docs: move xtensa documentation under Documentation/arch/

Architecture-specific documentation is being moved into Documentation/arch/
as a way of cleaning up the top-level documentation directory and making
the docs hierarchy more closely match the source hierarchy. Move
Documentation/xtensa into arch/ and fix all in-tree references.

Cc: Chris Zankel <chris@zankel.net>
Reviewed-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

xtensa: drop extraneous register load from initialize_mmu

Commit a9f2fc628e3a ("xtensa: cleanup MMU setup and kernel layout macros")
removed the use of a2 in the beginning of the initialize_mmu macro, but
left the register load that is no longer used. Remove it as well.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: initialize_mmu.h: fix a duplicated word

Change "The the" to "For the".

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: linux-xtensa@linux-xtensa.org
Message-Id: <20200721210044.15458-1-rdunlap@infradead.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

mm: introduce include/linux/pgtable.h

The include/linux/pgtable.h is going to be the home of generic page table
manipulation functions.

Start with moving asm-generic/pgtable.h to include/linux/pgtable.h and
make the latter include asm/pgtable.h.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/20200514170327.31389-3-rppt@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

xtensa: move MPU constants from .data to .ref.rodata

MPU attribute mapping table is R/O, move it from .data to __REFCONST
(as the rest of the _startup code where initialize_cacheattr is used is
in the __REF section). This allows executing initialize_cacheattr before
the data section of the XIP kernel is relocated to its place.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

docs: xtensa: convert to ReST

Rename the xtensa documentation files to ReST, add an
index for them and adjust in order to produce a nice html
output via the Sphinx build system.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

xtensa: implement initialize_cacheattr for MPU cores

Use CONFIG_MEMMAP_CACHEATTR to initialize MPU as described in the Xtensa
LSP RM document. Coalesce adjacent regions with the same cacheattr.
Update Kconfig help text.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: replace variant/core.h with asm/core.h

Introduce the header arch/xtensa/include/asm/core.h that provides
definitions for XCHAL macros missing in older xtensa releases. Use this
header instead of variant/core.h

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: rework noMMU cache attributes initialization

Marking default memory region as cached is not always sufficient and is
not flexible. Allow specifying cache attributes for the whole memory
address space with new config entry MEMMAP_CACHEATTR. Apply it after
cache initialization.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: cleanup MMU setup and kernel layout macros

Make kernel load address explicit, independent of the selected MMU
configuration and configurable from Kconfig. Do not restrict it to the
first 512MB of the physical address space.

Cleanup kernel memory layout macros:

- rename VECBASE_RESET_VADDR to VECBASE_VADDR, XC_VADDR to VECTOR_VADDR;
- drop VIRTUAL_MEMORY_ADDRESS and LOAD_MEMORY_ADDRESS;
- introduce PHYS_OFFSET and use it in __va and __pa definitions;
- synchronize MMU/noMMU vectors, drop unused NMI vector;
- replace hardcoded vectors offset of 0x3000 with Kconfig symbol.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: add alternative kernel memory layouts

MMUv3 is able to support low memory bigger than 128MB.
Implement 256MB and 512MB KSEG layouts:

- add Kconfig selector for KSEG layout;
- add KSEG base address, size and alignment definitions to
arch/xtensa/include/asm/kmem_layout.h;
- use new definitions in TLB initialization;
- add build time memory map consistency checks.

See Documentation/xtensa/mmu.txt for the details of new memory layouts.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: fix build for configs without cache options

- make cache-related assembly macros empty if core doesn't have
corresponding cache type;
- don't initialize cache attributes in instruction/data TLB entries if
there's no corresponding cache type.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: nommu: set up cache and atomctl in initialize_mmu

initialize_mmu sets up atomctl SR which is needed for s32c1i to function
correctly even in noMMU configurations. It's also a good place to set up
caching attributes of physical memory.

Allow enabling INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX in noMMU
configurations for setting up atomctl and cache attributes.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: move vecbase SR initialization to _startup

Instead of initializing vecbase in initialize_mmu macro, which may be
expanded either in Image.elf reset vector hadler or in the kernel
head.S, both times only when CONFIG_MMU is enabled, do this
initialization once in _startup function.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: remap io area defined in device tree

Use the simple-bus node to discover the io area, and remap the cached and
bypass io ranges. The parent-bus-address value of the first triplet in the
"ranges" property is used. This value is rounded down to the nearest 256MB
boundary. The length of the io area is fixed at 256MB; the "ranges" property
length value is ignored.

Other limitations: (1) only the first simple-bus node is considered, and (2)
only the first triplet of the "ranges" property is considered.

See ePAPR 1.1 §6.5 for the simple-bus node description, and §2.3.8 for the
"ranges" property description.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

xtensa: avoid duplicate of IO range definitions

Define IO addresses in a single place, to make it easier to change for
non-standard memory maps.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

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>

xtensa: initialize atomctl SR

In order to use S32C1I instruction on cores with ATOMCTL SR the register
must be properly initialized.

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