arch/ppc/lib/ticks.S

   1 /*
   2  * (C) Copyright 2000, 2001
   3  * Erik Theisen, Wave 7 Optics, etheisen@mindspring.com.
   4  *  base on code by
   5  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   6  *
   7  * See file CREDITS for list of people who contributed to this
   8  * project.
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License as
  12  * published by the Free Software Foundation; either version 2 of
  13  * the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  23  * MA 02111-1307 USA
  24  */
  25
  26 #include <ppc_asm.tmpl>
  27 #include <ppc_defs.h>
  28 #include <config.h>
  29 #include <watchdog.h>
  30
  31 /*
  32  * unsigned long long get_ticks(void);
  33  *
  34  * read timebase as "long long"
  35  */
  36         .globl  get_ticks
  37 get_ticks:
  38 1:      mftbu   r3
  39         mftb    r4
  40         mftbu   r5
  41         cmp     0,r3,r5
  42         bne     1b
  43         blr
  44
  45 /*
  46  * Delay for a number of ticks
  47  */
  48         .globl  wait_ticks
  49 wait_ticks:
  50         mflr    r8              /* save link register */
  51         mr      r7, r3          /* save tick count */
  52         bl      get_ticks       /* Get start time */
  53
  54         /* Calculate end time */
  55         addc    r7, r4, r7      /* Compute end time lower */
  56         addze   r6, r3          /*     and end time upper */
  57
  58         WATCHDOG_RESET          /* Trigger watchdog, if needed */
  59 1:      bl      get_ticks       /* Get current time */
  60         subfc   r4, r4, r7      /* Subtract current time from end time */
  61         subfe.  r3, r3, r6
  62         bge     1b              /* Loop until time expired */
  63
  64         mtlr    r8              /* restore link register */
  65         blr