socket-uart: refelct origin uart as pseudo tty device on local host

Bind pseudo tty and origin uart with socat usage (tcp socket)
Socat is started by systemd service.
BugzID: 52063

Signed-off-by: Ramon Moesching <ramon.moesching@netmodule.com>

recipes-core/images/netmodule-linux-image.bb

@@ -95,6 +95,7 @@ IMAGE_INSTALL_append_am335x-nmhw21 = " \
                 libgpiod \
                 battery-test \
                 cryptodev-module \
+                socket-uart \
 		"
 
 FPGA_INSTALL = " \

recipes-extended/socket-uart/files/socat-socket-uart

@@ -0,0 +1,16 @@
+#!/bin/sh -
+if [ -x "$(command -v socat)" ]; then
+    echo "start listening socket-uart services with server IP $SOCAT_SOCKET_UART_IP on port $SOCAT_SOCKET_UART_PORT"
+    cmd='socat -s pty,link=/dev/ttyUM0,rawer tcp:$SOCAT_SOCKET_UART_IP:$SOCAT_SOCKET_UART_PORT'
+
+    if [[ -n $SOCAT_SOCKET_UART_MSS ]]; then
+        eval $cmd,mss=$SOCAT_SOCKET_UART_MSS
+    else
+        eval $cmd    
+    fi
+
+else
+    echo "socat command not available on your target or environment"
+    # return 1 so that systemd knows the service failed to start
+    exit 1
+fi

recipes-extended/socket-uart/files/socket-uart.service

@@ -0,0 +1,22 @@
+[Unit]
+Description=Bind uart socket with pseudo tty based on socat 
+
+[Service]
+Type=forking
+ExecStart=/usr/bin/socat-socket-uart
+PIDFile=/var/run/socket-uart.pid
+
+#KillSignal=SIGQUIT
+
+Environment=SOCAT_SOCKET_UART_IP='192.168.1.42' SOCAT_SOCKET_UART_PORT='2204' SOCAT_SOCKET_UART_MSS='256'
+
+ExecReload=/bin/kill -HUP $MAINPID
+Restart=on-failure
+RestartSec=10
+
+[Unit]
+Wants=network-online.target
+After=network-online.target
+
+[Install]
+WantedBy=multi-user.target

recipes-extended/socket-uart/socket-uart_0.0.1.bb

@@ -0,0 +1,44 @@
+inherit systemd
+SUMMARY = "Bind socket-uart with speudo tty based on socat"
+DESCRIPTION = "Bind to origin uart which is provided as socket-uart as pseudo tty based on socat"
+LICENSE = "MIT"
+LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302 \
+                    "
+SRC_URI = " \
+           file://socket-uart.service \
+           file://socat-socket-uart \
+          "
+
+S = "${WORKDIR}"
+
+RDEPENS = "socat"
+
+# Override variable from local.conf with 
+# SOCAT_SOCKET_UART_DEFAULT_IP_pn-socket-uart = "6.6.6.6"
+# SOCAT_SOCKET_UART_DEFAULT_PORT_pn-socket-uart = "2222"
+# Don'"t set mss
+# SOCAT_SOCKET_UART_DEFAULT_MSS_pn-socket-uart = ""
+
+SOCAT_SOCKET_UART_DEFAULT_IP ??= "192.168.1.42"
+SOCAT_SOCKET_UART_DEFAULT_PORT ??= "2204"
+SOCAT_SOCKET_UART_DEFAULT_MSS ??= ""
+
+SYSTEMD_SERVICE_${PN} = "socket-uart.service"
+
+do_configure() {
+    sed -i "s/SOCAT_SOCKET_UART_IP='192.168.1.42'/SOCAT_SOCKET_UART_IP='${SOCAT_SOCKET_UART_DEFAULT_IP}'/g" ${S}/socket-uart.service
+    sed -i "s/SOCAT_SOCKET_UART_PORT='2204'/SOCAT_SOCKET_UART_PORT='${SOCAT_SOCKET_UART_DEFAULT_PORT}'/g" ${S}/socket-uart.service
+    sed -i "s/SOCAT_SOCKET_UART_MSS='256'/SOCAT_SOCKET_UART_MSS='${SOCAT_SOCKET_UART_DEFAULT_MSS}'/g" ${S}/socket-uart.service
+}
+
+do_install() {
+    install -d ${D}/lib/systemd/system
+    install -m 644 ${WORKDIR}/socket-uart.service ${D}/lib/systemd/system/
+
+    install -d ${D}/usr/bin/
+    install -m 744 ${WORKDIR}/socat-socket-uart ${D}/usr/bin/
+}
+
+# Add all SOCAT_SOCKET_* variables to sstate hash calculation and force package_write_rpm exectution from scratch everytime
+do_configure[vardeps] = "SOCAT_SOCKET_UART_DEFAULT_IP SOCAT_SOCKET_UART_DEFAULT_PORT SOCAT_SOCKET_UART_DEFAULT_MSS"
+do_package_write_rpm[nostamp] = "1"