iPXE
Defines | Functions
pit8254.h File Reference

8254 Programmable Interval Timer More...

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Defines

#define PIT8254_CH_IRQ0   0
 IRQ0 channel.
#define PIT8254_CH_SPKR   2
 PC speaker channel.
#define PIT8254_HZ   1193182UL
 Timer frequency (1.193182MHz)
#define PIT8254_DATA(channel)   ( 0x40 + (channel) )
 Data port.
#define PIT8254_CMD   0x43
 Mode/command register.
#define PIT8254_CMD_CHANNEL(channel)   ( (channel) << 6 )
 Select channel.
#define PIT8254_CMD_ACCESS_LATCH   0x00
 Access modes.
#define PIT8254_CMD_ACCESS_LO   0x10
 Low byte only.
#define PIT8254_CMD_ACCESS_HI   0x20
 High byte only.
#define PIT8254_CMD_ACCESS_LOHI   0x30
 Low-byte, high-byte pair.
#define PIT8254_CMD_OP_TERMINAL   0x00
 Interrupt on terminal count.
#define PIT8254_CMD_OP_ONESHOT   0x02
 Hardware re-triggerable one-shot.
#define PIT8254_CMD_OP_RATE   0x04
 Rate generator.
#define PIT8254_CMD_OP_SQUARE   0x06
 Square wave generator.
#define PIT8254_CMD_OP_SWSTROBE   0x08
 Software triggered strobe.
#define PIT8254_CMD_OP_HWSTROBE   0x0a
 Hardware triggered strobe.
#define PIT8254_CMD_OP_RATE2   0x0c
 Rate generator (duplicate)
#define PIT8254_CMD_OP_SQUARE2   0x0e
 Square wave generator (duplicate)
#define PIT8254_CMD_BINARY   0x00
 Binary mode.
#define PIT8254_CMD_BCD   0x01
 BCD mode.
#define PIT8254_SPKR   0x61
 PC speaker control register.
#define PIT8254_SPKR_GATE   0x01
 PC speaker channel gate.
#define PIT8254_SPKR_ENABLE   0x02
 PC speaker enabled.
#define PIT8254_SPKR_OUT   0x20
 PC speaker channel output.

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.
static __attribute__ ((always_inline)) void pit8254_udelay(unsigned long usecs)
 Delay for a fixed number of microseconds.

Detailed Description

8254 Programmable Interval Timer

Definition in file pit8254.h.


Define Documentation

#define PIT8254_CH_IRQ0   0

IRQ0 channel.

Definition at line 13 of file pit8254.h.

#define PIT8254_CH_SPKR   2

PC speaker channel.

Definition at line 16 of file pit8254.h.

Referenced by pit8254_speaker_delay().

#define PIT8254_HZ   1193182UL

Timer frequency (1.193182MHz)

Definition at line 19 of file pit8254.h.

Referenced by __attribute__().

#define PIT8254_DATA (   channel)    ( 0x40 + (channel) )

Data port.

Definition at line 22 of file pit8254.h.

Referenced by pit8254_speaker_delay().

#define PIT8254_CMD   0x43

Mode/command register.

Definition at line 25 of file pit8254.h.

Referenced by pit8254_speaker_delay().

#define PIT8254_CMD_CHANNEL (   channel)    ( (channel) << 6 )

Select channel.

Definition at line 28 of file pit8254.h.

Referenced by pit8254_speaker_delay().

#define PIT8254_CMD_ACCESS_LATCH   0x00

Access modes.

Latch count value command

Definition at line 31 of file pit8254.h.

#define PIT8254_CMD_ACCESS_LO   0x10

Low byte only.

Definition at line 32 of file pit8254.h.

#define PIT8254_CMD_ACCESS_HI   0x20

High byte only.

Definition at line 33 of file pit8254.h.

#define PIT8254_CMD_ACCESS_LOHI   0x30

Low-byte, high-byte pair.

Definition at line 34 of file pit8254.h.

Referenced by pit8254_speaker_delay().

#define PIT8254_CMD_OP_TERMINAL   0x00

Interrupt on terminal count.

Definition at line 37 of file pit8254.h.

Referenced by pit8254_speaker_delay().

#define PIT8254_CMD_OP_ONESHOT   0x02

Hardware re-triggerable one-shot.

Definition at line 38 of file pit8254.h.

#define PIT8254_CMD_OP_RATE   0x04

Rate generator.

Definition at line 39 of file pit8254.h.

#define PIT8254_CMD_OP_SQUARE   0x06

Square wave generator.

Definition at line 40 of file pit8254.h.

#define PIT8254_CMD_OP_SWSTROBE   0x08

Software triggered strobe.

Definition at line 41 of file pit8254.h.

#define PIT8254_CMD_OP_HWSTROBE   0x0a

Hardware triggered strobe.

Definition at line 42 of file pit8254.h.

#define PIT8254_CMD_OP_RATE2   0x0c

Rate generator (duplicate)

Definition at line 43 of file pit8254.h.

#define PIT8254_CMD_OP_SQUARE2   0x0e

Square wave generator (duplicate)

Definition at line 44 of file pit8254.h.

#define PIT8254_CMD_BINARY   0x00

Binary mode.

Definition at line 47 of file pit8254.h.

Referenced by pit8254_speaker_delay().

#define PIT8254_CMD_BCD   0x01

BCD mode.

Definition at line 50 of file pit8254.h.

#define PIT8254_SPKR   0x61

PC speaker control register.

Definition at line 53 of file pit8254.h.

Referenced by pit8254_speaker_delay().

#define PIT8254_SPKR_GATE   0x01

PC speaker channel gate.

Definition at line 56 of file pit8254.h.

Referenced by pit8254_speaker_delay().

#define PIT8254_SPKR_ENABLE   0x02

PC speaker enabled.

Definition at line 59 of file pit8254.h.

Referenced by pit8254_speaker_delay().

#define PIT8254_SPKR_OUT   0x20

PC speaker channel output.

Definition at line 62 of file pit8254.h.

Referenced by pit8254_speaker_delay().


Function Documentation

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.

Parameters:
ticksNumber of timer ticks for which to delay

Definition at line 41 of file pit8254.c.

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__().

                                                  {
        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 ) );
}
static __attribute__ ( (always_inline)  ) [inline, static]

Delay for a fixed number of microseconds.

Parameters:
usecsNumber of microseconds for which to delay

Definition at line 71 of file pit8254.h.

References PIT8254_HZ, and pit8254_speaker_delay().

                                       {

        /* Delays are invariably compile-time constants; force the
         * multiplication and division to take place at compilation
         * time rather than runtime.
         */
        pit8254_speaker_delay ( ( usecs * PIT8254_HZ ) / 1000000 );
}