1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Carsten Langgaard, carstenl@mips.com
4 * Copyright (C) 1999,2000 MIPS Technologies, Inc. All rights reserved.
5 *
6 * Setting up the clock on the MIPS boards.
7 */
8
9 #include <linux/init.h>
10 #include <linux/kernel_stat.h>
11 #include <linux/ptrace.h>
12 #include <linux/sched.h>
13 #include <linux/spinlock.h>
14 #include <linux/mc146818rtc.h>
15 #include <linux/irq.h>
16 #include <linux/timex.h>
17
18 #include <asm/mipsregs.h>
19 #include <asm/time.h>
20 #include <asm/mach-rc32434/rc32434.h>
21
22 extern unsigned int idt_cpu_freq;
23
24 /*
25 * Figure out the r4k offset, the amount to increment the compare
26 * register for each time tick. There is no RTC available.
27 *
28 * The RC32434 counts at half the CPU *core* speed.
29 */
30 static unsigned long __init cal_r4koff(void)
31 {
32 mips_hpt_frequency = idt_cpu_freq * IDT_CLOCK_MULT / 2;
33
34 return mips_hpt_frequency / HZ;
35 }
36
37 void __init plat_time_init(void)
38 {
39 unsigned int est_freq;
40 unsigned long flags, r4k_offset;
41
42 local_irq_save(flags);
43
44 printk(KERN_INFO "calculating r4koff... ");
45 r4k_offset = cal_r4koff();
46 printk("%08lx(%d)\n", r4k_offset, (int) r4k_offset);
47
48 est_freq = 2 * r4k_offset * HZ;
49 est_freq += 5000; /* round */
50 est_freq -= est_freq % 10000;
51 printk(KERN_INFO "CPU frequency %d.%02d MHz\n", est_freq / 1000000,
52 (est_freq % 1000000) * 100 / 1000000);
53 local_irq_restore(flags);
54 }
55
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.