iPXE
Functions
pit8254.c File Reference

8254 Programmable Interval Timer More...

#include <assert.h>
#include <ipxe/io.h>
#include <ipxe/pit8254.h>

Go to the source code of this file.

Functions

 FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
 
void pit8254_speaker_delay (unsigned int ticks)
 Delay for a fixed number of timer ticks using the speaker channel. More...
 

Detailed Description

8254 Programmable Interval Timer

Definition in file pit8254.c.

Function Documentation

◆ FILE_LICENCE()

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL  )

◆ pit8254_speaker_delay()

void pit8254_speaker_delay ( unsigned int  ticks)

Delay for a fixed number of timer ticks using the speaker channel.

Parameters
ticksNumber of timer ticks for which to delay

Definition at line 41 of file pit8254.c.

41  {
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 }
#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
#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
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
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
#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

References assert(), cmd, high, inb(), low, outb, PIT8254_CH_SPKR, PIT8254_CMD, PIT8254_CMD_ACCESS_LOHI, PIT8254_CMD_BINARY, PIT8254_CMD_CHANNEL, PIT8254_CMD_OP_TERMINAL, PIT8254_DATA, PIT8254_SPKR, PIT8254_SPKR_ENABLE, PIT8254_SPKR_GATE, and PIT8254_SPKR_OUT.

Referenced by __attribute__().