71 lines
2.1 KiB
C
71 lines
2.1 KiB
C
/*
|
|
* Copyright (C) 2015 Michael Brown <mbrown@fensystems.co.uk>.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License as
|
|
* published by the Free Software Foundation; either version 2 of the
|
|
* License, or (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful, but
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
|
|
* 02110-1301, USA.
|
|
*
|
|
* You can also choose to distribute this program under the terms of
|
|
* the Unmodified Binary Distribution Licence (as given in the file
|
|
* COPYING.UBDL), provided that you have satisfied its requirements.
|
|
*/
|
|
|
|
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
|
|
|
|
#include <assert.h>
|
|
#include <ipxe/io.h>
|
|
#include <ipxe/pit8254.h>
|
|
|
|
/** @file
|
|
*
|
|
* 8254 Programmable Interval Timer
|
|
*
|
|
*/
|
|
|
|
/**
|
|
* Delay for a fixed number of timer ticks using the speaker channel
|
|
*
|
|
* @v ticks Number of timer ticks for which to delay
|
|
*/
|
|
void pit8254_speaker_delay ( unsigned int ticks ) {
|
|
uint8_t spkr;
|
|
uint8_t cmd;
|
|
uint8_t low;
|
|
uint8_t high;
|
|
|
|
/* Sanity check */
|
|
assert ( ticks <= 0xffff );
|
|
|
|
/* Disable speaker, set speaker channel gate input high */
|
|
spkr = inb ( PIT8254_SPKR );
|
|
spkr &= ~PIT8254_SPKR_ENABLE;
|
|
spkr |= PIT8254_SPKR_GATE;
|
|
outb ( spkr, PIT8254_SPKR );
|
|
|
|
/* Program speaker channel to "interrupt" on terminal count */
|
|
cmd = ( PIT8254_CMD_CHANNEL ( PIT8254_CH_SPKR ) |
|
|
PIT8254_CMD_ACCESS_LOHI | PIT8254_CMD_OP_TERMINAL |
|
|
PIT8254_CMD_BINARY );
|
|
low = ( ( ticks >> 0 ) & 0xff );
|
|
high = ( ( ticks >> 8 ) & 0xff );
|
|
outb ( cmd, PIT8254_CMD );
|
|
outb ( low, PIT8254_DATA ( PIT8254_CH_SPKR ) );
|
|
outb ( high, PIT8254_DATA ( PIT8254_CH_SPKR ) );
|
|
|
|
/* Wait for channel to "interrupt" */
|
|
do {
|
|
spkr = inb ( PIT8254_SPKR );
|
|
} while ( ! ( spkr & PIT8254_SPKR_OUT ) );
|
|
}
|