cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

dummycon.c (3578B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 *  linux/drivers/video/dummycon.c -- A dummy console driver
      4 *
      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 driver
     19 */
     20
     21#if defined(__arm__)
     22#define DUMMY_COLUMNS	screen_info.orig_video_cols
     23#define DUMMY_ROWS	screen_info.orig_video_lines
     24#else
     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
     28#endif
     29
     30#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
     31/* These are both protected by the console_lock */
     32static RAW_NOTIFIER_HEAD(dummycon_output_nh);
     33static bool dummycon_putc_called;
     34
     35void dummycon_register_output_notifier(struct notifier_block *nb)
     36{
     37	WARN_CONSOLE_UNLOCKED();
     38
     39	raw_notifier_chain_register(&dummycon_output_nh, nb);
     40
     41	if (dummycon_putc_called)
     42		nb->notifier_call(nb, 0, NULL);
     43}
     44
     45void dummycon_unregister_output_notifier(struct notifier_block *nb)
     46{
     47	WARN_CONSOLE_UNLOCKED();
     48
     49	raw_notifier_chain_unregister(&dummycon_output_nh, nb);
     50}
     51
     52static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos)
     53{
     54	WARN_CONSOLE_UNLOCKED();
     55
     56	dummycon_putc_called = true;
     57	raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
     58}
     59
     60static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
     61			   int count, int ypos, int xpos)
     62{
     63	int i;
     64
     65	if (!dummycon_putc_called) {
     66		/* Ignore erases */
     67		for (i = 0 ; i < count; i++) {
     68			if (s[i] != vc->vc_video_erase_char)
     69				break;
     70		}
     71		if (i == count)
     72			return;
     73
     74		dummycon_putc_called = true;
     75	}
     76
     77	raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
     78}
     79
     80static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
     81{
     82	/* Redraw, so that we get putc(s) for output done while blanked */
     83	return 1;
     84}
     85#else
     86static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos) { }
     87static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
     88			   int count, int ypos, int xpos) { }
     89static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
     90{
     91	return 0;
     92}
     93#endif
     94
     95static const char *dummycon_startup(void)
     96{
     97    return "dummy device";
     98}
     99
    100static void dummycon_init(struct vc_data *vc, int init)
    101{
    102    vc->vc_can_do_color = 1;
    103    if (init) {
    104	vc->vc_cols = DUMMY_COLUMNS;
    105	vc->vc_rows = DUMMY_ROWS;
    106    } else
    107	vc_resize(vc, DUMMY_COLUMNS, DUMMY_ROWS);
    108}
    109
    110static void dummycon_deinit(struct vc_data *vc) { }
    111static void dummycon_clear(struct vc_data *vc, int sy, int sx, int height,
    112			   int width) { }
    113static void dummycon_cursor(struct vc_data *vc, int mode) { }
    114
    115static bool dummycon_scroll(struct vc_data *vc, unsigned int top,
    116			    unsigned int bottom, enum con_scroll dir,
    117			    unsigned int lines)
    118{
    119	return false;
    120}
    121
    122static int dummycon_switch(struct vc_data *vc)
    123{
    124	return 0;
    125}
    126
    127/*
    128 *  The console `switch' structure for the dummy console
    129 *
    130 *  Most of the operations are dummies.
    131 */
    132
    133const struct consw dummy_con = {
    134	.owner =		THIS_MODULE,
    135	.con_startup =	dummycon_startup,
    136	.con_init =		dummycon_init,
    137	.con_deinit =	dummycon_deinit,
    138	.con_clear =	dummycon_clear,
    139	.con_putc =		dummycon_putc,
    140	.con_putcs =	dummycon_putcs,
    141	.con_cursor =	dummycon_cursor,
    142	.con_scroll =	dummycon_scroll,
    143	.con_switch =	dummycon_switch,
    144	.con_blank =	dummycon_blank,
    145};
    146EXPORT_SYMBOL_GPL(dummy_con);