tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * linux/arch/arm/lib/delay.S
3 *
4 * Copyright (C) 1995, 1996 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10#include <linux/linkage.h>
11#include <asm/assembler.h>
12 .text
13
14LC0: .word loops_per_jiffy
15
16/*
17 * 0 <= r0 <= 2000
18 */
19ENTRY(__udelay)
20 mov r2, #0x6800
21 orr r2, r2, #0x00db
22 mul r0, r2, r0
23ENTRY(__const_udelay) @ 0 <= r0 <= 0x01ffffff
24 ldr r2, LC0
25 ldr r2, [r2] @ max = 0x0fffffff
26 mov r0, r0, lsr #11 @ max = 0x00003fff
27 mov r2, r2, lsr #11 @ max = 0x0003ffff
28 mul r0, r2, r0 @ max = 2^32-1
29 movs r0, r0, lsr #6
30 RETINSTR(moveq,pc,lr)
31
32/*
33 * loops = (r0 * 0x10c6 * 100 * loops_per_jiffy) / 2^32
34 *
35 * Oh, if only we had a cycle counter...
36 */
37
38@ Delay routine
39ENTRY(__delay)
40 subs r0, r0, #1
41#if 0
42 RETINSTR(movls,pc,lr)
43 subs r0, r0, #1
44 RETINSTR(movls,pc,lr)
45 subs r0, r0, #1
46 RETINSTR(movls,pc,lr)
47 subs r0, r0, #1
48 RETINSTR(movls,pc,lr)
49 subs r0, r0, #1
50 RETINSTR(movls,pc,lr)
51 subs r0, r0, #1
52 RETINSTR(movls,pc,lr)
53 subs r0, r0, #1
54 RETINSTR(movls,pc,lr)
55 subs r0, r0, #1
56#endif
57 bhi __delay
58 RETINSTR(mov,pc,lr)