control: Group configuration parsing

Groups are a list of dbus object paths that are to be used within
one-or-more configured fan control events. For fan control, groups are
generally comprised of one-or-more temperature sensors or inventory
objects that exist on the same base object path and implement the same
interface and property to be used in a configured fan control event.
The interface and property to be used on the members of the group are
given within each event.

ex.)
> Group made up of 4 fan inventory objects:

"name": "air_cooled_zone0_fans",
"description": "Group of fan inventory objects for air cooled zone 0",
"type": "/xyz/openbmc_project/inventory",
"members": [
    "/system/chassis/motherboard/fan0",
    "/system/chassis/motherboard/fan1",
    "/system/chassis/motherboard/fan2",
    "/system/chassis/motherboard/fan3"
]

> Event using this group that sets fans to 10500 RPMS when 1 of the
> fans in the group is changes to not present:

"name": "missing_fans_before_high_speed_air",
"groups": [
{
    "name": "air_cooled_zone0_fans",
    "interface": "xyz.openbmc_project.Inventory.Item",
    "property": {
        "name": "Present",
        "type": "bool"
    }
}],
"triggers": [
{
    "name": "signal",
    "signal": "propertiesChanged",
    "handler": "setProperty"
}],
"actions": [
{
    "name": "count_state_before_speed",
    "count": 1,
    "property": {
        "value": false,
        "type": "bool"
    },
    "speed": {
        "value": 10500,
        "type": "uint64_t"
    }
}]

Tested:
    Group objects created for each entry in "groups.json"
    A "groups.json" configuration is required
    Members are parsed and stored within the group object
    Service name is optional and stored in the group object when given

Change-Id: I258c14f4d4d5f6aeb1add3ba880cf403779564d8
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
4 files changed