delay-loop.S
1.34 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
/*
* linux/arch/arm/lib/delay.S
*
* Copyright (C) 1995, 1996 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/delay.h>
.text
.LC0: .word loops_per_jiffy
.LC1: .word UDELAY_MULT
/*
* r0 <= 2000
* lpj <= 0x01ffffff (max. 3355 bogomips)
* HZ <= 1000
*/
ENTRY(__loop_udelay)
ldr r2, .LC1
mul r0, r2, r0
ENTRY(__loop_const_udelay) @ 0 <= r0 <= 0x7fffff06
mov r1, #-1
ldr r2, .LC0
ldr r2, [r2] @ max = 0x01ffffff
add r0, r0, r1, lsr #32-14
mov r0, r0, lsr #14 @ max = 0x0001ffff
add r2, r2, r1, lsr #32-10
mov r2, r2, lsr #10 @ max = 0x00007fff
mul r0, r2, r0 @ max = 2^32-1
add r0, r0, r1, lsr #32-6
movs r0, r0, lsr #6
moveq pc, lr
/*
* loops = r0 * HZ * loops_per_jiffy / 1000000
*/
.align 3
@ Delay routine
ENTRY(__loop_delay)
subs r0, r0, #1
#if 0
movls pc, lr
subs r0, r0, #1
movls pc, lr
subs r0, r0, #1
movls pc, lr
subs r0, r0, #1
movls pc, lr
subs r0, r0, #1
movls pc, lr
subs r0, r0, #1
movls pc, lr
subs r0, r0, #1
movls pc, lr
subs r0, r0, #1
#endif
bhi __loop_delay
mov pc, lr
ENDPROC(__loop_udelay)
ENDPROC(__loop_const_udelay)
ENDPROC(__loop_delay)