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  *   http://lists.openwall.net/linux-kernel/2011/01/09/56
20  */
21 
22 #include <linux/kernel.h>
23 
24 extern unsigned long loops_per_jiffy;
25 
26 #include <asm/delay.h>
27 
28 /*
29  * Using udelay() for intervals greater than a few milliseconds can
30  * risk overflow for high loops_per_jiffy (high bogomips) machines. The
31  * mdelay() provides a wrapper to prevent this.  For delays greater
32  * than MAX_UDELAY_MS milliseconds, the wrapper is used.  Architecture
33  * specific values can be defined in asm-???/delay.h as an override.
34  * The 2nd mdelay() definition ensures GCC will optimize away the
35  * while loop for the common cases where n <= MAX_UDELAY_MS  --  Paul G.
36  */
37 
38 #ifndef MAX_UDELAY_MS
39 #define MAX_UDELAY_MS	5
40 #endif
41 
42 #ifndef mdelay
43 #define mdelay(n) (\
44 	(__builtin_constant_p(n) && (n)<=MAX_UDELAY_MS) ? udelay((n)*1000) : \
45 	({unsigned long __ms=(n); while (__ms--) udelay(1000);}))
46 #endif
47 
48 #ifndef ndelay
ndelay(unsigned long x)49 static inline void ndelay(unsigned long x)
50 {
51 	udelay(DIV_ROUND_UP(x, 1000));
52 }
53 #define ndelay(x) ndelay(x)
54 #endif
55 
56 extern unsigned long lpj_fine;
57 void calibrate_delay(void);
58 void msleep(unsigned int msecs);
59 unsigned long msleep_interruptible(unsigned int msecs);
60 void usleep_range(unsigned long min, unsigned long max);
61 
ssleep(unsigned int seconds)62 static inline void ssleep(unsigned int seconds)
63 {
64 	msleep(seconds * 1000);
65 }
66 
67 #endif /* defined(_LINUX_DELAY_H) */
68