for this console
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| 335 | * @rcuwait: RCU-safe wait object for @kthread waking
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| 336 | * @irq_work: Defer @kthread waking to IRQ work context
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| 337 |
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| 338 | struct console {
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| 339 | char name[16];
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| 340 | void (*write)(struct console *co, const char *s, unsigned int count);
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| 341 | int (*read)(struct console *co, char *s, unsigned int count);
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| 342 | struct tty_driver *(*device)(struct console *co, int *index);
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| 343 | void (*unblank)(void);
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| 344 | int (*setup)(struct console *co, char *options);
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| 345 | int (*exit)(struct console *co);
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| 346 | int (*match)(struct console *co, char *name, int idx, char *options);
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| 347 | short flags;
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| 348 | short index;
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| 349 | int cflag;
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| 350 | uint ispeed;
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| 351 | uint ospeed;
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| 352 | u64 seq;
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| 353 | unsigned long dropped;
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| 354 | void *data;
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| 355 | struct hlist_node node;
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| 356 |
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| 357 |
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| 358 |
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| 359 | |
| 360 | * @write_atomic:
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| 361 | *
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| 362 | * NBCON callback to write out text in any context. (Optional)
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| 363 | *
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| 364 | * This callback is called with the console already acquired. However,
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| 365 | * a higher priority context is allowed to take it over by default.
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| 366 | *
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| 367 | * The callback must call nbcon_enter_unsafe() and nbcon_exit_unsafe()
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| 368 | * around any code where the takeover is not safe, for example, when
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| 369 | * manipulating the serial port registers.
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| 370 | *
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| 371 | * nbcon_enter_unsafe() will fail if the context has lost the console
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| 372 | * ownership in the meantime. In this case, the callback is no longer
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| 373 | * allowed to go forward. It must back out immediately and carefully.
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| 374 | * The buffer content is also no longer trusted since it no longer
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| 375 | * belongs to the context.
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| 376 | *
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| 377 | * The callback should allow the takeover whenever it is safe. It
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| 378 | * increases the chance to see messages when the system is in trouble.
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| 379 | * If the driver must reacquire ownership in order to finalize or
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| 380 | * revert hardware changes, nbcon_reacquire_nobuf() can be used.
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| 381 | * However, on reacquire the buffer content is no longer available. A
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| 382 | * reacquire cannot be used to resume printing.
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| 383 | *
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| 384 | * The callback can be called from any context (including NMI).
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| 385 | * Therefore it must avoid usage of any locking and instead rely
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| 386 | * on the console ownership for synchronization.
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| 387 |
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| 388 | void (*write_atomic)(struct console *con, struct nbcon_write_context *wctxt);
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| 389 |
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| 390 | |
| 391 | * @write_thread:
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| 392 | *
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| 393 | * NBCON callback to write out text in task context.
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| 394 | *
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| 395 | * This callback must be called only in task context with both
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| 396 | * device_lock() and the nbcon console acquired with
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| 397 | * NBCON_PRIO_NORMAL.
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| 398 | *
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| 399 | * The same rules for console ownership verification and unsafe
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| 400 | * sections handling applies as with write_atomic().
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| 401 | *
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| 402 | * The console ownership handling is necessary for synchronization
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| 403 | * against write_atomic() which is synchronized only via the context.
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| 404 | *
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| 405 | * The device_lock() provides the primary serialization for operations
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| 406 | * on the device. It might be as relaxed (mutex)[*] or as tight
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| 407 | * (disabled preemption and interrupts) as needed. It allows
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| 408 | * the kthread to operate in the least restrictive mode[**].
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| 409 | *
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| 410 | * [*] Standalone nbcon_context_try_acquire() is not safe with
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| 411 | * the preemption enabled, see nbcon_owner_matches(). But it
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| 412 | * can be safe when always called in the preemptive context
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| 413 | * under the device_lock().
