mISDN: Allow to set a minimum length for transparent data

If the FIFO of the card is small, many short messages are queued up to
the upper layers and the userspace. This change allows the applications
to set a minimum datalen they want from the drivers.
Create a common control function to avoid code duplication in each
driver.

Signed-off-by: Karsten Keil <kkeil@linux-pingi.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/mISDNhw.h b/include/linux/mISDNhw.h
index a86d86b..226886c 100644
--- a/include/linux/mISDNhw.h
+++ b/include/linux/mISDNhw.h
@@ -154,7 +154,12 @@
 	struct timer_list	timer;
 	/* receive data */
 	struct sk_buff		*rx_skb;
-	int			maxlen;
+	unsigned short		maxlen;
+	unsigned short		init_maxlen; /* initial value */
+	unsigned short		next_maxlen; /* pending value */
+	unsigned short		minlen; /* for transparent data */
+	unsigned short		init_minlen; /* initial value */
+	unsigned short		next_minlen; /* pending value */
 	/* send data */
 	struct sk_buff		*next_skb;
 	struct sk_buff		*tx_skb;
@@ -169,10 +174,12 @@
 };
 
 extern int	mISDN_initdchannel(struct dchannel *, int, void *);
-extern int	mISDN_initbchannel(struct bchannel *, int);
+extern int	mISDN_initbchannel(struct bchannel *, unsigned short,
+				   unsigned short);
 extern int	mISDN_freedchannel(struct dchannel *);
 extern void	mISDN_clear_bchannel(struct bchannel *);
 extern int	mISDN_freebchannel(struct bchannel *);
+extern int	mISDN_ctrl_bchannel(struct bchannel *, struct mISDN_ctrl_req *);
 extern void	queue_ch_frame(struct mISDNchannel *, u_int,
 			int, struct sk_buff *);
 extern int	dchannel_senddata(struct dchannel *, struct sk_buff *);
@@ -180,7 +187,7 @@
 extern int      bchannel_get_rxbuf(struct bchannel *, int);
 extern void	recv_Dchannel(struct dchannel *);
 extern void	recv_Echannel(struct dchannel *, struct dchannel *);
-extern void	recv_Bchannel(struct bchannel *, unsigned int id);
+extern void	recv_Bchannel(struct bchannel *, unsigned int, bool);
 extern void	recv_Dchannel_skb(struct dchannel *, struct sk_buff *);
 extern void	recv_Bchannel_skb(struct bchannel *, struct sk_buff *);
 extern int	get_next_bframe(struct bchannel *);