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SubjectTSC changes detector
--- clean/arch/i386/kernel/time.c	Thu Nov  2 21:00:59 2000
+++ linux/arch/i386/kernel/time.c Wed Nov 22 11:12:05 2000
@@ -63,7 +63,7 @@
*/
#include <linux/irq.h>

-
+extern int x86_udelay_tsc;
unsigned long cpu_khz; /* Detected as we calibrate the TSC */

/* Number of usecs that the last interrupt was delayed */
@@ -152,7 +152,7 @@
* comp.protocols.time.ntp!
*/

-static unsigned long do_slow_gettimeoffset(void)
+static unsigned long do_read_hwtimer(void)
{
int count;

@@ -227,7 +227,7 @@

count -= 256;
#else
- printk("do_slow_gettimeoffset(): hardware timer problem?\n");
+ printk("do_read_hwtimer(): hardware timer problem?\n");
#endif
}
}
@@ -235,6 +235,12 @@
jiffies_p = jiffies_t;

count_p = count;
+ return count;
+}
+
+unsigned long do_slow_gettimeoffset(void)
+{
+ unsigned long count = do_read_hwtimer();

count = ((LATCH-1) - count) * TICK_SIZE;
count = (count + LATCH/2) / LATCH;
@@ -449,7 +455,39 @@
#endif
}

-static int use_tsc;
+int use_tsc;
+
+void big_calibrate_tsc(void)
+{
+ if (cpu_has_tsc) {
+ unsigned long tsc_quotient = calibrate_tsc();
+ if (tsc_quotient) {
+ fast_gettimeoffset_quotient = tsc_quotient;
+ use_tsc = 1;
+ /*
+ * We could be more selective here I suspect
+ * and just enable this for the next intel chips ?
+ */
+ x86_udelay_tsc = 1;
+#ifndef do_gettimeoffset
+ do_gettimeoffset = do_fast_gettimeoffset;
+#endif
+ do_get_fast_time = do_gettimeofday;
+
+ /* report CPU clock rate in Hz.
+ * The formula is (10^6 * 2^32) / (2^32 * 1 / (clocks/us)) =
+ * clock/second. Our precision is about 100 ppm.
+ */
+ { unsigned long eax=0, edx=1000;
+ __asm__("divl %2"
+ :"=a" (cpu_khz), "=d" (edx)
+ :"r" (tsc_quotient),
+ "0" (eax), "1" (edx));
+ printk("Detected %lu.%03lu MHz processor.\n", cpu_khz / 1000, cpu_khz % 1000);
+ }
+ } else { printk( "Failed to detect CPU Hz.\n" ); use_tsc = 0; }
+ } else use_tsc = 0;
+}

/*
* This is the same as the above, except we _also_ save the current
@@ -469,6 +507,28 @@
*/
write_lock(&xtime_lock);

+ if (use_tsc) {
+ long off = do_gettimeoffset();
+ /* Damn, kapmd plays hell with this. We'd need to busy loop in timer interrupt to calibrate reliably. */
+ static int faster = 0, slower = 0;
+ if (off > (1100000/HZ))
+ faster++;
+ else
+ faster = 0;
+
+ if (off < (900000/HZ))
+ slower++;
+ else
+ slower = 0;
+
+ if ((faster > 10) || (slower > 10)) {
+ printk( KERN_ERR "TSC is %s than it should be! ", (faster > 10) ? "faster" : "slower" );
+ big_calibrate_tsc();
+ faster = 0;
+ slower = 0;
+ }
+ }
+
if (use_tsc)
{
/*
@@ -558,7 +618,7 @@
#define CALIBRATE_LATCH (5 * LATCH)
#define CALIBRATE_TIME (5 * 1000020/HZ)

-static unsigned long __init calibrate_tsc(void)
+static unsigned long calibrate_tsc(void)
{
/* Set the Gate high, disable speaker */
outb((inb(0x61) & ~0x02) | 0x01, 0x61);
@@ -625,8 +685,6 @@

void __init time_init(void)
{
- extern int x86_udelay_tsc;
-
xtime.tv_sec = get_cmos_time();
xtime.tv_usec = 0;

@@ -657,34 +715,7 @@

dodgy_tsc();

- if (cpu_has_tsc) {
- unsigned long tsc_quotient = calibrate_tsc();
- if (tsc_quotient) {
- fast_gettimeoffset_quotient = tsc_quotient;
- use_tsc = 1;
- /*
- * We could be more selective here I suspect
- * and just enable this for the next intel chips ?
- */
- x86_udelay_tsc = 1;
-#ifndef do_gettimeoffset
- do_gettimeoffset = do_fast_gettimeoffset;
-#endif
- do_get_fast_time = do_gettimeofday;
-
- /* report CPU clock rate in Hz.
- * The formula is (10^6 * 2^32) / (2^32 * 1 / (clocks/us)) =
- * clock/second. Our precision is about 100 ppm.
- */
- { unsigned long eax=0, edx=1000;
- __asm__("divl %2"
- :"=a" (cpu_khz), "=d" (edx)
- :"r" (tsc_quotient),
- "0" (eax), "1" (edx));
- printk("Detected %lu.%03lu MHz processor.\n", cpu_khz / 1000, cpu_khz % 1000);
- }
- }
- }
+ big_calibrate_tsc();

#ifdef CONFIG_VISWS
printk("Starting Cobalt Timer system clock\n");
-
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