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 
vvar_read_begin(const struct vvar_data * s)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 
vvar_read_retry(const struct vvar_data * s,unsigned int start)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 
vvar_write_begin(struct vvar_data * s)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 
vvar_write_end(struct vvar_data * s)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 */
76