LXR linux/arch/mips/rb532/time.c

   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
  22extern 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 */
  30static 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
  37void __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