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#ifndef _IPXE_PIT8254_H
#define _IPXE_PIT8254_H
/** @file
*
* 8254 Programmable Interval Timer
*
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
/** IRQ0 channel */
#define PIT8254_CH_IRQ0 0
/** PC speaker channel */
#define PIT8254_CH_SPKR 2
/** Timer frequency (1.193182MHz) */
#define PIT8254_HZ 1193182UL
/** Data port */
#define PIT8254_DATA(channel) ( 0x40 + (channel) )
/** Mode/command register */
#define PIT8254_CMD 0x43
/** Select channel */
#define PIT8254_CMD_CHANNEL(channel) ( (channel) << 6 )
/** Access modes */
#define PIT8254_CMD_ACCESS_LATCH 0x00 /**< Latch count value command */
#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 */
/* Operating modes */
#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)*/
/** Binary mode */
#define PIT8254_CMD_BINARY 0x00
/** BCD mode */
#define PIT8254_CMD_BCD 0x01
/** PC speaker control register */
#define PIT8254_SPKR 0x61
/** PC speaker channel gate */
#define PIT8254_SPKR_GATE 0x01
/** PC speaker enabled */
#define PIT8254_SPKR_ENABLE 0x02
/** PC speaker channel output */
#define PIT8254_SPKR_OUT 0x20
extern void pit8254_speaker_delay ( unsigned int ticks );
/**
* Delay for a fixed number of microseconds
*
* @v usecs Number of microseconds for which to delay
*/
static inline __attribute__ (( always_inline )) void
pit8254_udelay ( unsigned long usecs ) {
/* 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 );
}
#endif /* _IPXE_PIT8254_H */
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