[PATCH] clean up kernel messages
[linux-2.6.git] / init / calibrate.c
1 /* calibrate.c: default delay calibration
2  *
3  * Excised from init/main.c
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6
7 #include <linux/sched.h>
8 #include <linux/delay.h>
9 #include <linux/init.h>
10
11 static unsigned long preset_lpj;
12 static int __init lpj_setup(char *str)
13 {
14         preset_lpj = simple_strtoul(str,NULL,0);
15         return 1;
16 }
17
18 __setup("lpj=", lpj_setup);
19
20 /*
21  * This is the number of bits of precision for the loops_per_jiffy.  Each
22  * bit takes on average 1.5/HZ seconds.  This (like the original) is a little
23  * better than 1%
24  */
25 #define LPS_PREC 8
26
27 void __devinit calibrate_delay(void)
28 {
29         unsigned long ticks, loopbit;
30         int lps_precision = LPS_PREC;
31
32         if (preset_lpj) {
33                 loops_per_jiffy = preset_lpj;
34                 printk("Calibrating delay loop (skipped)... "
35                         "%lu.%02lu BogoMIPS preset\n",
36                         loops_per_jiffy/(500000/HZ),
37                         (loops_per_jiffy/(5000/HZ)) % 100);
38         } else {
39                 loops_per_jiffy = (1<<12);
40
41                 printk(KERN_DEBUG "Calibrating delay loop... ");
42                 while ((loops_per_jiffy <<= 1) != 0) {
43                         /* wait for "start of" clock tick */
44                         ticks = jiffies;
45                         while (ticks == jiffies)
46                                 /* nothing */;
47                         /* Go .. */
48                         ticks = jiffies;
49                         __delay(loops_per_jiffy);
50                         ticks = jiffies - ticks;
51                         if (ticks)
52                                 break;
53                 }
54
55                 /*
56                  * Do a binary approximation to get loops_per_jiffy set to
57                  * equal one clock (up to lps_precision bits)
58                  */
59                 loops_per_jiffy >>= 1;
60                 loopbit = loops_per_jiffy;
61                 while (lps_precision-- && (loopbit >>= 1)) {
62                         loops_per_jiffy |= loopbit;
63                         ticks = jiffies;
64                         while (ticks == jiffies)
65                                 /* nothing */;
66                         ticks = jiffies;
67                         __delay(loops_per_jiffy);
68                         if (jiffies != ticks)   /* longer than 1 tick */
69                                 loops_per_jiffy &= ~loopbit;
70                 }
71
72                 /* Round the value and print it */
73                 printk("%lu.%02lu BogoMIPS (lpj=%lu)\n",
74                         loops_per_jiffy/(500000/HZ),
75                         (loops_per_jiffy/(5000/HZ)) % 100,
76                         loops_per_jiffy);
77         }
78
79 }