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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
1da177e4 LT |
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. | |
9f819798 RK |
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: | |
7f317d34 | 19 | * https://lists.openwall.net/linux-kernel/2011/01/09/56 |
1da177e4 LT |
20 | */ |
21 | ||
5f6286a6 | 22 | #include <linux/math.h> |
5cba6d22 | 23 | |
1da177e4 LT |
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 | ||
1e92a550 | 42 | #ifndef mdelay |
1da177e4 LT |
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 | |
5cba6d22 AM |
49 | static inline void ndelay(unsigned long x) |
50 | { | |
51 | udelay(DIV_ROUND_UP(x, 1000)); | |
52 | } | |
53 | #define ndelay(x) ndelay(x) | |
1da177e4 LT |
54 | #endif |
55 | ||
f3f3149f | 56 | extern unsigned long lpj_fine; |
1da177e4 | 57 | void calibrate_delay(void); |
8496ecd0 | 58 | void __attribute__((weak)) calibration_delay_done(void); |
1da177e4 LT |
59 | void msleep(unsigned int msecs); |
60 | unsigned long msleep_interruptible(unsigned int msecs); | |
5e7f5a17 | 61 | void usleep_range(unsigned long min, unsigned long max); |
1da177e4 LT |
62 | |
63 | static inline void ssleep(unsigned int seconds) | |
64 | { | |
65 | msleep(seconds * 1000); | |
66 | } | |
67 | ||
c6af13d3 HK |
68 | /* see Documentation/timers/timers-howto.rst for the thresholds */ |
69 | static inline void fsleep(unsigned long usecs) | |
70 | { | |
71 | if (usecs <= 10) | |
72 | udelay(usecs); | |
73 | else if (usecs <= 20000) | |
74 | usleep_range(usecs, 2 * usecs); | |
75 | else | |
76 | msleep(DIV_ROUND_UP(usecs, 1000)); | |
77 | } | |
78 | ||
1da177e4 | 79 | #endif /* defined(_LINUX_DELAY_H) */ |