124 lines
3.4 KiB
C
124 lines
3.4 KiB
C
/* Etherboot routines for PCBIOS firmware.
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*
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* Body of routines taken from old pcbios.S
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*/
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#include "stdint.h"
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#include "realmode.h"
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#include "compiler.h"
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#define BIOS_DATA_SEG 0x0040
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#define CF ( 1 << 0 )
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/**************************************************************************
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CURRTICKS - Get Time
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Use direct memory access to BIOS variables, longword 0040:006C (ticks
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today) and byte 0040:0070 (midnight crossover flag) instead of calling
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timeofday BIOS interrupt.
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**************************************************************************/
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#if defined(CONFIG_TSC_CURRTICKS)
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#undef CONFIG_BIOS_CURRTICKS
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#else
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#define CONFIG_BIOS_CURRTICKS 1
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#endif
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#if defined(CONFIG_BIOS_CURRTICKS)
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unsigned long currticks ( void ) {
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static uint32_t days = 0;
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uint32_t ticks;
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uint8_t midnight;
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/* Re-enable interrupts so that the timer interrupt can occur
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*/
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REAL_EXEC ( rm_currticks,
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"sti\n\t"
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"nop\n\t"
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"nop\n\t"
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"cli\n\t",
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0,
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OUT_CONSTRAINTS (),
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IN_CONSTRAINTS (),
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CLOBBER ( "eax" ) ); /* can't have an empty clobber list */
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get_real ( ticks, BIOS_DATA_SEG, 0x006c );
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get_real ( midnight, BIOS_DATA_SEG, 0x0070 );
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if ( midnight ) {
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midnight = 0;
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put_real ( midnight, BIOS_DATA_SEG, 0x0070 );
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days += 0x1800b0;
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}
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return ( days + ticks );
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}
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#endif /* CONFIG_BIOS_CURRTICKS */
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/**************************************************************************
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CPU_NAP - Save power by halting the CPU until the next interrupt
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**************************************************************************/
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void cpu_nap ( void ) {
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REAL_EXEC ( rm_cpu_nap,
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"sti\n\t"
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"hlt\n\t"
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"cli\n\t",
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0,
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OUT_CONSTRAINTS (),
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IN_CONSTRAINTS (),
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CLOBBER ( "eax" ) ); /* can't have an empty clobber list */
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}
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#if (TRY_FLOPPY_FIRST > 0)
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/**************************************************************************
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DISK_INIT - Initialize the disk system
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**************************************************************************/
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void disk_init ( void ) {
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REAL_EXEC ( rm_disk_init,
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"sti\n\t"
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"xorw %ax,%ax\n\t"
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"movb $0x80,%dl\n\t"
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"int $0x13\n\t"
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"cli\n\t",
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0,
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OUT_CONSTRAINTS (),
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IN_CONSTRAINTS (),
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CLOBBER ( "eax", "ebx", "ecx", "edx",
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"ebp", "esi", "edi" ) );
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}
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/**************************************************************************
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DISK_READ - Read a sector from disk
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**************************************************************************/
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unsigned int pcbios_disk_read ( int drive, int cylinder, int head, int sector,
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char *fixme_buf ) {
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uint16_t ax, flags, discard_c, discard_d;
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segoff_t buf = SEGOFF ( fixme_buf );
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/* FIXME: buf should be passed in as a segoff_t rather than a
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* char *
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*/
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REAL_EXEC ( rm_pcbios_disk_read,
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"sti\n\t"
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"pushl %%ebx\n\t" /* Convert %ebx to %es:bx */
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"popl %%bx\n\t"
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"popl %%es\n\t"
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"movb $0x02, %%ah\n\t" /* INT 13,2 - Read disk sector */
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"movb $0x01, %%al\n\t" /* Read one sector */
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"int $0x13\n\t"
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"pushfw\n\t"
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"popw %%bx\n\t"
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"cli\n\t",
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4,
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OUT_CONSTRAINTS ( "=a" ( ax ), "=b" ( flags ),
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"=c" ( discard_c ), "=d" ( discard_d ) ),
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IN_CONSTRAINTS ( "c" ( ( ( cylinder & 0xff ) << 8 ) |
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( ( cylinder >> 8 ) & 0x3 ) |
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sector ),
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"d" ( ( head << 8 ) | drive ),
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"b" ( buf ) ),
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CLOBBER ( "ebp", "esi", "edi" ) );
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);
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return ( flags & CF ) ? ax : 0;
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}
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#endif /* TRY_FLOPPY_FIRST */
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