92fed35da6
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21820 a1c6a512-1295-4272-9138-f99709370657
104 lines
2.7 KiB
C
104 lines
2.7 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2009 Bertrik Sikken
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include "config.h"
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#include "inttypes.h"
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#include "s5l8700.h"
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#include "system.h"
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#include "timer.h"
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/* Timer driver for the S5L8700
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The S5L8700 timer resolution is only 16-bit. Larger counts are done by using
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both the clock-select and the clock prescaler to bring the count down into
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the range of the 16-bit counter.
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TODO: investigate why the timer seems to count twice as fast as expected
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*/
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void INT_TIMERD(void)
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{
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/* clear interrupt */
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TDCON = TDCON;
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if (pfn_timer != NULL) {
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pfn_timer();
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}
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}
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bool timer_set(long cycles, bool start)
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{
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static const int cs_table[] = {1, 2, 4, 6};
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int prescale, cs;
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long count;
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/* stop and clear timer */
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TDCMD = (1 << 1); /* TD_CLR */
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/* optionally unregister any previously registered timer user */
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if (start) {
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if (pfn_unregister != NULL) {
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pfn_unregister();
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pfn_unregister = NULL;
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}
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}
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/* scale the count down with the clock select */
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for (cs = 0; cs < 4; cs++) {
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count = cycles >> cs_table[cs];
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if ((count < 65536) || (cs == 3)) {
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break;
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}
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}
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/* scale the count down with the prescaler */
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prescale = 1;
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while (count >= 65536) {
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count >>= 1;
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prescale <<= 1;
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}
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/* configure timer */
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TDCON = (1 << 12) | /* TD_INT0_EN */
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(cs << 8) | /* TS_CS */
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(0 << 4); /* TD_MODE_SEL, 0 = interval mode */
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TDPRE = prescale - 1;
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TDDATA0 = count;
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TDCMD = (1 << 0); /* TD_ENABLE */
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/* enable interrupt */
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INTMSK |= (1 << 9);
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return true;
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}
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bool timer_start(void)
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{
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TDCMD = (1 << 0); /* TD_ENABLE */
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return true;
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}
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void timer_stop(void)
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{
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TDCMD = (0 << 0); /* TD_ENABLE */
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}
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