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-rw-r--r--arch/x86/boot/a20.c166
1 files changed, 0 insertions, 166 deletions
diff --git a/arch/x86/boot/a20.c b/arch/x86/boot/a20.c
deleted file mode 100644
index f501feeedd..0000000000
--- a/arch/x86/boot/a20.c
+++ /dev/null
@@ -1,166 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-// SPDX-FileCopyrightText: 1991,1992 Linus Torvalds
-// SPDX-FileCopyrightText: 2007-2008 rPath, Inc.
-// SPDX-FileCopyrightText: 2009 Intel Corporation
-
-/* Author: H. Peter Anvin and others */
-
-/*
- * Enable A20 gate (return -1 on failure)
- */
-
-#include <asm/segment.h>
-#include <io.h>
-#include "boot.h"
-
-#define MAX_8042_LOOPS 100000
-#define MAX_8042_FF 32
-
-/* be aware of: */
-THIS_IS_REALMODE_CODE
-
-static int __bootcode empty_8042(void)
-{
- u8 status;
- int loops = MAX_8042_LOOPS;
- int ffs = MAX_8042_FF;
-
- while (loops--) {
- io_delay();
-
- status = inb(0x64);
- if (status == 0xff) {
- /* FF is a plausible, but very unlikely status */
- if (!--ffs)
- return -1; /* Assume no KBC present */
- }
- if (status & 1) {
- /* Read and discard input data */
- io_delay();
- (void)inb(0x60);
- } else if (!(status & 2)) {
- /* Buffers empty, finished! */
- return 0;
- }
- }
-
- return -1;
-}
-
-/* Returns nonzero if the A20 line is enabled. The memory address
- used as a test is the int $0x80 vector, which should be safe. */
-
-#define A20_TEST_ADDR (4*0x80)
-#define A20_TEST_SHORT 32
-#define A20_TEST_LONG 2097152 /* 2^21 */
-
-static int __bootcode a20_test(int loops)
-{
- int ok = 0;
- int saved, ctr;
-
- set_fs(0x0000);
- set_gs(0xffff);
-
- saved = ctr = rdfs32(A20_TEST_ADDR);
-
- while (loops--) {
- wrfs32(++ctr, A20_TEST_ADDR);
- io_delay(); /* Serialize and make delay constant */
- ok = rdgs32(A20_TEST_ADDR+0x10) ^ ctr;
- if (ok)
- break;
- }
-
- wrfs32(saved, A20_TEST_ADDR);
- return ok;
-}
-
-/* Quick test to see if A20 is already enabled */
-static int __bootcode a20_test_short(void)
-{
- return a20_test(A20_TEST_SHORT);
-}
-
-/* Longer test that actually waits for A20 to come on line; this
- is useful when dealing with the KBC or other slow external circuitry. */
-static int __bootcode a20_test_long(void)
-{
- return a20_test(A20_TEST_LONG);
-}
-
-static void __bootcode enable_a20_bios(void)
-{
- struct biosregs ireg;
-
- initregs(&ireg);
- ireg.ax = 0x2401;
- intcall(0x15, &ireg, NULL);
-}
-
-static void __bootcode enable_a20_kbc(void)
-{
- empty_8042();
-
- outb(0xd1, 0x64); /* Command write */
- empty_8042();
-
- outb(0xdf, 0x60); /* A20 on */
- empty_8042();
-
- outb(0xff, 0x64); /* Null command, but UHCI wants it */
- empty_8042();
-}
-
-static void __bootcode enable_a20_fast(void)
-{
- u8 port_a;
-
- port_a = inb(0x92); /* Configuration port A */
- port_a |= 0x02; /* Enable A20 */
- port_a &= ~0x01; /* Do not reset machine */
- outb(port_a, 0x92);
-}
-
-/*
- * Actual routine to enable A20; return 0 on ok, -1 on failure
- */
-
-#define A20_ENABLE_LOOPS 255 /* Number of times to try */
-
-int __bootcode enable_a20(void)
-{
- int loops = A20_ENABLE_LOOPS;
- int kbc_err;
-
- while (loops--) {
- /* First, check to see if A20 is already enabled
- (legacy free, etc.) */
- if (a20_test_short())
- return 0;
-
- /* Next, try the BIOS (INT 0x15, AX=0x2401) */
- enable_a20_bios();
- if (a20_test_short())
- return 0;
-
- /* Try enabling A20 through the keyboard controller */
- kbc_err = empty_8042();
-
- if (a20_test_short())
- return 0; /* BIOS worked, but with delayed reaction */
-
- if (!kbc_err) {
- enable_a20_kbc();
- if (a20_test_long())
- return 0;
- }
-
- /* Finally, try enabling the "fast A20 gate" */
- enable_a20_fast();
- if (a20_test_long())
- return 0;
- }
-
- return -1;
-}