diff options
Diffstat (limited to 'gpxe/src/arch/i386/firmware/pcbios/gateA20.c')
| -rw-r--r-- | gpxe/src/arch/i386/firmware/pcbios/gateA20.c | 176 |
1 files changed, 0 insertions, 176 deletions
diff --git a/gpxe/src/arch/i386/firmware/pcbios/gateA20.c b/gpxe/src/arch/i386/firmware/pcbios/gateA20.c deleted file mode 100644 index 1a71472d..00000000 --- a/gpxe/src/arch/i386/firmware/pcbios/gateA20.c +++ /dev/null @@ -1,176 +0,0 @@ -FILE_LICENCE ( GPL2_OR_LATER ); - -#include <stdio.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 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 KC_CMD_NULL 0xff /* null command ("pulse nothing") */ -#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 */ - -#define SCP_A 0x92 /* System Control Port A */ - -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 - */ -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 | K_OBUF_FUL ) ) && - currticks() < time ) { - 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 ( 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; - - 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(); - - /* Always retry at least once, to avoid false negatives */ - } while ( retries-- >= 0 ); - - /* Pattern matched every time; gate A20 is not set */ - return 0; -} - -/* - * 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; - static int a20_method = A20_UNKNOWN; - unsigned int discard_a; - unsigned int scp_a; - int retries = 0; - - /* Avoid potential infinite recursion */ - if ( reentry_guard ) - return; - reentry_guard = 1; - - /* Fast check to see if gate A20 is already enabled */ - if ( gateA20_is_set ( 0 ) ) - 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; -} - -void gateA20_unset ( void ) { - /* Not currently implemented */ -} |