91 lines
2.2 KiB
C
91 lines
2.2 KiB
C
|
#include "realmode.h"
|
||
|
#include "timer.h"
|
||
|
#include "latch.h"
|
||
|
#include "bios.h"
|
||
|
|
||
|
#define K_RDWR 0x60 /* keyboard data & cmds (read/write) */
|
||
|
#define K_STATUS 0x64 /* keyboard status */
|
||
|
#define K_CMD 0x64 /* keybd ctlr command (write-only) */
|
||
|
|
||
|
#define K_OBUF_FUL 0x01 /* output buffer full */
|
||
|
#define K_IBUF_FUL 0x02 /* input buffer full */
|
||
|
|
||
|
#define KC_CMD_WIN 0xd0 /* read output port */
|
||
|
#define KC_CMD_WOUT 0xd1 /* write output port */
|
||
|
#define KB_SET_A20 0xdf /* enable A20,
|
||
|
enable output buffer full interrupt
|
||
|
enable data line
|
||
|
disable clock line */
|
||
|
#define KB_UNSET_A20 0xdd /* enable A20,
|
||
|
enable output buffer full interrupt
|
||
|
enable data line
|
||
|
disable clock line */
|
||
|
|
||
|
enum { Disable_A20 = 0x2400, Enable_A20 = 0x2401, Query_A20_Status = 0x2402,
|
||
|
Query_A20_Support = 0x2403 };
|
||
|
|
||
|
#define CF ( 1 << 0 )
|
||
|
|
||
|
#ifndef IBM_L40
|
||
|
static void empty_8042 ( void )
|
||
|
{
|
||
|
unsigned long time;
|
||
|
char st;
|
||
|
|
||
|
time = currticks() + TICKS_PER_SEC; /* max wait of 1 second */
|
||
|
while ((((st = inb(K_CMD)) & K_OBUF_FUL) ||
|
||
|
(st & K_IBUF_FUL)) &&
|
||
|
currticks() < time)
|
||
|
inb(K_RDWR);
|
||
|
}
|
||
|
#endif /* IBM_L40 */
|
||
|
|
||
|
/*
|
||
|
* Gate A20 for high memory
|
||
|
*
|
||
|
* Note that this function gets called as part of the return path from
|
||
|
* librm's real_call, which is used to make the int15 call if librm is
|
||
|
* being used. To avoid an infinite recursion, we make gateA20_set
|
||
|
* return immediately if it is already part of the call stack.
|
||
|
*/
|
||
|
void gateA20_set ( void ) {
|
||
|
static char reentry_guard = 0;
|
||
|
uint16_t flags, status;
|
||
|
|
||
|
if ( reentry_guard )
|
||
|
return;
|
||
|
reentry_guard = 1;
|
||
|
|
||
|
REAL_EXEC ( rm_enableA20,
|
||
|
"sti\n\t"
|
||
|
"stc\n\t"
|
||
|
"int $0x15\n\t"
|
||
|
"pushfw\n\t"
|
||
|
"popw %%bx\n\t"
|
||
|
"cli\n\t",
|
||
|
2,
|
||
|
OUT_CONSTRAINTS ( "=a" ( status ), "=b" ( flags ) ),
|
||
|
IN_CONSTRAINTS ( "a" ( Enable_A20 ) ),
|
||
|
CLOBBER ( "ecx", "edx", "ebp", "esi", "edi" ) );
|
||
|
|
||
|
if ( ( flags & CF ) ||
|
||
|
( ( status >> 8 ) & 0xff ) ) {
|
||
|
/* INT 15 method failed, try alternatives */
|
||
|
#ifdef IBM_L40
|
||
|
outb(0x2, 0x92);
|
||
|
#else /* IBM_L40 */
|
||
|
empty_8042();
|
||
|
outb(KC_CMD_WOUT, K_CMD);
|
||
|
empty_8042();
|
||
|
outb(KB_SET_A20, K_RDWR);
|
||
|
empty_8042();
|
||
|
#endif /* IBM_L40 */
|
||
|
}
|
||
|
|
||
|
reentry_guard = 0;
|
||
|
}
|
||
|
|
||
|
void gateA20_unset ( void ) {
|
||
|
/* Not currently implemented */
|
||
|
}
|