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);