bluez: Add Offload SCO nodes routing sample (for PinePhone)

This script selects the correct PinePhone audio routes when the SCO
offload loopback nodes are running.

tests/examples/bt-pinephone.lua

@@ -0,0 +1,119 @@
+#!/usr/bin/wpexec
+--
+-- WirePlumber
+--
+-- Copyright © 2022 Collabora Ltd.
+--    @author Frédéric Danis <frederic.danis@collabora.com>
+--
+-- SPDX-License-Identifier: MIT
+--
+-- This is an example of the offload SCO nodes platform specific management,
+-- in this case for the PinePhone.
+--
+-- The PinePhone provides specific ALSA ports to route audio to the Bluetooth
+-- chipset. This script selects these ports when the offload SCO nodes state
+-- change to 'running'.
+--
+-- This scriptcan be executed as a standalone executable, or it can be placed
+-- in WirePlumber's scripts directory and loaded together with other scripts.
+-----------------------------------------------------------------------------
+
+devices_om = ObjectManager {
+  Interest {
+    type = "device",
+  }
+}
+
+nodes_om = ObjectManager {
+  Interest {
+    type = "node",
+    Constraint { "node.name", "#", "*.bluez_*put*"},
+    Constraint { "device.id", "+" },
+  }
+}
+
+function parseParam(param, id)
+  local route = param:parse()
+  if route.pod_type == "Object" and route.object_id == id then
+    return route.properties
+  else
+    return nil
+  end
+end
+
+function setPlatformRoute (route_name, direction)
+  local platform_sound = nil
+  local device_id = nil
+  local route_save = nil
+
+  local interest = Interest {
+    type = "device",
+    Constraint { "device.name", "=", "alsa_card.platform-sound"}
+  }
+  for d in devices_om:iterate (interest) do
+    platform_sound = d
+
+    for p in platform_sound:iterate_params("Route") do
+      route = parseParam(p, "Route")
+      if route.direction == direction then
+        device_id = route.device
+        route_save = route.save
+      end
+    end
+
+    for p in platform_sound:iterate_params("EnumRoute") do
+      enum_route = parseParam(p, "EnumRoute")
+
+      if enum_route.name == route_name then
+        route_index = enum_route.index
+      end
+    end
+  end
+
+  if route.index == route_index then
+    return
+  end
+
+  -- default props
+  local props = {
+    "Spa:Pod:Object:Param:Props", "Route",
+    mute = false,
+  }
+
+  -- construct Route param
+  local param = Pod.Object {
+    "Spa:Pod:Object:Param:Route", "Route",
+    index = route_index,
+    device = device_id,
+    props = Pod.Object(props),
+    save = route_save,
+  }
+
+  Log.info(param, "setting route on " .. tostring(platform_sound))
+  platform_sound:set_param("Route", param)
+
+  route.prev_active = true
+  route.active = true
+end
+
+nodes_om:connect("object-added", function(_, node)
+  node:connect("state-changed", function(node, old_state, cur_state)
+    local interest = Interest {
+      type = "device",
+      Constraint { "object.id", "=", node.properties["device.id"]}
+    }
+    for d in devices_om:iterate (interest) do
+      if cur_state == "running" then
+        -- Both direction should be set to allow audio streaming
+        setPlatformRoute("[Out] BluetoothHeadset", "Output")
+        setPlatformRoute("[In] BluetoothHeadset", "Input")
+      else
+        setPlatformRoute("[Out] Earpiece", "Output")
+        setPlatformRoute("[In] DigitalMic", "Input")
+      end
+    end
+  end)
+end)
+
+nodes_om:activate()
+devices_om:activate()