driver/power: Add power backend for RPM1521

Add power backend for the Minuteman RPM1521 series of
power switches(2,4,8 ports).

Signed-off-by: Caleb Ethridge <caleb.ethridge@analog.com>

Author: CalebEthridgeADI

labgrid/driver/power/rpm1521.py

@@ -0,0 +1,58 @@
+"""Power backend for the Minuteman RPM1521 networked power controller.
+
+The RPM1521 is controlled via an HTTP CGI endpoint using HTTP basic auth::
+
+    curl --user user:pwd \\
+        "http://192.168.1.100/nagios_powerctrl.csp?slave_id=1&port=<PORT>&ctrl_kind=<KIND>"
+
+where ``ctrl_kind=1`` turns the outlet on and ``ctrl_kind=2`` turns it off.
+
+The outlet state is read back from a separate status CGI::
+
+    curl --user user:pwd "http://192.168.1.100/nagios_power_status.csp"
+
+which returns a list whose second to last element holds the on/off state of each
+outlet (0 = off, 1 = on).
+
+    NetworkPowerPort:
+        model: rpm1521
+        host: 'http://admin:secret@192.168.1.10'
+        index: 1
+"""
+
+import json
+
+import requests
+
+SLAVE_ID = 1
+CTRL_KIND_ON = 1
+CTRL_KIND_OFF = 2
+
+
+def power_set(host, port, index, value):
+    index = int(index)
+    ctrl_kind = CTRL_KIND_ON if value else CTRL_KIND_OFF
+    params = {
+        "slave_id": SLAVE_ID,
+        "port": index,
+        "ctrl_kind": ctrl_kind,
+    }
+    r = requests.get(f"{host}/nagios_powerctrl.csp", params=params)
+    r.raise_for_status()
+
+
+def power_get(host, port, index):
+    index = int(index)
+    params = {
+        "slave_id": SLAVE_ID,
+    }
+    r = requests.get(f"{host}/nagios_power_status.csp", params=params)
+    r.raise_for_status()
+
+    # The status CGI returns a list literal, e.g.
+    #   ['RPM1521E','0.0','NULL','1','1','109.9',['1','0'],['0','1'],['0.0','0.0']]
+    # It contains several bracketed sub-lists; the second to last one holds the
+    # on/off status of each outlet.
+    data = json.loads(r.text.replace("'", '"'))
+    socket_states = data[-2]
+    return int(socket_states[index - 1]) == 1

tests/test_powerdriver.py

@@ -295,6 +295,7 @@ def test_import_backends(self):
         import labgrid.driver.power.pe6216
         import labgrid.driver.power.poe_netgear_plus
         import labgrid.driver.power.rest
+        import labgrid.driver.power.rpm1521
         import labgrid.driver.power.sentry
         import labgrid.driver.power.eg_pms2_network
         import labgrid.driver.power.shelly_gen1