xtensa: add MMU v3 support

MMUv3 comes out of reset with identity vaddr -> paddr mapping in the TLB
way 6:

Way 6 (512 MB)
        Vaddr       Paddr       ASID  Attr RWX Cache
        ----------  ----------  ----  ---- --- -------
        0x00000000  0x00000000  0x01  0x03 RWX Bypass
        0x20000000  0x20000000  0x01  0x03 RWX Bypass
        0x40000000  0x40000000  0x01  0x03 RWX Bypass
        0x60000000  0x60000000  0x01  0x03 RWX Bypass
        0x80000000  0x80000000  0x01  0x03 RWX Bypass
        0xa0000000  0xa0000000  0x01  0x03 RWX Bypass
        0xc0000000  0xc0000000  0x01  0x03 RWX Bypass
        0xe0000000  0xe0000000  0x01  0x03 RWX Bypass

This patch adds remapping code at the reset vector or at the kernel
_start (depending on CONFIG_INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX) that
reconfigures MMUv3 as MMUv2:

Way 5 (128 MB)
        Vaddr       Paddr       ASID  Attr RWX Cache
        ----------  ----------  ----  ---- --- -------
        0xd0000000  0x00000000  0x01  0x07 RWX WB
        0xd8000000  0x00000000  0x01  0x03 RWX Bypass
Way 6 (256 MB)
        Vaddr       Paddr       ASID  Attr RWX Cache
        ----------  ----------  ----  ---- --- -------
        0xe0000000  0xf0000000  0x01  0x07 RWX WB
        0xf0000000  0xf0000000  0x01  0x03 RWX Bypass

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

3 files changed, 113 insertions, 53 deletions

diff --git a/arch/xtensa/boot/boot-elf/Makefile b/arch/xtensa/boot/boot-elf/Makefile
index 1fe01b78c124..89db089f5a12 100644
--- a/arch/xtensa/boot/boot-elf/Makefile
+++ b/arch/xtensa/boot/boot-elf/Makefile
@@ -12,6 +12,7 @@ endif
 
 export OBJCOPY_ARGS
 export CPPFLAGS_boot.lds += -P -C
+export KBUILD_AFLAGS += -mtext-section-literals
 
 boot-y		:= bootstrap.o
 
diff --git a/arch/xtensa/boot/boot-elf/boot.lds.S b/arch/xtensa/boot/boot-elf/boot.lds.S
index 7b646e0a6486..932b58ef33d4 100644
--- a/arch/xtensa/boot/boot-elf/boot.lds.S
+++ b/arch/xtensa/boot/boot-elf/boot.lds.S
@@ -1,41 +1,29 @@
-#include <variant/core.h>
+/*
+ *  linux/arch/xtensa/boot/boot-elf/boot.lds.S
+ *
+ *  Copyright (C) 2008 - 2013 by Tensilica Inc.
+ *
+ *  Chris Zankel <chris@zankel.net>
+ *  Marc Gauthier <marc@tensilica.com
+ *  Pete Delaney <piet@tensilica.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <asm/vectors.h>
 OUTPUT_ARCH(xtensa)
 ENTRY(_ResetVector)
 
 SECTIONS
 {
-	.start 0xD0000000 : { *(.start) }
-
-	.text 0xD0000000:
-	{
-		__reloc_start = . ;
-		_text_start = . ;
-		*(.literal .text.literal .text)
-		_text_end = . ;
-	}
-
-	.rodata ALIGN(0x04):
-	{
-		*(.rodata)
-		*(.rodata1)
-	}
-
-	.data ALIGN(0x04):
+	.ResetVector.text XCHAL_RESET_VECTOR_VADDR :
 	{
-		*(.data)
-		*(.data1)
-		*(.sdata)
-		*(.sdata2)
-		*(.got.plt)
-		*(.got)
-		*(.dynamic)
+		*(.ResetVector.text)
 	}
 
-	__reloc_end = . ;
-
-	. = ALIGN(0x10);
-	__image_load = . ;
-	.image 0xd0001000:
+	.image KERNELOFFSET: AT (LOAD_MEMORY_ADDRESS)
 	{
 		_image_start = .;
 		*(image)
@@ -43,7 +31,6 @@ SECTIONS
 		_image_end = .	;
 	}
 
