fbcon: add parameter to toggle bind on startup

Documentation/fb/fbcon.txt

@@ -123,7 +123,7 @@ C. Boot options
 	is typically located on the same video card.  Thus, the consoles that
 	are controlled by the VGA console will be garbled.
 
-4. fbcon=rotate:<n>
+5. fbcon=rotate:<n>
 
         This option changes the orientation angle of the console display. The
         value 'n' accepts the following:
@@ -148,6 +148,16 @@ C. Boot options
 	Actually, the underlying fb driver is totally ignorant of console
 	rotation.
 
+6. fbcon=bind:<01>
+
+	This option controls whether or not the console should be bound to the
+	terminal when the kernel starts. In any case, the framebuffer console
+	can be bound / unbound at any time through sysfs.
+
+	This parameter can be useful in some cases, for instance when the
+	bootloader or the video driver display a logo that should be shown
+	during the whole boot.
+
 C. Attaching, Detaching and Unloading
 
 Before going on on how to attach, detach and unload the framebuffer console, an

drivers/tty/vt/vt.c

@@ -3473,7 +3473,7 @@ int con_debug_leave(void)
 }
 EXPORT_SYMBOL_GPL(con_debug_leave);
 
-static int do_register_con_driver(const struct consw *csw, int first, int last)
+int do_register_con_driver(const struct consw *csw, int first, int last)
 {
 	struct module *owner = csw->owner;
 	struct con_driver *con_driver;
@@ -3540,6 +3540,7 @@ static int do_register_con_driver(const struct consw *csw, int first, int last)
 	module_put(owner);
 	return retval;
 }
+EXPORT_SYMBOL_GPL(do_register_con_driver);
 
 
 /**

drivers/video/console/fbcon.c

@@ -114,6 +114,7 @@ static int fbcon_is_default = 1;
 static int fbcon_has_exited;
 static int primary_device = -1;
 static int fbcon_has_console_bind;
+static unsigned int bind_on_startup = 1;
 
 #ifdef CONFIG_FRAMEBUFFER_CONSOLE_DETECT_PRIMARY
 static int map_override;
@@ -539,6 +540,14 @@ static int __init fb_console_setup(char *this_opt)
 			}
 			continue;
 		}
+
+		if (!strncmp(options, "bind:", 5)) {
+			options += 5;
+			ret = kstrtouint(options, 0, &bind_on_startup);
+			if (ret)
+				printk(KERN_WARNING "fbcon: bind: incorrect value.\n");
+			continue;
+		}
 	}
 	return 1;
 }
@@ -581,15 +590,18 @@ static int do_fbcon_takeover(int show_logo)
 	for (i = first_fb_vc; i <= last_fb_vc; i++)
 		con2fb_map[i] = info_idx;
 
-	err = do_take_over_console(&fb_con, first_fb_vc, last_fb_vc,
-				fbcon_is_default);
+	if (bind_on_startup)
+		err = do_take_over_console(&fb_con, first_fb_vc, last_fb_vc,
+					   fbcon_is_default);
+	else
+		err = do_register_con_driver(&fb_con, first_fb_vc, last_fb_vc);
 
 	if (err) {
 		for (i = first_fb_vc; i <= last_fb_vc; i++)
 			con2fb_map[i] = -1;
 		info_idx = -1;
 	} else {
-		fbcon_has_console_bind = 1;
+		fbcon_has_console_bind = bind_on_startup;
 	}
 
 	return err;

include/linux/console.h

@@ -75,6 +75,7 @@ extern const struct consw newport_con;	/* SGI Newport console  */
 extern const struct consw prom_con;	/* SPARC PROM console */
 
 int con_is_bound(const struct consw *csw);
+int do_register_con_driver(const struct consw *csw, int first, int last);
 int do_unregister_con_driver(const struct consw *csw);
 int do_take_over_console(const struct consw *sw, int first, int last, int deflt);
 void give_up_console(const struct consw *sw);