blob: 05b7d39e4391218775b701c12d5138b25ca2ca34 [file] [log] [blame]
Michal Simek216f0342009-03-27 14:25:27 +01001/*
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
16extern 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
42extern unsigned long loops_per_jiffy;
43
44extern 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
59extern void __bad_udelay(void); /* deliberately undefined */
60extern 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 */