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Commit e85e335f authored by Max Filippov's avatar Max Filippov Committed by Chris Zankel
Browse files

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: default avatarMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: default avatarChris Zankel <chris@zankel.net>
parent d83ff0bb

arch/xtensa/Kconfig

+29 −0
Original line number Diff line number Diff line
@@ -103,6 +103,35 @@ config MATH_EMULATION 
	help

	Can we use information of configuration file?



config INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX

	bool "Initialize Xtensa MMU inside the Linux kernel code"

	default y

	help

	  Earlier version initialized the MMU in the exception vector

	  before jumping to _startup in head.S and had an advantage that

	  it was possible to place a software breakpoint at 'reset' and

	  then enter your normal kernel breakpoints once the MMU was mapped

	  to the kernel mappings (0XC0000000).



	  This unfortunately doesn't work for U-Boot and likley also wont

	  work for using KEXEC to have a hot kernel ready for doing a

	  KDUMP.



	  So now the MMU is initialized in head.S but it's necessary to

	  use hardware breakpoints (gdb 'hbreak' cmd) to break at _startup.

	  xt-gdb can't place a Software Breakpoint in the  0XD region prior

	  to mapping the MMU and after mapping even if the area of low memory

	  was mapped gdb wouldn't remove the breakpoint on hitting it as the

	  PC wouldn't match. Since Hardware Breakpoints are recommended for

	  Linux configurations it seems reasonable to just assume they exist

	  and leave this older mechanism for unfortunate souls that choose

	  not to follow Tensilica's recommendation.



	  Selecting this will cause U-Boot to set the KERNEL Load and Entry

	  address at 0x00003000 instead of the mapped std of 0xD0003000.



	  If in doubt, say Y.



endmenu



config XTENSA_CALIBRATE_CCOUNT

arch/xtensa/boot/boot-elf/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ endif 


export OBJCOPY_ARGS

export CPPFLAGS_boot.lds += -P -C

export KBUILD_AFLAGS += -mtext-section-literals



boot-y		:= bootstrap.o

arch/xtensa/boot/boot-elf/boot.lds.S

+26 −38
Original line number Diff line number Diff line 
#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 = .);

}

arch/xtensa/boot/boot-elf/bootstrap.S

+86 −15
Original line number Diff line number Diff line 
/*

 * 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"

	.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

arch/xtensa/boot/boot-uboot/Makefile

+5 −1
Original line number Diff line number Diff line
@@ -4,7 +4,11 @@ 
# for more details.

#



UIMAGE_LOADADDR = 0xd0001000

ifdef CONFIG_INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX

UIMAGE_LOADADDR = 0x00003000

else

UIMAGE_LOADADDR = 0xd0003000

endif

UIMAGE_COMPRESSION = gzip



$(obj)/../uImage: vmlinux.bin.gz FORCE