[PATCH skeleton v2] skeleton: fixed hard-coding of master OCC hwmon sysfs path for PowerCap object

[OpenBMC Patches]

From: Yi Li <adamliyi at msn.com>

Currently master OCC hwmon sysfs path is hardcoded to '/sys/class/hwmon/hwmon3/'.
This make the '/org/openbmc/sensors/host/PowerCap' interface cannot work when
master OCC is initilized as hwmon device other than 'hwmon3'.

'usr_powercap' attribute should be searched when OCC is active.
When skeleton creates 'PowerCap' objects, OCC may not be active.
So do the search each time setting power cap. Raise an exception when
there is no 'user_powercap' attribute.

This would fix the issue: https://github.com/openbmc/skeleton/issues/42

Also raise an exception when setting power cap fails. The exception
will be returned to REST API caller. Need to specify the exception
name to trigger a '400' return code.
This would fix the issue:
https://github.com/openbmc/skeleton/issues/43

Signed-off-by: Yi Li <adamliyi at msn.com>
---
 bin/Sensors.py         | 22 ++++++++++++++++++----
 bin/sensor_manager2.py |  3 ---
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/bin/Sensors.py b/bin/Sensors.py
index f951eeb..889590c 100755
--- a/bin/Sensors.py
+++ b/bin/Sensors.py
@@ -8,6 +8,7 @@ import dbus
 import dbus.service
 import dbus.mainloop.glib
 import os
+import glob
 import Openbmc
 
 ## Abstract class, must subclass
@@ -137,17 +138,30 @@ class PowerCap(VirtualSensor):
 	def __init__(self, bus, name):
 		VirtualSensor.__init__(self, bus, name)
 		SensorValue.setValue(self, 0)
-		self.sysfs_attr = "/sys/class/hwmon/hwmon3/user_powercap"
 	##override setValue method
 	@dbus.service.method(SensorValue.IFACE_NAME,
 		in_signature='v', out_signature='')
 	def setValue(self, value):
+		# master occ hwmon path is created dymanically when occ is active
+		# scan hwmon sysfs directory for update
+		for pcap_file in glob.glob('/sys/class/hwmon/*/user_powercap'):
+			occ_i2c_dev = os.path.dirname(pcap_file)+'/device'
+			occ_i2c_dev = os.path.realpath(occ_i2c_dev).split('/').pop()
+			if occ_i2c_dev == '3-0050':
+				self.sysfs_attr = pcap_file
+				break
+		else:
+			raise dbus.exceptions.DBusException(
+				"Cannot find user_powercap hwmon attribute, "+
+				"check occ status.")
+			return
 		try:
-			cmd_str = "echo "+str(value)+" > "+self.sysfs_attr
+			cmd_str = 'echo '+str(value)+' > '+self.sysfs_attr
 			ret = subprocess.check_output(cmd_str, shell=True)
 		except subprocess.CalledProcessError as powerexc:
-			print "Set PowerCap Error", powerexc.returncode,
-			powerexc.output
+			raise dbus.exceptions.DBusException(
+				"Set PowerCap error: check value range",
+				name='org.freedesktop.DBus.Error.InvalidArgs')
 			return
 		print "Set PowerCap: ", value
 		SensorValue.setValue(self, value)
diff --git a/bin/sensor_manager2.py b/bin/sensor_manager2.py
index b5aac53..926bfea 100755
--- a/bin/sensor_manager2.py
+++ b/bin/sensor_manager2.py
@@ -54,9 +54,6 @@ if __name__ == '__main__':
 
 	obj_path = OBJ_PATH+"/host/PowerCap"
 	sensor_obj = Sensors.PowerCap(bus,obj_path)
-	## hwmon3 is default for master OCC on Barreleye.
-	## should rewrite sensor_manager to remove hardcode
-	sensor_obj.sysfs_attr = "/sys/class/hwmon/hwmon3/user_powercap"
 	root_sensor.add(obj_path,sensor_obj)
 
 	obj_path = OBJ_PATH+"/host/BootProgress"
-- 
2.7.1