1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
4 */
5 #include <linux/delay.h>
6 #include <linux/export.h>
7 #include <linux/smp.h>
8 #include <linux/timex.h>
9
10 #include <asm/processor.h>
11
12 void __delay(unsigned long cycles)
13 {
14 u64 t0 = get_cycles();
15
16 while ((unsigned long)(get_cycles() - t0) < cycles)
17 cpu_relax();
18 }
19 EXPORT_SYMBOL(__delay);
20
21 /*
22 * Division by multiplication: you don't have to worry about
23 * loss of precision.
24 *
25 * Use only for very small delays ( < 1 msec). Should probably use a
26 * lookup table, really, as the multiplications take much too long with
27 * short delays. This is a "reasonable" implementation, though (and the
28 * first constant multiplications gets optimized away if the delay is
29 * a constant)
30 */
31
32 void __udelay(unsigned long us)
33 {
34 __delay((us * 0x000010c7ull * HZ * lpj_fine) >> 32);
35 }
36 EXPORT_SYMBOL(__udelay);
37
38 void __ndelay(unsigned long ns)
39 {
40 __delay((ns * 0x00000005ull * HZ * lpj_fine) >> 32);
41 }
42 EXPORT_SYMBOL(__ndelay);
43
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