[PATCH] Time: i386 Conversion - part 3: Enable Generic Timekeeping

This converts the i386 arch to use the generic timeofday subsystem.  It
enabled the GENERIC_TIME option, disables the timer_opts code and other arch
specific timekeeping code and reworks the delay code.

While this patch enables the generic timekeeping, please note that this patch
does not provide any i386 clocksource.  Thus only the jiffies clocksource will
be available.  To get full replacements for the code being disabled here, the
timeofday-clocks-i386 patch will needed.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

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);