docs: Improve/clean-up doxygen for datagram.[ch]

* make sure datagram.h is part of the group
* don't expose private #defines from C files to API documentation

Change-Id: I64a9ee3306bcc01ba785da476aea581ce31150bd

include/osmocom/netif/datagram.h

@@ -1,6 +1,19 @@
 #ifndef _OSMO_DGRAM_H_
 #define _OSMO_DGRAM_H_
 
+/*! \defgroup datagram Osmocom Datagram Socket
+ *  @{
+ *
+ *  This code is intended to abstract any use of datagram type sockets,
+ *  such as UDP.  It offers both transmitter and receiver side
+ *  implementations, fully integrated with the libosmocore select loop
+ *  abstraction.
+ */
+
+/*! \file datagram.h
+ *  \brief Osmocom datagram socket helpers
+ */
+
 struct osmo_dgram_tx;
 
 struct osmo_dgram_tx *osmo_dgram_tx_create(void *ctx);

src/datagram.c

@@ -41,13 +41,12 @@
 
 #include <osmocom/netif/datagram.h>
 
-/*! \addtogroup datagram Osmocom Datagram Socket
+#define OSMO_DGRAM_CLI_F_RECONF	(1 << 0)
+
+#define OSMO_DGRAM_RX_F_RECONF	(1 << 0)
+
+/*! \addtogroup datagram
  *  @{
- *
- *  This code is intended to abstract any use of datagram type sockets,
- *  such as UDP.  It offers both transmitter and receiver side
- *  implementations, fully integrated with the libosmocore select loop
- *  abstraction.
  */
 
 /*! \file datagram.c
@@ -59,8 +58,6 @@
  * Client side.
  */
 
-#define OSMO_DGRAM_CLI_F_RECONF	(1 << 0)
-
 struct osmo_dgram_tx {
 	struct osmo_fd			ofd;
 	struct llist_head		tx_queue;
@@ -243,8 +240,6 @@ void osmo_dgram_tx_send(struct osmo_dgram_tx *conn,
  * Server side.
  */
 
-#define OSMO_DGRAM_RX_F_RECONF	(1 << 0)
-
 struct osmo_dgram_rx {
 	struct osmo_fd		ofd;
 	char			*addr;