Change real mode API to allow passing intXX number or entry point and

some register values from C. 

This theoretically fixes non-vga option roms, but it also allows to use
the same assembler code for option roms and vsm.
It will also make using the bootsplash without yabel a lot easier.

Factor out and improve BDA setup, do some rom segment setup for those
option roms that need it. 

Don't call the coreboot exception handler if an exception occurs in real
mode. It's only partly usable, but mainly the Kontron 986LCD-M (and other
i945GM boards) choke on an exception #6 (invalid opcode). This particular
issue is not introduced by the changes in this patch but has been around
for quite a while at least.

Signed-off-by: Stefan Reinauer <stepan@coresystems.de>
Acked-by: Patrick Georgi <patrick.georgi@coresystems.de>



git-svn-id: svn://svn.coreboot.org/coreboot/trunk@5543 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

1 files changed, 89 insertions, 133 deletions

diff --git a/src/devices/oprom/x86_asm.S b/src/devices/oprom/x86_asm.S
index 469c42f90b..ee7c5faaab 100644
--- a/src/devices/oprom/x86_asm.S
+++ b/src/devices/oprom/x86_asm.S
@@ -1,7 +1,7 @@
 /*
  * This file is part of the coreboot project.
  *
- * Copyright (C) 2009 coresystems GmbH
+ * Copyright (C) 2009-2010 coresystems GmbH
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -57,21 +57,49 @@ __realmode_idt = RELOCATED(.)
 __stack = RELOCATED(.)
 	.long 0
 
+/* Register store for realmode_call and realmode_interrupt */
+__registers = RELOCATED(.)
+	.long 0 /* 0x00 - EAX */
+	.long 0 /* 0x04 - EBX */
+	.long 0 /* 0x08 - ECX */
+	.long 0 /* 0x0c - EDX */
+	.long 0 /* 0x10 - EDI */
+	.long 0 /* 0x14 - ESI */
+
 	.code32
-	.globl __run_optionrom
-__run_optionrom = RELOCATED(.)
+	.globl __realmode_call
+__realmode_call = RELOCATED(.)
 	/* save all registers to the stack */
 	pushal
 
 	/* Move the protected mode stack to a safe place */
-	mov 	%esp, __stack
-
-	/* Get devfn into %ecx */
+	movl	%esp, __stack
 	movl    %esp, %ebp
+
 	/* This function is called with regparm=0 and we have
-	 * to skip the 32 byte from pushal:
+	 * to skip the 32 byte from pushal. Hence start at 36.
 	 */
-	movl    36(%ebp), %ecx
+
+	/* entry point */
+	movl    36(%ebp), %eax
+	movw	%ax, __lcall_instr + 1
+	andl	$0xffff0000, %eax
+	shrl	$4, %eax
+	movw	%ax, __lcall_instr + 3
+
+	/* initial register values */
+	movl	40(%ebp), %eax
+	movl	%eax, __registers + 0x00 /* eax */
+	movl	44(%ebp), %eax
+	movl	%eax, __registers + 0x04 /* ebx */
+	movl	48(%ebp), %eax
+	movl	%eax, __registers + 0x08 /* ecx */
+	movl	52(%ebp), %eax
+	movl	%eax, __registers + 0x0c /* edx */
+	movl	56(%ebp), %eax
+	movl	%eax, __registers + 0x10 /* esi */
+	movl	60(%ebp), %eax
+	movl	%eax, __registers + 0x14 /* esi */
 
 	/* Activate the right segment descriptor real mode. */
 	ljmp	$0x28, $RELOCATED(1f)
@@ -120,11 +148,18 @@ __run_optionrom = RELOCATED(.)
 	mov	$0x40, %ax
 	mov	%ax, %ds
 
