doc: rsl: add RSL_IE_IPAC_RTP_CSD_FORMAT

Add documentation for rsl_ipac_rtp_csd_format_d/_ir from
libosmocore.git, include/osmocom/gsm/protocol/gsm_08_58.h and
wireshark.git, epan/dissectors/packet-rsl.c.

Related: OS#4393
Change-Id: Ic8f40076698f2b341cc0096fd96ba2051a41f077

doc/manuals/abis/rsl.adoc

@@ -517,6 +517,7 @@ number*.
 | Destination IP Port | <<RSL_IE_IPAC_REMOTE_PORT>> | O | TV | 3
 | IP Speech Mode | <<RSL_IE_IPAC_SPEECH_MODE>> | O | TV | 2
 | RTP Payload Type 2 | <<RSL_IE_IPAC_RTP_PAYLOAD2>> | O | TV | 2
+| RTP CSD Format | <<RSL_IE_IPAC_RTP_CSD_FORMAT>> | O | TV | 2
 |===
 
 [[rsl_crcx_msg_ack]]
@@ -577,6 +578,7 @@ properties of a user-plane RTP connection.
 | Destination IP Port | <<RSL_IE_IPAC_REMOTE_PORT>> | O | TV | 3
 | IP Speech Mode | <<RSL_IE_IPAC_SPEECH_MODE>> | O | TV | 2
 | RTP Payload Type 2 | <<RSL_IE_IPAC_RTP_PAYLOAD2>> | O | TV | 2
+| RTP CSD Format | <<RSL_IE_IPAC_RTP_CSD_FORMAT>> | O | TV | 2
 |===
 
 [[rsl_mdcx_msg_ack]]
@@ -872,6 +874,7 @@ addition to those indicated in 3GPP TS 48.058 Section 9.3:
 | 0xf5 | RSL_IE_IPAC_LOCAL_IP | <<RSL_IE_IPAC_LOCAL_IP>>
 | 0xf6 | RSL_IE_IPAC_CONN_STAT | <<RSL_IE_IPAC_CONN_STAT>>
 | 0xf8 | RSL_IE_IPAC_CONN_ID | <<RSL_IE_IPAC_CONN_ID>>
+| 0xf9 | RSL_IE_IPAC_RTP_CSD_FORMAT | <<RSL_IE_IPAC_RTP_CSD_FORMAT>>
 | 0xfc | RSL_IE_IPAC_RTP_PAYLOAD2 | <<RSL_IE_IPAC_RTP_PAYLOAD2>>
 |===
 
@@ -1086,6 +1089,39 @@ for future use.
 | 8..255 | reserved values
 |===
 
+[[RSL_IE_IPAC_RTP_CSD_FORMAT]]
+==== RSL_IE_IPAC_RTP_CSD_FORMAT
+
+This information element contains the RTP Circuit Switched Data format.
+
+.A-bis/IP RTP CSD Format
+[options="header",width="60%",cols="15%,15%,70%"]
+|===
+| Offset | Size | Description
+| 0 | 4 | RTP CSD Format D
+| 4 | 4 | RTP CSD Format IR
+|===
+
+.A-bis/IP RTP CSD Format D Values
+[options="header",width="40%",cols="20%,80%"]
+|===
+| Value | Description
+| 0 | External TRAU format
+| 1 | Non-TRAU Packed format
+| 2 | TRAU within the BTS
+| 3 | IWF-Free BTS-BTS Data
+|===
+
+.A-bis/IP RTP CSD Format IR Values
+[options="header",width="40%",cols="20%,80%"]
+|===
+| Value | Description
+| 0 | 8 kb/s
+| 1 | 16 kb/s
+| 2 | 32 kb/s
+| 3 | 48 kb/s
+|===
+
 === A-bis RSL Initialization / BTS bring-up
 
 Upon receiving the 'IPA RSL CONNECT' OML message by the respective