arch/powerpc/lib/time.c

   1 /*
   2  * (C) Copyright 2000, 2001
   3  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23
  24 #include <common.h>
  25
  26 /* ------------------------------------------------------------------------- */
  27
  28 /*
  29  * This function is intended for SHORT delays only.
  30  * It will overflow at around 10 seconds @ 400MHz,
  31  * or 20 seconds @ 200MHz.
  32  */
  33 unsigned long usec2ticks(unsigned long usec)
  34 {
  35         ulong ticks;
  36
  37         if (usec < 1000) {
  38                 ticks = ((usec * (get_tbclk()/1000)) + 500) / 1000;
  39         } else {
  40                 ticks = ((usec / 10) * (get_tbclk() / 100000));
  41         }
  42
  43         return (ticks);
  44 }
  45
  46 /* ------------------------------------------------------------------------- */
  47
  48 /*
  49  * We implement the delay by converting the delay (the number of
  50  * microseconds to wait) into a number of time base ticks; then we
  51  * watch the time base until it has incremented by that amount.
  52  */
  53 void __udelay(unsigned long usec)
  54 {
  55         ulong ticks = usec2ticks (usec);
  56         wait_ticks (ticks);
  57 }
  58
  59 /* ------------------------------------------------------------------------- */
  60 #ifndef CONFIG_NAND_SPL
  61 unsigned long ticks2usec(unsigned long ticks)
  62 {
  63         ulong tbclk = get_tbclk();
  64
  65         /* usec = ticks * 1000000 / tbclk
  66          * Multiplication would overflow at ~4.2e3 ticks,
  67          * so we break it up into
  68          * usec = ( ( ticks * 1000) / tbclk ) * 1000;
  69          */
  70         ticks *= 1000L;
  71         ticks /= tbclk;
  72         ticks *= 1000L;
  73
  74         return ((ulong)ticks);
  75 }
  76 #endif
  77 /* ------------------------------------------------------------------------- */
  78
  79 int init_timebase (void)
  80 {
  81 #if defined(CONFIG_5xx) || defined(CONFIG_8xx)
  82         volatile immap_t *immap = (immap_t *) CONFIG_SYS_IMMR;
  83
  84         /* unlock */
  85         immap->im_sitk.sitk_tbk = KAPWR_KEY;
  86 #endif
  87
  88         /* reset */
  89         asm ("li 3,0 ; mttbu 3 ; mttbl 3 ;");
  90
  91 #if defined(CONFIG_5xx) || defined(CONFIG_8xx)
  92         /* enable */
  93         immap->im_sit.sit_tbscr |= TBSCR_TBE;
  94 #endif
  95         return (0);
  96 }
  97 /* ------------------------------------------------------------------------- */