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| 414 | *
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| 415 | * [**] The device_lock() makes sure that nbcon_context_try_acquire()
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| 416 | * would never need to spin which is important especially with
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| 417 | * PREEMPT_RT.
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| 418 |
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| 419 | void (*write_thread)(struct console *con, struct nbcon_write_context *wctxt);
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| 420 |
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| 421 | |
| 422 | * @device_lock:
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| 423 | *
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| 424 | * NBCON callback to begin synchronization with driver code.
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| 425 | *
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| 426 | * Console drivers typically must deal with access to the hardware
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| 427 | * via user input/output (such as an interactive login shell) and
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| 428 | * output of kernel messages via printk() calls. This callback is
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| 429 | * called by the printk-subsystem whenever it needs to synchronize
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| 430 | * with hardware access by the driver. It should be implemented to
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| 431 | * use whatever synchronization mechanism the driver is using for
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| 432 | * itself (for example, the port lock for uart serial consoles).
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| 433 | *
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| 434 | * The callback is always called from task context. It may use any
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| 435 | * synchronization method required by the driver.
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| 436 | *
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| 437 | * IMPORTANT: The callback MUST disable migration. The console driver
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| 438 | * may be using a synchronization mechanism that already takes
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| 439 | * care of this (such as spinlocks). Otherwise this function must
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| 440 | * explicitly call migrate_disable().
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| 441 | *
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| 442 | * The flags argument is provided as a convenience to the driver. It
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| 443 | * will be passed again to device_unlock(). It can be ignored if the
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| 444 | * driver does not need it.
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| 445 |
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| 446 | void (*device_lock)(struct console *con, unsigned long *flags);
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| 447 |
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| 448 | |
| 449 | * @device_unlock:
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| 450 | *
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| 451 | * NBCON callback to finish synchronization with driver code.
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| 452 | *
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| 453 | * It is the counterpart to device_lock().
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| 454 | *
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| 455 | * This callback is always called from task context. It must
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| 456 | * appropriately re-enable migration (depending on how device_lock()
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| 457 | * disabled migration).
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| 458 | *
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| 459 | * The flags argument is the value of the same variable that was
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| 460 | * passed to device_lock().
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| 461 |
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| 462 | void (*device_unlock)(struct console *con, unsigned long flags);
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| 463 |
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| 464 | atomic_t __private nbcon_state;
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| 465 | atomic_long_t __private nbcon_seq;
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| 466 | struct nbcon_context __private nbcon_device_ctxt;
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| 467 | atomic_long_t __private nbcon_prev_seq;
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| 468 |
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| 469 | struct printk_buffers *pbufs;
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| 470 | struct task_struct *kthread;
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| 471 | struct rcuwait rcuwait;
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| 472 | struct irq_work irq_work;
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| 473 | };
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| 474 |
|
| 475 | #ifdef CONFIG_LOCKDEP
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| 476 | extern void lockdep_assert_console_list_lock_held(void);
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| 477 | #else
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| 478 | static inline void lockdep_assert_console_list_lock_held(void)
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| 479 | {
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| 480 | }
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| 481 | #endif
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| 482 |
|
| 483 | #ifdef CONFIG_DEBUG_LOCK_ALLOC
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| 484 | extern bool console_srcu_read_lock_is_held(void);
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| 485 | #else
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| 486 | static inline bool console_srcu_read_lock_is_held(void)
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| 487 | {
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| 488 | return 1;
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| 489 | }
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| 490 | #endif
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| 491 |
|
| 492 | extern int console_srcu_read_lock(void);
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| 493 | extern void console_srcu_read_unlock(int cookie);
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| 494 |
|
| 495 | extern void console_list_lock(void);
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| 496 | extern void console_list_unlock(void);
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| 497 |
|
| 498 | extern struct hlist_head console_list;
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| 499 |
|
| 500 | |
| 501 | * console_srcu_read_flags - Locklessly read flags of a possibly registered
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| 502 | * console
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| 503 | * @con: struct console pointer of console to read flags from
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| 504 | *
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| 505 | * Locklessly reading @con->flags provides a consistent read value because
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| 506 | * there is at most one CPU modifying @con->flags and that CPU is using only
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| 507 | * read-modify-write operations to do so.
