| 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/export.h> |
| 11 | #include <linux/delay.h> |
| 12 | #include <asm/div64.h> |
| 13 | #include <asm/timex.h> |
| 14 | |
| 15 | void __delay(unsigned long loops) |
| 16 | { |
| 17 | /* |
| 18 | * Loop 'loops' times. Callers must not assume a specific |
| 19 | * amount of time passes before this function returns. |
| 20 | */ |
| 21 | asm volatile("0: brct %0,0b": : "d"((loops/2) + 1)); |
| 22 | } |
| 23 | EXPORT_SYMBOL(__delay); |
| 24 | |
| 25 | static void delay_loop(unsigned long delta) |
| 26 | { |
| 27 | unsigned long end; |
| 28 | |
| 29 | end = get_tod_clock_monotonic() + delta; |
| 30 | while (!tod_after(get_tod_clock_monotonic(), end)) |
| 31 | cpu_relax(); |
| 32 | } |
| 33 | |
| 34 | void __udelay(unsigned long usecs) |
| 35 | { |
| 36 | delay_loop(delta: usecs << 12); |
| 37 | } |
| 38 | EXPORT_SYMBOL(__udelay); |
| 39 | |
| 40 | void __ndelay(unsigned long nsecs) |
| 41 | { |
| 42 | nsecs <<= 9; |
| 43 | do_div(nsecs, 125); |
| 44 | delay_loop(delta: nsecs); |
| 45 | } |
| 46 | EXPORT_SYMBOL(__ndelay); |
| 47 |