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/arch/mips/lib/delay.c

http://github.com/mirrors/linux
C | 69 lines | 39 code | 10 blank | 20 comment | 0 complexity | 06d74bf9021541ecadd407ee710a8111 MD5 | raw file
 1/*
 2 * This file is subject to the terms and conditions of the GNU General Public
 3 * License.  See the file "COPYING" in the main directory of this archive
 4 * for more details.
 5 *
 6 * Copyright (C) 1994 by Waldorf Electronics
 7 * Copyright (C) 1995 - 2000, 01, 03 by Ralf Baechle
 8 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
 9 * Copyright (C) 2007, 2014 Maciej W. Rozycki
10 */
11#include <linux/delay.h>
12#include <linux/export.h>
13#include <linux/param.h>
14#include <linux/smp.h>
15#include <linux/stringify.h>
16
17#include <asm/asm.h>
18#include <asm/compiler.h>
19#include <asm/war.h>
20
21#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
22#define GCC_DADDI_IMM_ASM() "I"
23#else
24#define GCC_DADDI_IMM_ASM() "r"
25#endif
26
27#ifndef CONFIG_HAVE_PLAT_DELAY
28
29void __delay(unsigned long loops)
30{
31	__asm__ __volatile__ (
32	"	.set	noreorder				\n"
33	"	.align	3					\n"
34	"1:	bnez	%0, 1b					\n"
35	"	 " __stringify(LONG_SUBU) "	%0, %1		\n"
36	"	.set	reorder					\n"
37	: "=r" (loops)
38	: GCC_DADDI_IMM_ASM() (1), "0" (loops));
39}
40EXPORT_SYMBOL(__delay);
41
42/*
43 * Division by multiplication: you don't have to worry about
44 * loss of precision.
45 *
46 * Use only for very small delays ( < 1 msec).	Should probably use a
47 * lookup table, really, as the multiplications take much too long with
48 * short delays.  This is a "reasonable" implementation, though (and the
49 * first constant multiplications gets optimized away if the delay is
50 * a constant)
51 */
52
53void __udelay(unsigned long us)
54{
55	unsigned int lpj = raw_current_cpu_data.udelay_val;
56
57	__delay((us * 0x000010c7ull * HZ * lpj) >> 32);
58}
59EXPORT_SYMBOL(__udelay);
60
61void __ndelay(unsigned long ns)
62{
63	unsigned int lpj = raw_current_cpu_data.udelay_val;
64
65	__delay((ns * 0x00000005ull * HZ * lpj) >> 32);
66}
67EXPORT_SYMBOL(__ndelay);
68
69#endif