LXR linux/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
  14struct 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
  38extern struct vvar_data *vvar_data;
  39extern int vdso_fix_stick;
  40
  41static inline unsigned int vvar_read_begin(const struct vvar_data *s)
  42{
  43        unsigned int ret;
  44
  45repeat:
  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
  55static 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
  62static 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
  68static 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 */
  76