s390/con3270: optionally disable auto update

This patch adds a parameter 'auto_update' to the con3270
driver, causing the 'auto_update' feature to be disabled
if unset.
The 'auto_update' feature will cause the con3270 driver
to switch to the console view whenever new system messages
are displayed, which makes working on the 3270 terminal
awkward.

Signed-off-by: Martin Schwidefsky <[e-mail]>

drivers/s390/char/con3270.c

···
  *     Copyright IBM Corp. 2003, 2009
  */
 
+#include <linux/module.h>
 #include <linux/console.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
···
 #define CON3270_STRING_PAGES 4
 
 static struct raw3270_fn con3270_fn;
+
+static bool auto_update = 1;
+module_param(auto_update, bool, 0);
 
 /*
  * Main 3270 console view data structure.
···
 	struct string *s, *n;
 	int rc;
 
+	if (!auto_update && !raw3270_view_active(&cp->view))
+		return;
 	if (cp->view.dev)
 		raw3270_activate_view(&cp->view);
 
···
 	if (!cp->view.dev)
 		return;
 	raw3270_pm_unfreeze(&cp->view);
+	raw3270_activate_view(&cp->view);
 	spin_lock_irqsave(&cp->view.lock, flags);
 	con3270_wait_write(cp);
 	cp->nr_up = 0;

drivers/s390/char/raw3270.c

···
 }
 
 int
+raw3270_view_active(struct raw3270_view *view)
+{
+	struct raw3270 *rp = view->dev;
+
+	return rp && rp->view == view &&
+		!test_bit(RAW3270_FLAGS_FROZEN, &rp->flags);
+}
+
+int
 raw3270_start(struct raw3270_view *view, struct raw3270_request *rq)
 {
 	unsigned long flags;

drivers/s390/char/raw3270.h

···
 int raw3270_start_irq(struct raw3270_view *, struct raw3270_request *);
 int raw3270_reset(struct raw3270_view *);
 struct raw3270_view *raw3270_view(struct raw3270_view *);
+int raw3270_view_active(struct raw3270_view *);
 
 /* Reference count inliner for view structures. */
 static inline void