printk: add con_printk() macro for console details

It is useful to generate log messages that include details about
the related console. Rather than duplicate the code to assemble
the details, put that code into a macro con_printk().

Once console printers become threaded, this macro will find more
users.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220421212250.565456-9-john.ogness@linutronix.de

kernel/printk/printk.c

@@ -3015,6 +3015,11 @@ static void try_enable_default_console(struct console *newcon)
 		newcon->flags |= CON_CONSDEV;
 }
 
+#define con_printk(lvl, con, fmt, ...)			\
+	printk(lvl pr_fmt("%sconsole [%s%d] " fmt),	\
+	       (con->flags & CON_BOOT) ? "boot" : "",	\
+	       con->name, con->index, ##__VA_ARGS__)
+
 /*
  * The console driver calls this routine during kernel initialization
  * to register the console printing procedure with printk() and to
@@ -3153,9 +3158,7 @@ void register_console(struct console *newcon)
 	 * users know there might be something in the kernel's log buffer that
 	 * went to the bootconsole (that they do not see on the real console)
 	 */
-	pr_info("%sconsole [%s%d] enabled\n",
-		(newcon->flags & CON_BOOT) ? "boot" : "" ,
-		newcon->name, newcon->index);
+	con_printk(KERN_INFO, newcon, "enabled\n");
 	if (bootcon_enabled &&
 	    ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV) &&
 	    !keep_bootcon) {
@@ -3174,9 +3177,7 @@ int unregister_console(struct console *console)
 	struct console *con;
 	int res;
 
-	pr_info("%sconsole [%s%d] disabled\n",
-		(console->flags & CON_BOOT) ? "boot" : "" ,
-		console->name, console->index);
+	con_printk(KERN_INFO, console, "disabled\n");
 
 	res = _braille_unregister_console(console);
 	if (res < 0)