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x86: provide delay loop for x86_64.
This is for consistency with i386. We call use_tsc_delay() at tsc initialization for x86_64, so we'll be always using it. Signed-off-by: Glauber Costa <gcosta@redhat.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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2 changed files with 41 additions and 4 deletions
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@ -513,6 +513,7 @@ void __init tsc_init(void)
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*/
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for_each_possible_cpu(cpu)
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set_cyc2ns_scale(cpu_khz, cpu);
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use_tsc_delay();
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if (tsc_disabled > 0)
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return;
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@ -22,13 +22,28 @@
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#include <asm/smp.h>
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#endif
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int __devinit read_current_timer(unsigned long *timer_value)
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/* simple loop based delay: */
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static void delay_loop(unsigned long loops)
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{
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rdtscll(*timer_value);
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return 0;
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asm volatile(
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" test %0,%0 \n"
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" jz 3f \n"
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" jmp 1f \n"
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".align 16 \n"
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"1: jmp 2f \n"
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".align 16 \n"
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"2: dec %0 \n"
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" jnz 2b \n"
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"3: dec %0 \n"
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: /* we don't need output */
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:"a" (loops)
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);
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}
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void __delay(unsigned long loops)
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static void delay_tsc(unsigned long loops)
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{
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unsigned bclock, now;
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int cpu;
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@ -63,6 +78,27 @@ void __delay(unsigned long loops)
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}
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preempt_enable();
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}
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static void (*delay_fn)(unsigned long) = delay_loop;
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void use_tsc_delay(void)
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{
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delay_fn = delay_tsc;
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}
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int __devinit read_current_timer(unsigned long *timer_value)
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{
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if (delay_fn == delay_tsc) {
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rdtscll(*timer_value);
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return 0;
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}
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return -1;
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}
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void __delay(unsigned long loops)
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{
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delay_fn(loops);
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}
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EXPORT_SYMBOL(__delay);
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inline void __const_udelay(unsigned long xloops)
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