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| 508 | *
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| 509 | * Requires console_srcu_read_lock to be held, which implies that @con might
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| 510 | * be a registered console. The purpose of holding console_srcu_read_lock is
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| 511 | * to guarantee that the console state is valid (CON_SUSPENDED/CON_ENABLED)
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| 512 | * and that no exit/cleanup routines will run if the console is currently
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| 513 | * undergoing unregistration.
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| 514 | *
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| 515 | * If the caller is holding the console_list_lock or it is _certain_ that
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| 516 | * @con is not and will not become registered, the caller may read
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| 517 | * @con->flags directly instead.
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| 518 | *
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| 519 | * Context: Any context.
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| 520 | * Return: The current value of the @con->flags field.
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| 521 |
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| 522 | static inline short console_srcu_read_flags(const struct console *con)
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| 523 | {
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| 524 | WARN_ON_ONCE(!console_srcu_read_lock_is_held());
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| 525 |
|
| 526 | |
| 527 | * The READ_ONCE() matches the WRITE_ONCE() when @flags are modified
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| 528 | * for registered consoles with console_srcu_write_flags().
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| 529 |
|
| 530 | return data_race(READ_ONCE(con->flags));
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| 531 | }
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| 532 |
|
| 533 | |
| 534 | * console_srcu_write_flags - Write flags for a registered console
|
| 535 | * @con: struct console pointer of console to write flags to
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| 536 | * @flags: new flags value to write
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| 537 | *
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| 538 | * Only use this function to write flags for registered consoles. It
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| 539 | * requires holding the console_list_lock.
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| 540 | *
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| 541 | * Context: Any context.
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| 542 |
|
| 543 | static inline void console_srcu_write_flags(struct console *con, short flags)
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| 544 | {
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| 545 | lockdep_assert_console_list_lock_held();
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| 546 |
|
| 547 |
|
| 548 | WRITE_ONCE(con->flags, flags);
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| 549 | }
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| 550 |
|
| 551 |
|
| 552 | static inline bool console_is_registered_locked(const struct console *con)
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| 553 | {
|
| 554 | lockdep_assert_console_list_lock_held();
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| 555 | return !hlist_unhashed(&con->node);
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| 556 | }
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| 557 |
|
| 558 | |
| 559 | * console_is_registered - Check if the console is registered
|
| 560 | * @con: struct console pointer of console to check
|
| 561 | *
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| 562 | * Context: Process context. May sleep while acquiring console list lock.
|
| 563 | * Return: true if the console is in the console list, otherwise false.
|
| 564 | *
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| 565 | * If false is returned for a console that was previously registered, it
|
| 566 | * can be assumed that the console's unregistration is fully completed,
|
| 567 | * including the exit() callback after console list removal.
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| 568 |
|
| 569 | static inline bool console_is_registered(const struct console *con)
|
| 570 | {
|
| 571 | bool ret;
|
| 572 |
|
| 573 | console_list_lock();
|
| 574 | ret = console_is_registered_locked(con);
|
| 575 | console_list_unlock();
|
| 576 | return ret;
|
| 577 | }
|
| 578 |
|
| 579 | |
| 580 | * for_each_console_srcu() - Iterator over registered consoles
|
| 581 | * @con: struct console pointer used as loop cursor
|
| 582 | *
|
| 583 | * Although SRCU guarantees the console list will be consistent, the
|
| 584 | * struct console fields may be updated by other CPUs while iterating.
|
| 585 | *
|
| 586 | * Requires console_srcu_read_lock to be held. Can be invoked from
|
| 587 | * any context.
