1 files changed, 56 insertions, 0 deletions

diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c
index 35ad94e65d0d..d29fbd44bdca 100644
--- a/drivers/char/vt_ioctl.c
+++ b/drivers/char/vt_ioctl.c
@@ -16,6 +16,7 @@
 #include <linux/tty.h>
 #include <linux/timer.h>
 #include <linux/kernel.h>
+#include <linux/module.h>
 #include <linux/kd.h>
 #include <linux/vt.h>
 #include <linux/string.h>
@@ -1483,3 +1484,58 @@ void change_console(struct vc_data *new_vc)
 
         complete_change_console(new_vc);
 }
+
+/* Perform a kernel triggered VT switch for suspend/resume */
+
+static int disable_vt_switch;
+
+int vt_move_to_console(unsigned int vt, int alloc)
+{
+        int prev;
+
+        acquire_console_sem();
+        /* Graphics mode - up to X */
+        if (disable_vt_switch) {
+                release_console_sem();
+                return 0;
+        }
+        prev = fg_console;
+
+        if (alloc && vc_allocate(vt)) {
+                /* we can't have a free VC for now. Too bad,
+                 * we don't want to mess the screen for now. */
+                release_console_sem();
+                return -ENOSPC;
+        }
+
+        if (set_console(vt)) {
+                /*
+                 * We're unable to switch to the SUSPEND_CONSOLE.
+                 * Let the calling function know so it can decide
+                 * what to do.
+                 */
+                release_console_sem();
+                return -EIO;
+        }
+        release_console_sem();
+        if (vt_waitactive(vt)) {
+                pr_debug("Suspend: Can't switch VCs.");
+                return -EINTR;
+        }
+        return prev;
+}
+
+/*
+ * Normally during a suspend, we allocate a new console and switch to it.
+ * When we resume, we switch back to the original console.  This switch
+ * can be slow, so on systems where the framebuffer can handle restoration
+ * of video registers anyways, there's little point in doing the console
+ * switch.  This function allows you to disable it by passing it '0'.
+ */
+void pm_set_vt_switch(int do_switch)
+{
+        acquire_console_sem();
+        disable_vt_switch = !do_switch;
+        release_console_sem();
+}
+EXPORT_SYMBOL(pm_set_vt_switch);