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 <div64.h>
  22 #include <asm/io.h>
  23 #include <faraday/ftpmu010.h>
  24 #include <faraday/fttmr010.h>
  25
  26 DECLARE_GLOBAL_DATA_PTR;
  27
  28 #define TIMER_CLOCK     32768
  29 #define TIMER_LOAD_VAL  0xffffffff
  30
  31 static inline unsigned long long tick_to_time(unsigned long long tick)
  32 {
  33         tick *= CONFIG_SYS_HZ;
  34         do_div(tick, gd->arch.timer_rate_hz);
  35
  36         return tick;
  37 }
  38
  39 static inline unsigned long long usec_to_tick(unsigned long long usec)
  40 {
  41         usec *= gd->arch.timer_rate_hz;
  42         do_div(usec, 1000000);
  43
  44         return usec;
  45 }
  46
  47 int timer_init(void)
  48 {
  49         struct fttmr010 *tmr = (struct fttmr010 *)CONFIG_FTTMR010_BASE;
  50         unsigned int cr;
  51
  52         debug("%s()\n", __func__);
  53
  54         /* disable timers */
  55         writel(0, &tmr->cr);
  56
  57         /* use 32768Hz oscillator for RTC, WDT, TIMER */
  58         ftpmu010_32768osc_enable();
  59
  60         /* setup timer */
  61         writel(TIMER_LOAD_VAL, &tmr->timer3_load);
  62         writel(TIMER_LOAD_VAL, &tmr->timer3_counter);
  63         writel(0, &tmr->timer3_match1);
  64         writel(0, &tmr->timer3_match2);
  65
  66         /* we don't want timer to issue interrupts */
  67         writel(FTTMR010_TM3_MATCH1 |
  68                FTTMR010_TM3_MATCH2 |
  69                FTTMR010_TM3_OVERFLOW,
  70                &tmr->interrupt_mask);
  71
  72         cr = readl(&tmr->cr);
  73         cr |= FTTMR010_TM3_CLOCK;       /* use external clock */
  74         cr |= FTTMR010_TM3_ENABLE;
  75         writel(cr, &tmr->cr);
  76
  77         gd->arch.timer_rate_hz = TIMER_CLOCK;
  78         gd->arch.tbu = gd->arch.tbl = 0;
  79
  80         return 0;
  81 }
  82
  83 /*
  84  * Get the current 64 bit timer tick count
  85  */
  86 unsigned long long get_ticks(void)
  87 {
  88         struct fttmr010 *tmr = (struct fttmr010 *)CONFIG_FTTMR010_BASE;
  89         ulong now = TIMER_LOAD_VAL - readl(&tmr->timer3_counter);
  90
  91         /* increment tbu if tbl has rolled over */
  92         if (now < gd->arch.tbl)
  93                 gd->arch.tbu++;
  94         gd->arch.tbl = now;
  95         return (((unsigned long long)gd->arch.tbu) << 32) | gd->arch.tbl;
  96 }
  97
  98 void __udelay(unsigned long usec)
  99 {
 100         unsigned long long start;
 101         ulong tmo;
 102
 103         start = get_ticks();            /* get current timestamp */
 104         tmo = usec_to_tick(usec);       /* convert usecs to ticks */
 105         while ((get_ticks() - start) < tmo)
 106                 ;                       /* loop till time has passed */
 107 }
 108
 109 /*
 110  * get_timer(base) can be used to check for timeouts or
 111  * to measure elasped time relative to an event:
 112  *
 113  * ulong start_time = get_timer(0) sets start_time to the current
 114  * time value.
 115  * get_timer(start_time) returns the time elapsed since then.
 116  *
 117  * The time is used in CONFIG_SYS_HZ units!
 118  */
 119 ulong get_timer(ulong base)
 120 {
 121         return tick_to_time(get_ticks()) - base;
 122 }
 123
 124 /*
 125  * Return the number of timer ticks per second.
 126  */
 127 ulong get_tbclk(void)
 128 {
 129         return gd->arch.timer_rate_hz;
 130 }