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 */ 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 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