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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * linux/drivers/video/dummycon.c -- A dummy console driver4 *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.7 */8 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>16 17/*18 * Dummy console driver19 */20 21#if defined(CONFIG_ARCH_FOOTBRIDGE) && defined(CONFIG_VGA_CONSOLE)22#include <asm/vga.h>23#define DUMMY_COLUMNS vgacon_screen_info.orig_video_cols24#define DUMMY_ROWS vgacon_screen_info.orig_video_lines25#else26/* set by Kconfig. Use 80x25 for 640x480 and 160x64 for 1280x1024 */27#define DUMMY_COLUMNS CONFIG_DUMMY_CONSOLE_COLUMNS28#define DUMMY_ROWS CONFIG_DUMMY_CONSOLE_ROWS29#endif30 31#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER32/* These are both protected by the console_lock */33static RAW_NOTIFIER_HEAD(dummycon_output_nh);34static bool dummycon_putc_called;35 36void dummycon_register_output_notifier(struct notifier_block *nb)37{38 WARN_CONSOLE_UNLOCKED();39 40 raw_notifier_chain_register(&dummycon_output_nh, nb);41 42 if (dummycon_putc_called)43 nb->notifier_call(nb, 0, NULL);44}45 46void dummycon_unregister_output_notifier(struct notifier_block *nb)47{48 WARN_CONSOLE_UNLOCKED();49 50 raw_notifier_chain_unregister(&dummycon_output_nh, nb);51}52 53static void dummycon_putc(struct vc_data *vc, u16 c, unsigned int y,54 unsigned int x)55{56 WARN_CONSOLE_UNLOCKED();57 58 dummycon_putc_called = true;59 raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);60}61 62static void dummycon_putcs(struct vc_data *vc, const u16 *s, unsigned int count,63 unsigned int ypos, unsigned int xpos)64{65 unsigned int i;66 67 if (!dummycon_putc_called) {68 /* Ignore erases */69 for (i = 0 ; i < count; i++) {70 if (s[i] != vc->vc_video_erase_char)71 break;72 }73 if (i == count)74 return;75 76 dummycon_putc_called = true;77 }78 79 raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);80}81 82static bool dummycon_blank(struct vc_data *vc, enum vesa_blank_mode blank,83 bool mode_switch)84{85 /* Redraw, so that we get putc(s) for output done while blanked */86 return true;87}88#else89static void dummycon_putc(struct vc_data *vc, u16 c, unsigned int y,90 unsigned int x) { }91static void dummycon_putcs(struct vc_data *vc, const u16 *s, unsigned int count,92 unsigned int ypos, unsigned int xpos) { }93static bool dummycon_blank(struct vc_data *vc, enum vesa_blank_mode blank,94 bool mode_switch)95{96 return false;97}98#endif99 100static const char *dummycon_startup(void)101{102 return "dummy device";103}104 105static void dummycon_init(struct vc_data *vc, bool init)106{107 vc->vc_can_do_color = 1;108 if (init) {109 vc->vc_cols = DUMMY_COLUMNS;110 vc->vc_rows = DUMMY_ROWS;111 } else112 vc_resize(vc, DUMMY_COLUMNS, DUMMY_ROWS);113}114 115static void dummycon_deinit(struct vc_data *vc) { }116static void dummycon_clear(struct vc_data *vc, unsigned int sy, unsigned int sx,117 unsigned int width) { }118static void dummycon_cursor(struct vc_data *vc, bool enable) { }119 120static bool dummycon_scroll(struct vc_data *vc, unsigned int top,121 unsigned int bottom, enum con_scroll dir,122 unsigned int lines)123{124 return false;125}126 127static bool dummycon_switch(struct vc_data *vc)128{129 return false;130}131 132/*133 * The console `switch' structure for the dummy console134 *135 * Most of the operations are dummies.136 */137 138const struct consw dummy_con = {139 .owner = THIS_MODULE,140 .con_startup = dummycon_startup,141 .con_init = dummycon_init,142 .con_deinit = dummycon_deinit,143 .con_clear = dummycon_clear,144 .con_putc = dummycon_putc,145 .con_putcs = dummycon_putcs,146 .con_cursor = dummycon_cursor,147 .con_scroll = dummycon_scroll,148 .con_switch = dummycon_switch,149 .con_blank = dummycon_blank,150};151EXPORT_SYMBOL_GPL(dummy_con);152