1 files changed, 57 insertions, 8 deletions

diff --git a/arch/i386/lib/delay.c b/arch/i386/lib/delay.c
index c49a6acbee56..3c0714c4b669 100644
--- a/arch/i386/lib/delay.c
+++ b/arch/i386/lib/delay.c
@@ -10,43 +10,92 @@
  *	we have to worry about.
  */
 
+#include <linux/module.h>
 #include <linux/config.h>
 #include <linux/sched.h>
 #include <linux/delay.h>
-#include <linux/module.h>
+
 #include <asm/processor.h>
 #include <asm/delay.h>
 #include <asm/timer.h>
 
 #ifdef CONFIG_SMP
-#include <asm/smp.h>
+# include <asm/smp.h>
 #endif
 
-extern struct timer_opts* timer;
+/* simple loop based delay: */
+static void delay_loop(unsigned long loops)
+{
+	int d0;
+
+	__asm__ __volatile__(
+		"\tjmp 1f\n"
+		".align 16\n"
+		"1:\tjmp 2f\n"
+		".align 16\n"
+		"2:\tdecl %0\n\tjns 2b"
+		:"=&a" (d0)
+		:"0" (loops));
+}
+
+/* TSC based delay: */
+static void delay_tsc(unsigned long loops)
+{
+	unsigned long bclock, now;
+
+	rdtscl(bclock);
+	do {
+		rep_nop();
+		rdtscl(now);
+	} while ((now-bclock) < loops);
+}
+
+/*
+ * Since we calibrate only once at boot, this
+ * function should be set once at boot and not changed
+ */
+static void (*delay_fn)(unsigned long) = delay_loop;
+
+void use_tsc_delay(void)
+{
+	delay_fn = delay_tsc;
+}
+
+int read_current_timer(unsigned long *timer_val)
+{
+	if (delay_fn == delay_tsc) {
+		rdtscl(*timer_val);
+		return 0;
+	}
+	return -1;
+}
 
 void __delay(unsigned long loops)
 {
-	cur_timer->delay(loops);
+	delay_fn(loops);
 }
 
 inline void __const_udelay(unsigned long xloops)
 {
 	int d0;
+
 	xloops *= 4;
 	__asm__("mull %0"
 		:"=d" (xloops), "=&a" (d0)
-		:"1" (xloops),"0" (cpu_data[raw_smp_processor_id()].loops_per_jiffy * (HZ/4)));
-        __delay(++xloops);
+		:"1" (xloops), "0"
+		(cpu_data[raw_smp_processor_id()].loops_per_jiffy * (HZ/4)));
+
+	__delay(++xloops);
 }
 
 void __udelay(unsigned long usecs)
 {
-	__const_udelay(usecs * 0x000010c7);  /* 2**32 / 1000000 (rounded up) */
+	__const_udelay(usecs * 0x000010c7); /* 2**32 / 1000000 (rounded up) */
 }
 
 void __ndelay(unsigned long nsecs)
 {
-	__const_udelay(nsecs * 0x00005);  /* 2**32 / 1000000000 (rounded up) */
+	__const_udelay(nsecs * 0x00005); /* 2**32 / 1000000000 (rounded up) */
 }
 
 EXPORT_SYMBOL(__delay);