1 /*
2 * Carsten Langgaard, carstenl@mips.com
3 * Copyright (C) 1999,2000 MIPS Technologies, Inc. All rights reserved.
4 *
5 * This program is free software; you can distribute it and/or modify it
6 * under the terms of the GNU General Public License (Version 2) as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * for more details.
13 *
14 * You should have received a copy of the GNU General Public License along
15 * with this program; if not, write to the Free Software Foundation, Inc.,
16 * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
17 *
18 * Setting up the clock on the MIPS boards.
19 */
20
21 #include <linux/init.h>
22 #include <linux/kernel_stat.h>
23 #include <linux/ptrace.h>
24 #include <linux/sched.h>
25 #include <linux/spinlock.h>
26 #include <linux/mc146818rtc.h>
27 #include <linux/irq.h>
28 #include <linux/timex.h>
29
30 #include <asm/mipsregs.h>
31 #include <asm/time.h>
32 #include <asm/mach-rc32434/rc32434.h>
33
34 extern unsigned int idt_cpu_freq;
35
36 /*
37 * Figure out the r4k offset, the amount to increment the compare
38 * register for each time tick. There is no RTC available.
39 *
40 * The RC32434 counts at half the CPU *core* speed.
41 */
cal_r4koff(void)42 static unsigned long __init cal_r4koff(void)
43 {
44 mips_hpt_frequency = idt_cpu_freq * IDT_CLOCK_MULT / 2;
45
46 return mips_hpt_frequency / HZ;
47 }
48
plat_time_init(void)49 void __init plat_time_init(void)
50 {
51 unsigned int est_freq;
52 unsigned long flags, r4k_offset;
53
54 local_irq_save(flags);
55
56 printk(KERN_INFO "calculating r4koff... ");
57 r4k_offset = cal_r4koff();
58 printk("%08lx(%d)\n", r4k_offset, (int) r4k_offset);
59
60 est_freq = 2 * r4k_offset * HZ;
61 est_freq += 5000; /* round */
62 est_freq -= est_freq % 10000;
63 printk(KERN_INFO "CPU frequency %d.%02d MHz\n", est_freq / 1000000,
64 (est_freq % 1000000) * 100 / 1000000);
65 local_irq_restore(flags);
66 }
67