1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * OpenRISC Linux
4  *
5  * Linux architectural port borrowing liberally from similar works of
6  * others.  All original copyrights apply as per the original source
7  * declaration.
8  *
9  * Modifications for the OpenRISC architecture:
10  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
11  *
12  * Precise Delay Loops
13  */
14 
15 #include <linux/kernel.h>
16 #include <linux/export.h>
17 #include <linux/init.h>
18 #include <linux/timex.h>
19 #include <asm/param.h>
20 #include <asm/delay.h>
21 #include <asm/timex.h>
22 #include <asm/processor.h>
23 
read_current_timer(unsigned long * timer_value)24 int read_current_timer(unsigned long *timer_value)
25 {
26 	*timer_value = get_cycles();
27 	return 0;
28 }
29 
__delay(unsigned long cycles)30 void __delay(unsigned long cycles)
31 {
32 	cycles_t start = get_cycles();
33 
34 	while ((get_cycles() - start) < cycles)
35 		cpu_relax();
36 }
37 EXPORT_SYMBOL(__delay);
38 
__const_udelay(unsigned long xloops)39 inline void __const_udelay(unsigned long xloops)
40 {
41 	unsigned long long loops;
42 
43 	loops = (unsigned long long)xloops * loops_per_jiffy * HZ;
44 
45 	__delay(loops >> 32);
46 }
47 EXPORT_SYMBOL(__const_udelay);
48 
__udelay(unsigned long usecs)49 void __udelay(unsigned long usecs)
50 {
51 	__const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */
52 }
53 EXPORT_SYMBOL(__udelay);
54 
__ndelay(unsigned long nsecs)55 void __ndelay(unsigned long nsecs)
56 {
57 	__const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */
58 }
59 EXPORT_SYMBOL(__ndelay);
60