app: Don't start PPP without a request

PPP connection has been opened automatically when AT+CFUN=1 is done and
PDN has been activated even without PPP request using AT#XPPP=1.
This is now changed so you need to issue AT#XPPP=1
in order to start PPP. This can be done before or after AT+CFUN=1.

Jira: SLM-85

Signed-off-by: Tommi Rantanen <tommi.rantanen@nordicsemi.no>

Author: trantanen

app/Kconfig

@@ -143,10 +143,6 @@ config SM_FULL_FOTA
 
 config SM_PPP
 	bool "PPP support"
-	help
-	  When enabled, Serial Modem automatically brings up/down the PPP link
-	  when the LTE link (default PDN) is connected/disconnected,
-	  regardless of what is done with AT#XPPP.
 
 if SM_PPP
 

app/scripts/sm_start_ppp.sh

@@ -54,6 +54,7 @@ stty -F $AT_CMUX clocal
 
 echo "Connect and wait for PPP link..."
 test -c $AT_CMUX
+chat $CHATOPT -t$TIMEOUT "" "AT#XPPP=1" "OK" >$AT_CMUX <$AT_CMUX
 chat $CHATOPT -t$TIMEOUT "" "AT+CFUN=1" "OK" "\c" "#XPPP: 1,0" >$AT_CMUX <$AT_CMUX
 
 pppd $PPP_CMUX noauth novj nodeflate nobsdcomp debug noipdefault passive +ipv6 noremoteip \

app/src/sm_ppp.c

@@ -476,7 +476,7 @@ static void subscribe_cgev_notifications(void)
 	}
 }
 
-AT_MONITOR(sm_ppp_on_cgev, "CGEV", at_notif_on_cgev);
+AT_MONITOR(sm_ppp_on_cgev, "CGEV", at_notif_on_cgev, PAUSED);
 
 static void at_notif_on_cgev(const char *notify)
 {
@@ -694,8 +694,10 @@ static int handle_at_ppp(enum at_parser_cmd_type cmd_type, struct at_parser *par
 		/* Store PPP PDN if given */
 		at_parser_num_get(parser, 2, &ppp_pdn_cid);
 		delegate_ppp_event(PPP_START, PPP_REASON_DEFAULT);
+		at_monitor_resume(&sm_ppp_on_cgev);
 	} else {
 		delegate_ppp_event(PPP_STOP, PPP_REASON_DEFAULT);
+		at_monitor_pause(&sm_ppp_on_cgev);
 	}
 	return -SILENT_AT_COMMAND_RET;
 }

doc/app/PPP_AT_commands.rst

@@ -31,9 +31,7 @@ The set command allows you to start and stop PPP, and optionally define the PDN
 
 .. note::
 
-   PPP is automatically started and stopped by |SM| when the PDN connection requested for PPP
-   is established and lost, respectively.
-   This happens even if PPP has previously been stopped or started with this command.
+   PPP connection only needs to be started once, and then it is automatically started and stopped by |SM| when the PDN connection requested for PPP is established and lost, respectively.
 
 Syntax
 ~~~~~~
@@ -77,22 +75,12 @@ PPP with default PDN connection:
 
 ::
 
-  AT+CFUN=1
-
-  OK
-
-  // PPP is automatically started when the default PDN is activated.
-  #XPPP: 1,0,0
-
-  // Stop PPP.
-  AT#XPPP=0
+  // Start PPP.
+  AT#XPPP=1
 
   OK
 
-  #XPPP: 0,0
-
-  // Start PPP.
-  AT#XPPP=1
+  AT+CFUN=1
 
   OK
 
@@ -113,7 +101,7 @@ PPP with default PDN connection:
 
   OK
 
-  #XPPP: 0,0
+  #XPPP: 0,0,0
 
 PPP with non-default PDN connection:
 
@@ -172,8 +160,8 @@ If you are using CMUX, see :ref:`sm_as_linux_modem` for more information on sett
 
 For the process described here, |SM|'s UARTs must be connected to the Linux host.
 
-1. Get PPP running on |SM|.
-   To do this, start |SM| and issue an ``AT+CFUN=1`` command.
+1. Start PPP with ``AT#XPPP=1`` command.
+#. Set modem to online mode with ``AT+CFUN=1`` command.
 #. Wait for ``#XPPP: 1,0,0``, which is sent when the network registration succeeds and PPP has started successfully with the default PDN connection.
 #. Run the following command on the Linux host:
 
@@ -184,7 +172,7 @@ For the process described here, |SM|'s UARTs must be connected to the Linux host
    Replace ``<PPP_UART_dev>`` by the device file assigned to the PPP UART and ``<baud_rate>`` by the baud rate of the UART that PPP is using (which is set in the :file:`overlay-ppp-without-cmux.overlay` file).
    Typically, when ``uart1`` is assigned to be the PPP UART (in the devicetree overlay), the device file assigned to it is :file:`/dev/ttyACM2` for an nRF9160 DK, and :file:`/dev/ttyACM1` for the other nRF91 Series DKs.
 
-#. After the PPP link negotiation has completed successfully, a new network interface will be available, typically ``ppp0``.
+#. After the PPP link negotiation has completed successfully, |SM| will send ``#XPPP: 1,1,0`` notification over UART, and a new network interface will be available, typically ``ppp0``.
    This network interface will allow sending and receiving IP traffic through the modem of the nRF91 Series SiP running |SM|.
 
 .. note::

doc/migration_notes.rst

@@ -55,6 +55,11 @@ The following changes are mandatory to make your application work in the same wa
    * Removed the ``AT#XPOLL`` command.
      Use ``AT#XAPOLL`` instead.
 
+   * PPP connection must be requested with ``AT#XPPP=1`` in order to get it started when modem is put to online mode with ``AT+CFUN=1``.
+     ``AT#XPPP=1`` can be done before or after ``AT+CFUN=1``.
+     So PPP connection is not started automatically anymore when ``AT+CFUN=1`` is done.
+     However, ``AT#XPPP=1`` needs to be done only once and after that PPP is started when ``AT+CFUN=1`` is done and stopped when ``AT+CFUN=4`` or ``AT+CFUN=0`` is done.
+
 DTR and RI GPIOs replace Power and Indicate pins
 ------------------------------------------------