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 */
  36 static unsigned long long total_count = 0;
  37 static unsigned long long lastdec;       /* Timer reading at last call     */
  38 /* Divisor applied to timer clock */
  39 static unsigned long long div_clock = DIV_CLOCK_INIT;
  40 static 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) */
  44 static 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 */
  54 int 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  */
  97 ulong get_timer (ulong base_ticks)
  98 {
  99         return get_timer_masked () - base_ticks;
 100 }
 101
 102 /* delay usec useconds */
 103 void __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    */
 121 ulong 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 */
 143 void 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  */
 152 unsigned 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  */
 161 ulong 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 }