--- zzzz-none-000/linux-3.10.107/drivers/isdn/gigaset/ser-gigaset.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/isdn/gigaset/ser-gigaset.c	2021-02-04 17:41:59.000000000 +0000
@@ -67,8 +67,7 @@
 	struct sk_buff *skb = bcs->tx_skb;
 	int sent = -EOPNOTSUPP;
 
-	if (!tty || !tty->driver || !skb)
-		return -EINVAL;
+	WARN_ON(!tty || !tty->ops || !skb);
 
 	if (!skb->len) {
 		dev_kfree_skb_any(skb);
@@ -109,8 +108,7 @@
 	unsigned long flags;
 	int sent = 0;
 
-	if (!tty || !tty->driver)
-		return -EFAULT;
+	WARN_ON(!tty || !tty->ops);
 
 	cb = cs->cmdbuf;
 	if (!cb)
@@ -370,19 +368,18 @@
 	tasklet_kill(&cs->write_tasklet);
 	if (!cs->hw.ser)
 		return;
-	dev_set_drvdata(&cs->hw.ser->dev.dev, NULL);
 	platform_device_unregister(&cs->hw.ser->dev);
-	kfree(cs->hw.ser);
-	cs->hw.ser = NULL;
 }
 
 static void gigaset_device_release(struct device *dev)
 {
-	struct platform_device *pdev = to_platform_device(dev);
+	struct cardstate *cs = dev_get_drvdata(dev);
 
-	/* adapted from platform_device_release() in drivers/base/platform.c */
-	kfree(dev->platform_data);
-	kfree(pdev->resource);
+	if (!cs)
+		return;
+	dev_set_drvdata(dev, NULL);
+	kfree(cs->hw.ser);
+	cs->hw.ser = NULL;
 }
 
 /*
@@ -432,7 +429,9 @@
 	struct tty_struct *tty = cs->hw.ser->tty;
 	unsigned int set, clear;
 
-	if (!tty || !tty->driver || !tty->ops->tiocmset)
+	WARN_ON(!tty || !tty->ops);
+	/* tiocmset is an optional tty driver method */
+	if (!tty->ops->tiocmset)
 		return -EINVAL;
 	set = new_state & ~old_state;
 	clear = old_state & ~new_state;
@@ -607,28 +606,6 @@
 }
 
 /*
- * Read on the tty.
- * Unused, received data goes only to the Gigaset driver.
- */
-static ssize_t
-gigaset_tty_read(struct tty_struct *tty, struct file *file,
-		 unsigned char __user *buf, size_t count)
-{
-	return -EAGAIN;
-}
-
-/*
- * Write on the tty.
- * Unused, transmit data comes only from the Gigaset driver.
- */
-static ssize_t
-gigaset_tty_write(struct tty_struct *tty, struct file *file,
-		  const unsigned char *buf, size_t count)
-{
-	return -EAGAIN;
-}
-
-/*
  * Ioctl on the tty.
  * Called in process context only.
  * May be re-entered by multiple ioctl calling threads.
@@ -761,8 +738,6 @@
 	.open		= gigaset_tty_open,
 	.close		= gigaset_tty_close,
 	.hangup		= gigaset_tty_hangup,
-	.read		= gigaset_tty_read,
-	.write		= gigaset_tty_write,
 	.ioctl		= gigaset_tty_ioctl,
 	.receive_buf	= gigaset_tty_receive,
 	.write_wakeup	= gigaset_tty_wakeup,