+	/* initialize registers for option rom lcall */
+	movl	__registers +  0, %eax
+	movl	__registers +  4, %ebx
+	movl	__registers +  8, %ecx
+	movl	__registers + 12, %edx
+	movl	__registers + 16, %esi
+	movl	__registers + 20, %edi
+
 	/* ************************************ */
-	mov	%cx, %ax	// restore ax
-	// TODO this will not work for non-VGA option ROMs
-	/* run VGA BIOS at 0xc000:0003 */
-	lcall	$0xc000, $0x0003
+__lcall_instr = RELOCATED(.)
+	.byte 0x9a
+	.word 0x0000, 0x0000
 	/* ************************************ */
 
 	/* If we got here, just about done.
@@ -151,126 +186,47 @@ __run_optionrom = RELOCATED(.)
 	lidt	idtarg
 
 	/* and exit */
-	mov	__stack, %esp
+	movl	__stack, %esp
 	popal
-	ret
 
-#if defined(CONFIG_GEODE_VSA) && CONFIG_GEODE_VSA
-#define VSA2_ENTRY_POINT	0x60020
+	// TODO return AX from OPROM call
+	ret
 
-	.globl __run_vsa
-__run_vsa = RELOCATED(.)
+	.globl __realmode_interrupt
+__realmode_interrupt = RELOCATED(.)
 	/* save all registers to the stack */
 	pushal
-
-	/* Move the protected mode stack to a safe place */
-	mov 	%esp, __stack
-
+	/* save the stack */
+	movl	%esp, __stack
 	movl    %esp, %ebp
-	/* This function is called with regparm=0 and we have
-	 * to skip the 32 byte from pushal:
-	 */
-	movl    36(%ebp), %ecx
-	movl    40(%ebp), %edx
-
-	/* Activate the right segment descriptor real mode. */
-	ljmp	$0x28, $RELOCATED(1f)
-1:
-.code16
-	/* 16 bit code from here on... */
-
-	/* Load the segment registers w/ properly configured
-	 * segment descriptors. They will retain these
-	 * configurations (limits, writability, etc.) once
-	 * protected mode is turned off.
-	 */
-	mov	$0x30, %ax
-	mov	%ax, %ds
-	mov	%ax, %es
-	mov	%ax, %fs
-	mov	%ax, %gs
-	mov	%ax, %ss
-
-	/* Turn off protection */
-	movl	%cr0, %eax
-	andl	$~PE, %eax
-	movl	%eax, %cr0
-
-	/* Now really going into real mode */
-	ljmp	$0, $RELOCATED(1f)
-1:
-	/* Setup a stack: Put the stack at the end of page zero.
-	 * That way we can easily share it between real and
-	 * protected, since the 16 bit ESP at segment 0 will
-	 * work for any case. */
-	mov	$0x0, %ax
-	mov	%ax, %ss
-	movl	$0x1000, %eax
-	movl	%eax, %esp
 
-	/* Load our 16 bit idt */
-	xor	%ax, %ax
-	mov	%ax, %ds
-	lidt	__realmode_idt
-
-	/* Set all segments to 0x0000, ds to 0x0040 */
-	mov	%ax, %es
-	mov	%ax, %fs
-	mov	%ax, %gs
-	mov	$0x40, %ax
-	mov	%ax, %ds
-	mov	%cx, %ax	// restore ax
-
-	/* ************************************ */
-	lcall	$((VSA2_ENTRY_POINT & 0xffff0000) >> 4), $(VSA2_ENTRY_POINT & 0xffff)
-	/* ************************************ */
-
-	/* If we got here, just about done.
-	 * Need to get back to protected mode
+	/* This function is called with regparm=0 and we have
+	 * to skip the 32 byte from pushal. Hence start at 36.
 	 */
-	movl	%cr0, %eax
-	orl	$PE, %eax
-	movl	%eax, %cr0
-
-	/* Now that we are in protected mode
-	 * jump to a 32 bit code segment.
-	 */
-	data32	ljmp	$0x10, $RELOCATED(1f)
-1:
-	.code32
-	movw	$0x18, %ax
-	mov	%ax, %ds
-	mov	%ax, %es
-	mov	%ax, %fs
-	mov	%ax, %gs
-	mov	%ax, %ss
-
-	/* restore proper idt */
-	lidt	idtarg
-
-	/* and exit */
-	mov	__stack, %esp
-	popal
-	ret
-#endif
-
-	.globl __run_interrupt
-__run_interrupt = RELOCATED(.)
-
-	pushal
-	/* save the stack */
-	mov	%esp, __stack
 
