+FILE_LICENCE ( GPL2_OR_LATER );
+
#include <stdio.h>
-#include "realmode.h"
-#include "timer.h"
-#include "latch.h"
-#include "bios.h"
+#include <realmode.h>
+#include <bios.h>
+#include <gpxe/io.h>
+#include <gpxe/timer.h>
#define K_RDWR 0x60 /* keyboard data & cmds (read/write) */
#define K_STATUS 0x64 /* keyboard status */
#define KC_CMD_WIN 0xd0 /* read output port */
#define KC_CMD_WOUT 0xd1 /* write output port */
+#define KC_CMD_NULL 0xff /* null command ("pulse nothing") */
#define KB_SET_A20 0xdf /* enable A20,
enable output buffer full interrupt
enable data line
#define SCP_A 0x92 /* System Control Port A */
-#define A20_MAX_RETRIES 32
-
enum { Disable_A20 = 0x2400, Enable_A20 = 0x2401, Query_A20_Status = 0x2402,
Query_A20_Support = 0x2403 };
+enum a20_methods {
+ A20_UNKNOWN = 0,
+ A20_INT15,
+ A20_KBC,
+ A20_SCPA,
+};
+
+#define A20_MAX_RETRIES 32
+#define A20_INT15_RETRIES 32
+#define A20_KBC_RETRIES (2^21)
+#define A20_SCPA_RETRIES (2^21)
+
/**
* Drain keyboard controller
*/
time = currticks() + TICKS_PER_SEC; /* max wait of 1 second */
while ( ( inb ( K_CMD ) & ( K_IBUF_FUL | K_OBUF_FUL ) ) &&
currticks() < time ) {
- SLOW_DOWN_IO;
- ( void ) inb ( K_RDWR );
- SLOW_DOWN_IO;
+ iodelay();
+ ( void ) inb_p ( K_RDWR );
+ iodelay();
}
}
/**
* Fast test to see if gate A20 is already set
*
+ * @v retries Number of times to retry before giving up
* @ret set Gate A20 is set
*/
-static int gateA20_is_set ( void ) {
+static int gateA20_is_set ( int retries ) {
static uint32_t test_pattern = 0xdeadbeef;
physaddr_t test_pattern_phys = virt_to_phys ( &test_pattern );
physaddr_t verify_pattern_phys = ( test_pattern_phys ^ 0x100000 );
userptr_t verify_pattern_user = phys_to_user ( verify_pattern_phys );
uint32_t verify_pattern;
- /* Check for difference */
- copy_from_user ( &verify_pattern, verify_pattern_user, 0,
- sizeof ( verify_pattern ) );
- if ( verify_pattern != test_pattern )
- return 1;
+ do {
+ /* Check for difference */
+ copy_from_user ( &verify_pattern, verify_pattern_user, 0,
+ sizeof ( verify_pattern ) );
+ if ( verify_pattern != test_pattern )
+ return 1;
+
+ /* Avoid false negatives */
+ test_pattern++;
+
+ iodelay();
- /* Invert pattern and retest, just to be sure */
- test_pattern ^= 0xffffffff;
- copy_from_user ( &verify_pattern, verify_pattern_user, 0,
- sizeof ( verify_pattern ) );
- if ( verify_pattern != test_pattern )
- return 1;
+ /* Always retry at least once, to avoid false negatives */
+ } while ( retries-- >= 0 );
- /* Pattern matched both times; gate A20 is not set */
+ /* Pattern matched every time; gate A20 is not set */
return 0;
}
*/
void gateA20_set ( void ) {
static char reentry_guard = 0;
+ static int a20_method = A20_UNKNOWN;
unsigned int discard_a;
unsigned int scp_a;
int retries = 0;
reentry_guard = 1;
/* Fast check to see if gate A20 is already enabled */
- if ( gateA20_is_set() )
+ if ( gateA20_is_set ( 0 ) )
goto out;
for ( ; retries < A20_MAX_RETRIES ; retries++ ) {
-
- /* Try INT 15 method first */
- __asm__ __volatile__ ( REAL_CODE ( "int $0x15" )
- : "=a" ( discard_a )
- : "a" ( Enable_A20 ) );
- if ( gateA20_is_set() ) {
- DBG ( "Enabled gate A20 using BIOS\n" );
- goto out;
- }
-
- /* Try keyboard controller method */
- empty_8042();
- outb ( KC_CMD_WOUT, K_CMD );
- empty_8042();
- outb ( KB_SET_A20, K_RDWR );
- empty_8042();
- if ( gateA20_is_set() ) {
- DBG ( "Enabled gate A20 using keyboard controller\n" );
- goto out;
- }
-
- /* Try "Fast gate A20" method */
- scp_a = inb ( SCP_A );
- scp_a &= ~0x01; /* Avoid triggering a reset */
- scp_a |= 0x02; /* Enable A20 */
- SLOW_DOWN_IO;
- outb ( scp_a, SCP_A );
- SLOW_DOWN_IO;
- if ( gateA20_is_set() ) {
- DBG ( "Enabled gate A20 using Fast Gate A20\n" );
- goto out;
+ switch ( a20_method ) {
+ case A20_UNKNOWN:
+ case A20_INT15:
+ /* Try INT 15 method */
+ __asm__ __volatile__ ( REAL_CODE ( "int $0x15" )
+ : "=a" ( discard_a )
+ : "a" ( Enable_A20 ) );
+ if ( gateA20_is_set ( A20_INT15_RETRIES ) ) {
+ DBG ( "Enabled gate A20 using BIOS\n" );
+ a20_method = A20_INT15;
+ goto out;
+ }
+ /* fall through */
+ case A20_KBC:
+ /* Try keyboard controller method */
+ empty_8042();
+ outb ( KC_CMD_WOUT, K_CMD );
+ empty_8042();
+ outb ( KB_SET_A20, K_RDWR );
+ empty_8042();
+ outb ( KC_CMD_NULL, K_CMD );
+ empty_8042();
+ if ( gateA20_is_set ( A20_KBC_RETRIES ) ) {
+ DBG ( "Enabled gate A20 using "
+ "keyboard controller\n" );
+ a20_method = A20_KBC;
+ goto out;
+ }
+ /* fall through */
+ case A20_SCPA:
+ /* Try "Fast gate A20" method */
+ scp_a = inb ( SCP_A );
+ scp_a &= ~0x01; /* Avoid triggering a reset */
+ scp_a |= 0x02; /* Enable A20 */
+ iodelay();
+ outb ( scp_a, SCP_A );
+ iodelay();
+ if ( gateA20_is_set ( A20_SCPA_RETRIES ) ) {
+ DBG ( "Enabled gate A20 using "
+ "Fast Gate A20\n" );
+ a20_method = A20_SCPA;
+ goto out;
+ }
}
}
http://git.etherboot.org / gpxe.git / blobdiff