Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | #ifdef __KERNEL__ |
2 | #ifndef _PPC_DELAY_H | |
3 | #define _PPC_DELAY_H | |
4 | ||
5 | #include <asm/param.h> | |
6 | ||
7 | /* | |
8 | * Copyright 1996, Paul Mackerras. | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public License | |
12 | * as published by the Free Software Foundation; either version | |
13 | * 2 of the License, or (at your option) any later version. | |
14 | */ | |
15 | ||
16 | extern unsigned long loops_per_jiffy; | |
17 | ||
18 | extern void __delay(unsigned int loops); | |
19 | ||
20 | /* | |
21 | * Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so | |
22 | * loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32. | |
23 | * | |
24 | * The mulhwu instruction gives us loops = (a * b) / 2^32. | |
25 | * We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226 | |
26 | * because this lets us support a wide range of HZ and | |
27 | * loops_per_jiffy values without either a or b overflowing 2^32. | |
28 | * Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and | |
29 | * loops_per_jiffy <= (2^32 - 1) / 226 = 19004280 | |
30 | * (which corresponds to ~3800 bogomips at HZ = 100). | |
31 | * -- paulus | |
32 | */ | |
33 | #define __MAX_UDELAY (226050910UL/HZ) /* maximum udelay argument */ | |
34 | #define __MAX_NDELAY (4294967295UL/HZ) /* maximum ndelay argument */ | |
35 | ||
36 | extern __inline__ void __udelay(unsigned int x) | |
37 | { | |
38 | unsigned int loops; | |
39 | ||
40 | __asm__("mulhwu %0,%1,%2" : "=r" (loops) : | |
41 | "r" (x), "r" (loops_per_jiffy * 226)); | |
42 | __delay(loops); | |
43 | } | |
44 | ||
45 | extern __inline__ void __ndelay(unsigned int x) | |
46 | { | |
47 | unsigned int loops; | |
48 | ||
49 | __asm__("mulhwu %0,%1,%2" : "=r" (loops) : | |
50 | "r" (x), "r" (loops_per_jiffy * 5)); | |
51 | __delay(loops); | |
52 | } | |
53 | ||
54 | extern void __bad_udelay(void); /* deliberately undefined */ | |
55 | extern void __bad_ndelay(void); /* deliberately undefined */ | |
56 | ||
57 | #define udelay(n) (__builtin_constant_p(n)? \ | |
58 | ((n) > __MAX_UDELAY? __bad_udelay(): __udelay((n) * (19 * HZ))) : \ | |
59 | __udelay((n) * (19 * HZ))) | |
60 | ||
61 | #define ndelay(n) (__builtin_constant_p(n)? \ | |
62 | ((n) > __MAX_NDELAY? __bad_ndelay(): __ndelay((n) * HZ)) : \ | |
63 | __ndelay((n) * HZ)) | |
64 | ||
65 | #endif /* defined(_PPC_DELAY_H) */ | |
66 | #endif /* __KERNEL__ */ |