Until now, we have always entered the spu page fault handler
with a mutex for the spu context held. This has multiple
bad side-effects:
- it becomes impossible to suspend the context during
  page faults
- if an spu program attempts to access its own mmio
  areas through DMA, we get an immediate livelock when
  the nopage function tries to acquire the same mutex

This patch makes the page fault logic operate on a
struct spu_context instead of a struct spu, and moves it
from spu_base.c to a new file fault.c inside of spufs.

We now also need to copy the dar and dsisr contents
of the last fault into the saved context to have it
accessible in case we schedule out the context before
activating the page fault handler.
Signed-off-by: NArnd Bergmann <arnd.bergmann@de.ibm.com>

This change adds a read accessor for the SPE problem-state run control
register.

This is required for for applying (userspace) changes made to the run
control register while the SPE is stopped - simply asserting the master
run control bit is not sufficient. My next patch for isolated-mode
setup requires this.
Signed-off-by: NJeremy Kerr <jk@ozlabs.org>
Signed-off-by: NArnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

When the user changes the runcontrol register, an SPU might be
running without a process being attached to it and waiting for
events. In order to prevent this, make sure we always disable
the priv1 master control when we're not inside of spu_run.
Signed-off-by: NArnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

The /lslr file gives read access to the SPU_LSLR register in hex; 0x3fff
for example The /dma_info file provides read access to the SPU Command
Queue in a binary format. The /proxydma_info files provides read access
access to the Proxy Command Queue in a binary format. The spu_info.h
file provides data structures for interpreting the binary format of
/dma_info and /proxydma_info.
Signed-off-by: NDwayne Grant McConnell <decimal@us.ibm.com>
Signed-off-by: NArnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Signed-off-by: NJörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

This patch adds a new file called 'mfc' to each spufs directory.
The file accepts DMA commands that are a subset of what would
be legal DMA commands for problem state register access. Upon
reading the file, a bitmask is returned with the completed
tag groups set.

The file is meant to be used from an abstraction in libspe
that is added by a different patch.

From the kernel perspective, this means a process can now
offload a memory copy from or into an SPE local store
without having to run code on the SPE itself.

The transfer will only be performed while the SPE is owned
by one thread that is waiting in the spu_run system call
and the data will be transferred into that thread's
address space, independent of which thread started the
transfer.
Signed-off-by: NArnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Handling mailbox interrupts was broken in multiple respects,
the combination of which was hiding the bugs most of the time.

- The ibox interrupt mask was open initially even though there
  are no waiters on a newly created SPU.

- Acknowledging the mailbox interrupt did not work because
  it is level triggered and the mailbox data is never retrieved
  from inside the interrupt handler.

- The interrupt handler delivered interrupts with a disabled
  mask if another interrupt is triggered for the same class
  but a different mask.

- The poll function did not enable the interrupt if it had not
  been enabled, so we might run into the poll timeout if none of
  the other bugs saved us and no signal was delivered.

We probably still have a similar problem with blocking
read/write on mailbox files, but that will result in extra
wakeup in the worst case, not in incorrect behaviour.
Signed-off-by: NArnd Bergmann <arndb@de.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

This patch makes it easier to preempt an SPU context by
having the scheduler hold ctx->state_sema for much shorter
periods of time.

As part of this restructuring, the control logic for the "run"
operation is moved from arch/ppc64/kernel/spu_base.c to
fs/spufs/file.c.  Of course the base retains "bottom half"
handlers for class{0,1} irqs.  The new run loop will re-acquire
an SPU if preempted.

From: Mark Nutter <mnutter@us.ibm.com>
Signed-off-by: NArnd Bergmann <arndb@de.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

This adds a scheduler for SPUs to make it possible to use
more logical SPUs than physical ones are present in the
system.

Currently, there is no support for preempting a running
SPU thread, they have to leave the SPU by either triggering
an event on the SPU that causes it to return to the
owning thread or by sending a signal to it.

This patch also adds operations that enable accessing an SPU
in either runnable or saved state. We use an RW semaphore
to protect the state of the SPU from changing underneath
us, while we are holding it readable. In order to change
the state, it is acquired writeable and a context save
or restore is executed before downgrading the semaphore
to read-only.

From: Mark Nutter <mnutter@us.ibm.com>,
      Uli Weigand <Ulrich.Weigand@de.ibm.com>
Signed-off-by: NArnd Bergmann <arndb@de.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>