cpu/arm925t/timer.c

   1 /*
   2  * (C) Copyright 2009
   3  * 2N Telekomunikace, <www.2n.cz>
   4  *
   5  * (C) Copyright 2003
   6  * Texas Instruments, <www.ti.com>
   7  *
   8  * (C) Copyright 2002
   9  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
  10  * Marius Groeger <mgroeger@sysgo.de>
  11  *
  12  * (C) Copyright 2002
  13  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
  14  * Alex Zuepke <azu@sysgo.de>
  15  *
  16  * (C) Copyright 2002
  17  * Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
  18  *
  19  * See file CREDITS for list of people who contributed to this
  20  * project.
  21  *
  22  * This program is free software; you can redistribute it and/or
  23  * modify it under the terms of the GNU General Public License as
  24  * published by the Free Software Foundation; either version 2 of
  25  * the License, or (at your option) any later version.
  26  *
  27  * This program is distributed in the hope that it will be useful,
  28  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  29  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  30  * GNU General Public License for more details.
  31  *
  32  * You should have received a copy of the GNU General Public License
  33  * along with this program; if not, write to the Free Software
  34  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  35  * MA 02111-1307 USA
  36  */
  37
  38 #include <common.h>
  39 #include <arm925t.h>
  40 #include <configs/omap1510.h>
  41 #include <asm/io.h>
  42
  43 #define TIMER_LOAD_VAL  0xffffffff
  44 #define TIMER_CLOCK     (CONFIG_SYS_CLK_FREQ / (2 << CONFIG_SYS_PTV))
  45
  46 static uint32_t timestamp;
  47 static uint32_t lastdec;
  48
  49 /* nothing really to do with interrupts, just starts up a counter. */
  50 int timer_init (void)
  51 {
  52         /* Start the decrementer ticking down from 0xffffffff */
  53         __raw_writel(TIMER_LOAD_VAL, CONFIG_SYS_TIMERBASE + LOAD_TIM);
  54         __raw_writel(MPUTIM_ST | MPUTIM_AR | MPUTIM_CLOCK_ENABLE |
  55                 (CONFIG_SYS_PTV << MPUTIM_PTV_BIT),
  56                 CONFIG_SYS_TIMERBASE + CNTL_TIMER);
  57
  58         /* init the timestamp and lastdec value */
  59         reset_timer_masked();
  60
  61         return 0;
  62 }
  63
  64 /*
  65  * timer without interrupts
  66  */
  67
  68 void reset_timer (void)
  69 {
  70         reset_timer_masked ();
  71 }
  72
  73 ulong get_timer (ulong base)
  74 {
  75         return get_timer_masked () - base;
  76 }
  77
  78 void set_timer (ulong t)
  79 {
  80         timestamp = t;
  81 }
  82
  83 /* delay x useconds AND preserve advance timestamp value */
  84 void udelay (unsigned long usec)
  85 {
  86         int32_t tmo = usec * (TIMER_CLOCK / 1000) / 1000;
  87         uint32_t now, last = __raw_readl(CONFIG_SYS_TIMERBASE + READ_TIM);
  88
  89         while (tmo > 0) {
  90                 now = __raw_readl(CONFIG_SYS_TIMERBASE + READ_TIM);
  91                 if (last < now) /* count down timer underflow */
  92                         tmo -= TIMER_LOAD_VAL - now + last;
  93                 else
  94                         tmo -= last - now;
  95                 last = now;
  96         }
  97 }
  98
  99 void reset_timer_masked (void)
 100 {
 101         /* reset time */
 102         lastdec = __raw_readl(CONFIG_SYS_TIMERBASE + READ_TIM) /
 103                         (TIMER_CLOCK / CONFIG_SYS_HZ);
 104         timestamp = 0;         /* start "advancing" time stamp from 0 */
 105 }
 106
 107 ulong get_timer_masked (void)
 108 {
 109         uint32_t now = __raw_readl(CONFIG_SYS_TIMERBASE + READ_TIM) /
 110                         (TIMER_CLOCK / CONFIG_SYS_HZ);
 111         if (lastdec < now)      /* count down timer underflow */
 112                 timestamp += TIMER_LOAD_VAL / (TIMER_CLOCK / CONFIG_SYS_HZ) -
 113                                 now + lastdec;
 114         else
 115                 timestamp += lastdec - now;
 116         lastdec = now;
 117
 118         return timestamp;
 119 }
 120
 121 /*
 122  * This function is derived from PowerPC code (read timebase as long long).
 123  * On ARM it just returns the timer value.
 124  */
 125 unsigned long long get_ticks(void)
 126 {
 127         return get_timer(0);
 128 }
 129
 130 /*
 131  * This function is derived from PowerPC code (timebase clock frequency).
 132  * On ARM it returns the number of timer ticks per second.
 133  */
 134 ulong get_tbclk (void)
 135 {
 136         return CONFIG_SYS_HZ;
 137 }