Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * arch/s390/kernel/delay.c |
| 3 | * Precise Delay Loops for S390 |
| 4 | * |
| 5 | * S390 version |
| 6 | * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation |
| 7 | * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com), |
| 8 | * |
| 9 | * Derived from "arch/i386/lib/delay.c" |
| 10 | * Copyright (C) 1993 Linus Torvalds |
| 11 | * Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz> |
| 12 | */ |
| 13 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 14 | #include <linux/sched.h> |
| 15 | #include <linux/delay.h> |
| 16 | |
| 17 | #ifdef CONFIG_SMP |
| 18 | #include <asm/smp.h> |
| 19 | #endif |
| 20 | |
| 21 | void __delay(unsigned long loops) |
| 22 | { |
| 23 | /* |
| 24 | * To end the bloody studid and useless discussion about the |
| 25 | * BogoMips number I took the liberty to define the __delay |
| 26 | * function in a way that that resulting BogoMips number will |
| 27 | * yield the megahertz number of the cpu. The important function |
| 28 | * is udelay and that is done using the tod clock. -- martin. |
| 29 | */ |
Martin Schwidefsky | 94c12cc | 2006-09-28 16:56:43 +0200 | [diff] [blame^] | 30 | asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | } |
| 32 | |
| 33 | /* |
| 34 | * Waits for 'usecs' microseconds using the tod clock, giving up the time slice |
| 35 | * of the virtual PU inbetween to avoid congestion. |
| 36 | */ |
| 37 | void __udelay(unsigned long usecs) |
| 38 | { |
Martin Schwidefsky | 94c12cc | 2006-09-28 16:56:43 +0200 | [diff] [blame^] | 39 | uint64_t start_cc; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 40 | |
| 41 | if (usecs == 0) |
| 42 | return; |
Martin Schwidefsky | 94c12cc | 2006-09-28 16:56:43 +0200 | [diff] [blame^] | 43 | start_cc = get_clock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 44 | do { |
| 45 | cpu_relax(); |
Martin Schwidefsky | 94c12cc | 2006-09-28 16:56:43 +0200 | [diff] [blame^] | 46 | } while (((get_clock() - start_cc)/4096) < usecs); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 47 | } |