cpu/arm1176/s3c64xx/interrupts.c

   1 /*
   2  * (C) Copyright 2003
   3  * Texas Instruments <www.ti.com>
   4  *
   5  * (C) Copyright 2002
   6  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
   7  * Marius Groeger <mgroeger@sysgo.de>
   8  *
   9  * (C) Copyright 2002
  10  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
  11  * Alex Zuepke <azu@sysgo.de>
  12  *
  13  * (C) Copyright 2002-2004
  14  * Gary Jennejohn, DENX Software Engineering, <gj@denx.de>
  15  *
  16  * (C) Copyright 2004
  17  * Philippe Robin, ARM Ltd. <philippe.robin@arm.com>
  18  *
  19  * (C) Copyright 2008
  20  * Guennadi Liakhovetki, DENX Software Engineering, <lg@denx.de>
  21  *
  22  * See file CREDITS for list of people who contributed to this
  23  * project.
  24  *
  25  * This program is free software; you can redistribute it and/or
  26  * modify it under the terms of the GNU General Public License as
  27  * published by the Free Software Foundation; either version 2 of
  28  * the License, or (at your option) any later version.
  29  *
  30  * This program is distributed in the hope that it will be useful,
  31  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  32  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  33  * GNU General Public License for more details.
  34  *
  35  * You should have received a copy of the GNU General Public License
  36  * along with this program; if not, write to the Free Software
  37  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  38  * MA 02111-1307 USA
  39  */
  40
  41 #include <common.h>
  42 #include <asm/proc-armv/ptrace.h>
  43 #include <s3c6400.h>
  44 #include <div64.h>
  45
  46 static ulong timer_load_val;
  47
  48 #define PRESCALER       167
  49
  50 static s3c64xx_timers *s3c64xx_get_base_timers(void)
  51 {
  52         return (s3c64xx_timers *)ELFIN_TIMER_BASE;
  53 }
  54
  55 /* macro to read the 16 bit timer */
  56 static inline ulong read_timer(void)
  57 {
  58         s3c64xx_timers *const timers = s3c64xx_get_base_timers();
  59
  60         return timers->TCNTO4;
  61 }
  62
  63 /* Internal tick units */
  64 /* Last decremneter snapshot */
  65 static unsigned long lastdec;
  66 /* Monotonic incrementing timer */
  67 static unsigned long long timestamp;
  68
  69 int interrupt_init(void)
  70 {
  71         s3c64xx_timers *const timers = s3c64xx_get_base_timers();
  72
  73         /* use PWM Timer 4 because it has no output */
  74         /*
  75          * We use the following scheme for the timer:
  76          * Prescaler is hard fixed at 167, divider at 1/4.
  77          * This gives at PCLK frequency 66MHz approx. 10us ticks
  78          * The timer is set to wrap after 100s, at 66MHz this obviously
  79          * happens after 10,000,000 ticks. A long variable can thus
  80          * keep values up to 40,000s, i.e., 11 hours. This should be
  81          * enough for most uses:-) Possible optimizations: select a
  82          * binary-friendly frequency, e.g., 1ms / 128. Also calculate
  83          * the prescaler automatically for other PCLK frequencies.
  84          */
  85         timers->TCFG0 = PRESCALER << 8;
  86         if (timer_load_val == 0) {
  87                 timer_load_val = get_PCLK() / PRESCALER * (100 / 4); /* 100s */
  88                 timers->TCFG1 = (timers->TCFG1 & ~0xf0000) | 0x20000;
  89         }
  90
  91         /* load value for 10 ms timeout */
  92         lastdec = timers->TCNTB4 = timer_load_val;
  93         /* auto load, manual update of Timer 4 */
  94         timers->TCON = (timers->TCON & ~0x00700000) | TCON_4_AUTO |
  95                 TCON_4_UPDATE;
  96
  97         /* auto load, start Timer 4 */
  98         timers->TCON = (timers->TCON & ~0x00700000) | TCON_4_AUTO | COUNT_4_ON;
  99         timestamp = 0;
 100
 101         return 0;
 102 }
 103
 104 /*
 105  * timer without interrupts
 106  */
 107
 108 /*
 109  * This function is derived from PowerPC code (read timebase as long long).
 110  * On ARM it just returns the timer value.
 111  */
 112 unsigned long long get_ticks(void)
 113 {
 114         ulong now = read_timer();
 115
 116         if (lastdec >= now) {
 117                 /* normal mode */
 118                 timestamp += lastdec - now;
 119         } else {
 120                 /* we have an overflow ... */
 121                 timestamp += lastdec + timer_load_val - now;
 122         }
 123         lastdec = now;
 124
 125         return timestamp;
 126 }
 127
 128 /*
 129  * This function is derived from PowerPC code (timebase clock frequency).
 130  * On ARM it returns the number of timer ticks per second.
 131  */
 132 ulong get_tbclk(void)
 133 {
 134         /* We overrun in 100s */
 135         return (ulong)(timer_load_val / 100);
 136 }
 137
 138 void reset_timer_masked(void)
 139 {
 140         /* reset time */
 141         lastdec = read_timer();
 142         timestamp = 0;
 143 }
 144
 145 void reset_timer(void)
 146 {
 147         reset_timer_masked();
 148 }
 149
 150 ulong get_timer_masked(void)
 151 {
 152         unsigned long long res = get_ticks();
 153         do_div (res, (timer_load_val / (100 * CONFIG_SYS_HZ)));
 154         return res;
 155 }
 156
 157 ulong get_timer(ulong base)
 158 {
 159         return get_timer_masked() - base;
 160 }
 161
 162 void set_timer(ulong t)
 163 {
 164         timestamp = t * (timer_load_val / (100 * CONFIG_SYS_HZ));
 165 }
 166
 167 void udelay(unsigned long usec)
 168 {
 169         unsigned long long tmp;
 170         ulong tmo;
 171
 172         tmo = (usec + 9) / 10;
 173         tmp = get_ticks() + tmo;        /* get current timestamp */
 174
 175         while (get_ticks() < tmp)/* loop till event */
 176                  /*NOP*/;
 177 }