rtu: implement modbus rtu inventory source service
Implement phosphor-modbus-rtu inventory source service based on [1].
[1]: https://gerrit.openbmc.org/c/openbmc/docs/+/77318
Tested: Unit test passes and tested on qemu with simulated modbus
server.
```
root@bmc:~# busctl tree xyz.openbmc_project.ModbusRTU
└─ /xyz
└─ /xyz/openbmc_project
└─ /xyz/openbmc_project/inventory_source
└─ /xyz/openbmc_project/inventory_source/modbus
├─ /xyz/openbmc_project/inventory_source/modbus/Heat_Exchanger_12_DevTTYUSB0
├─ /xyz/openbmc_project/inventory_source/modbus/Heat_Exchanger_12_DevTTYUSB1
├─ /xyz/openbmc_project/inventory_source/modbus/Reservoir_Pumping_Unit_12_DevTTYUSB0
└─ /xyz/openbmc_project/inventory_source/modbus/Reservoir_Pumping_Unit_12_DevTTYUSB1
root@bmc:~# busctl tree xyz.openbmc_project.EntityManager
└─ /xyz
└─ /xyz/openbmc_project
├─ /xyz/openbmc_project/EntityManager
└─ /xyz/openbmc_project/inventory
└─ /xyz/openbmc_project/inventory/system
├─ /xyz/openbmc_project/inventory/system/board
│ └─ /xyz/openbmc_project/inventory/system/board/Ventura_Modbus
│ ├─ /xyz/openbmc_project/inventory/system/board/Ventura_Modbus/DevTTYUSB0
│ ├─ /xyz/openbmc_project/inventory/system/board/Ventura_Modbus/DevTTYUSB1
│ ├─ /xyz/openbmc_project/inventory/system/board/Ventura_Modbus/Heat_Exchanger
│ └─ /xyz/openbmc_project/inventory/system/board/Ventura_Modbus/Reservoir_Pumping_Unit
└─ /xyz/openbmc_project/inventory/system/chassis
├─ /xyz/openbmc_project/inventory/system/chassis/Heat_Exchanger_12_DevTTYUSB0
├─ /xyz/openbmc_project/inventory/system/chassis/Heat_Exchanger_12_DevTTYUSB1
├─ /xyz/openbmc_project/inventory/system/chassis/Reservoir_Pumping_Unit_12_DevTTYUSB0
└─ /xyz/openbmc_project/inventory/system/chassis/Reservoir_Pumping_Unit_12_DevTTYUSB1
root@bmc:~# busctl introspect xyz.openbmc_project.EntityManager /xyz/openbmc_project/inventory/system/chassis/Heat_Exchanger_12_DevTTYUSB0
NAME TYPE SIGNATURE RESULT/VALUE FLAGS
org.freedesktop.DBus.Introspectable interface - - -
.Introspect method - s -
org.freedesktop.DBus.Peer interface - - -
.GetMachineId method - s -
.Ping method - - -
org.freedesktop.DBus.Properties interface - - -
.Get method ss v -
.GetAll method s a{sv} -
.Set method ssv - -
.PropertiesChanged signal sa{sv}as - -
xyz.openbmc_project.AddObject interface - - -
.AddObject method a{sv} - -
xyz.openbmc_project.Inventory.Decorator.Asset interface - - -
.BuildDate property s "Unknown" emits-change
.Manufacturer property s "Unknown" emits-change
.Model property s "Unknown" emits-change
.PartNumber property s "Unknown" emits-change
.SerialNumber property s "Unknown" emits-change
.SparePartNumber property s "ABABABAB" emits-change
xyz.openbmc_project.Inventory.Item.Chassis interface - - -
.Name property s "Heat Exchanger 12 DevTTYUSB0" emits-change
.Probe property s "xyz.openbmc_project.Inventory.Source.M… emits-change
.Type property s "Chassis" emits-change
root@bmc:~# busctl introspect xyz.openbmc_project.EntityManager /xyz/openbmc_project/inventory/system/chassis/Heat_Exchanger_12_DevTTYUSB1
NAME TYPE SIGNATURE RESULT/VALUE FLAGS
org.freedesktop.DBus.Introspectable interface - - -
.Introspect method - s -
org.freedesktop.DBus.Peer interface - - -
.GetMachineId method - s -
.Ping method - - -
org.freedesktop.DBus.Properties interface - - -
.Get method ss v -
.GetAll method s a{sv} -
.Set method ssv - -
.PropertiesChanged signal sa{sv}as - -
xyz.openbmc_project.AddObject interface - - -
.AddObject method a{sv} - -
xyz.openbmc_project.Inventory.Decorator.Asset interface - - -
