arch/ia64/sn/kernel/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) 2004-2007 Silicon Graphics, Inc.  All Rights Reserved.
   7  */
   8
   9
  10 /*
  11  * The xp_nofault_PIOR function takes a pointer to a remote PIO register
  12  * and attempts to load and consume a value from it.  This function
  13  * will be registered as a nofault code block.  In the event that the
  14  * PIO read fails, the MCA handler will force the error to look
  15  * corrected and vector to the xp_error_PIOR which will return an error.
  16  *
  17  * The definition of "consumption" and the time it takes for an MCA
  18  * to surface is processor implementation specific.  This code
  19  * is sufficient on Itanium through the Montvale processor family.
  20  * It may need to be adjusted for future processor implementations.
  21  *
  22  *      extern int xp_nofault_PIOR(void *remote_register);
  23  */
  24
  25         .global xp_nofault_PIOR
  26 xp_nofault_PIOR:
  27         mov     r8=r0                   // Stage a success return value
  28         ld8.acq r9=[r32];;              // PIO Read the specified register
  29         adds    r9=1,r9;;               // Add to force consumption
  30         srlz.i;;                        // Allow time for MCA to surface
  31         br.ret.sptk.many b0;;           // Return success
  32
  33         .global xp_error_PIOR
  34 xp_error_PIOR:
  35         mov     r8=1                    // Return value of 1
  36         br.ret.sptk.many b0;;           // Return failure