Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Fri, 11 Nov 2011 10:34:07 -0600

Hi Zen,

On 2011-11-11 Szalata, Zenon M. wrote:
> >        drvAb link 0 sysBusTas failed
> >        drvAb link 0 sysBusTas failed
> >        drvAb: link 0 sc_lock failure fl_lock 0
> >
> > Has anyone successfully used AB R2.2 with mvme6100, EPICS R3.14.11, and
> > vxWorks 6.6?

We use AB Scanners on 3.14.11 IOCs here, although not with vxWorks 6.x yet.  
the problem is not with EPICS, it's the MVME6100 but I think you'll find the 
same issues with almost any PowerPC-based board using the default Wind River 
BSP.

The above sysBusTas failure messages tell me that your MVME6100 BSP is not 
configured to do an 8-bit read-modify-write cycle on the VMEbus when the AB 
driver calls sysBusTas(), which is an essential requirement for controlling an 
AB scanner.  VxWorks has an alternative method for atomic access across the 
VMEbus which involves acquiring bus mastership and not releasing it until the 
access is complete, but that doesn't work if the TAS location is on another 
VME card which doesn't itself follow the same protocol.  In the case of the AB 
cards the TAS location is in the scanner's shared memory, and you really do 
have to use a VMEbus 8-bit read-modify-write cycle — the board's CPU uses a 
68K TAS instruction to acquire access to its internal command buffer.  I make 
changes to all our BSPs here at APS to ensure that sysBusTas() does that, so 
Mark Rivers won't normally see that problem as he uses my BSPs.

That may not be the only issue, but it's one that you will definitely have to 
fix before this can work properly.  You need to ensure that sysBusTas() ends 
up calling sysVmeRmwTas(), and that it will generate an D08 cycle.  Among 
others I make the changes below to the sysVmeRmw() routine in the file 
mv6100/sysLib.c, but I'm not sure if these will be sufficient for you:

 LOCAL BOOL sysVmeRmw
     (
     char * vmeAdrs          /* VME address to be tested and set */
     )
     {

     BOOL state = FALSE;  /* semaphore state */
     int  lockKey;        /* interrupt lock key */
+    UINT32 mask = 0x80000000 >> ((UINT32) vmeAdrs & 3) * 8; /* bit to TAS */

     lockKey = intLock ();

     /* Enable RMW cycle */

-    sysBusRmwEnable(VME_RMW_ENABLE_BITS,		/* enable bits */
-                    VME_RMW_COMPARE_BITS,		/* cmpare */
-                    VME_RMW_SWAP_TO_SET,		/* swap */
-                    (char *)vmeAdrs);
+    sysBusRmwEnable(mask, 0x00000000, 0x80808080, vmeAdrs);

     /* perform RMW to try and set TAS location */

-    state = *((UINT32 *)vmeAdrs);
+    state = *vmeAdrs;
     EIEIO_SYNC;

     /* Disable RMW cycle */

     sysBusRmwDisable();

     /* unlock the interrupt */

     intUnlock (lockKey);

     /* return TAS test result */

-    return (state ? FALSE : TRUE);
+    return (state & 0x80) ? FALSE : TRUE;
     }

- Andrew
-- 
Optimization is the process of taking something that works and
replacing it with something that almost works, but costs less.
-- Roger Needham

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System