|
| 588 |
|
| 589 | #define for_each_console_srcu(con) \
|
| 590 | hlist_for_each_entry_srcu(con, &console_list, node, \
|
| 591 | console_srcu_read_lock_is_held())
|
| 592 |
|
| 593 | |
| 594 | * for_each_console() - Iterator over registered consoles
|
| 595 | * @con: struct console pointer used as loop cursor
|
| 596 | *
|
| 597 | * The console list and the &console.flags are immutable while iterating.
|
| 598 | *
|
| 599 | * Requires console_list_lock to be held.
|
| 600 |
|
| 601 | #define for_each_console(con) \
|
| 602 | lockdep_assert_console_list_lock_held(); \
|
| 603 | hlist_for_each_entry(con, &console_list, node)
|
| 604 |
|
| 605 | #ifdef CONFIG_PRINTK
|
| 606 | extern void nbcon_cpu_emergency_enter(void);
|
| 607 | extern void nbcon_cpu_emergency_exit(void);
|
| 608 | extern bool nbcon_can_proceed(struct nbcon_write_context *wctxt);
|
| 609 | extern void nbcon_write_context_set_buf(struct nbcon_write_context *wctxt,
|
| 610 | char *buf, unsigned int len);
|
| 611 | extern bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt);
|
| 612 | extern bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt);
|
| 613 | extern void nbcon_reacquire_nobuf(struct nbcon_write_context *wctxt);
|
| 614 | extern bool nbcon_allow_unsafe_takeover(void);
|
| 615 | extern bool nbcon_kdb_try_acquire(struct console *con,
|
| 616 | struct nbcon_write_context *wctxt);
|
| 617 | extern void nbcon_kdb_release(struct nbcon_write_context *wctxt);
|
| 618 |
|
| 619 | |
| 620 | * Check if the given console is currently capable and allowed to print
|
| 621 | * records. Note that this function does not consider the current context,
|
| 622 | * which can also play a role in deciding if @con can be used to print
|
| 623 | * records.
|
| 624 |
|
| 625 | static inline bool console_is_usable(struct console *con, short flags, bool use_atomic)
|
| 626 | {
|
| 627 | if (!(flags & CON_ENABLED))
|
| 628 | return false;
|
| 629 |
|
| 630 | if ((flags & CON_SUSPENDED))
|
| 631 | return false;
|
| 632 |
|
| 633 | if (flags & CON_NBCON) {
|
| 634 | if (use_atomic) {
|
| 635 |
|
| 636 | if (!con->write_atomic)
|
| 637 | return false;
|
| 638 |
|
| 639 | |
| 640 | * An unsafe write_atomic() callback is only usable
|
| 641 | * when unsafe takeovers are allowed.
|
| 642 |
|
| 643 | if ((flags & CON_NBCON_ATOMIC_UNSAFE) && !nbcon_allow_unsafe_takeover())
|
| 644 | return false;
|
| 645 | }
|
| 646 |
|
| 647 | |
| 648 | * For the !use_atomic case, @printk_kthreads_running is not
|
| 649 | * checked because the write_thread() callback is also used
|
| 650 | * via the legacy loop when the printer threads are not
|
| 651 | * available.
|
| 652 |
|
| 653 | } else {
|
| 654 | if (!con->write)
|
| 655 | return false;
|
| 656 | }
|
| 657 |
|
| 658 | |
| 659 | * Console drivers may assume that per-cpu resources have been
|
| 660 | * allocated. So unless they're explicitly marked as being able to
|
| 661 | * cope (CON_ANYTIME) don't call them until this CPU is officially up.
