Audio XSD: Allow vendor extension for audio devices

Without this patch vendors can not do any vendor extension extending
the audio enums as it would fails the XSD validation.

Long term, the config xml parsing should be moved in the HAL, until then
allow extension if they are prefixed with EX_.

Test: xmllint --noout --schema hardware/interfaces/audio/4.0/config/audio_policy_configuration.xsd  --xinclude out/target/product/*/vendor/etc/audio_policy_configuration.xml
Bug: 117967786
Change-Id: Ie44490824b5b50fdebb50a82299ea348d2a34b84
Signed-off-by: Kevin Rocard <krocard@google.com>

audio/4.0/config/audio_policy_configuration.xsd

@@ -280,6 +280,19 @@
             <xs:enumeration value="AUDIO_DEVICE_IN_STUB"/>
         </xs:restriction>
     </xs:simpleType>
+    <xs:simpleType name="vendorExtension">
+        <!-- Vendor extension names must be prefixed by "VX_" to distinguish them from AOSP values.
+             Vendor are encouraged to namespace their module names to avoid conflicts.
+             Example for an hypothetical Google virtual reality device:
+                <devicePort tagName="VR" type="VX_GOOGLE_VR" role="sink">
+        -->
+        <xs:restriction base="xs:string">
+            <xs:pattern value="VX_[_a-zA-Z0-9]+"/>
+        </xs:restriction>
+    </xs:simpleType>
+    <xs:simpleType name="extendableAudioDevice">
+        <xs:union memberTypes="audioDevice vendorExtension"/>
+    </xs:simpleType>
     <!-- Enum values of audio_format_t in audio.h
          TODO: generate from hidl to avoid manual sync. -->
     <xs:simpleType name="audioFormat">
@@ -346,6 +359,9 @@
             <xs:enumeration value="AUDIO_FORMAT_LDAC"/>
         </xs:restriction>
     </xs:simpleType>
+    <xs:simpleType name="extendableAudioFormat">
+        <xs:union memberTypes="audioFormat vendorExtension"/>
+    </xs:simpleType>
     <!-- Enum values of audio::common::4_0::AudioUsage
          TODO: generate from HIDL to avoid manual sync. -->
     <xs:simpleType name="audioUsage">
@@ -388,7 +404,7 @@
     </xs:simpleType>
     <xs:complexType name="profile">
         <xs:attribute name="name" type="xs:token" use="optional"/>
-        <xs:attribute name="format" type="audioFormat" use="optional"/>
+        <xs:attribute name="format" type="extendableAudioFormat" use="optional"/>
         <xs:attribute name="samplingRates" type="samplingRates" use="optional"/>
         <xs:attribute name="channelMasks" type="channelMask" use="optional"/>
     </xs:complexType>
@@ -425,7 +441,7 @@
                         <xs:element name="gains" type="gains" minOccurs="0"/>
                     </xs:sequence>
                     <xs:attribute name="tagName" type="xs:token" use="required"/>
-                    <xs:attribute name="type" type="audioDevice" use="required"/>
+                    <xs:attribute name="type" type="extendableAudioDevice" use="required"/>
                     <xs:attribute name="role" type="role" use="required"/>
                     <xs:attribute name="address" type="xs:string" use="optional" default=""/>
                     <!-- Note that XSD 1.0 can not check that a type only has one default. -->