release/src-rt-6.x.4708/linux/linux-2.6.36/arch/mips/bcm47xx/time.c

   1 /*
   2  *  Copyright (C) 2004 Florian Schirmer <jolt@tuxbox.org>
   3  *
   4  *  This program is free software; you can redistribute  it and/or modify it
   5  *  under  the terms of  the GNU General  Public License as published by the
   6  *  Free Software Foundation;  either version 2 of the  License, or (at your
   7  *  option) any later version.
   8  *
   9  *  THIS  SOFTWARE  IS PROVIDED   ``AS  IS'' AND   ANY  EXPRESS OR IMPLIED
  10  *  WARRANTIES,   INCLUDING, BUT NOT  LIMITED  TO, THE IMPLIED WARRANTIES OF
  11  *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
  12  *  NO  EVENT  SHALL   THE AUTHOR  BE    LIABLE FOR ANY   DIRECT, INDIRECT,
  13  *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  14  *  NOT LIMITED   TO, PROCUREMENT OF  SUBSTITUTE GOODS  OR SERVICES; LOSS OF
  15  *  USE, DATA,  OR PROFITS; OR  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
  16  *  ANY THEORY OF LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT
  17  *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  18  *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  19  *
  20  *  You should have received a copy of the  GNU General Public License along
  21  *  with this program; if not, write  to the Free Software Foundation, Inc.,
  22  *  675 Mass Ave, Cambridge, MA 02139, USA.
  23  */
  24
  25
  26 #include <linux/init.h>
  27 #include <linux/ssb/ssb.h>
  28 #include <asm/time.h>
  29 #include <bcm47xx.h>
  30
  31 void __init plat_time_init(void)
  32 {
  33         unsigned long hz;
  34
  35         /*
  36          * Use deterministic values for initial counter interrupt
  37          * so that calibrate delay avoids encountering a counter wrap.
  38          */
  39         write_c0_count(0);
  40         write_c0_compare(0xffff);
  41
  42         hz = ssb_cpu_clock(&ssb_bcm47xx.mipscore) / 2;
  43         if (!hz)
  44                 hz = 100000000;
  45
  46         /* Set MIPS counter frequency for fixed_rate_gettimeoffset() */
  47         mips_hpt_frequency = hz;
  48 }