XSCOM/LPC Workaround for Nimbus DD1

There is a shared resource between the XSCOM and LPC logic that
leads to errors at the XSCOM level causing errors to be detected
during LPC operations.  This commit adds an external interface
to access block LPC operations while an XSCOM operation is in
flight.

Change-Id: I571094dfb666aa9198fabec5280a0f45c62c90ba
RTC: 167291
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/36399
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: Jenkins OP Build CI <op-jenkins+hostboot@us.ibm.com>
Tested-by: FSP CI Jenkins <fsp-CI-jenkins+hostboot@us.ibm.com>
Reviewed-by: Thi N. Tran <thi@us.ibm.com>
Reviewed-by: Dean Sanner <dsanner@us.ibm.com>
Reviewed-by: Daniel M. Crowell <dcrowell@us.ibm.com>

1 files changed, 47 insertions, 1 deletions

diff --git a/src/usr/xscom/xscom.C b/src/usr/xscom/xscom.C
index fb487c55b..b112b2294 100644
--- a/src/usr/xscom/xscom.C
+++ b/src/usr/xscom/xscom.C
@@ -5,7 +5,7 @@
 /*                                                                        */
 /* OpenPOWER HostBoot Project                                             */
 /*                                                                        */
-/* Contributors Listed Below - COPYRIGHT 2011,2016                        */
+/* Contributors Listed Below - COPYRIGHT 2011,2017                        */
 /* [+] International Business Machines Corp.                              */
 /*                                                                        */
 /*                                                                        */
@@ -47,6 +47,7 @@
 #include <errl/errludlogregister.H>
 #include <xscom/piberror.H>
 #include <arch/pirformat.H>
+#include <lpc/lpcif.H>
 
 // Trace definition
 trace_desc_t* g_trac_xscom = NULL;
@@ -701,6 +702,38 @@ void collectXscomFFDC(TARGETING::Target* i_target,
 
 ///////////////////////////////////////////////////////////////////////////////
 ///////////////////////////////////////////////////////////////////////////////
+bool checkForLpcBug( void )
+{
+    //  See HW400314 for description of hardware bug
+    //  The Power Bus Snooper Interface on the ADU is shared by both PIB
+    //  and LPC. Once an error occurred in the Xscom while accessing the
+    //  PIB space, the interface is overriding the data that is sent out
+    //  as all ?F?  for any operation which may be XSCOM to PIB address
+    //  space or to a LPC address Space. Further XSCOM operation are
+    //  locked till the pending error is cleared.  But an XSCOM Status
+    //  pmisc is sent with pib response info (in this case the type of
+    //  the error) and for the next operations i.e. XSCOM to PIB or to
+    //  LPC it sends info value as 1 which indicates ADU has pending
+    //  XSCOM Error. This is indicated in the (48 :50) bits in the address
+    //  sent.
+
+    ProcessorCoreType l_coreType = cpu_core_type();
+    uint8_t l_ddLevel = cpu_dd_level();
+
+    // Bug is only present in Nimbus DD1
+    if( (l_coreType == CORE_POWER9_NIMBUS) && (l_ddLevel == 0x10) )
+    {
+        TRACFCOMP( g_trac_xscom, "Activating LPC mutex workaround" );
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+///////////////////////////////////////////////////////////////////////////////
 errlHndl_t xscomPerformOp(DeviceFW::OperationType i_opType,
                           TARGETING::Target* i_target,
                           void* io_buffer,
@@ -738,6 +771,13 @@ errlHndl_t xscomPerformOp(DeviceFW::OperationType i_opType,
         // Pin this thread to current CPU
         task_affinity_pin();
 
+        // Block the LPC driver from running while an xscom is in progress
+        static bool l_hasLpcBug = checkForLpcBug();
+        if( l_hasLpcBug )
+        {
+            LPC::block_lpc_ops(true);
+        }
+
         // Lock other XSCom in this same thread from running
         l_XSComMutex = mmio_xscom_mutex();
         mutex_lock(l_XSComMutex);
@@ -778,6 +818,12 @@ errlHndl_t xscomPerformOp(DeviceFW::OperationType i_opType,
         // Unlock
         mutex_unlock(l_XSComMutex);
 
+        // Unblock the LPC driver
+        if( l_hasLpcBug )
+        {
+            LPC::block_lpc_ops(false);
+        }
+
         // Done, un-pin
         task_affinity_unpin();