firmware/target/arm/s5l8700/timer-s5l8700.c

   1 /***************************************************************************
   2 *             __________               __   ___.
   3 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7 *                     \/            \/     \/    \/            \/
   8 * $Id$
   9 *
  10 * Copyright (C) 2009 Bertrik Sikken
  11 *
  12 * This program is free software; you can redistribute it and/or
  13 * modify it under the terms of the GNU General Public License
  14 * as published by the Free Software Foundation; either version 2
  15 * of the License, or (at your option) any later version.
  16 *
  17 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18 * KIND, either express or implied.
  19 *
  20 ****************************************************************************/
  21
  22 #include "config.h"
  23
  24 #include "inttypes.h"
  25 #include "s5l8700.h"
  26 #include "system.h"
  27 #include "timer.h"
  28
  29 /*  Timer driver for the S5L8700
  30
  31     The S5L8700 timer resolution is only 16-bit. Larger counts are done by using
  32     both the clock-select and the clock prescaler to bring the count down into
  33     the range of the 16-bit counter.
  34 */
  35
  36 void INT_TIMERC(void)
  37 {
  38     /* clear interrupt */
  39     TCCON = TCCON;
  40
  41     if (pfn_timer != NULL) {
  42         pfn_timer();
  43     }
  44 }
  45
  46 bool timer_set(long cycles, bool start)
  47 {
  48     static const int cs_table[] = {1, 2, 4, 6};
  49     int prescale, cs;
  50     long count;
  51
  52     /* stop and clear timer */
  53     TCCMD = (1 << 1);   /* TD_CLR */
  54
  55     /* optionally unregister any previously registered timer user */
  56     if (start) {
  57         if (pfn_unregister != NULL) {
  58             pfn_unregister();
  59             pfn_unregister = NULL;
  60         }
  61     }
  62
  63     /* scale the count down with the clock select */
  64     for (cs = 0; cs < 4; cs++) {
  65         count = cycles >> cs_table[cs];
  66         if ((count < 65536) || (cs == 3)) {
  67             break;
  68         }
  69     }
  70
  71     /* scale the count down with the prescaler */
  72     prescale = 1;
  73     while (count >= 65536) {
  74         count >>= 1;
  75         prescale <<= 1;
  76     }
  77
  78     /* configure timer */
  79     TCCON = (1 << 12) |     /* TD_INT0_EN */
  80             (cs << 8) |     /* TS_CS */
  81             (0 << 4);       /* TD_MODE_SEL, 0 = interval mode */
  82     TCPRE = prescale - 1;
  83     TCDATA0 = count;
  84     TCCMD = (1 << 0);       /* TD_ENABLE */
  85
  86     /* enable interrupt */
  87     INTMSK |=  INTMSK_TIMERC;
  88
  89     return true;
  90 }
  91
  92 bool timer_start(void)
  93 {
  94     TCCMD = (1 << 0);       /* TD_ENABLE */
  95     return true;
  96 }
  97
  98 void timer_stop(void)
  99 {
 100     TCCMD = (0 << 0);       /* TD_ENABLE */
 101 }
 102