PM/gxfb: add hook to PM console layer that allows disabling of suspend VT switch
[linux-2.6.git] / kernel / power / console.c
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 <linux/module.h>
11 #include "power.h"
12
13 #if defined(CONFIG_VT) && defined(CONFIG_VT_CONSOLE)
14 #define SUSPEND_CONSOLE (MAX_NR_CONSOLES-1)
15
16 static int orig_fgconsole, orig_kmsg;
17 static int disable_vt_switch;
18
19 /*
20  * Normally during a suspend, we allocate a new console and switch to it.
21  * When we resume, we switch back to the original console.  This switch
22  * can be slow, so on systems where the framebuffer can handle restoration
23  * of video registers anyways, there's little point in doing the console
24  * switch.  This function allows you to disable it by passing it '0'.
25  */
26 void pm_set_vt_switch(int do_switch)
27 {
28         acquire_console_sem();
29         disable_vt_switch = !do_switch;
30         release_console_sem();
31 }
32 EXPORT_SYMBOL(pm_set_vt_switch);
33
34 int pm_prepare_console(void)
35 {
36         acquire_console_sem();
37
38         if (disable_vt_switch) {
39                 release_console_sem();
40                 return 0;
41         }
42
43         orig_fgconsole = fg_console;
44
45         if (vc_allocate(SUSPEND_CONSOLE)) {
46           /* we can't have a free VC for now. Too bad,
47            * we don't want to mess the screen for now. */
48                 release_console_sem();
49                 return 1;
50         }
51
52         if (set_console(SUSPEND_CONSOLE)) {
53                 /*
54                  * We're unable to switch to the SUSPEND_CONSOLE.
55                  * Let the calling function know so it can decide
56                  * what to do.
57                  */
58                 release_console_sem();
59                 return 1;
60         }
61         release_console_sem();
62
63         if (vt_waitactive(SUSPEND_CONSOLE)) {
64                 pr_debug("Suspend: Can't switch VCs.");
65                 return 1;
66         }
67         orig_kmsg = kmsg_redirect;
68         kmsg_redirect = SUSPEND_CONSOLE;
69         return 0;
70 }
71
72 void pm_restore_console(void)
73 {
74         acquire_console_sem();
75         if (disable_vt_switch) {
76                 release_console_sem();
77                 return;
78         }
79         set_console(orig_fgconsole);
80         release_console_sem();
81         kmsg_redirect = orig_kmsg;
82 }
83 #endif