This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / init / calibrate.c

diff --git a/init/calibrate.c b/init/calibrate.c
new file mode 100644 (file)
index 0000000..c698e04
--- /dev/null
+++ b/init/calibrate.c
@@ -0,0 +1,79 @@
+/* calibrate.c: default delay calibration
+ *
+ * Excised from init/main.c
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+
+static unsigned long preset_lpj;
+static int __init lpj_setup(char *str)
+{
+       preset_lpj = simple_strtoul(str,NULL,0);
+       return 1;
+}
+
+__setup("lpj=", lpj_setup);
+
+/*
+ * This is the number of bits of precision for the loops_per_jiffy.  Each
+ * bit takes on average 1.5/HZ seconds.  This (like the original) is a little
+ * better than 1%
+ */
+#define LPS_PREC 8
+
+void __devinit calibrate_delay(void)
+{
+       unsigned long ticks, loopbit;
+       int lps_precision = LPS_PREC;
+
+       if (preset_lpj) {
+               loops_per_jiffy = preset_lpj;
+               printk("Calibrating delay loop (skipped)... "
+                       "%lu.%02lu BogoMIPS preset\n",
+                       loops_per_jiffy/(500000/HZ),
+                       (loops_per_jiffy/(5000/HZ)) % 100);
+       } else {
+               loops_per_jiffy = (1<<12);
+
+               printk(KERN_DEBUG "Calibrating delay loop... ");
+               while ((loops_per_jiffy <<= 1) != 0) {
+                       /* wait for "start of" clock tick */
+                       ticks = jiffies;
+                       while (ticks == jiffies)
+                               /* nothing */;
+                       /* Go .. */
+                       ticks = jiffies;
+                       __delay(loops_per_jiffy);
+                       ticks = jiffies - ticks;
+                       if (ticks)
+                               break;
+               }
+
+               /*
+                * Do a binary approximation to get loops_per_jiffy set to
+                * equal one clock (up to lps_precision bits)
+                */
+               loops_per_jiffy >>= 1;
+               loopbit = loops_per_jiffy;
+               while (lps_precision-- && (loopbit >>= 1)) {
+                       loops_per_jiffy |= loopbit;
+                       ticks = jiffies;
+                       while (ticks == jiffies)
+                               /* nothing */;
+                       ticks = jiffies;
+                       __delay(loops_per_jiffy);
+                       if (jiffies != ticks)   /* longer than 1 tick */
+                               loops_per_jiffy &= ~loopbit;
+               }
+
+               /* Round the value and print it */
+               printk("%lu.%02lu BogoMIPS (lpj=%lu)\n",
+                       loops_per_jiffy/(500000/HZ),
+                       (loops_per_jiffy/(5000/HZ)) % 100,
+                       loops_per_jiffy);
+       }
+
+}