diff options
Diffstat (limited to 'arch/x86/lib')
| -rw-r--r-- | arch/x86/lib/delay_64.c | 44 |
1 files changed, 40 insertions, 4 deletions
diff --git a/arch/x86/lib/delay_64.c b/arch/x86/lib/delay_64.c index 4c441be9264..d0326d07c84 100644 --- a/arch/x86/lib/delay_64.c +++ b/arch/x86/lib/delay_64.c @@ -22,13 +22,28 @@ #include <asm/smp.h> #endif -int __devinit read_current_timer(unsigned long *timer_value) +/* simple loop based delay: */ +static void delay_loop(unsigned long loops) { - rdtscll(*timer_value); - return 0; + asm volatile( + " test %0,%0 \n" + " jz 3f \n" + " jmp 1f \n" + + ".align 16 \n" + "1: jmp 2f \n" + + ".align 16 \n" + "2: dec %0 \n" + " jnz 2b \n" + "3: dec %0 \n" + + : /* we don't need output */ + :"a" (loops) + ); } -void __delay(unsigned long loops) +static void delay_tsc(unsigned long loops) { unsigned bclock, now; int cpu; @@ -63,6 +78,27 @@ void __delay(unsigned long loops) } preempt_enable(); } + +static void (*delay_fn)(unsigned long) = delay_loop; + +void use_tsc_delay(void) +{ + delay_fn = delay_tsc; +} + +int __devinit read_current_timer(unsigned long *timer_value) +{ + if (delay_fn == delay_tsc) { + rdtscll(*timer_value); + return 0; + } + return -1; +} + +void __delay(unsigned long loops) +{ + delay_fn(loops); +} EXPORT_SYMBOL(__delay); inline void __const_udelay(unsigned long xloops) |