arch/arm/cpu/armv7/omap-common/timer.c

   1 /*
   2  * (C) Copyright 2008
   3  * Texas Instruments
   4  *
   5  * Richard Woodruff <r-woodruff2@ti.com>
   6  * Syed Moahmmed Khasim <khasim@ti.com>
   7  *
   8  * (C) Copyright 2002
   9  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
  10  * Marius Groeger <mgroeger@sysgo.de>
  11  * Alex Zuepke <azu@sysgo.de>
  12  *
  13  * (C) Copyright 2002
  14  * Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
  15  *
  16  * See file CREDITS for list of people who contributed to this
  17  * project.
  18  *
  19  * This program is free software; you can redistribute it and/or
  20  * modify it under the terms of the GNU General Public License as
  21  * published by the Free Software Foundation; either version 2 of
  22  * the License, or (at your option) any later version.
  23  *
  24  * This program is distributed in the hope that it will be useful,
  25  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  26  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  27  * GNU General Public License for more details.
  28  *
  29  * You should have received a copy of the GNU General Public License
  30  * along with this program; if not, write to the Free Software
  31  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  32  * MA 02111-1307 USA
  33  */
  34
  35 #include <common.h>
  36 #include <asm/io.h>
  37
  38 DECLARE_GLOBAL_DATA_PTR;
  39
  40 static struct gptimer *timer_base = (struct gptimer *)CONFIG_SYS_TIMERBASE;
  41
  42 /*
  43  * Nothing really to do with interrupts, just starts up a counter.
  44  */
  45
  46 #define TIMER_CLOCK             (V_SCLK / (2 << CONFIG_SYS_PTV))
  47 #define TIMER_OVERFLOW_VAL      0xffffffff
  48 #define TIMER_LOAD_VAL          0
  49
  50 int timer_init(void)
  51 {
  52         /* start the counter ticking up, reload value on overflow */
  53         writel(TIMER_LOAD_VAL, &timer_base->tldr);
  54         /* enable timer */
  55         writel((CONFIG_SYS_PTV << 2) | TCLR_PRE | TCLR_AR | TCLR_ST,
  56                 &timer_base->tclr);
  57
  58         /* reset time, capture current incrementer value time */
  59         gd->arch.lastinc = readl(&timer_base->tcrr) /
  60                                         (TIMER_CLOCK / CONFIG_SYS_HZ);
  61         gd->arch.tbl = 0;       /* start "advancing" time stamp from 0 */
  62
  63         return 0;
  64 }
  65
  66 /*
  67  * timer without interrupts
  68  */
  69 ulong get_timer(ulong base)
  70 {
  71         return get_timer_masked() - base;
  72 }
  73
  74 /* delay x useconds */
  75 void __udelay(unsigned long usec)
  76 {
  77         long tmo = usec * (TIMER_CLOCK / 1000) / 1000;
  78         unsigned long now, last = readl(&timer_base->tcrr);
  79
  80         while (tmo > 0) {
  81                 now = readl(&timer_base->tcrr);
  82                 if (last > now) /* count up timer overflow */
  83                         tmo -= TIMER_OVERFLOW_VAL - last + now + 1;
  84                 else
  85                         tmo -= now - last;
  86                 last = now;
  87         }
  88 }
  89
  90 ulong get_timer_masked(void)
  91 {
  92         /* current tick value */
  93         ulong now = readl(&timer_base->tcrr) / (TIMER_CLOCK / CONFIG_SYS_HZ);
  94
  95         if (now >= gd->arch.lastinc) {  /* normal mode (non roll) */
  96                 /* move stamp fordward with absoulte diff ticks */
  97                 gd->arch.tbl += (now - gd->arch.lastinc);
  98         } else {        /* we have rollover of incrementer */
  99                 gd->arch.tbl += ((TIMER_LOAD_VAL / (TIMER_CLOCK /
 100                                 CONFIG_SYS_HZ)) - gd->arch.lastinc) + now;
 101         }
 102         gd->arch.lastinc = now;
 103         return gd->arch.tbl;
 104 }
 105
 106 /*
 107  * This function is derived from PowerPC code (read timebase as long long).
 108  * On ARM it just returns the timer value.
 109  */
 110 unsigned long long get_ticks(void)
 111 {
 112         return get_timer(0);
 113 }
 114
 115 /*
 116  * This function is derived from PowerPC code (timebase clock frequency).
 117  * On ARM it returns the number of timer ticks per second.
 118  */
 119 ulong get_tbclk(void)
 120 {
 121         return CONFIG_SYS_HZ;
 122 }