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