xref: /openbmc/linux/arch/s390/include/asm/timex.h (revision a2cce7a9)
1 /*
2  *  S390 version
3  *    Copyright IBM Corp. 1999
4  *
5  *  Derived from "include/asm-i386/timex.h"
6  *    Copyright (C) 1992, Linus Torvalds
7  */
8 
9 #ifndef _ASM_S390_TIMEX_H
10 #define _ASM_S390_TIMEX_H
11 
12 #include <asm/lowcore.h>
13 #include <linux/time64.h>
14 
15 /* The value of the TOD clock for 1.1.1970. */
16 #define TOD_UNIX_EPOCH 0x7d91048bca000000ULL
17 
18 /* Inline functions for clock register access. */
19 static inline int set_tod_clock(__u64 time)
20 {
21 	int cc;
22 
23 	asm volatile(
24 		"   sck   %1\n"
25 		"   ipm   %0\n"
26 		"   srl   %0,28\n"
27 		: "=d" (cc) : "Q" (time) : "cc");
28 	return cc;
29 }
30 
31 static inline int store_tod_clock(__u64 *time)
32 {
33 	int cc;
34 
35 	asm volatile(
36 		"   stck  %1\n"
37 		"   ipm   %0\n"
38 		"   srl   %0,28\n"
39 		: "=d" (cc), "=Q" (*time) : : "cc");
40 	return cc;
41 }
42 
43 static inline void set_clock_comparator(__u64 time)
44 {
45 	asm volatile("sckc %0" : : "Q" (time));
46 }
47 
48 static inline void store_clock_comparator(__u64 *time)
49 {
50 	asm volatile("stckc %0" : "=Q" (*time));
51 }
52 
53 void clock_comparator_work(void);
54 
55 static inline unsigned long long local_tick_disable(void)
56 {
57 	unsigned long long old;
58 
59 	old = S390_lowcore.clock_comparator;
60 	S390_lowcore.clock_comparator = -1ULL;
61 	set_clock_comparator(S390_lowcore.clock_comparator);
62 	return old;
63 }
64 
65 static inline void local_tick_enable(unsigned long long comp)
66 {
67 	S390_lowcore.clock_comparator = comp;
68 	set_clock_comparator(S390_lowcore.clock_comparator);
69 }
70 
71 #define CLOCK_TICK_RATE		1193180 /* Underlying HZ */
72 #define STORE_CLOCK_EXT_SIZE	16	/* stcke writes 16 bytes */
73 
74 typedef unsigned long long cycles_t;
75 
76 static inline void get_tod_clock_ext(char *clk)
77 {
78 	typedef struct { char _[STORE_CLOCK_EXT_SIZE]; } addrtype;
79 
80 	asm volatile("stcke %0" : "=Q" (*(addrtype *) clk) : : "cc");
81 }
82 
83 static inline unsigned long long get_tod_clock(void)
84 {
85 	unsigned char clk[STORE_CLOCK_EXT_SIZE];
86 
87 	get_tod_clock_ext(clk);
88 	return *((unsigned long long *)&clk[1]);
89 }
90 
91 static inline unsigned long long get_tod_clock_fast(void)
92 {
93 #ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES
94 	unsigned long long clk;
95 
96 	asm volatile("stckf %0" : "=Q" (clk) : : "cc");
97 	return clk;
98 #else
99 	return get_tod_clock();
100 #endif
101 }
102 
103 static inline cycles_t get_cycles(void)
104 {
105 	return (cycles_t) get_tod_clock() >> 2;
106 }
107 
108 int get_sync_clock(unsigned long long *clock);
109 void init_cpu_timer(void);
110 unsigned long long monotonic_clock(void);
111 
112 void tod_to_timeval(__u64 todval, struct timespec64 *xt);
113 
114 static inline
115 void stck_to_timespec64(unsigned long long stck, struct timespec64 *ts)
116 {
117 	tod_to_timeval(stck - TOD_UNIX_EPOCH, ts);
118 }
119 
120 extern u64 sched_clock_base_cc;
121 
122 /**
123  * get_clock_monotonic - returns current time in clock rate units
124  *
125  * The caller must ensure that preemption is disabled.
126  * The clock and sched_clock_base get changed via stop_machine.
127  * Therefore preemption must be disabled when calling this
128  * function, otherwise the returned value is not guaranteed to
129  * be monotonic.
130  */
131 static inline unsigned long long get_tod_clock_monotonic(void)
132 {
133 	return get_tod_clock() - sched_clock_base_cc;
134 }
135 
136 /**
137  * tod_to_ns - convert a TOD format value to nanoseconds
138  * @todval: to be converted TOD format value
139  * Returns: number of nanoseconds that correspond to the TOD format value
140  *
141  * Converting a 64 Bit TOD format value to nanoseconds means that the value
142  * must be divided by 4.096. In order to achieve that we multiply with 125
143  * and divide by 512:
144  *
145  *    ns = (todval * 125) >> 9;
146  *
147  * In order to avoid an overflow with the multiplication we can rewrite this.
148  * With a split todval == 2^32 * th + tl (th upper 32 bits, tl lower 32 bits)
149  * we end up with
150  *
151  *    ns = ((2^32 * th + tl) * 125 ) >> 9;
152  * -> ns = (2^23 * th * 125) + ((tl * 125) >> 9);
153  *
154  */
155 static inline unsigned long long tod_to_ns(unsigned long long todval)
156 {
157 	unsigned long long ns;
158 
159 	ns = ((todval >> 32) << 23) * 125;
160 	ns += ((todval & 0xffffffff) * 125) >> 9;
161 	return ns;
162 }
163 
164 #endif
165