cmake: Add serial port for ppp in qemu

In order to simplify ppp testing, use ppp specific serial port
when starting qemu.

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>

cmake/emu/qemu.cmake

@@ -75,12 +75,15 @@ endif()
 # If we are running a networking application in QEMU, then set proper
 # QEMU variables. This also allows two QEMUs to be hooked together and
 # pass data between them. The QEMU flags are not set for standalone
-# tests defined by CONFIG_NET_TEST.
+# tests defined by CONFIG_NET_TEST. For PPP, the serial port file is
+# not available if we run unit tests which define CONFIG_NET_TEST.
 if(CONFIG_NETWORKING)
   if(CONFIG_NET_QEMU_SLIP)
     if((CONFIG_NET_SLIP_TAP) OR (CONFIG_IEEE802154_UPIPE))
       set(QEMU_NET_STACK 1)
     endif()
+  elseif((CONFIG_NET_QEMU_PPP) AND NOT (CONFIG_NET_TEST))
+      set(QEMU_NET_STACK 1)
   endif()
 endif()
 
@@ -143,15 +146,28 @@ elseif(QEMU_NET_STACK)
       # appending the instance name to the pid file we can easily run more
       # instances of the same sample.
 
-      if(${CMAKE_GENERATOR} STREQUAL "Unix Makefiles")
+      if(CONFIG_NET_QEMU_PPP)
-        set(tmp_file unix:/tmp/slip.sock\${QEMU_INSTANCE})
+	if(${CMAKE_GENERATOR} STREQUAL "Unix Makefiles")
+	  set(ppp_path unix:/tmp/ppp\${QEMU_INSTANCE})
+	else()
+	  set(ppp_path unix:/tmp/ppp${QEMU_INSTANCE})
+	endif()
+
+	list(APPEND MORE_FLAGS_FOR_${target}
+          -serial ${ppp_path}
+          )
       else()
-        set(tmp_file unix:/tmp/slip.sock${QEMU_INSTANCE})
+	if(${CMAKE_GENERATOR} STREQUAL "Unix Makefiles")
+          set(tmp_file unix:/tmp/slip.sock\${QEMU_INSTANCE})
+	else()
+          set(tmp_file unix:/tmp/slip.sock${QEMU_INSTANCE})
+	endif()
+
+	list(APPEND MORE_FLAGS_FOR_${target}
+          -serial ${tmp_file}
+          )
       endif()
 
-      list(APPEND MORE_FLAGS_FOR_${target}
-        -serial ${tmp_file}
-        )
     endif()
   endforeach()