-
 	.bss ((LOADADDR(.image) + SIZEOF(.image) + 3) & ~ 3):
 	{
 		__bss_start = .;
@@ -53,14 +40,15 @@ SECTIONS
 		*(.bss)
 		__bss_end = .;
 	}
-	_end = .;
-	_param_start = .;
 
-	.ResetVector.text XCHAL_RESET_VECTOR_VADDR :
+	/*
+	 * This is a remapped copy of the Reset Vector Code.
+	 * It keeps gdb in sync with the PC after switching
+	 * to the temporary mapping used while setting up
+	 * the V2 MMU mappings for Linux.
+	 */
+	.ResetVector.remapped_text 0x46000000 (INFO):
 	{
-		*(.ResetVector.text)
+		*(.ResetVector.remapped_text)
 	}
-
-
-	PROVIDE (end = .);
 }
diff --git a/arch/xtensa/boot/boot-elf/bootstrap.S b/arch/xtensa/boot/boot-elf/bootstrap.S
index 464298bc348b..1388a499753b 100644
--- a/arch/xtensa/boot/boot-elf/bootstrap.S
+++ b/arch/xtensa/boot/boot-elf/bootstrap.S
@@ -1,18 +1,77 @@
+/*
+ * arch/xtensa/boot/boot-elf/bootstrap.S
+ *
+ * Low-level exception handling
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2004 - 2013 by Tensilica Inc.
+ *
+ * Chris Zankel <chris@zankel.net>
+ * Marc Gauthier <marc@tensilica.com>
+ * Piet Delaney <piet@tensilica.com>
+ */
 
 #include <asm/bootparam.h>
+#include <asm/processor.h>
+#include <asm/pgtable.h>
+#include <asm/page.h>
+#include <asm/cacheasm.h>
+#include <asm/initialize_mmu.h>
+#include <linux/linkage.h>
 
-
-/* ResetVector
- */
-	.section        .ResetVector.text, "ax"
+	.section	.ResetVector.text, "ax"
 	.global         _ResetVector
+	.global         reset
+
 _ResetVector:
-	_j reset
+	_j _SetupMMU
+
+	.begin  no-absolute-literals
+	.literal_position
+
 	.align 4
 RomInitAddr:
-	.word 0xd0001000
+#if defined(CONFIG_INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX) && \
+	XCHAL_HAVE_PTP_MMU && XCHAL_HAVE_SPANNING_WAY
+	.word 0x00003000
+#else
+	.word 0xd0003000
+#endif
 RomBootParam:
 	.word _bootparam
+_bootparam:
+	.short	BP_TAG_FIRST
+	.short	4
+	.long	BP_VERSION
+	.short	BP_TAG_LAST
+	.short	0
+	.long	0
+
+	.align  4
+_SetupMMU:
+	movi	a0, 0
+	wsr	a0, windowbase
+	rsync
+	movi	a0, 1
+	wsr	a0, windowstart
+	rsync
+	movi	a0, 0x1F
+	wsr	a0, ps
+	rsync
+
+	Offset = _SetupMMU - _ResetVector
+
+#ifndef CONFIG_INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
+	initialize_mmu
+#endif
+
+	.end    no-absolute-literals
+
+	rsil    a0, XCHAL_DEBUGLEVEL-1
+	rsync
 reset:
 	l32r    a0, RomInitAddr
 	l32r	a2, RomBootParam
@@ -21,13 +80,25 @@ reset:
 	jx      a0
 
 	.align 4
-	.section .bootstrap.data, "aw"
 
-	.globl _bootparam
-_bootparam:
-	.short	BP_TAG_FIRST
-	.short	4
-	.long	BP_VERSION
-	.short	BP_TAG_LAST
-	.short	0
-	.long	0
+	.section	.ResetVector.remapped_text, "x"
+	.global         _RemappedResetVector
+
+	/* Do org before literals */
+	.org 0
+
+_RemappedResetVector:
+	.begin  no-absolute-literals
+	.literal_position
+
+	_j	_RemappedSetupMMU
+
+	/* Position Remapped code at the same location as the original code */
+	. = _RemappedResetVector + Offset
+
+_RemappedSetupMMU:
+#ifndef CONFIG_INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
+	initialize_mmu
+#endif
+
+	.end    no-absolute-literals