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 "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         if (set_console(SUSPEND_CONSOLE)) {
  31                 /*
  32                  * We're unable to switch to the SUSPEND_CONSOLE.
  33                  * Let the calling function know so it can decide
  34                  * what to do.
  35                  */
  36                 release_console_sem();
  37                 return 1;
  38         }
  39         release_console_sem();
  40
  41         if (vt_waitactive(SUSPEND_CONSOLE)) {
  42                 pr_debug("Suspend: Can't switch VCs.");
  43                 return 1;
  44         }
  45         orig_kmsg = kmsg_redirect;
  46         kmsg_redirect = SUSPEND_CONSOLE;
  47         return 0;
  48 }
  49
  50 void pm_restore_console(void)
  51 {
  52         acquire_console_sem();
  53         set_console(orig_fgconsole);
  54         release_console_sem();
  55         kmsg_redirect = orig_kmsg;
  56         return;
  57 }
  58 #endif