UltraSPARC has special sets of global registers which are switched to
for certain trap types.  There is one set for MMU related traps, one
set of Interrupt Vector processing, and another set (called the
Alternate globals) for all other trap types.

For what seems like forever we've hard coded the values in some of
these trap registers.  Some examples include:

1) Interrupt Vector global %g6 holds current processors interrupt
   work struct where received interrupts are managed for IRQ handler
   dispatch.

2) MMU global %g7 holds the base of the page tables of the currently
   active address space.

3) Alternate global %g6 held the current_thread_info() value.

Such hardcoding has resulted in some serious issues in many areas.
There are some code sequences where having another register available
would help clean up the implementation.  Taking traps such as
cross-calls from the OBP firmware requires some trick code sequences
wherein we have to save away and restore all of the special sets of
global registers when we enter/exit OBP.

We were also using the IMMU TSB register on SMP to hold the per-cpu
area base address, which doesn't work any longer now that we actually
use the TSB facility of the cpu.

The implementation is pretty straight forward.  One tricky bit is
getting the current processor ID as that is different on different cpu
variants.  We use a stub with a fancy calling convention which we
patch at boot time.  The calling convention is that the stub is
branched to and the (PC - 4) to return to is in register %g1.  The cpu
number is left in %g6.  This stub can be invoked by using the
__GET_CPUID macro.

We use an array of per-cpu trap state to store the current thread and
physical address of the current address space's page tables.  The
TRAP_LOAD_THREAD_REG loads %g6 with the current thread from this
table, it uses __GET_CPUID and also clobbers %g1.

TRAP_LOAD_IRQ_WORK is used by the interrupt vector processing to load
the current processor's IRQ software state into %g6.  It also uses
__GET_CPUID and clobbers %g1.

Finally, TRAP_LOAD_PGD_PHYS loads the physical address base of the
current address space's page tables into %g7, it clobbers %g1 and uses
__GET_CPUID.

Many refinements are possible, as well as some tuning, with this stuff
in place.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The change to kernel/sched.c's init code to use for_each_cpu()
requires that the cpu_possible_map be setup much earlier.

Set it up via setup_arch(), constrained to NR_CPUS, and later
constrain it to max_cpus in smp_prepare_cpus().

This fixes SMP booting on sparc64.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

From: Eddie C. Dost <ecd@brainaid.de>

I have the following patch for serial console over the RSC
(remote system controller) on my E250 machine. It basically adds
support for input-device=rsc and output-device=rsc from OBP, and
allows 115200,8,n,1,- serial mode setting.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Noticed by Tom 'spot' Callaway.

Even on uniprocessor we always reported the number of physical
cpus in the system via /proc/cpuinfo.  But when this got changed
to use num_possible_cpus() it always reads as "1" on uniprocessor.
This change was unintentional.

So scan the firmware device tree and count the number of cpu
nodes, and report that, as we always did.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

sparc64 prom_callback and new_setup_frame32 each operates on a user page
table without holding lock, and no doubt they've good reason.  But I'd
feel more confident if they were to do a "pte = *ptep" and then operate
on pte, rather than re-evaluating *ptep.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Instead of code patching to handle the page size fields in
the context registers, just use variables from which we get
the proper values.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Also, move prom_probe_memory() into arch/sparc64/mm/init.c
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

At boot time, determine the D-cache, I-cache and E-cache size and
line-size.  Use them in cache flushes when appropriate.

This change was motivated by discovering that the D-cache on
UltraSparc-IIIi and later are 64K not 32K, and the flushes done by the
Cheetah error handlers were assuming a 32K size.

There are still some pieces of code that are hard coding things and
will need to be fixed up at some point.

While we're here, fix the D-cache and I-cache parity error handlers
to run with interrupts disabled, and when the trap occurs at trap
level > 1 log the event via a counter displayed in /proc/cpuinfo.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

'highest_paddr' is set, but never actually used.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Instead of all of this cpu-specific code to remap the kernel
to the correct location, use portable firmware calls to do
this instead.

What we do now is the following in position independant
assembler:

	chosen_node = prom_finddevice("/chosen");
	prom_mmu_ihandle_cache = prom_getint(chosen_node, "mmu");
	vaddr = 4MB_ALIGN(current_text_addr());
	prom_translate(vaddr, &paddr_high, &paddr_low, &mode);
	prom_boot_mapping_mode = mode;
	prom_boot_mapping_phys_high = paddr_high;
	prom_boot_mapping_phys_low = paddr_low;
	prom_map(-1, 8 * 1024 * 1024, KERNBASE, paddr_low);

and that replaces the massive amount of by-hand TLB probing and
programming we used to do here.

The new code should also handle properly the case where the kernel
is mapped at the correct address already (think: future kexec
support).

Consequently, the bulk of remap_kernel() dies as does the entirety
of arch/sparc64/prom/map.S

We try to share some strings in the PROM library with the ones used
at bootup, and while we're here mark input strings to oplib.h routines
with "const" when appropriate.

There are many more simplifications now possible.  For one thing, we
can consolidate the two copies we now have of a lot of cpu setup code
sitting in head.S and trampoline.S.

This is a significant step towards CONFIG_DEBUG_PAGEALLOC support.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We can put the __softirq_pending mask in the cpudata,
no need for the silly NR_CPUS array in kernel/softirq.c
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Removed sparc64 architecture specific users of asm/segment.h and
asm-sparc64/segment.h itself
Signed-off-by: NKumar Gala <kumar.gala@freescale.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Older UltraSPARC-III chips have a P-Cache bug that makes us disable it
by default at boot time.

However, this does hurt performance substantially, particularly with
memcpy(), and the bug is _incredibly_ obscure.  I have never seen it
triggered in practice, ever.

So provide a "-P" boot option that forces the P-Cache on.  It taints
the kernel, so if it does trigger and cause some data corruption or
OOPS, we will find out in the logs that this option was on when it
happened.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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!