projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
1 | /* |
| 2 | * Precise Delay Loops for x86-64 | |
| 3 | * | |
| 4 | * Copyright (C) 1993 Linus Torvalds | |
| 5 | * Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz> | |
| 6 | * | |
| 7 | * The __delay function must _NOT_ be inlined as its execution time | |
| 8 | * depends wildly on alignment on many x86 processors. | |
| 9 | */ | |
| 10 | ||
| 2ee60e17 | 11 | #include <linux/module.h> |
| 1da177e4 | 12 | #include <linux/sched.h> |
| 941e492b | 13 | #include <linux/timex.h> |
| 35d5d08a | 14 | #include <linux/preempt.h> |
| 1da177e4 | 15 | #include <linux/delay.h> |
| 941e492b | 16 | #include <linux/init.h> |
| 35d5d08a | 17 | |
| 1da177e4 | 18 | #include <asm/delay.h> |
| 8a9e1b0f | 19 | #include <asm/msr.h> |
| 1da177e4 LT |
20 | |
| 21 | #ifdef CONFIG_SMP | |
| 22 | #include <asm/smp.h> | |
| 23 | #endif | |
| 24 | ||
| 941e492b | 25 | int __devinit read_current_timer(unsigned long *timer_value) |
| 8a9e1b0f VP |
26 | { |
| 27 | rdtscll(*timer_value); | |
| 28 | return 0; | |
| 29 | } | |
| 30 | ||
| 1da177e4 LT |
31 | void __delay(unsigned long loops) |
| 32 | { | |
| 33 | unsigned bclock, now; | |
| 5c1ea082 | 34 | int cpu; |
| 35d5d08a | 35 | |
| 5c1ea082 SR |
36 | preempt_disable(); |
| 37 | cpu = smp_processor_id(); | |
| 1da177e4 | 38 | rdtscl(bclock); |
| 5c1ea082 | 39 | for (;;) { |
| 1da177e4 | 40 | rdtscl(now); |
| 5c1ea082 SR |
41 | if ((now - bclock) >= loops) |
| 42 | break; | |
| 43 | ||
| 44 | /* Allow RT tasks to run */ | |
| 45 | preempt_enable(); | |
| 46 | rep_nop(); | |
| 47 | preempt_disable(); | |
| 48 | ||
| 49 | /* | |
| 50 | * It is possible that we moved to another CPU, and | |
| 51 | * since TSC's are per-cpu we need to calculate | |
| 52 | * that. The delay must guarantee that we wait "at | |
| 53 | * least" the amount of time. Being moved to another | |
| 54 | * CPU could make the wait longer but we just need to | |
| 55 | * make sure we waited long enough. Rebalance the | |
| 56 | * counter for this CPU. | |
| 57 | */ | |
| 58 | if (unlikely(cpu != smp_processor_id())) { | |
| 59 | loops -= (now - bclock); | |
| 60 | cpu = smp_processor_id(); | |
| 61 | rdtscl(bclock); | |
| 62 | } | |
| 1da177e4 | 63 | } |
| 35d5d08a | 64 | preempt_enable(); |
| 1da177e4 | 65 | } |
| 2ee60e17 | 66 | EXPORT_SYMBOL(__delay); |
| 1da177e4 LT |
67 | |
| 68 | inline void __const_udelay(unsigned long xloops) | |
| 69 | { | |
| 92cb7612 MT |
70 | __delay(((xloops * HZ * |
| 71 | cpu_data(raw_smp_processor_id()).loops_per_jiffy) >> 32) + 1); | |
| 1da177e4 | 72 | } |
| 2ee60e17 | 73 | EXPORT_SYMBOL(__const_udelay); |
| 1da177e4 LT |
74 | |
| 75 | void __udelay(unsigned long usecs) | |
| 76 | { | |
| b9a8d94a | 77 | __const_udelay(usecs * 0x000010c7); /* 2**32 / 1000000 (rounded up) */ |
| 1da177e4 | 78 | } |
| 2ee60e17 | 79 | EXPORT_SYMBOL(__udelay); |
| 1da177e4 LT |
80 | |
| 81 | void __ndelay(unsigned long nsecs) | |
| 82 | { | |
| 83 | __const_udelay(nsecs * 0x00005); /* 2**32 / 1000000000 (rounded up) */ | |
| 84 | } | |
| 2ee60e17 | 85 | EXPORT_SYMBOL(__ndelay); |