sysdeps/powerpc/sys/platform/ppc.h

   1 /* Facilities specific to the PowerPC architecture
   2    Copyright (C) 2012-2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _SYS_PLATFORM_PPC_H
  20 #define _SYS_PLATFORM_PPC_H     1
  21
  22 #include <features.h>
  23 #include <stdint.h>
  24 #include <bits/ppc.h>
  25
  26 /* Read the Time Base Register.   */
  27 static inline uint64_t
  28 __ppc_get_timebase (void)
  29 {
  30 #if __GNUC_PREREQ (4, 8)
  31   return __builtin_ppc_get_timebase ();
  32 #else
  33 # ifdef __powerpc64__
  34   uint64_t __tb;
  35   /* "volatile" is necessary here, because the user expects this assembly
  36      isn't moved after an optimization.  */
  37   __asm__ volatile ("mfspr %0, 268" : "=r" (__tb));
  38   return __tb;
  39 # else  /* not __powerpc64__ */
  40   uint32_t __tbu, __tbl, __tmp; \
  41   __asm__ volatile ("0:\n\t"
  42                     "mftbu %0\n\t"
  43                     "mftbl %1\n\t"
  44                     "mftbu %2\n\t"
  45                     "cmpw %0, %2\n\t"
  46                     "bne- 0b"
  47                     : "=r" (__tbu), "=r" (__tbl), "=r" (__tmp));
  48   return (((uint64_t) __tbu << 32) | __tbl);
  49 # endif  /* not __powerpc64__ */
  50 #endif
  51 }
  52
  53 /* The following functions provide hints about the usage of shared processor
  54    resources, as defined in ISA 2.06 and newer. */
  55
  56 /* Provides a hint that performance will probably be improved if shared
  57    resources dedicated to the executing processor are released for use by other
  58    processors.  */
  59 static inline void
  60 __ppc_yield (void)
  61 {
  62   __asm__ volatile ("or 27,27,27");
  63 }
  64
  65 /* Provides a hint that performance will probably be improved if shared
  66    resources dedicated to the executing processor are released until
  67    all outstanding storage accesses to caching-inhibited storage have been
  68    completed.  */
  69 static inline void
  70 __ppc_mdoio (void)
  71 {
  72   __asm__ volatile ("or 29,29,29");
  73 }
  74
  75 /* Provides a hint that performance will probably be improved if shared
  76    resources dedicated to the executing processor are released until all
  77    outstanding storage accesses to cacheable storage for which the data is not
  78    in the cache have been completed.  */
  79 static inline void
  80 __ppc_mdoom (void)
  81 {
  82   __asm__ volatile ("or 30,30,30");
  83 }
  84
  85
  86 /* ISA 2.05 and beyond support the Program Priority Register (PPR) to adjust
  87    thread priorities based on lock acquisition, wait and release. The ISA
  88    defines the use of form 'or Rx,Rx,Rx' as the way to modify the PRI field.
  89    The unprivileged priorities are:
  90      Rx = 1 (low)
  91      Rx = 2 (medium)
  92      Rx = 6 (medium-low/normal)
  93    The 'or' instruction form is a nop in previous hardware, so it is safe to
  94    use unguarded. The default value is 'medium'.
  95  */
  96
  97 static inline void
  98 __ppc_set_ppr_med (void)
  99 {
 100   __asm__ volatile ("or 2,2,2");
 101 }
 102
 103 static inline void
 104 __ppc_set_ppr_med_low (void)
 105 {
 106   __asm__ volatile ("or 6,6,6");
 107 }
 108
 109 static inline void
 110 __ppc_set_ppr_low (void)
 111 {
 112   __asm__ volatile ("or 1,1,1");
 113 }
 114
 115 #endif  /* sys/platform/ppc.h */