1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Copyright (C) 2008 Michal Simek
4  * Copyright (C) 2007 John Williams
5  * Copyright (C) 2006 Atmark Techno, Inc.
6  */
7 
8 #ifndef _ASM_MICROBLAZE_DELAY_H
9 #define _ASM_MICROBLAZE_DELAY_H
10 
11 #include <linux/param.h>
12 
__delay(unsigned long loops)13 static inline void __delay(unsigned long loops)
14 {
15 	asm volatile ("# __delay		\n\t"		\
16 			"1: addi	%0, %0, -1\t\n"		\
17 			"bneid	%0, 1b		\t\n"		\
18 			"nop			\t\n"
19 			: "=r" (loops)
20 			: "0" (loops));
21 }
22 
23 /*
24  * Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so
25  * loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32.
26  *
27  * The mul instruction gives us loops = (a * b) / 2^32.
28  * We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226
29  * because this lets us support a wide range of HZ and
30  * loops_per_jiffy values without either a or b overflowing 2^32.
31  * Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and
32  * loops_per_jiffy <= (2^32 - 1) / 226 = 19004280
33  * (which corresponds to ~3800 bogomips at HZ = 100).
34  * -- paulus
35  */
36 #define __MAX_UDELAY	(226050910UL/HZ)	/* maximum udelay argument */
37 #define __MAX_NDELAY	(4294967295UL/HZ)	/* maximum ndelay argument */
38 
39 extern unsigned long loops_per_jiffy;
40 
__udelay(unsigned int x)41 static inline void __udelay(unsigned int x)
42 {
43 
44 	unsigned long long tmp =
45 		(unsigned long long)x * (unsigned long long)loops_per_jiffy \
46 			* 226LL;
47 	unsigned loops = tmp >> 32;
48 
49 /*
50 	__asm__("mulxuu %0,%1,%2" : "=r" (loops) :
51 		"r" (x), "r" (loops_per_jiffy * 226));
52 */
53 	__delay(loops);
54 }
55 
56 extern void __bad_udelay(void);		/* deliberately undefined */
57 extern void __bad_ndelay(void);		/* deliberately undefined */
58 
59 #define udelay(n)						\
60 	({							\
61 		if (__builtin_constant_p(n)) {			\
62 			if ((n) / __MAX_UDELAY >= 1)		\
63 				__bad_udelay();			\
64 			else					\
65 				__udelay((n) * (19 * HZ));	\
66 		} else {					\
67 			__udelay((n) * (19 * HZ));		\
68 		}						\
69 	})
70 
71 #define ndelay(n)						\
72 	({							\
73 		if (__builtin_constant_p(n)) {			\
74 			if ((n) / __MAX_NDELAY >= 1)		\
75 				__bad_ndelay();			\
76 			else					\
77 				__udelay((n) * HZ);		\
78 		} else {					\
79 			__udelay((n) * HZ);			\
80 		}						\
81 	})
82 
83 #define muldiv(a, b, c)		(((a)*(b))/(c))
84 
85 #endif /* _ASM_MICROBLAZE_DELAY_H */
86