cpu/sh4/time.c

   1 /*
   2  * (C) Copyright 2007
   3  * Nobobuhiro Iwamatsu <iwamatsu@nigauri.org>
   4  *
   5  * (C) Copyright 2003
   6  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   7  *
   8  * See file CREDITS for list of people who contributed to this
   9  * project.
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License as
  13  * published by the Free Software Foundation; either version 2 of
  14  * the License, or (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  24  * MA 02111-1307 USA
  25  */
  26
  27 #include <common.h>
  28 #include <asm/processor.h>
  29
  30 #define TMU_MAX_COUNTER (~0UL)
  31
  32 static void tmu_timer_start (unsigned int timer)
  33 {
  34         if (timer > 2)
  35                 return;
  36
  37         *((volatile unsigned char *) TSTR) |= (1 << timer);
  38 }
  39
  40 static void tmu_timer_stop (unsigned int timer)
  41 {
  42         u8 val = *((volatile u8 *)TSTR);
  43         if (timer > 2)
  44                 return;
  45         *((volatile unsigned char *)TSTR) = val &~(1 << timer);
  46 }
  47
  48 int timer_init (void)
  49 {
  50         /* Divide clock by 4 */
  51         *(volatile u16 *)TCR0 = 0;
  52
  53         tmu_timer_stop(0);
  54         tmu_timer_start(0);
  55         return 0;
  56 }
  57
  58 /*
  59    In theory we should return a true 64bit value (ie something that doesn't
  60    overflow). However, we don't. Therefore if TMU runs at fastest rate of
  61    6.75 MHz this value will wrap after u-boot has been running for approx
  62    10 minutes.
  63 */
  64 unsigned long long get_ticks (void)
  65 {
  66         return (0 - *((volatile u32 *) TCNT0));
  67 }
  68
  69 unsigned long get_timer (unsigned long base)
  70 {
  71         return ((0 - *((volatile u32 *) TCNT0)) - base);
  72 }
  73
  74 void set_timer (unsigned long t)
  75 {
  76         *((volatile unsigned int *) TCNT0) = (0 - t);
  77 }
  78
  79 void reset_timer (void)
  80 {
  81         tmu_timer_stop(0);
  82         set_timer (0);
  83         tmu_timer_start(0);
  84 }
  85
  86 void udelay (unsigned long usec)
  87 {
  88         unsigned int start = get_timer (0);
  89         unsigned int end = start + (usec * ((CFG_HZ + 500000) / 1000000));
  90
  91         while (get_timer (0) < end)
  92                 continue;
  93 }
  94
  95 unsigned long get_tbclk (void)
  96 {
  97         return CFG_HZ;
  98 }