arch/powerpc/lib/time.c

   1 /*
   2  * (C) Copyright 2000, 2001
   3  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 #include <common.h>
   9
  10 /* ------------------------------------------------------------------------- */
  11
  12 /*
  13  * This function is intended for SHORT delays only.
  14  * It will overflow at around 10 seconds @ 400MHz,
  15  * or 20 seconds @ 200MHz.
  16  */
  17 unsigned long usec2ticks(unsigned long usec)
  18 {
  19         ulong ticks;
  20
  21         if (usec < 1000) {
  22                 ticks = ((usec * (get_tbclk()/1000)) + 500) / 1000;
  23         } else {
  24                 ticks = ((usec / 10) * (get_tbclk() / 100000));
  25         }
  26
  27         return (ticks);
  28 }
  29
  30 /* ------------------------------------------------------------------------- */
  31
  32 /*
  33  * We implement the delay by converting the delay (the number of
  34  * microseconds to wait) into a number of time base ticks; then we
  35  * watch the time base until it has incremented by that amount.
  36  */
  37 void __udelay(unsigned long usec)
  38 {
  39         ulong ticks = usec2ticks (usec);
  40         wait_ticks (ticks);
  41 }
  42
  43 /* ------------------------------------------------------------------------- */
  44 #ifndef CONFIG_NAND_SPL
  45 unsigned long ticks2usec(unsigned long ticks)
  46 {
  47         ulong tbclk = get_tbclk();
  48
  49         /* usec = ticks * 1000000 / tbclk
  50          * Multiplication would overflow at ~4.2e3 ticks,
  51          * so we break it up into
  52          * usec = ( ( ticks * 1000) / tbclk ) * 1000;
  53          */
  54         ticks *= 1000L;
  55         ticks /= tbclk;
  56         ticks *= 1000L;
  57
  58         return ((ulong)ticks);
  59 }
  60 #endif
  61 /* ------------------------------------------------------------------------- */
  62
  63 int timer_init(void)
  64 {
  65         unsigned long temp;
  66
  67         /* reset */
  68         asm volatile("li %0,0 ; mttbu %0 ; mttbl %0;"
  69              : "=&r"(temp) );
  70
  71         return (0);
  72 }
  73 /* ------------------------------------------------------------------------- */