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1da177e4 LT |
1 | #ifndef _M68KNOMMU_DELAY_H |
2 | #define _M68KNOMMU_DELAY_H | |
3 | ||
4 | /* | |
5 | * Copyright (C) 1994 Hamish Macdonald | |
6 | * Copyright (C) 2004 Greg Ungerer <gerg@snapgear.com> | |
7 | */ | |
8 | ||
9 | #include <asm/param.h> | |
10 | ||
11 | extern __inline__ void __delay(unsigned long loops) | |
12 | { | |
13 | #if defined(CONFIG_COLDFIRE) | |
14 | /* The coldfire runs this loop at significantly different speeds | |
15 | * depending upon long word alignment or not. We'll pad it to | |
16 | * long word alignment which is the faster version. | |
17 | * The 0x4a8e is of course a 'tstl %fp' instruction. This is better | |
18 | * than using a NOP (0x4e71) instruction because it executes in one | |
19 | * cycle not three and doesn't allow for an arbitary delay waiting | |
20 | * for bus cycles to finish. Also fp/a6 isn't likely to cause a | |
21 | * stall waiting for the register to become valid if such is added | |
22 | * to the coldfire at some stage. | |
23 | */ | |
24 | __asm__ __volatile__ ( ".balignw 4, 0x4a8e\n\t" | |
25 | "1: subql #1, %0\n\t" | |
26 | "jcc 1b" | |
27 | : "=d" (loops) : "0" (loops)); | |
28 | #else | |
29 | __asm__ __volatile__ ( "1: subql #1, %0\n\t" | |
30 | "jcc 1b" | |
31 | : "=d" (loops) : "0" (loops)); | |
32 | #endif | |
33 | } | |
34 | ||
35 | /* | |
36 | * Ideally we use a 32*32->64 multiply to calculate the number of | |
37 | * loop iterations, but the older standard 68k and ColdFire do not | |
38 | * have this instruction. So for them we have a clsoe approximation | |
39 | * loop using 32*32->32 multiplies only. This calculation based on | |
40 | * the ARM version of delay. | |
41 | * | |
42 | * We want to implement: | |
43 | * | |
44 | * loops = (usecs * 0x10c6 * HZ * loops_per_jiffy) / 2^32 | |
45 | */ | |
46 | ||
47 | #define HZSCALE (268435456 / (1000000/HZ)) | |
48 | ||
49 | extern unsigned long loops_per_jiffy; | |
50 | ||
51 | extern __inline__ void _udelay(unsigned long usecs) | |
52 | { | |
53 | #if defined(CONFIG_M68328) || defined(CONFIG_M68EZ328) || \ | |
54 | defined(CONFIG_M68VZ328) || defined(CONFIG_M68360) || \ | |
55 | defined(CONFIG_COLDFIRE) | |
56 | __delay((((usecs * HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6); | |
57 | #else | |
58 | unsigned long tmp; | |
59 | ||
60 | usecs *= 4295; /* 2**32 / 1000000 */ | |
61 | __asm__ ("mulul %2,%0:%1" | |
62 | : "=d" (usecs), "=d" (tmp) | |
63 | : "d" (usecs), "1" (loops_per_jiffy*HZ)); | |
64 | __delay(usecs); | |
65 | #endif | |
66 | } | |
67 | ||
68 | /* | |
69 | * Moved the udelay() function into library code, no longer inlined. | |
70 | * I had to change the algorithm because we are overflowing now on | |
71 | * the faster ColdFire parts. The code is a little biger, so it makes | |
72 | * sense to library it. | |
73 | */ | |
74 | extern void udelay(unsigned long usecs); | |
75 | ||
76 | #endif /* defined(_M68KNOMMU_DELAY_H) */ |