projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 086e9dc0 JH |
2 | /* |
| 3 | * Precise Delay Loops for Meta | |
| 4 | * | |
| 5 | * Copyright (C) 1993 Linus Torvalds | |
| 6 | * Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz> | |
| 7 | * Copyright (C) 2007,2009 Imagination Technologies Ltd. | |
| 8 | * | |
| 9 | */ | |
| 10 | ||
| 11 | #include <linux/export.h> | |
| 12 | #include <linux/sched.h> | |
| 13 | #include <linux/delay.h> | |
| 14 | ||
| 15 | #include <asm/core_reg.h> | |
| 16 | #include <asm/processor.h> | |
| 17 | ||
| 18 | /* | |
| 19 | * TXTACTCYC is only 24 bits, so on chips with fast clocks it will wrap | |
| 20 | * many times per-second. If it does wrap __delay will return prematurely, | |
| 21 | * but this is only likely with large delay values. | |
| 22 | * | |
| 23 | * We also can't implement read_current_timer() with TXTACTCYC due to | |
| 24 | * this wrapping behaviour. | |
| 25 | */ | |
| 26 | #define rdtimer(t) t = __core_reg_get(TXTACTCYC) | |
| 27 | ||
| 28 | void __delay(unsigned long loops) | |
| 29 | { | |
| 30 | unsigned long bclock, now; | |
| 31 | ||
| 32 | rdtimer(bclock); | |
| 33 | do { | |
| 34 | asm("NOP"); | |
| 35 | rdtimer(now); | |
| 36 | } while ((now-bclock) < loops); | |
| 37 | } | |
| 38 | EXPORT_SYMBOL(__delay); | |
| 39 | ||
| 40 | inline void __const_udelay(unsigned long xloops) | |
| 41 | { | |
| 42 | u64 loops = (u64)xloops * (u64)loops_per_jiffy * HZ; | |
| 43 | __delay(loops >> 32); | |
| 44 | } | |
| 45 | EXPORT_SYMBOL(__const_udelay); | |
| 46 | ||
| 47 | void __udelay(unsigned long usecs) | |
| 48 | { | |
| 49 | __const_udelay(usecs * 0x000010c7); /* 2**32 / 1000000 (rounded up) */ | |
| 50 | } | |
| 51 | EXPORT_SYMBOL(__udelay); | |
| 52 | ||
| 53 | void __ndelay(unsigned long nsecs) | |
| 54 | { | |
| 55 | __const_udelay(nsecs * 0x00005); /* 2**32 / 1000000000 (rounded up) */ | |
| 56 | } | |
| 57 | EXPORT_SYMBOL(__ndelay); |