Previously we were masking the PMB DATA array values with the value of
__MEMORY_START | PMB_V, which misses some PFN bits off the mask.
Signed-off-by: NMatt Fleming <matt@console-pimps.org>

All of the regular CPU init path needs to be __cpuinit annotated for CPU
hotplug.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This implements a bit of rework for the PMB code, which permits us to
kill off the legacy PMB mode completely. Rather than trusting the boot
loader to do the right thing, we do a quick verification of the PMB
contents to determine whether to have the kernel setup the initial
mappings or whether it needs to mangle them later on instead.

If we're booting from legacy mappings, the kernel will now take control
of them and make them match the kernel's initial mapping configuration.
This is accomplished by breaking the initialization phase out in to
multiple steps: synchronization, merging, and resizing. With the recent
rework, the synchronization code establishes page links for compound
mappings already, so we build on top of this for promoting mappings and
reclaiming unused slots.

At the same time, the changes introduced for the uncached helpers also
permit us to dynamically resize the uncached mapping without any
particular headaches. The smallest page size is more than sufficient for
mapping all of kernel text, and as we're careful not to jump to any far
off locations in the setup code the mapping can safely be resized
regardless of whether we are executing from it or not.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This adds some helper routines for uncached mapping support. This
simplifies some of the cases where we need to check the uncached mapping
boundaries in addition to giving us a centralized location for building
more complex manipulation on top of.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

Some overdue cleanup of the PMB code, killing off unused functionality
and duplication sprinkled about the tree.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This provides a variable for tracking the uncached mapping size, and uses
it for pretty printing the uncached lowmem range. Beyond this, we'll also
be building on top of this for figuring out from where the remainder of
P2 becomes usable when constructing unrelated mappings.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This effectively neutralizes P2 by getting rid of P1 identity mapping
for all available memory and instead only establishes a single unbuffered
PMB entry (16MB -- the smallest available) that covers the kernel.

As using segmentation for abusing caching attributes in drivers is no
longer supported (and there are no drivers that can be enabled in 32-bit
mode that do this), this provides us with all of the uncached access
needs by the kernel itself.

Drivers and their ilk need to specify their caching attributes when
remapping through page tables, as usual.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

All of the cached/uncached mapping setup is duplicated for each size, and
also misses out on the 16MB case. Rather than duplicating the same iter
code for that we just consolidate it in to a helper macro that builds an
iter for each size. The 16MB case is then trivially bolted on at the end.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

More and more boards are going to start shipping that boot with the MMU
in 32BIT mode by default. Previously we relied on the bootloader to
setup PMB mappings for use by the kernel but we also need to cater for
boards whose bootloaders don't set them up.

If CONFIG_PMB_LEGACY is not enabled we have full control over our PMB
mappings and can compress our address space. Usually, the distance
between the the cached and uncached mappings of RAM is always 512MB,
however we can compress the distance to be the amount of RAM on the
board.

pmb_init() now becomes much simpler. It no longer has to calculate any
mappings, it just has to synchronise the software PMB table with the
hardware.

Tested on SDK7786 and SH7785LCR.
Signed-off-by: NMatt Fleming <matt@console-pimps.org>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This introduces some much overdue chainsawing of the fixed PMB support.
fixed PMB was introduced initially to work around the fact that dynamic
PMB mode was relatively broken, though they were never intended to
converge. The main areas where there are differences are whether the
system is booted in 29-bit mode or 32-bit mode, and whether legacy
mappings are to be preserved. Any system booting in true 32-bit mode will
not care about legacy mappings, so these are roughly decoupled.

Regardless of the entry point, PMB and 32BIT are directly related as far
as the kernel is concerned, so we also switch back to having one select
the other.

With legacy mappings iterated through and applied in the initialization
path it's now possible to finally merge the two implementations and
permit dynamic remapping overtop of remaining entries regardless of
whether boot mappings are crafted by hand or inherited from the boot
loader.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

CONFIG_PMB will eventually allow the MMU to be switched between 29-bit
and 32-bit mode dynamically at runtime.
Signed-off-by: NMatt Fleming <matt@console-pimps.org>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This has the consequence of changing the section name use for head
code from ".text.head" to ".head.text".  Since this commit changes all
users in the architecture, this change should be harmless.
Signed-off-by: NTim Abbott <tabbott@mit.edu>
Cc: Paul Mundt <lethal@linux-sh.org>
Acked-by: NSam Ravnborg <sam@ravnborg.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This enables the same functionality that sh64 has for sh32. When running
on simulated hardware or via remote memory via the debug interface,
memory is gauranteed to be zero on boot already, and skipping the zeroing
of BSS has measurable boot time benefits.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

When using initramfs on systems that don't explicitly clear LOADER_TYPE,
unpack_to_rootfs() tramples tramples the range with the defaults taken
out of .empty_zero_page. This causes kernels with valid initramfs images
to bail out with crc or gzip magic mismatch errors after the second
unpack takes place on certain platform configurations.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

Shoves a magic word in to the empty_zero_page section for the
bootloader to work out whether to start the kernel in 29-bit
or 32-bit mode.

[ Renesas CPUs already take care of the initial PMB mappings entirely
  in hardware and decide on 29-bit/32-bit physical depending on which
  pin powered up the CPU, so this is mostly for ST parts. -- PFM ].
Signed-off-by: NStuart Menefy <stuart.menefy@st.com>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

There was a very preliminary bunch of SMP code scattered around for the
SH7604 microcontrollers from way back when, and it has mostly suffered
bitrot since then. With the tree already having been slowly getting
prepped for SMP, this plugs in most of the remaining platform-independent
bits.
Signed-off-by: NMagnus Damm <damm@igel.co.jp>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

Follow Al Viro's m68k change from l-k:

	i.e. tell modpost that entry point code (that has to be outside
	of .init.text for external reasons) is OK to refer to .init.*

Shuts up some section mismatch warnings from modpost.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

There were a number of places that made evil PAGE_SIZE == 4k
assumptions that ended up breaking when trying to play with
8k and 64k page sizes, this fixes those up.

The most significant change is the way we load THREAD_SIZE,
previously this was done via:

	mov	#(THREAD_SIZE >> 8), reg
	shll8	reg

to avoid a memory access and allow the immediate load. With
a 64k PAGE_SIZE, we're out of range for the immediate load
size without resorting to special instructions available in
later ISAs (movi20s and so on). The "workaround" for this is
to bump up the shift to 10 and insert a shll2, which gives a
bit more flexibility while still being much cheaper than a
memory access.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This splits out common bits from the existing exception handler for
use between SH-2/SH-2A and SH-3/4, and adds support for the SH-2/2A
exceptions.
Signed-off-by: NYoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This enables support for 4K stacks on SH.

Currently this depends on DEBUG_KERNEL, but likely all boards
will switch to this as the default in the future.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This adds a DEBUG_STACK_USAGE and DEBUG_STACKOVERFLOW for SH.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

A synco is needed before we jump to start_kernel().

While we're at it, also move the sh_cpu_init() jump until after
we've zeroed BSS, as this has caused some undesirable results
in sh_cpu_init().
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

We had a special .stack section in the ld script that
was being used to position r15 initially. This is
nonsensical, as we can just use a THREAD_SIZE offset
from the init_thread_union instead (as every other arch
does).
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!