+	/* prepare interrupt calling code */
+	movl    36(%ebp), %eax
+	movb	%al, __intXX_instr + 1 /* intno */
+
+	/* initial register values */
+	movl	40(%ebp), %eax
+	movl	%eax, __registers + 0x00 /* eax */
+	movl	44(%ebp), %eax
+	movl	%eax, __registers + 0x04 /* ebx */
+	movl	48(%ebp), %eax
+	movl	%eax, __registers + 0x08 /* ecx */
+	movl	52(%ebp), %eax
+	movl	%eax, __registers + 0x0c /* edx */
+	movl	56(%ebp), %eax
+	movl	%eax, __registers + 0x10 /* esi */
+	movl	60(%ebp), %eax
+	movl	%eax, __registers + 0x14 /* esi */
 
 	/*  This configures CS properly for real mode. */
 	ljmp 	$0x28, $RELOCATED(1f)
 1:
 	.code16 /* 16 bit code from here on... */
 
-	// DEBUG
-	movb    $0xec, %al
-	outb    %al, $0x80
-
 	/* Load the segment registers w/ properly configured segment
 	 * descriptors.  They will retain these configurations (limits,
 	 * writability, etc.) once protected mode is turned off.
@@ -291,9 +247,9 @@ __run_interrupt = RELOCATED(.)
 	data32 ljmp	$0, $RELOCATED(1f)
 1:
 
-	/* put the stack at the end of page zero.
-	 * that way we can easily share it between real and protected,
-	 * since the 16-bit ESP at segment 0 will work for any case.
+	/* put the stack at the end of page zero.  That way we can easily 
+	 * share it between real mode and protected mode, because %esp and
+	 * %ss:%sp point to the same memory.
 	 */
 	/* setup a stack */
 	mov	$0x0, %ax
@@ -312,18 +268,16 @@ __run_interrupt = RELOCATED(.)
 	mov	%ax, %fs
 	mov	%ax, %gs
 
-	/* Call VGA BIOS int10 function 0x4f14 to enable main console
-	 * Epia-M does not always autosence the main console so forcing
-	 * it on is good.
-	 */
+	/* initialize registers for intXX call */
+	movl	__registers +  0, %eax
+	movl	__registers +  4, %ebx
+	movl	__registers +  8, %ecx
+	movl	__registers + 12, %edx
+	movl	__registers + 16, %esi
+	movl	__registers + 20, %edi
 
-	/* Ask VGA option rom to enable main console */
-	movw	$0x4f14,%ax
-	movw	$0x8003,%bx
-	movw	$1, %cx
-	movw	$0, %dx
-	movw	$0, %di
-	int	$0x10
+__intXX_instr = RELOCATED(.)
+	.byte 0xcd, 0x00 /* This becomes intXX */
 
 	/* Ok, the job is done, now go back to protected mode coreboot */
 	movl	%cr0, %eax
@@ -345,13 +299,15 @@ __run_interrupt = RELOCATED(.)
 	lidt	idtarg
 
 	/* Exit */
-	mov	__stack, %esp
+	movl	__stack, %esp
 	popal
 	ret
 
 /* This is the 16-bit interrupt entry point called by the IDT stub code.
+ *
  * Before this code code is called, %eax is pushed to the stack, and the
- * interrupt number is loaded into %al
+ * interrupt number is loaded into %al. On return this function cleans up
+ * for its caller.
  */
 	.code16
 __interrupt_handler_16bit = RELOCATED(.)