TTY: sclp_tty, add tty_port

tty_port will hold tty buffers in the future. So we need to have it
even here. The only needed member here is tty, so let us store it in
the structure now.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux390@de.ibm.com
Cc: linux-s390@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/s390/char/sclp_tty.c

@@ -48,7 +48,7 @@ static struct sclp_buffer *sclp_ttybuf;
 /* Timer for delayed output of console messages. */
 static struct timer_list sclp_tty_timer;
 
-static struct tty_struct *sclp_tty;
+static struct tty_port sclp_port;
 static unsigned char sclp_tty_chars[SCLP_TTY_BUF_SIZE];
 static unsigned short int sclp_tty_chars_count;
 
@@ -64,7 +64,7 @@ static int sclp_tty_columns = 80;
 static int
 sclp_tty_open(struct tty_struct *tty, struct file *filp)
 {
-	sclp_tty = tty;
+	tty_port_tty_set(&sclp_port, tty);
 	tty->driver_data = NULL;
 	tty->low_latency = 0;
 	return 0;
@@ -76,7 +76,7 @@ sclp_tty_close(struct tty_struct *tty, struct file *filp)
 {
 	if (tty->count > 1)
 		return;
-	sclp_tty = NULL;
+	tty_port_tty_set(&sclp_port, NULL);
 }
 
 /*
@@ -108,6 +108,7 @@ sclp_tty_write_room (struct tty_struct *tty)
 static void
 sclp_ttybuf_callback(struct sclp_buffer *buffer, int rc)
 {
+	struct tty_struct *tty;
 	unsigned long flags;
 	void *page;
 
@@ -126,8 +127,10 @@ sclp_ttybuf_callback(struct sclp_buffer *buffer, int rc)
 		spin_unlock_irqrestore(&sclp_tty_lock, flags);
 	} while (buffer && sclp_emit_buffer(buffer, sclp_ttybuf_callback));
 	/* check if the tty needs a wake up call */
-	if (sclp_tty != NULL) {
-		tty_wakeup(sclp_tty);
+	tty = tty_port_tty_get(&sclp_port);
+	if (tty != NULL) {
+		tty_wakeup(tty);
+		tty_kref_put(tty);
 	}
 }
 
@@ -326,21 +329,22 @@ sclp_tty_flush_buffer(struct tty_struct *tty)
 static void
 sclp_tty_input(unsigned char* buf, unsigned int count)
 {
+	struct tty_struct *tty = tty_port_tty_get(&sclp_port);
 	unsigned int cchar;
 
 	/*
 	 * If this tty driver is currently closed
 	 * then throw the received input away.
 	 */
-	if (sclp_tty == NULL)
+	if (tty == NULL)
 		return;
-	cchar = ctrlchar_handle(buf, count, sclp_tty);
+	cchar = ctrlchar_handle(buf, count, tty);
 	switch (cchar & CTRLCHAR_MASK) {
 	case CTRLCHAR_SYSRQ:
 		break;
 	case CTRLCHAR_CTRL:
-		tty_insert_flip_char(sclp_tty, cchar, TTY_NORMAL);
-		tty_flip_buffer_push(sclp_tty);
+		tty_insert_flip_char(tty, cchar, TTY_NORMAL);
+		tty_flip_buffer_push(tty);
 		break;
 	case CTRLCHAR_NONE:
 		/* send (normal) input to line discipline */
@@ -348,13 +352,14 @@ sclp_tty_input(unsigned char* buf, unsigned int count)
 		    (strncmp((const char *) buf + count - 2, "^n", 2) &&
 		     strncmp((const char *) buf + count - 2, "\252n", 2))) {
 			/* add the auto \n */
-			tty_insert_flip_string(sclp_tty, buf, count);
-			tty_insert_flip_char(sclp_tty, '\n', TTY_NORMAL);
+			tty_insert_flip_string(tty, buf, count);
+			tty_insert_flip_char(tty, '\n', TTY_NORMAL);
 		} else
-			tty_insert_flip_string(sclp_tty, buf, count - 2);
-		tty_flip_buffer_push(sclp_tty);
+			tty_insert_flip_string(tty, buf, count - 2);
+		tty_flip_buffer_push(tty);
 		break;
 	}
+	tty_kref_put(tty);
 }
 
 /*
@@ -543,7 +548,7 @@ sclp_tty_init(void)
 		sclp_tty_tolower = 1;
 	}
 	sclp_tty_chars_count = 0;
-	sclp_tty = NULL;
+	tty_port_init(&sclp_port);
 
 	rc = sclp_register(&sclp_input_event);
 	if (rc) {