drivers/misc/sgi-xp/xp_nofault.S

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (c) 2004-2008 Silicon Graphics, Inc.  All Rights Reserved.
   7  */
   8
   9 /*
  10  * The xp_nofault_PIOR function takes a pointer to a remote PIO register
  11  * and attempts to load and consume a value from it.  This function
  12  * will be registered as a nofault code block.  In the event that the
  13  * PIO read fails, the MCA handler will force the error to look
  14  * corrected and vector to the xp_error_PIOR which will return an error.
  15  *
  16  * The definition of "consumption" and the time it takes for an MCA
  17  * to surface is processor implementation specific.  This code
  18  * is sufficient on Itanium through the Montvale processor family.
  19  * It may need to be adjusted for future processor implementations.
  20  *
  21  *      extern int xp_nofault_PIOR(void *remote_register);
  22  */
  23
  24         .global xp_nofault_PIOR
  25 xp_nofault_PIOR:
  26         mov     r8=r0                   // Stage a success return value
  27         ld8.acq r9=[r32];;              // PIO Read the specified register
  28         adds    r9=1,r9;;               // Add to force consumption
  29         srlz.i;;                        // Allow time for MCA to surface
  30         br.ret.sptk.many b0;;           // Return success
  31
  32         .global xp_error_PIOR
  33 xp_error_PIOR:
  34         mov     r8=1                    // Return value of 1
  35         br.ret.sptk.many b0;;           // Return failure