1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/drivers/video/dummycon.c -- A dummy console driver
5 * To be used if there's no other console driver (e.g. for plain VGA text)
6 * available, usually until fbcon takes console over.
9 #include <linux/types.h>
10 #include <linux/kdev_t.h>
11 #include <linux/console.h>
12 #include <linux/vt_kern.h>
13 #include <linux/screen_info.h>
14 #include <linux/init.h>
15 #include <linux/module.h>
18 * Dummy console driver
22 #define DUMMY_COLUMNS screen_info.orig_video_cols
23 #define DUMMY_ROWS screen_info.orig_video_lines
25 /* set by Kconfig. Use 80x25 for 640x480 and 160x64 for 1280x1024 */
26 #define DUMMY_COLUMNS CONFIG_DUMMY_CONSOLE_COLUMNS
27 #define DUMMY_ROWS CONFIG_DUMMY_CONSOLE_ROWS
30 #ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
31 /* These are both protected by the console_lock */
32 static RAW_NOTIFIER_HEAD(dummycon_output_nh);
33 static bool dummycon_putc_called;
35 void dummycon_register_output_notifier(struct notifier_block *nb)
37 raw_notifier_chain_register(&dummycon_output_nh, nb);
39 if (dummycon_putc_called)
40 nb->notifier_call(nb, 0, NULL);
43 void dummycon_unregister_output_notifier(struct notifier_block *nb)
45 raw_notifier_chain_unregister(&dummycon_output_nh, nb);
48 static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos)
50 dummycon_putc_called = true;
51 raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
54 static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
55 int count, int ypos, int xpos)
59 if (!dummycon_putc_called) {
61 for (i = 0 ; i < count; i++) {
62 if (s[i] != vc->vc_video_erase_char)
68 dummycon_putc_called = true;
71 raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
74 static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
76 /* Redraw, so that we get putc(s) for output done while blanked */
80 static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos) { }
81 static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
82 int count, int ypos, int xpos) { }
83 static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
89 static const char *dummycon_startup(void)
91 return "dummy device";
94 static void dummycon_init(struct vc_data *vc, int init)
96 vc->vc_can_do_color = 1;
98 vc->vc_cols = DUMMY_COLUMNS;
99 vc->vc_rows = DUMMY_ROWS;
101 vc_resize(vc, DUMMY_COLUMNS, DUMMY_ROWS);
104 static void dummycon_deinit(struct vc_data *vc) { }
105 static void dummycon_clear(struct vc_data *vc, int sy, int sx, int height,
107 static void dummycon_cursor(struct vc_data *vc, int mode) { }
109 static bool dummycon_scroll(struct vc_data *vc, unsigned int top,
110 unsigned int bottom, enum con_scroll dir,
116 static int dummycon_switch(struct vc_data *vc)
121 static int dummycon_font_set(struct vc_data *vc, struct console_font *font,
127 static int dummycon_font_default(struct vc_data *vc,
128 struct console_font *font, char *name)
133 static int dummycon_font_copy(struct vc_data *vc, int con)
139 * The console `switch' structure for the dummy console
141 * Most of the operations are dummies.
144 const struct consw dummy_con = {
145 .owner = THIS_MODULE,
146 .con_startup = dummycon_startup,
147 .con_init = dummycon_init,
148 .con_deinit = dummycon_deinit,
149 .con_clear = dummycon_clear,
150 .con_putc = dummycon_putc,
151 .con_putcs = dummycon_putcs,
152 .con_cursor = dummycon_cursor,
153 .con_scroll = dummycon_scroll,
154 .con_switch = dummycon_switch,
155 .con_blank = dummycon_blank,
156 .con_font_set = dummycon_font_set,
157 .con_font_default = dummycon_font_default,
158 .con_font_copy = dummycon_font_copy,
160 EXPORT_SYMBOL_GPL(dummy_con);