iPXE
pit8254.c
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1 /*
2  * Copyright (C) 2015 Michael Brown <mbrown@fensystems.co.uk>.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License as
6  * published by the Free Software Foundation; either version 2 of the
7  * License, or (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful, but
10  * WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17  * 02110-1301, USA.
18  *
19  * You can also choose to distribute this program under the terms of
20  * the Unmodified Binary Distribution Licence (as given in the file
21  * COPYING.UBDL), provided that you have satisfied its requirements.
22  */
23 
24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
25 
26 #include <assert.h>
27 #include <ipxe/io.h>
28 #include <ipxe/pit8254.h>
29 
30 /** @file
31  *
32  * 8254 Programmable Interval Timer
33  *
34  */
35 
36 /**
37  * Delay for a fixed number of timer ticks using the speaker channel
38  *
39  * @v ticks Number of timer ticks for which to delay
40  */
41 void pit8254_speaker_delay ( unsigned int ticks ) {
42  uint8_t spkr;
43  uint8_t cmd;
44  uint8_t low;
45  uint8_t high;
46 
47  /* Sanity check */
48  assert ( ticks <= 0xffff );
49 
50  /* Disable speaker, set speaker channel gate input high */
51  spkr = inb ( PIT8254_SPKR );
52  spkr &= ~PIT8254_SPKR_ENABLE;
53  spkr |= PIT8254_SPKR_GATE;
54  outb ( spkr, PIT8254_SPKR );
55 
56  /* Program speaker channel to "interrupt" on terminal count */
60  low = ( ( ticks >> 0 ) & 0xff );
61  high = ( ( ticks >> 8 ) & 0xff );
62  outb ( cmd, PIT8254_CMD );
65 
66  /* Wait for channel to "interrupt" */
67  do {
68  spkr = inb ( PIT8254_SPKR );
69  } while ( ! ( spkr & PIT8254_SPKR_OUT ) );
70 }
iPXE I/O API
#define PIT8254_CMD_CHANNEL(channel)
Select channel.
Definition: pit8254.h:28
#define PIT8254_CMD_ACCESS_LOHI
Low-byte, high-byte pair.
Definition: pit8254.h:34
#define PIT8254_SPKR_ENABLE
PC speaker enabled.
Definition: pit8254.h:59
#define PIT8254_CMD
Mode/command register.
Definition: pit8254.h:25
void pit8254_speaker_delay(unsigned int ticks)
Delay for a fixed number of timer ticks using the speaker channel.
Definition: pit8254.c:41
#define PIT8254_CMD_OP_TERMINAL
Interrupt on terminal count.
Definition: pit8254.h:37
#define PIT8254_SPKR_OUT
PC speaker channel output.
Definition: pit8254.h:62
#define PIT8254_SPKR
PC speaker control register.
Definition: pit8254.h:53
Assertions.
assert((readw(&hdr->flags) &(GTF_reading|GTF_writing))==0)
#define PIT8254_DATA(channel)
Data port.
Definition: pit8254.h:22
uint32_t low
Low 16 bits of address.
Definition: intel.h:21
#define PIT8254_CH_SPKR
PC speaker channel.
Definition: pit8254.h:16
#define PIT8254_CMD_BINARY
Binary mode.
Definition: pit8254.h:47
8254 Programmable Interval Timer
unsigned char uint8_t
Definition: stdint.h:10
uint8_t inb(volatile uint8_t *io_addr)
Read byte from I/O-mapped device.
#define outb(data, io_addr)
Definition: io.h:309
FILE_LICENCE(GPL2_OR_LATER_OR_UBDL)
#define PIT8254_SPKR_GATE
PC speaker channel gate.
Definition: pit8254.h:56
uint32_t high
High 32 bits of address.
Definition: intel.h:22
struct golan_eqe_cmd cmd
Definition: CIB_PRM.h:29