[PATCH] Alpha cypress CPU frequency calibration

This fixes (again...) CPU frequency calibration on some platforms with
the Cypress chip.  That is, at some point CLOCK_TICK_RATE has been
changed to represent RTC reference clock instead of PIC one.  Which
makes calibrate_cc_with_pic() produce utterly bogus results.

arch/alpha/kernel/time.c

@@ -249,8 +249,9 @@ validate_cc_value(unsigned long cc)
  * arch/i386/time.c.
  */
 
-#define CALIBRATE_LATCH	(52 * LATCH)
-#define CALIBRATE_TIME	(52 * 1000020 / HZ)
+#define PIC_TICK_RATE	1193180UL
+#define CALIBRATE_LATCH	0xffff
+#define TIMEOUT_COUNT	0x100000
 
 static unsigned long __init
 calibrate_cc_with_pic(void)
@@ -273,19 +274,15 @@ calibrate_cc_with_pic(void)
 
 	cc = rpcc();
 	do {
-	  count+=100; /* by 1 takes too long to timeout from 0 */
-	} while ((inb(0x61) & 0x20) == 0 && count > 0);
+		count++;
+	} while ((inb(0x61) & 0x20) == 0 && count < TIMEOUT_COUNT);
 	cc = rpcc() - cc;
 
 	/* Error: ECTCNEVERSET or ECPUTOOFAST.  */
-	if (count <= 100)
+	if (count <= 1 || count == TIMEOUT_COUNT)
 		return 0;
 
-	/* Error: ECPUTOOSLOW.  */
-	if (cc <= CALIBRATE_TIME)
-		return 0;
-
-	return (cc * 1000000UL) / CALIBRATE_TIME;
+	return ((long)cc * PIC_TICK_RATE) / (CALIBRATE_LATCH + 1);
 }
 
 /* The Linux interpretation of the CMOS clock register contents: