cpu/arm1136/mx31/interrupts.c

   1 /*
   2  * (C) Copyright 2007
   3  * Sascha Hauer, Pengutronix
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23
  24 #include <common.h>
  25 #include <asm/arch/mx31-regs.h>
  26
  27 #define TIMER_BASE 0x53f90000 /* General purpose timer 1 */
  28
  29 /* General purpose timers registers */
  30 #define GPTCR   __REG(TIMER_BASE)               /* Control register     */
  31 #define GPTPR   __REG(TIMER_BASE + 0x4)         /* Prescaler register   */
  32 #define GPTSR   __REG(TIMER_BASE + 0x8)         /* Status register      */
  33 #define GPTCNT  __REG(TIMER_BASE + 0x24)        /* Counter register     */
  34
  35 /* General purpose timers bitfields */
  36 #define GPTCR_SWR               (1 << 15)       /* Software reset       */
  37 #define GPTCR_FRR               (1 << 9)        /* Freerun / restart    */
  38 #define GPTCR_CLKSOURCE_32      (4 << 6)        /* Clock source         */
  39 #define GPTCR_TEN               1               /* Timer enable         */
  40
  41 /* "time" is measured in 1 / CONFIG_SYS_HZ seconds, "tick" is internal timer period */
  42 #ifdef CONFIG_MX31_TIMER_HIGH_PRECISION
  43 /* ~0.4% error - measured with stop-watch on 100s boot-delay */
  44 #define TICK_TO_TIME(t) ((t) * CONFIG_SYS_HZ / CONFIG_MX31_CLK32)
  45 #define TIME_TO_TICK(t) ((unsigned long long)(t) * CONFIG_MX31_CLK32 / CONFIG_SYS_HZ)
  46 #define US_TO_TICK(t)   (((unsigned long long)(t) * CONFIG_MX31_CLK32 + \
  47                         999999) / 1000000)
  48 #else
  49 /* ~2% error */
  50 #define TICK_PER_TIME   ((CONFIG_MX31_CLK32 + CONFIG_SYS_HZ / 2) / CONFIG_SYS_HZ)
  51 #define US_PER_TICK     (1000000 / CONFIG_MX31_CLK32)
  52 #define TICK_TO_TIME(t) ((t) / TICK_PER_TIME)
  53 #define TIME_TO_TICK(t) ((unsigned long long)(t) * TICK_PER_TIME)
  54 #define US_TO_TICK(t)   (((t) + US_PER_TICK - 1) / US_PER_TICK)
  55 #endif
  56
  57 static ulong timestamp;
  58 static ulong lastinc;
  59
  60 /* nothing really to do with interrupts, just starts up a counter. */
  61 /* The 32768Hz 32-bit timer overruns in 131072 seconds */
  62 int interrupt_init (void)
  63 {
  64         int i;
  65
  66         /* setup GP Timer 1 */
  67         GPTCR = GPTCR_SWR;
  68         for (i = 0; i < 100; i++)
  69                 GPTCR = 0; /* We have no udelay by now */
  70         GPTPR = 0; /* 32Khz */
  71         /* Freerun Mode, PERCLK1 input */
  72         GPTCR |= GPTCR_CLKSOURCE_32 | GPTCR_TEN;
  73
  74         return 0;
  75 }
  76
  77 void reset_timer_masked (void)
  78 {
  79         /* reset time */
  80         lastinc = GPTCNT; /* capture current incrementer value time */
  81         timestamp = 0; /* start "advancing" time stamp from 0 */
  82 }
  83
  84 void reset_timer(void)
  85 {
  86         reset_timer_masked();
  87 }
  88
  89 unsigned long long get_ticks (void)
  90 {
  91         ulong now = GPTCNT; /* current tick value */
  92
  93         if (now >= lastinc)     /* normal mode (non roll) */
  94                 /* move stamp forward with absolut diff ticks */
  95                 timestamp += (now - lastinc);
  96         else                    /* we have rollover of incrementer */
  97                 timestamp += (0xFFFFFFFF - lastinc) + now;
  98         lastinc = now;
  99         return timestamp;
 100 }
 101
 102 ulong get_timer_masked (void)
 103 {
 104         /*
 105          * get_ticks() returns a long long (64 bit), it wraps in
 106          * 2^64 / CONFIG_MX31_CLK32 = 2^64 / 2^15 = 2^49 ~ 5 * 10^14 (s) ~
 107          * 5 * 10^9 days... and get_ticks() * CONFIG_SYS_HZ wraps in
 108          * 5 * 10^6 days - long enough.
 109          */
 110         return TICK_TO_TIME(get_ticks());
 111 }
 112
 113 ulong get_timer (ulong base)
 114 {
 115         return get_timer_masked () - base;
 116 }
 117
 118 void set_timer (ulong t)
 119 {
 120         timestamp = TIME_TO_TICK(t);
 121 }
 122
 123 /* delay x useconds AND perserve advance timstamp value */
 124 void udelay (unsigned long usec)
 125 {
 126         unsigned long long tmp;
 127         ulong tmo;
 128
 129         tmo = US_TO_TICK(usec);
 130         tmp = get_ticks() + tmo;        /* get current timestamp */
 131
 132         while (get_ticks() < tmp)       /* loop till event */
 133                  /*NOP*/;
 134 }
 135
 136 void reset_cpu (ulong addr)
 137 {
 138         __REG16(WDOG_BASE) = 4;
 139 }