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 #include <asm/io.h>
  10
  11 /* ------------------------------------------------------------------------- */
  12
  13 /*
  14  * This function is intended for SHORT delays only.
  15  * It will overflow at around 10 seconds @ 400MHz,
  16  * or 20 seconds @ 200MHz.
  17  */
  18 unsigned long usec2ticks(unsigned long usec)
  19 {
  20         ulong ticks;
  21
  22         if (usec < 1000) {
  23                 ticks = ((usec * (get_tbclk()/1000)) + 500) / 1000;
  24         } else {
  25                 ticks = ((usec / 10) * (get_tbclk() / 100000));
  26         }
  27
  28         return (ticks);
  29 }
  30
  31 /* ------------------------------------------------------------------------- */
  32
  33 /*
  34  * We implement the delay by converting the delay (the number of
  35  * microseconds to wait) into a number of time base ticks; then we
  36  * watch the time base until it has incremented by that amount.
  37  */
  38 void __udelay(unsigned long usec)
  39 {
  40         ulong ticks = usec2ticks (usec);
  41         wait_ticks (ticks);
  42 }
  43
  44 /* ------------------------------------------------------------------------- */
  45 #ifndef CONFIG_NAND_SPL
  46 unsigned long ticks2usec(unsigned long ticks)
  47 {
  48         ulong tbclk = get_tbclk();
  49
  50         /* usec = ticks * 1000000 / tbclk
  51          * Multiplication would overflow at ~4.2e3 ticks,
  52          * so we break it up into
  53          * usec = ( ( ticks * 1000) / tbclk ) * 1000;
  54          */
  55         ticks *= 1000L;
  56         ticks /= tbclk;
  57         ticks *= 1000L;
  58
  59         return ((ulong)ticks);
  60 }
  61 #endif
  62 /* ------------------------------------------------------------------------- */
  63
  64 int timer_init(void)
  65 {
  66         unsigned long temp;
  67
  68         /* reset */
  69         asm volatile("li %0,0 ; mttbl %0 ; mttbu %0;"
  70              : "=&r"(temp) );
  71
  72         return (0);
  73 }
  74 /* ------------------------------------------------------------------------- */