arch/sparc/include/asm/vvar.h

   1 /*
   2  * Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved.
   3  */
   4
   5 #ifndef _ASM_SPARC_VVAR_DATA_H
   6 #define _ASM_SPARC_VVAR_DATA_H
   7
   8 #include <asm/clocksource.h>
   9 #include <asm/processor.h>
  10 #include <asm/barrier.h>
  11 #include <linux/time.h>
  12 #include <linux/types.h>
  13
  14 struct vvar_data {
  15         unsigned int seq;
  16
  17         int vclock_mode;
  18         struct { /* extract of a clocksource struct */
  19                 u64     cycle_last;
  20                 u64     mask;
  21                 int     mult;
  22                 int     shift;
  23         } clock;
  24         /* open coded 'struct timespec' */
  25         u64             wall_time_sec;
  26         u64             wall_time_snsec;
  27         u64             monotonic_time_snsec;
  28         u64             monotonic_time_sec;
  29         u64             monotonic_time_coarse_sec;
  30         u64             monotonic_time_coarse_nsec;
  31         u64             wall_time_coarse_sec;
  32         u64             wall_time_coarse_nsec;
  33
  34         int             tz_minuteswest;
  35         int             tz_dsttime;
  36 };
  37
  38 extern struct vvar_data *vvar_data;
  39 extern int vdso_fix_stick;
  40
  41 static inline unsigned int vvar_read_begin(const struct vvar_data *s)
  42 {
  43         unsigned int ret;
  44
  45 repeat:
  46         ret = READ_ONCE(s->seq);
  47         if (unlikely(ret & 1)) {
  48                 cpu_relax();
  49                 goto repeat;
  50         }
  51         smp_rmb(); /* Finish all reads before we return seq */
  52         return ret;
  53 }
  54
  55 static inline int vvar_read_retry(const struct vvar_data *s,
  56                                         unsigned int start)
  57 {
  58         smp_rmb(); /* Finish all reads before checking the value of seq */
  59         return unlikely(s->seq != start);
  60 }
  61
  62 static inline void vvar_write_begin(struct vvar_data *s)
  63 {
  64         ++s->seq;
  65         smp_wmb(); /* Makes sure that increment of seq is reflected */
  66 }
  67
  68 static inline void vvar_write_end(struct vvar_data *s)
  69 {
  70         smp_wmb(); /* Makes the value of seq current before we increment */
  71         ++s->seq;
  72 }
  73
  74
  75 #endif /* _ASM_SPARC_VVAR_DATA_H */