xref: /linux/kernel/power/console.c (revision d8327c784b51b57dac2c26cfad87dce0d68dfd98)
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 #if defined(CONFIG_VT) && defined(CONFIG_VT_CONSOLE)
13 #define SUSPEND_CONSOLE	(MAX_NR_CONSOLES-1)
14 
15 static int orig_fgconsole, orig_kmsg;
16 
17 int pm_prepare_console(void)
18 {
19 	acquire_console_sem();
20 
21 	orig_fgconsole = fg_console;
22 
23 	if (vc_allocate(SUSPEND_CONSOLE)) {
24 	  /* we can't have a free VC for now. Too bad,
25 	   * we don't want to mess the screen for now. */
26 		release_console_sem();
27 		return 1;
28 	}
29 
30 	set_console(SUSPEND_CONSOLE);
31 	release_console_sem();
32 
33 	if (vt_waitactive(SUSPEND_CONSOLE)) {
34 		pr_debug("Suspend: Can't switch VCs.");
35 		return 1;
36 	}
37 	orig_kmsg = kmsg_redirect;
38 	kmsg_redirect = SUSPEND_CONSOLE;
39 	return 0;
40 }
41 
42 void pm_restore_console(void)
43 {
44 	acquire_console_sem();
45 	set_console(orig_fgconsole);
46 	release_console_sem();
47 	kmsg_redirect = orig_kmsg;
48 	return;
49 }
50 #endif
51