.BuildDate property s "Unknown" emits-change
.Manufacturer property s "Unknown" emits-change
.Model property s "Unknown" emits-change
.PartNumber property s "Unknown" emits-change
.SerialNumber property s "Unknown" emits-change
.SparePartNumber property s "ABABABAB" emits-change
xyz.openbmc_project.Inventory.Item.Chassis interface - - -
.Name property s "Heat Exchanger 12 DevTTYUSB1" emits-change
.Probe property s "xyz.openbmc_project.Inventory.Source.M… emits-change
.Type property s "Chassis" emits-change
root@bmc:~# busctl introspect xyz.openbmc_project.EntityManager /xyz/openbmc_project/inventory/system/chassis/Reservoir_Pumping_Unit_12_DevTTYUSB0
NAME TYPE SIGNATURE RESULT/VALUE FLAGS
org.freedesktop.DBus.Introspectable interface - - -
.Introspect method - s -
org.freedesktop.DBus.Peer interface - - -
.GetMachineId method - s -
.Ping method - - -
org.freedesktop.DBus.Properties interface - - -
.Get method ss v -
.GetAll method s a{sv} -
.Set method ssv - -
.PropertiesChanged signal sa{sv}as - -
xyz.openbmc_project.AddObject interface - - -
.AddObject method a{sv} - -
xyz.openbmc_project.Inventory.Decorator.Asset interface - - -
.BuildDate property s "ABABABAB" emits-change
.Manufacturer property s "Unknown" emits-change
.Model property s "ABABABABABABABAB" emits-change
.PartNumber property s "Unknown" emits-change
.SerialNumber property s "ABABABABABABABAB" emits-change
.SparePartNumber property s "ABABABAB" emits-change
xyz.openbmc_project.Inventory.Item.Chassis interface - - -
.Name property s "Reservoir Pumping Unit 12 DevTTYUSB0" emits-change
.Probe property s "xyz.openbmc_project.Inventory.Source.M… emits-change
.Type property s "Chassis" emits-change
root@bmc:~# busctl introspect xyz.openbmc_project.EntityManager /xyz/openbmc_project/inventory/system/chassis/Reservoir_Pumping_Unit_12_DevTTYUSB1
NAME TYPE SIGNATURE RESULT/VALUE FLAGS
org.freedesktop.DBus.Introspectable interface - - -
.Introspect method - s -
org.freedesktop.DBus.Peer interface - - -
.GetMachineId method - s -
.Ping method - - -
org.freedesktop.DBus.Properties interface - - -
.Get method ss v -
.GetAll method s a{sv} -
.Set method ssv - -
.PropertiesChanged signal sa{sv}as - -
xyz.openbmc_project.AddObject interface - - -
.AddObject method a{sv} - -
xyz.openbmc_project.Inventory.Decorator.Asset interface - - -
.BuildDate property s "ABABABAB" emits-change
.Manufacturer property s "Unknown" emits-change
.Model property s "ABABABABABABABAB" emits-change
.PartNumber property s "Unknown" emits-change
.SerialNumber property s "ABABABABABABABAB" emits-change
.SparePartNumber property s "ABABABAB" emits-change
xyz.openbmc_project.Inventory.Item.Chassis interface - - -
.Name property s "Reservoir Pumping Unit 12 DevTTYUSB1" emits-change
.Probe property s "xyz.openbmc_project.Inventory.Source.M… emits-change
.Type property s "Chassis" emits-change
```
Change-Id: Ic0ea739de3833044c95da8164be1e2f3f8e6a063
Signed-off-by: Jagpal Singh Gill <paligill@gmail.com>
diff --git a/rtu/xyz.openbmc_project.ModbusRTU.service b/rtu/xyz.openbmc_project.ModbusRTU.service
new file mode 100644
index 0000000..564fc94
--- /dev/null
+++ b/rtu/xyz.openbmc_project.ModbusRTU.service
@@ -0,0 +1,14 @@
+[Unit]
+Description=Modbus RTU Service
+Requires=xyz.openbmc_project.EntityManager.service
+After=xyz.openbmc_project.EntityManager.service
+
+[Service]
+Type=dbus
+BusName=xyz.openbmc_project.ModbusRTU
+Restart=always
+RestartSec=5
+ExecStart=/usr/libexec/phosphor-modbus/phosphor-modbus-rtu
+
+[Install]
+WantedBy=multi-user.target