Add submodule dependency filesHEADmaster

Change-Id: Iaf8d18082d3991dec7c0ebbea540f092188eb4ec

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diff --git a/roms/skiboot/doc/opal-api/opal-check-token-80.rst b/roms/skiboot/doc/opal-api/opal-check-token-80.rst
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+.. _OPAL_CHECK_TOKEN:
+
+OPAL_CHECK_TOKEN
+================
+
+.. code-block:: c
+
+   #define OPAL_CHECK_TOKEN			80
+
+   int64_t opal_check_token(uint64_t token);
+
+This OPAL call allows the host OS to determine if a particular OPAL call is present
+on a system. This allows for simple compatibility between OPAL versions and different
+OPAL implementations/platforms.
+
+One parameter is accepted: the OPAL token number.
+
+``OPAL_CHECK_TOKEN`` will return: ::
+
+  enum OpalCheckTokenStatus {
+    OPAL_TOKEN_ABSENT = 0,
+    OPAL_TOKEN_PRESENT = 1
+  };
+
+indicating the presence/absence of the particular OPAL_CALL.
+
+``OPAL_CHECK_TOKEN`` is REQUIRED to be implemented by a conformant OPAL implementation.
+
+For skiboot, only positively ancient internal-to-IBM versions were missing
+OPAL_CHECK_TOKEN. In this case, OPAL_PARAMETER would be returned. There is no
+reason for a host OS to support this behaviour.