1 | // SPDX-License-Identifier: GPL-2.0 |
---|---|
2 | /* |
3 | * Precise Delay Loops for S390 |
4 | * |
5 | * Copyright IBM Corp. 1999, 2008 |
6 | * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>, |
7 | */ |
8 | |
9 | #include <linux/processor.h> |
10 | #include <linux/delay.h> |
11 | #include <asm/div64.h> |
12 | #include <asm/timex.h> |
13 | |
14 | void __delay(unsigned long loops) |
15 | { |
16 | /* |
17 | * Loop 'loops' times. Callers must not assume a specific |
18 | * amount of time passes before this function returns. |
19 | */ |
20 | asm volatile("0: brct %0,0b": : "d"((loops/2) + 1)); |
21 | } |
22 | EXPORT_SYMBOL(__delay); |
23 | |
24 | static void delay_loop(unsigned long delta) |
25 | { |
26 | unsigned long end; |
27 | |
28 | end = get_tod_clock_monotonic() + delta; |
29 | while (!tod_after(get_tod_clock_monotonic(), end)) |
30 | cpu_relax(); |
31 | } |
32 | |
33 | void __udelay(unsigned long usecs) |
34 | { |
35 | delay_loop(delta: usecs << 12); |
36 | } |
37 | EXPORT_SYMBOL(__udelay); |
38 | |
39 | void __ndelay(unsigned long nsecs) |
40 | { |
41 | nsecs <<= 9; |
42 | do_div(nsecs, 125); |
43 | delay_loop(delta: nsecs); |
44 | } |
45 | EXPORT_SYMBOL(__ndelay); |
46 |