First shot at factoring SMM code into generic parts and southbridge specific

parts.

This should help to reduce the code duplication for Rudolf's K8/VIA SMM
implementation...

Signed-off-by: Stefan Reinauer <stepan@coresystems.de>
Acked-by: Joseph Smith <joe@settoplinux.org>



git-svn-id: svn://svn.coreboot.org/coreboot/trunk@3870 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

1 files changed, 201 insertions, 0 deletions

diff --git a/src/cpu/x86/smm/smmhandler.S b/src/cpu/x86/smm/smmhandler.S
new file mode 100644
index 0000000000..f1bc550365
--- /dev/null
+++ b/src/cpu/x86/smm/smmhandler.S
@@ -0,0 +1,201 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2008 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 the Free Software Foundation; version 2 of
+ * the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ */
+
+/* NOTE: This handler assumes the SMM window goes from 0xa0000
+ * to 0xaffff. In fact, at least on Intel Core CPUs (i945 chipset)
+ * the SMM window is 128K big, covering 0xa0000 to 0xbffff.
+ * So there is a lot of potential for growth in here. Let's stick
+ * to 64k if we can though.
+ */
+
+/*
+ * +--------------------------------+ 0xaffff
+ * |  Save State Map Node 0         |
+ * |  Save State Map Node 1         |
+ * |  Save State Map Node 2         |
+ * |  Save State Map Node 3         |
+ * |  ...                           |
+ * +--------------------------------+ 0xaf000
+ * |                                |
+ * |                                |
+ * |                                |
+ * +--------------------------------+ 0xa8400
+ * | SMM Entry Node 0 (+ stack)     | 
+ * +--------------------------------+ 0xa8000
+ * | SMM Entry Node 1 (+ stack)     | 
+ * | SMM Entry Node 2 (+ stack)     | 
+ * | SMM Entry Node 3 (+ stack)     | 
+ * | ...                            |
+ * +--------------------------------+ 0xa7400
+ * |                                |
+ * | SMM Handler                    |
+ * |                                |
+ * +--------------------------------+ 0xa0000
+ *
+ */
+
+#include <arch/asm.h>
+
+#define LAPIC_ID 0xfee00020
+
+/* SMM_HANDLER_OFFSET is the 16bit offset within the ASEG
+ * at which smm_handler_start lives. At the moment the handler
+ * lives right at 0xa0000, so the offset is 0. 
+ */
+
+#define SMM_HANDLER_OFFSET 0x0000
+
+/* initially SMM is some sort of real mode. Let gcc know
+ * how to treat the SMM handler stub
+ */
+
+.section ".handler", "a", @progbits
+
+.code16
+
+/**
+ * SMM code to enable protected mode and jump to the
+ * C-written function void smi_handler(u32 smm_revision)
+ *
+ * All the bad magic is not all that bad after all.
+ */
+smm_handler_start:
+	movw    $(smm_gdtptr16 - smm_handler_start + SMM_HANDLER_OFFSET), %bx
+	data32  lgdt %cs:(%bx)
+
+	movl    %cr0, %eax
+	andl    $0x7FFAFFD1, %eax /* PG,AM,WP,NE,TS,EM,MP = 0 */
+	orl     $0x60000001, %eax /* CD, NW, PE = 1 */
+	movl    %eax, %cr0
+
+	/* Enable protected mode */
+	data32  ljmp    $0x08, $1f
+
+.code32
+1:
+	/* Use flat data segment */
+	movw    $0x10, %ax
+	movw    %ax, %ds
+	movw    %ax, %es
+	movw    %ax, %ss
+	movw    %ax, %fs
+	movw    %ax, %gs
+
+	/* Get this CPU's LAPIC ID */
+	movl $LAPIC_ID, %esi
+	movl (%esi), %ecx
+	shr  $24, %ecx
+	
+	/* calculate stack offset by multiplying the APIC ID
+	 * by 1024 (0x400), and save that offset in ebp.
+	 */
+	shl $10, %ecx
+	movl %ecx, %ebp
+
+	/* We put the stack for each core right above 
+	 * its SMM entry point. Core 0 starts at 0xa8000, 
+	 * we spare 0x10 bytes for the jump to be sure.
+	 */
+	movl $0xa8010, %eax
+	subl %ecx, %eax		/* subtract offset, see above */
+	movl %eax, %ebx		/* Save bottom of stack in ebx */
+
+#define SMM_STACK_SIZE	(0x400 - 0x10)
+	/* clear stack */
+	cld
+	movl	%eax, %edi
+	movl	$(SMM_STACK_SIZE >> 2), %ecx
+	xorl	%eax, %eax
+	rep	stosl
+
+	/* set new stack */
+	addl	$SMM_STACK_SIZE, %ebx
+	movl	%ebx, %esp
+
+	/* Get SMM revision */
+	movl $0xa8000 + 0x7efc, %ebx	/* core 0 address */
+	subl %ebp, %ebx			/* subtract core X offset */
+	movl (%ebx), %eax
+	pushl %eax
+
+	/* Call 32bit C handler */
+	call smi_handler
+
+	/* To return, just do rsm. It will "clean up" protected mode */
+	rsm
+
+.code16
+
+.align	4, 0xff
+
+smm_gdtptr16:
+	.word	smm_gdt_end - smm_gdt - 1
+	.long	smm_gdt - smm_handler_start + 0xa0000 + SMM_HANDLER_OFFSET
+
+.code32
+
+smm_gdt:
+	/* The first GDT entry can not be used. Keep it zero */
+	.long	0x00000000, 0x00000000
+
+	/* gdt selector 0x08, flat code segment */
+	.word	0xffff, 0x0000		
+	.byte	0x00, 0x9b, 0xcf, 0x00 /* G=1 and 0x0f, 4GB limit */	
+
+	/* gdt selector 0x10, flat data segment */
+	.word	0xffff, 0x0000		
+	.byte	0x00, 0x93, 0xcf, 0x00
+
+smm_gdt_end:
+
+
+.section ".jumptable", "a", @progbits
+
+/* This is the SMM jump table. All cores use the same SMM handler
+ * for simplicity. But SMM Entry needs to be different due to the 
+ * save state area. The jump table makes sure all CPUs jump into the
+ * real handler on SMM entry.
+ */
+
+/* This code currently supports up to 4 CPU cores. If more than 4 CPU cores
+ * shall be used, below table has to be updated, as well as smm.ld
+ */
+
+/* GNU AS/LD will always generate code that assumes CS is 0xa000. In reality
+ * CS will be set to SMM_BASE[19:4] though. Knowing that the smm handler is the
+ * first thing in the ASEG, we do a far jump here, to set CS to 0xa000.
+ */
+
+.code16
+jumptable:
+	/* core 3 */
+	ljmp $0xa000, $SMM_HANDLER_OFFSET 
+.align 1024, 0x00
+	/* core 2 */
+	ljmp $0xa000, $SMM_HANDLER_OFFSET 
+.align 1024, 0x00
+	/* core 1 */
+	ljmp $0xa000, $SMM_HANDLER_OFFSET 
+.align 1024, 0x00
+	/* core 0 */
+	ljmp $0xa000, $SMM_HANDLER_OFFSET
+.align 1024, 0x00
+