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
13static 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
39extern unsigned long loops_per_jiffy;
40
41static 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
56extern void __bad_udelay(void);		/* deliberately undefined */
57extern 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