release/src-rt-6.x.4708/linux/linux-2.6.36/arch/mips/cobalt/time.c

   1 /*
   2  *  Cobalt time initialization.
   3  *
   4  *  Copyright (C) 2007  Yoichi Yuasa <yuasa@linux-mips.org>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20 #include <linux/init.h>
  21
  22 #include <asm/gt64120.h>
  23 #include <asm/i8253.h>
  24 #include <asm/time.h>
  25
  26 #define GT641XX_BASE_CLOCK      50000000        /* 50MHz */
  27
  28 void __init plat_time_init(void)
  29 {
  30         u32 start, end;
  31         int i = HZ / 10;
  32
  33         setup_pit_timer();
  34
  35         gt641xx_set_base_clock(GT641XX_BASE_CLOCK);
  36
  37         /*
  38          * MIPS counter frequency is measured during a 100msec interval
  39          * using GT64111 timer0.
  40          */
  41         while (!gt641xx_timer0_state())
  42                 ;
  43
  44         start = read_c0_count();
  45
  46         while (i--)
  47                 while (!gt641xx_timer0_state())
  48                         ;
  49
  50         end = read_c0_count();
  51
  52         mips_hpt_frequency = (end - start) * 10;
  53         printk(KERN_INFO "MIPS counter frequency %dHz\n", mips_hpt_frequency);
  54 }