arch/arm/cpu/arm920t/a320/timer.c

   1 /*
   2  * (C) Copyright 2009 Faraday Technology
   3  * Po-Yu Chuang <ratbert@faraday-tech.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19
  20 #include <common.h>
  21 #include <asm/io.h>
  22 #include <faraday/ftpmu010.h>
  23 #include <faraday/fttmr010.h>
  24
  25 static ulong timestamp;
  26 static ulong lastdec;
  27
  28 static struct fttmr010 *tmr = (struct fttmr010 *)CONFIG_FTTMR010_BASE;
  29
  30 #define TIMER_CLOCK     32768
  31 #define TIMER_LOAD_VAL  0xffffffff
  32
  33 int timer_init(void)
  34 {
  35         unsigned int cr;
  36
  37         debug("%s()\n", __func__);
  38
  39         /* disable timers */
  40         writel(0, &tmr->cr);
  41
  42         /* use 32768Hz oscillator for RTC, WDT, TIMER */
  43         ftpmu010_32768osc_enable();
  44
  45         /* setup timer */
  46         writel(TIMER_LOAD_VAL, &tmr->timer3_load);
  47         writel(TIMER_LOAD_VAL, &tmr->timer3_counter);
  48         writel(0, &tmr->timer3_match1);
  49         writel(0, &tmr->timer3_match2);
  50
  51         /* we don't want timer to issue interrupts */
  52         writel(FTTMR010_TM3_MATCH1 |
  53                FTTMR010_TM3_MATCH2 |
  54                FTTMR010_TM3_OVERFLOW,
  55                &tmr->interrupt_mask);
  56
  57         cr = readl(&tmr->cr);
  58         cr |= FTTMR010_TM3_CLOCK;       /* use external clock */
  59         cr |= FTTMR010_TM3_ENABLE;
  60         writel(cr, &tmr->cr);
  61
  62         /* init the timestamp and lastdec value */
  63         reset_timer_masked();
  64
  65         return 0;
  66 }
  67
  68 /*
  69  * timer without interrupts
  70  */
  71
  72 /*
  73  * reset time
  74  */
  75 void reset_timer_masked(void)
  76 {
  77         /* capure current decrementer value time */
  78         lastdec = readl(&tmr->timer3_counter) / (TIMER_CLOCK / CONFIG_SYS_HZ);
  79         timestamp = 0;          /* start "advancing" time stamp from 0 */
  80
  81         debug("%s(): lastdec = %lx\n", __func__, lastdec);
  82 }
  83
  84 void reset_timer(void)
  85 {
  86         debug("%s()\n", __func__);
  87         reset_timer_masked();
  88 }
  89
  90 /*
  91  * return timer ticks
  92  */
  93 ulong get_timer_masked(void)
  94 {
  95         /* current tick value */
  96         ulong now = readl(&tmr->timer3_counter) / (TIMER_CLOCK / CONFIG_SYS_HZ);
  97
  98         debug("%s(): now = %lx, lastdec = %lx\n", __func__, now, lastdec);
  99
 100         if (lastdec >= now) {
 101                 /*
 102                  * normal mode (non roll)
 103                  * move stamp fordward with absoulte diff ticks
 104                  */
 105                 timestamp += lastdec - now;
 106         } else {
 107                 /*
 108                  * we have overflow of the count down timer
 109                  *
 110                  * nts = ts + ld + (TLV - now)
 111                  * ts=old stamp, ld=time that passed before passing through -1
 112                  * (TLV-now) amount of time after passing though -1
 113                  * nts = new "advancing time stamp"...it could also roll and
 114                  * cause problems.
 115                  */
 116                 timestamp += lastdec + TIMER_LOAD_VAL - now;
 117         }
 118
 119         lastdec = now;
 120
 121         debug("%s() returns %lx\n", __func__, timestamp);
 122
 123         return timestamp;
 124 }
 125
 126 /*
 127  * return difference between timer ticks and base
 128  */
 129 ulong get_timer(ulong base)
 130 {
 131         debug("%s(%lx)\n", __func__, base);
 132         return get_timer_masked() - base;
 133 }
 134
 135 /* delay x useconds AND preserve advance timestamp value */
 136 void __udelay(unsigned long usec)
 137 {
 138         long tmo = usec * (TIMER_CLOCK / 1000) / 1000;
 139         unsigned long now, last = readl(&tmr->timer3_counter);
 140
 141         debug("%s(%lu)\n", __func__, usec);
 142         while (tmo > 0) {
 143                 now = readl(&tmr->timer3_counter);
 144                 if (now > last) /* count down timer overflow */
 145                         tmo -= TIMER_LOAD_VAL + last - now;
 146                 else
 147                         tmo -= last - now;
 148                 last = now;
 149         }
 150 }
 151
 152 /*
 153  * This function is derived from PowerPC code (read timebase as long long).
 154  * On ARM it just returns the timer value.
 155  */
 156 unsigned long long get_ticks(void)
 157 {
 158         debug("%s()\n", __func__);
 159         return get_timer(0);
 160 }
 161
 162 /*
 163  * This function is derived from PowerPC code (timebase clock frequency).
 164  * On ARM it returns the number of timer ticks per second.
 165  */
 166 ulong get_tbclk(void)
 167 {
 168         debug("%s()\n", __func__);
 169         return CONFIG_SYS_HZ;
 170 }