Add DP16 workarounds for Nimbus DD1.0

  VREF override
  VCCD override

Change-Id: I480efe28d299da37a717199933889d9bfecf8e11
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/32011
Dev-Ready: Brian R. Silver <bsilver@us.ibm.com>
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Reviewed-by: ANDRE A. MARIN <aamarin@us.ibm.com>
Reviewed-by: STEPHEN GLANCY <sglancy@us.ibm.com>
Tested-by: Hostboot CI <hostboot-ci+hostboot@us.ibm.com>
Reviewed-by: Christian R. Geddes <crgeddes@us.ibm.com>
Reviewed-by: Matt K. Light <mklight@us.ibm.com>
Reviewed-by: Brian R. Silver <bsilver@us.ibm.com>
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/69789
Reviewed-by: Sachin Gupta <sgupta2m@in.ibm.com>
Tested-by: Sachin Gupta <sgupta2m@in.ibm.com>

src/import/chips/p9/procedures/xml/attribute_info/memory_mcs_attributes.xml

@@ -1948,6 +1948,21 @@
         <mssAccessorName>cal_step_enable</mssAccessorName>
     </attribute>
 
+    <attribute>
+        <id>ATTR_MSS_VREF_CAL_ENABLE</id>
+        <targetType>TARGET_TYPE_MCS</targetType>
+        <description>
+            A bit vector denoting bits in every DP16 on the port to be calibrated.
+            That is, all of the set bits will be calibrated for all DP16. A value
+            of zero indicates the calibration should not be run.
+        </description>
+        <initToZero></initToZero>
+        <valueType>uint16</valueType>
+        <writeable/>
+        <array>2</array>
+        <mssAccessorName>vref_cal_enable</mssAccessorName>
+    </attribute>
+
     <attribute>
         <id>ATTR_MSS_CAL_ABORT_ON_ERROR</id>
         <targetType>TARGET_TYPE_SYSTEM</targetType>
@@ -2127,6 +2142,27 @@
         <mssAccessorName>vmem_regulator_max_dimm_count</mssAccessorName>
     </attribute>
 
+    <attribute>
+        <id>ATTR_MSS_VREF_DAC_NIBBLE</id>
+        <targetType>TARGET_TYPE_SYSTEM</targetType>
+        <description>Value for VREF DAC nibbles</description>
+        <initToZero></initToZero>
+        <valueType>uint8</valueType>
+        <writeable/>
+        <mssAccessorName>vref_dac_nibble</mssAccessorName>
+    </attribute>
+
+    <attribute>
+        <id>ATTR_MSS_VCCD_OVERRIDE</id>
+        <targetType>TARGET_TYPE_SYSTEM</targetType>
+        <description>Whether or not to override VCCD. Defaults to no.</description>
+        <initToZero></initToZero>
+        <valueType>uint8</valueType>
+        <enum>NO = 0, YES = 1</enum>
+        <writeable/>
+        <mssAccessorName>vccd_override</mssAccessorName>
+    </attribute>
+
     <attribute>
         <id>ATTR_EFF_DRAM_MAC</id>
         <targetType>TARGET_TYPE_MCS</targetType>