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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#include <linux/param.h>
17
18extern inline void __delay(unsigned long loops)
19{
20 asm volatile ("# __delay \n\t" \
21 "1: addi %0, %0, -1\t\n" \
22 "bneid %0, 1b \t\n" \
23 "nop \t\n"
24 : "=r" (loops)
25 : "0" (loops));
26}
27
28/*
29 * Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so
30 * loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32.
31 *
32 * The mul instruction gives us loops = (a * b) / 2^32.
33 * We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226
34 * because this lets us support a wide range of HZ and
35 * loops_per_jiffy values without either a or b overflowing 2^32.
36 * Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and
37 * loops_per_jiffy <= (2^32 - 1) / 226 = 19004280
38 * (which corresponds to ~3800 bogomips at HZ = 100).
39 * -- paulus
40 */
41#define __MAX_UDELAY (226050910UL/HZ) /* maximum udelay argument */
42#define __MAX_NDELAY (4294967295UL/HZ) /* maximum ndelay argument */
43
44extern unsigned long loops_per_jiffy;
45
46extern inline void __udelay(unsigned int x)
47{
48
49 unsigned long long tmp =
50 (unsigned long long)x * (unsigned long long)loops_per_jiffy \
51 * 226LL;
52 unsigned loops = tmp >> 32;
53
54/*
55 __asm__("mulxuu %0,%1,%2" : "=r" (loops) :
56 "r" (x), "r" (loops_per_jiffy * 226));
57*/
58 __delay(loops);
59}
60
61extern void __bad_udelay(void); /* deliberately undefined */
62extern void __bad_ndelay(void); /* deliberately undefined */
63
64#define udelay(n) (__builtin_constant_p(n) ? \
65 ((n) > __MAX_UDELAY ? __bad_udelay() : __udelay((n) * (19 * HZ))) : \
66 __udelay((n) * (19 * HZ)))
67
68#define ndelay(n) (__builtin_constant_p(n) ? \
69 ((n) > __MAX_NDELAY ? __bad_ndelay() : __udelay((n) * HZ)) : \
70 __udelay((n) * HZ))
71
72#define muldiv(a, b, c) (((a)*(b))/(c))
73
74#endif /* _ASM_MICROBLAZE_DELAY_H */