|
| 662 |
|
| 663 | if (!cpu_online(raw_smp_processor_id()) && !(flags & CON_ANYTIME))
|
| 664 | return false;
|
| 665 |
|
| 666 | return true;
|
| 667 | }
|
| 668 |
|
| 669 | #else
|
| 670 | static inline void nbcon_cpu_emergency_enter(void) { }
|
| 671 | static inline void nbcon_cpu_emergency_exit(void) { }
|
| 672 | static inline bool nbcon_can_proceed(struct nbcon_write_context *wctxt) { return false; }
|
| 673 | static inline void nbcon_write_context_set_buf(struct nbcon_write_context *wctxt,
|
| 674 | char *buf, unsigned int len) { }
|
| 675 | static inline bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt) { return false; }
|
| 676 | static inline bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt) { return false; }
|
| 677 | static inline void nbcon_reacquire_nobuf(struct nbcon_write_context *wctxt) { }
|
| 678 | static inline bool nbcon_kdb_try_acquire(struct console *con,
|
| 679 | struct nbcon_write_context *wctxt) { return false; }
|
| 680 | static inline void nbcon_kdb_release(struct nbcon_write_context *wctxt) { }
|
| 681 | static inline bool console_is_usable(struct console *con, short flags,
|
| 682 | bool use_atomic) { return false; }
|
| 683 | #endif
|
| 684 |
|
| 685 | extern int console_set_on_cmdline;
|
| 686 | extern struct console *early_console;
|
| 687 |
|
| 688 | enum con_flush_mode {
|
| 689 | CONSOLE_FLUSH_PENDING,
|
| 690 | CONSOLE_REPLAY_ALL,
|
| 691 | };
|
| 692 |
|
| 693 | extern int add_preferred_console(const char *name, const short idx, char *options);
|
| 694 | extern void console_force_preferred_locked(struct console *con);
|
| 695 | extern void register_console(struct console *);
|
| 696 | extern int unregister_console(struct console *);
|
| 697 | extern void console_lock(void);
|
| 698 | extern int console_trylock(void);
|
| 699 | extern void console_unlock(void);
|
| 700 | extern void console_unblank(void);
|
| 701 | extern void console_flush_on_panic(enum con_flush_mode mode);
|
| 702 | extern struct tty_driver *console_device(int *);
|
| 703 | extern void console_suspend(struct console *);
|
| 704 | extern void console_resume(struct console *);
|
| 705 | extern int is_console_locked(void);
|
| 706 | extern int braille_register_console(struct console *, int index,
|
| 707 | char *console_options, char *braille_options);
|
| 708 | extern int braille_unregister_console(struct console *);
|
| 709 | #ifdef CONFIG_TTY
|
| 710 | extern void console_sysfs_notify(void);
|
| 711 | #else
|
| 712 | static inline void console_sysfs_notify(void)
|
| 713 | { }
|
| 714 | #endif
|
| 715 | extern bool console_suspend_enabled;
|
| 716 |
|
| 717 |
|
| 718 | extern void console_suspend_all(void);
|
| 719 | extern void console_resume_all(void);
|
| 720 |
|
| 721 | int mda_console_init(void);
|
| 722 |
|
| 723 | void vcs_make_sysfs(int index);
|
| 724 | void vcs_remove_sysfs(int index);
|
| 725 |
|
| 726 |
|
| 727 | #define WARN_CONSOLE_UNLOCKED() \
|
| 728 | WARN_ON(!atomic_read(&ignore_console_lock_warning) && \
|
| 729 | !is_console_locked() && !oops_in_progress)
|
| 730 | |
| 731 | * Increment ignore_console_lock_warning if you need to quiet
|
| 732 | * WARN_CONSOLE_UNLOCKED() for debugging purposes.
|
| 733 |
|
| 734 | extern atomic_t ignore_console_lock_warning;
|
| 735 |
|
| 736 | DEFINE_LOCK_GUARD_0(console_lock, console_lock(), console_unlock());
|
| 737 |
|
| 738 | extern void console_init(void);
|
| 739 |
|
| 740 |
|
| 741 | void dummycon_register_output_notifier(struct notifier_block *nb);
|
| 742 | void dummycon_unregister_output_notifier(struct notifier_block *nb);
|
| 743 |
|
| 744 | #endif
|