xref: /linux-6.15/kernel/power/console.c (revision 4bedea94)
1 /*
2  * drivers/power/process.c - Functions for saving/restoring console.
3  *
4  * Originally from swsusp.
5  */
6 
7 #include <linux/vt_kern.h>
8 #include <linux/kbd_kern.h>
9 #include <linux/console.h>
10 #include "power.h"
11 
12 static int new_loglevel = 10;
13 static int orig_loglevel;
14 #ifdef SUSPEND_CONSOLE
15 static int orig_fgconsole, orig_kmsg;
16 #endif
17 
18 int pm_prepare_console(void)
19 {
20 	orig_loglevel = console_loglevel;
21 	console_loglevel = new_loglevel;
22 
23 #ifdef SUSPEND_CONSOLE
24 	acquire_console_sem();
25 
26 	orig_fgconsole = fg_console;
27 
28 	if (vc_allocate(SUSPEND_CONSOLE)) {
29 	  /* we can't have a free VC for now. Too bad,
30 	   * we don't want to mess the screen for now. */
31 		release_console_sem();
32 		return 1;
33 	}
34 
35 	set_console(SUSPEND_CONSOLE);
36 	release_console_sem();
37 
38 	if (vt_waitactive(SUSPEND_CONSOLE)) {
39 		pr_debug("Suspend: Can't switch VCs.");
40 		return 1;
41 	}
42 	orig_kmsg = kmsg_redirect;
43 	kmsg_redirect = SUSPEND_CONSOLE;
44 #endif
45 	return 0;
46 }
47 
48 void pm_restore_console(void)
49 {
50 	console_loglevel = orig_loglevel;
51 #ifdef SUSPEND_CONSOLE
52 	acquire_console_sem();
53 	set_console(orig_fgconsole);
54 	release_console_sem();
55 	kmsg_redirect = orig_kmsg;
56 #endif
57 	return;
58 }
59