target/linux/rb532/files-2.6.23/arch/mips/rb500/time.c

   1 /*
   2 ****************************************************************************
   3 * Carsten Langgaard, carstenl@mips.com
   4 * Copyright (C) 1999,2000 MIPS Technologies, Inc.  All rights reserved.
   5 *
   6 ***************************************************************************
   7 *
   8 *  This program is free software; you can distribute it and/or modify it
   9 *  under the terms of the GNU General Public License (Version 2) as
  10 *  published by the Free Software Foundation.
  11 *
  12 *  This program is distributed in the hope it will be useful, but WITHOUT
  13 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 *  for more details.
  16 *
  17 *  You should have received a copy of the GNU General Public License along
  18 *  with this program; if not, write to the Free Software Foundation, Inc.,
  19 *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
  20 *
  21 ****************************************************************************
  22 *
  23 * Setting up the clock on the MIPS boards.
  24 *
  25 ****************************************************************************
  26 * P. Sadik Oct 10, 2003
  27 *
  28 * Started change log.
  29 * mips_counter_frequency is now calculated at run time, based on idt_cpu_freq.
  30 * Code cleanup
  31 ****************************************************************************
  32 */
  33
  34 #include <linux/autoconf.h>
  35 #include <linux/init.h>
  36 #include <linux/kernel_stat.h>
  37 #include <linux/sched.h>
  38 #include <linux/spinlock.h>
  39 #include <linux/mc146818rtc.h>
  40 #include <linux/irq.h>
  41 #include <linux/timex.h>
  42
  43 #include <asm/irq_cpu.h>
  44 #include <asm/mipsregs.h>
  45 #include <asm/ptrace.h>
  46 #include <asm/debug.h>
  47 #include <asm/rc32434/rc32434.h>
  48
  49 static unsigned long r4k_offset; /* Amount to incr compare reg each time */
  50 static unsigned long r4k_cur;    /* What counter should be at next timer irq */
  51 extern unsigned int mips_hpt_frequency;
  52 extern unsigned int idt_cpu_freq;
  53
  54 /*
  55  * Figure out the r4k offset, the amount to increment the compare
  56  * register for each time tick. There is no RTC available.
  57  *
  58  * The RC32434 counts at half the CPU *core* speed.
  59  */
  60 static unsigned long __init cal_r4koff(void)
  61 {
  62         mips_hpt_frequency = idt_cpu_freq * IDT_CLOCK_MULT / 2;
  63         return (mips_hpt_frequency / HZ);
  64 }
  65
  66
  67 void __init rc32434_time_init(void)
  68 {
  69         unsigned int est_freq, flags;
  70
  71         local_irq_save(flags);
  72
  73         printk("calculating r4koff... ");
  74         r4k_offset = cal_r4koff();
  75         printk("%08lx(%d)\n", r4k_offset, (int) r4k_offset);
  76
  77         est_freq = 2*r4k_offset*HZ;
  78         est_freq += 5000;       /* round */
  79         est_freq -= est_freq%10000;
  80         printk("CPU frequency %d.%02d MHz\n", est_freq/1000000,
  81                (est_freq%1000000)*100/1000000);
  82         local_irq_restore(flags);
  83 }
  84
  85 void __init plat_timer_setup(struct irqaction *irq)
  86 {
  87         /* we are using the cpu counter for timer interrupts */
  88         setup_irq(MIPS_CPU_TIMER_IRQ, irq);
  89
  90         /* to generate the first timer interrupt */
  91         r4k_cur = (read_c0_count() + r4k_offset);
  92         write_c0_compare(r4k_cur);
  93 }
  94