1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_DELAY_H
3 #define _LINUX_DELAY_H
4
5 /*
6 * Copyright (C) 1993 Linus Torvalds
7 *
8 * Delay routines, using a pre-computed "loops_per_jiffy" value.
9 *
10 * Please note that ndelay(), udelay() and mdelay() may return early for
11 * several reasons:
12 * 1. computed loops_per_jiffy too low (due to the time taken to
13 * execute the timer interrupt.)
14 * 2. cache behaviour affecting the time it takes to execute the
15 * loop function.
16 * 3. CPU clock rate changes.
17 *
18 * Please see this thread:
19 * https://lists.openwall.net/linux-kernel/2011/01/09/56
20 */
21
22 #include <linux/math.h>
23 #include <linux/sched.h>
24
25 extern unsigned long loops_per_jiffy;
26
27 #include <asm/delay.h>
28
29 /*
30 * Using udelay() for intervals greater than a few milliseconds can
31 * risk overflow for high loops_per_jiffy (high bogomips) machines. The
32 * mdelay() provides a wrapper to prevent this. For delays greater
33 * than MAX_UDELAY_MS milliseconds, the wrapper is used. Architecture
34 * specific values can be defined in asm-???/delay.h as an override.
35 * The 2nd mdelay() definition ensures GCC will optimize away the
36 * while loop for the common cases where n <= MAX_UDELAY_MS -- Paul G.
37 */
38
39 #ifndef MAX_UDELAY_MS
40 #define MAX_UDELAY_MS 5
41 #endif
42
43 #ifndef mdelay
44 #define mdelay(n) (\
45 (__builtin_constant_p(n) && (n)<=MAX_UDELAY_MS) ? udelay((n)*1000) : \
46 ({unsigned long __ms=(n); while (__ms--) udelay(1000);}))
47 #endif
48
49 #ifndef ndelay
ndelay(unsigned long x)50 static inline void ndelay(unsigned long x)
51 {
52 udelay(DIV_ROUND_UP(x, 1000));
53 }
54 #define ndelay(x) ndelay(x)
55 #endif
56
57 extern unsigned long lpj_fine;
58 void calibrate_delay(void);
59 unsigned long calibrate_delay_is_known(void);
60 void __attribute__((weak)) calibration_delay_done(void);
61 void msleep(unsigned int msecs);
62 unsigned long msleep_interruptible(unsigned int msecs);
63 void usleep_range_state(unsigned long min, unsigned long max,
64 unsigned int state);
65
usleep_range(unsigned long min,unsigned long max)66 static inline void usleep_range(unsigned long min, unsigned long max)
67 {
68 usleep_range_state(min, max, TASK_UNINTERRUPTIBLE);
69 }
70
usleep_idle_range(unsigned long min,unsigned long max)71 static inline void usleep_idle_range(unsigned long min, unsigned long max)
72 {
73 usleep_range_state(min, max, TASK_IDLE);
74 }
75
ssleep(unsigned int seconds)76 static inline void ssleep(unsigned int seconds)
77 {
78 msleep(seconds * 1000);
79 }
80
81 /* see Documentation/timers/timers-howto.rst for the thresholds */
fsleep(unsigned long usecs)82 static inline void fsleep(unsigned long usecs)
83 {
84 if (usecs <= 10)
85 udelay(usecs);
86 else if (usecs <= 20000)
87 usleep_range(usecs, 2 * usecs);
88 else
89 msleep(DIV_ROUND_UP(usecs, 1000));
90 }
91
92 #endif /* defined(_LINUX_DELAY_H) */
93