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1 | /* |
2 | * include/asm-microblaze/delay.h | |
3 | * | |
4 | * This file is subject to the terms and conditions of the GNU General Public | |
5 | * License. See the file "COPYING" in the main directory of this archive | |
6 | * for more details. | |
7 | * | |
8 | * Copyright (C) 2008 Michal Simek | |
9 | * Copyright (C) 2007 John Williams | |
10 | * Copyright (C) 2006 Atmark Techno, Inc. | |
11 | */ | |
12 | ||
13 | #ifndef _ASM_MICROBLAZE_DELAY_H | |
14 | #define _ASM_MICROBLAZE_DELAY_H | |
15 | ||
16 | extern inline void __delay(unsigned long loops) | |
17 | { | |
18 | asm volatile ("# __delay \n\t" \ | |
19 | "1: addi %0, %0, -1\t\n" \ | |
20 | "bneid %0, 1b \t\n" \ | |
21 | "nop \t\n" | |
22 | : "=r" (loops) | |
23 | : "0" (loops)); | |
24 | } | |
25 | ||
26 | /* | |
27 | * Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so | |
28 | * loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32. | |
29 | * | |
30 | * The mul instruction gives us loops = (a * b) / 2^32. | |
31 | * We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226 | |
32 | * because this lets us support a wide range of HZ and | |
33 | * loops_per_jiffy values without either a or b overflowing 2^32. | |
34 | * Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and | |
35 | * loops_per_jiffy <= (2^32 - 1) / 226 = 19004280 | |
36 | * (which corresponds to ~3800 bogomips at HZ = 100). | |
37 | * -- paulus | |
38 | */ | |
39 | #define __MAX_UDELAY (226050910UL/HZ) /* maximum udelay argument */ | |
40 | #define __MAX_NDELAY (4294967295UL/HZ) /* maximum ndelay argument */ | |
41 | ||
42 | extern unsigned long loops_per_jiffy; | |
43 | ||
44 | extern inline void __udelay(unsigned int x) | |
45 | { | |
46 | ||
47 | unsigned long long tmp = | |
48 | (unsigned long long)x * (unsigned long long)loops_per_jiffy \ | |
49 | * 226LL; | |
50 | unsigned loops = tmp >> 32; | |
51 | ||
52 | /* | |
53 | __asm__("mulxuu %0,%1,%2" : "=r" (loops) : | |
54 | "r" (x), "r" (loops_per_jiffy * 226)); | |
55 | */ | |
56 | __delay(loops); | |
57 | } | |
58 | ||
59 | extern void __bad_udelay(void); /* deliberately undefined */ | |
60 | extern void __bad_ndelay(void); /* deliberately undefined */ | |
61 | ||
62 | #define udelay(n) (__builtin_constant_p(n) ? \ | |
63 | ((n) > __MAX_UDELAY ? __bad_udelay() : __udelay((n) * (19 * HZ))) : \ | |
64 | __udelay((n) * (19 * HZ))) | |
65 | ||
66 | #define ndelay(n) (__builtin_constant_p(n) ? \ | |
67 | ((n) > __MAX_NDELAY ? __bad_ndelay() : __udelay((n) * HZ)) : \ | |
68 | __udelay((n) * HZ)) | |
69 | ||
70 | #define muldiv(a, b, c) (((a)*(b))/(c)) | |
71 | ||
72 | #endif /* _ASM_MICROBLAZE_DELAY_H */ |