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 
18 extern 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 
44 extern unsigned long loops_per_jiffy;
45 
46 extern 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 
61 extern void __bad_udelay(void);		/* deliberately undefined */
62 extern 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 */
75