xref: /OK3568_Linux_fs/kernel/arch/x86/um/delay.c (revision 4882a59341e53eb6f0b4789bf948001014eff981) 
1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun  * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
4*4882a593Smuzhiyun  * Mostly copied from arch/x86/lib/delay.c
5*4882a593Smuzhiyun  */
6*4882a593Smuzhiyun 
7*4882a593Smuzhiyun #include <linux/export.h>
8*4882a593Smuzhiyun #include <linux/kernel.h>
9*4882a593Smuzhiyun #include <linux/delay.h>
10*4882a593Smuzhiyun #include <asm/param.h>
11*4882a593Smuzhiyun 
__delay(unsigned long loops)12*4882a593Smuzhiyun void __delay(unsigned long loops)
13*4882a593Smuzhiyun {
14*4882a593Smuzhiyun 	asm volatile(
15*4882a593Smuzhiyun 		"test %0,%0\n"
16*4882a593Smuzhiyun 		"jz 3f\n"
17*4882a593Smuzhiyun 		"jmp 1f\n"
18*4882a593Smuzhiyun 
19*4882a593Smuzhiyun 		".align 16\n"
20*4882a593Smuzhiyun 		"1: jmp 2f\n"
21*4882a593Smuzhiyun 
22*4882a593Smuzhiyun 		".align 16\n"
23*4882a593Smuzhiyun 		"2: dec %0\n"
24*4882a593Smuzhiyun 		" jnz 2b\n"
25*4882a593Smuzhiyun 		"3: dec %0\n"
26*4882a593Smuzhiyun 
27*4882a593Smuzhiyun 		: /* we don't need output */
28*4882a593Smuzhiyun 		: "a" (loops)
29*4882a593Smuzhiyun 	);
30*4882a593Smuzhiyun }
31*4882a593Smuzhiyun EXPORT_SYMBOL(__delay);
32*4882a593Smuzhiyun 
__const_udelay(unsigned long xloops)33*4882a593Smuzhiyun inline void __const_udelay(unsigned long xloops)
34*4882a593Smuzhiyun {
35*4882a593Smuzhiyun 	int d0;
36*4882a593Smuzhiyun 
37*4882a593Smuzhiyun 	xloops *= 4;
38*4882a593Smuzhiyun 	asm("mull %%edx"
39*4882a593Smuzhiyun 		: "=d" (xloops), "=&a" (d0)
40*4882a593Smuzhiyun 		: "1" (xloops), "0"
41*4882a593Smuzhiyun 		(loops_per_jiffy * (HZ/4)));
42*4882a593Smuzhiyun 
43*4882a593Smuzhiyun 	__delay(++xloops);
44*4882a593Smuzhiyun }
45*4882a593Smuzhiyun EXPORT_SYMBOL(__const_udelay);
46*4882a593Smuzhiyun 
__udelay(unsigned long usecs)47*4882a593Smuzhiyun void __udelay(unsigned long usecs)
48*4882a593Smuzhiyun {
49*4882a593Smuzhiyun 	__const_udelay(usecs * 0x000010c7); /* 2**32 / 1000000 (rounded up) */
50*4882a593Smuzhiyun }
51*4882a593Smuzhiyun EXPORT_SYMBOL(__udelay);
52*4882a593Smuzhiyun 
__ndelay(unsigned long nsecs)53*4882a593Smuzhiyun void __ndelay(unsigned long nsecs)
54*4882a593Smuzhiyun {
55*4882a593Smuzhiyun 	__const_udelay(nsecs * 0x00005); /* 2**32 / 1000000000 (rounded up) */
56*4882a593Smuzhiyun }
57*4882a593Smuzhiyun EXPORT_SYMBOL(__ndelay);
58