+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
enable data line
disable clock line */
+#define SCP_A 0x92 /* System Control Port A */
+
enum { Disable_A20 = 0x2400, Enable_A20 = 0x2401, Query_A20_Status = 0x2402,
Query_A20_Support = 0x2403 };
-#define CF ( 1 << 0 )
+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)
-#ifndef IBM_L40
+/**
+ * Drain keyboard controller
+ */
static void empty_8042 ( void ) {
unsigned long time;
time = currticks() + TICKS_PER_SEC; /* max wait of 1 second */
- while ( ( inb ( K_CMD ) & K_IBUF_FUL ) &&
+ while ( ( inb ( K_CMD ) & ( K_IBUF_FUL | K_OBUF_FUL ) ) &&
currticks() < time ) {
- /* Do nothing. In particular, do *not* read from
- * K_RDWR, because that will drain the keyboard buffer
- * and lose keypresses.
- */
+ iodelay();
+ ( void ) inb_p ( K_RDWR );
+ iodelay();
}
}
-#endif /* IBM_L40 */
/**
* 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;
- /* 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;
+ /* Avoid false negatives */
+ test_pattern++;
- /* Pattern matched both times; gate A20 is not set */
+ iodelay();
+
+ /* Always retry at least once, to avoid false negatives */
+ } while ( retries-- >= 0 );
+
+ /* 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;
/* Avoid potential infinite recursion */
if ( reentry_guard )
reentry_guard = 1;
/* Fast check to see if gate A20 is already enabled */
- if ( gateA20_is_set() )
+ if ( gateA20_is_set ( 0 ) )
goto out;
- /* Try INT 15 method first */
- __asm__ __volatile__ ( REAL_CODE ( "int $0x15" )
- : "=a" ( discard_a )
- : "a" ( Enable_A20 ) );
- if ( gateA20_is_set() )
- goto out;
-
- /* 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 */
- if ( gateA20_is_set() )
- goto out;
+ for ( ; retries < A20_MAX_RETRIES ; retries++ ) {
+ 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;
+ }
+ }
+ }
/* Better to die now than corrupt memory later */
printf ( "FATAL: Gate A20 stuck\n" );
while ( 1 ) {}
out:
+ if ( retries )
+ DBG ( "%d attempts were required to enable A20\n",
+ ( retries + 1 ) );
reentry_guard = 0;
}
http://git.etherboot.org / gpxe.git / blobdiff