LXR uboot/board/armltd/integrator/timer.c

   1/*
   2 * (C) Copyright 2002
   3 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
   4 * Marius Groeger <mgroeger@sysgo.de>
   5 *
   6 * (C) Copyright 2002
   7 * David Mueller, ELSOFT AG, <d.mueller@elsoft.ch>
   8 *
   9 * (C) Copyright 2003
  10 * Texas Instruments, <www.ti.com>
  11 * Kshitij Gupta <Kshitij@ti.com>
  12 *
  13 * (C) Copyright 2004
  14 * ARM Ltd.
  15 * Philippe Robin, <philippe.robin@arm.com>
  16 *
  17 * SPDX-License-Identifier:     GPL-2.0+
  18 */
  19
  20#include <common.h>
  21#include <div64.h>
  22
  23#ifdef CONFIG_ARCH_CINTEGRATOR
  24#define DIV_CLOCK_INIT  1
  25#define TIMER_LOAD_VAL  0xFFFFFFFFL
  26#else
  27#define DIV_CLOCK_INIT  256
  28#define TIMER_LOAD_VAL  0x0000FFFFL
  29#endif
  30/* The Integrator/CP timer1 is clocked at 1MHz
  31 * can be divided by 16 or 256
  32 * and can be set up as a 32-bit timer
  33 */
  34/* U-Boot expects a 32 bit timer, running at CONFIG_SYS_HZ */
  35/* Keep total timer count to avoid losing decrements < div_timer */
  36static unsigned long long total_count = 0;
  37static unsigned long long lastdec;       /* Timer reading at last call     */
  38/* Divisor applied to timer clock */
  39static unsigned long long div_clock = DIV_CLOCK_INIT;
  40static unsigned long long div_timer = 1; /* Divisor to convert timer reading
  41                                          * change to U-Boot ticks
  42                                          */
  43/* CONFIG_SYS_HZ = CONFIG_SYS_HZ_CLOCK/(div_clock * div_timer) */
  44static ulong timestamp;         /* U-Boot ticks since startup */
  45
  46#define READ_TIMER (*(volatile ulong *)(CONFIG_SYS_TIMERBASE+4))
  47
  48/* all function return values in U-Boot ticks i.e. (1/CONFIG_SYS_HZ) sec
  49 *  - unless otherwise stated
  50 */
  51
  52/* starts up a counter
  53 * - the Integrator/CP timer can be set up to issue an interrupt */
  54int timer_init (void)
  55{
  56        /* Load timer with initial value */
  57        *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 0) = TIMER_LOAD_VAL;
  58#ifdef CONFIG_ARCH_CINTEGRATOR
  59        /* Set timer to be
  60         *      enabled          1
  61         *      periodic         1
  62         *      no interrupts    0
  63         *      X                0
  64         *      divider 1       00 == less rounding error
  65         *      32 bit           1
  66         *      wrapping         0
  67         */
  68        *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8) = 0x000000C2;
  69#else
  70        /* Set timer to be
  71         *      enabled          1
  72         *      free-running     0
  73         *      XX              00
  74         *      divider 256     10
  75         *      XX              00
  76         */
  77        *(volatile ulong *)(CONFIG_SYS_TIMERBASE + 8) = 0x00000088;
  78#endif
  79
  80        /* init the timestamp */
  81        total_count = 0ULL;
  82        /* capure current decrementer value    */
  83        lastdec   = READ_TIMER;
  84        /* start "advancing" time stamp from 0 */
  85        timestamp = 0L;
  86
  87        div_timer = CONFIG_SYS_HZ_CLOCK;
  88        do_div(div_timer, CONFIG_SYS_HZ);
  89        do_div(div_timer, div_clock);
  90
  91        return (0);
  92}
  93
  94/*
  95 * timer without interrupts
  96 */
  97ulong get_timer (ulong base_ticks)
  98{
  99        return get_timer_masked () - base_ticks;
 100}
 101
 102/* delay usec useconds */
 103void __udelay (unsigned long usec)
 104{
 105        ulong tmo, tmp;
 106
 107        /* Convert to U-Boot ticks */
 108        tmo  = usec * CONFIG_SYS_HZ;
 109        tmo /= (1000000L);
 110
 111        tmp  = get_timer_masked();      /* get current timestamp */
 112        tmo += tmp;                     /* form target timestamp */
 113
 114        while (get_timer_masked () < tmo) {/* loop till event */
 115                /*NOP*/;
 116        }
 117}
 118
 119/* converts the timer reading to U-Boot ticks          */
 120/* the timestamp is the number of ticks since reset    */
 121ulong get_timer_masked (void)
 122{
 123        /* get current count */
 124        unsigned long long now = READ_TIMER;
 125
 126        if(now > lastdec) {
 127                /* Must have wrapped */
 128                total_count += lastdec + TIMER_LOAD_VAL + 1 - now;
 129        } else {
 130                total_count += lastdec - now;
 131        }
 132        lastdec = now;
 133
 134        /* Reuse "now" */
 135        now = total_count;
 136        do_div(now, div_timer);
 137        timestamp = now;
 138
 139        return timestamp;
 140}
 141
 142/* waits specified delay value and resets timestamp */
 143void udelay_masked (unsigned long usec)
 144{
 145        udelay(usec);
 146}
 147
 148/*
 149 * This function is derived from PowerPC code (read timebase as long long).
 150 * On ARM it just returns the timer value.
 151 */
 152unsigned long long get_ticks(void)
 153{
 154        return get_timer(0);
 155}
 156
 157/*
 158 * Return the timebase clock frequency
 159 * i.e. how often the timer decrements
 160 */
 161ulong get_tbclk (void)
 162{
 163        unsigned long long tmp = CONFIG_SYS_HZ_CLOCK;
 164
 165        do_div(tmp, div_clock);
 166
 167        return tmp;
 168}
 169