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
18static 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
46static 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)						\
65	({							\
66		if (__builtin_constant_p(n)) {			\
67			if ((n) / __MAX_UDELAY >= 1)		\
68				__bad_udelay();			\
69			else					\
70				__udelay((n) * (19 * HZ));	\
71		} else {					\
72			__udelay((n) * (19 * HZ));		\
73		}						\
74	})
75
76#define ndelay(n)						\
77	({							\
78		if (__builtin_constant_p(n)) {			\
79			if ((n) / __MAX_NDELAY >= 1)		\
80				__bad_ndelay();			\
81			else					\
82				__udelay((n) * HZ);		\
83		} else {					\
84			__udelay((n) * HZ);			\
85		}						\
86	})
87
88#define muldiv(a, b, c)		(((a)*(b))/(c))
89
90#endif /* _ASM_MICROBLAZE_DELAY_H */
91