Upon inspection of the implementation specific registers, it was
discovered that the high bit of the implementation specific RXCTL
register was enabled, which enables the DEADB00F debug feature.

The debug feature causes MMIO reads to a disabled AFU to respond with
0xDEADB00F instead of all Fs. In general this should not be visible as
the kernel will only allow MMIO access to enabled AFUs, but there may be
some circumstances where an AFU may become disabled while it is use.
One such case would be an AFU designed to only be used in the dedicated
process mode and to disable itself after it has completed it's work
(however even in that case the effects of this debug flag would be
limited as the userspace application must have completed any required
MMIO accesses before the AFU disables itself with or without the flag).

This patch removes the debug flag and replaces the magic value
programmed into this register with a preprocessor define so it is
clearer what the rest of this initialisation does.
Signed-off-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

If we need to force detach a context (e.g. due to EEH or simply force
unbinding the driver) we should prevent the userspace contexts from
being able to access the Problem State Area MMIO region further, which
they may have mapped with mmap().

This patch unmaps any mapped MMIO regions when detaching a userspace
context.

Cc: stable@vger.kernel.org
Signed-off-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

We had a known sleep while atomic bug if a CXL device was forcefully
unbound while it was in use. This could occur as a result of EEH, or
manually induced with something like this while the device was in use:

echo 0000:01:00.0 > /sys/bus/pci/drivers/cxl-pci/unbind

The issue was that in this code path we iterated over each context and
forcefully detached it with the contexts_lock spin lock held, however
the detach also needed to take the spu_mutex, and call schedule.

This patch changes the contexts_lock to a mutex so that we are not in
atomic context while doing the detach, thereby avoiding the sleep while
atomic.

Also delete the related TODO comment, which suggested an alternate
solution which turned out to not be workable.

Cc: stable@vger.kernel.org
Signed-off-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Currently all interrupts generated by cxl are named "cxl".  This is not very
informative as we can't distinguish between cards, AFUs, error interrupts, user
contexts and user interrupts numbers.  Being able to distinguish them is useful
for setting affinity.

This patch gives each of these names in /proc/interrupts.

A two card CAPI system, with afu0.0 having 2 active contexts each with 4 user
IRQs each, will now look like this:

    % grep cxl /proc/interrupts
    444:          0  OPAL ICS 141312 Level     cxl-card1-err
    445:          0  OPAL ICS 141313 Level     cxl-afu1.0-err
    446:          0  OPAL ICS 141314 Level     cxl-afu1.0
    462:          0  OPAL ICS 2052 Level     cxl-afu0.0-pe0-1
    463:      75517  OPAL ICS 2053 Level     cxl-afu0.0-pe0-2
    468:          0  OPAL ICS 2054 Level     cxl-afu0.0-pe0-3
    469:          0  OPAL ICS 2055 Level     cxl-afu0.0-pe0-4
    470:          0  OPAL ICS 2056 Level     cxl-afu0.0-pe1-1
    471:      75506  OPAL ICS 2057 Level     cxl-afu0.0-pe1-2
    472:          0  OPAL ICS 2058 Level     cxl-afu0.0-pe1-3
    473:          0  OPAL ICS 2059 Level     cxl-afu0.0-pe1-4
    502:       1066  OPAL ICS 2050 Level     cxl-afu0.0
    514:          0  OPAL ICS 2048 Level     cxl-card0-err
    515:          0  OPAL ICS 2049 Level     cxl-afu0.0-err
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

If an AFU has a hardware bug that causes it to acknowledge a context
terminate or remove while that context has outstanding transactions, it
is possible for the kernel to receive an interrupt for that context
after we have removed it from the context list.

The kernel will not be able to demultiplex the interrupt (or worse - if
we have already reallocated the process handle we could mis-attribute it
to the new context), and printed a big scary warning.

It did not acknowledge the interrupt, which would effectively halt
further translation fault processing on the PSL.

This patch makes the warning clearer about the likely cause of the issue
(i.e. hardware bug) to make it obvious to future AFU designers of what
needs to be fixed. It also prints out the process handle which can then
be matched up with hardware and software traces for debugging.

It also acknowledges the interrupt to the PSL with either an address
error or acknowledge, so that the PSL can continue with other
translations.
Signed-off-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently all interrupts generated by cxl are named "cxl".  This is not very
informative as we can't distinguish between cards, AFUs, error interrupts, user
contexts and user interrupts numbers.  Being able to distinguish them is useful
for setting affinity.

This patch gives each of these names in /proc/interrupts.

A two card CAPI system, with afu0.0 having 2 active contexts each with 4 user
IRQs each, will now look like this:

    % grep cxl /proc/interrupts
    444:          0  OPAL ICS 141312 Level     cxl-card1-err
    445:          0  OPAL ICS 141313 Level     cxl-afu1.0-err
    446:          0  OPAL ICS 141314 Level     cxl-afu1.0
    462:          0  OPAL ICS 2052 Level     cxl-afu0.0-pe0-1
    463:      75517  OPAL ICS 2053 Level     cxl-afu0.0-pe0-2
    468:          0  OPAL ICS 2054 Level     cxl-afu0.0-pe0-3
    469:          0  OPAL ICS 2055 Level     cxl-afu0.0-pe0-4
    470:          0  OPAL ICS 2056 Level     cxl-afu0.0-pe1-1
    471:      75506  OPAL ICS 2057 Level     cxl-afu0.0-pe1-2
    472:          0  OPAL ICS 2058 Level     cxl-afu0.0-pe1-3
    473:          0  OPAL ICS 2059 Level     cxl-afu0.0-pe1-4
    502:       1066  OPAL ICS 2050 Level     cxl-afu0.0
    514:          0  OPAL ICS 2048 Level     cxl-card0-err
    515:          0  OPAL ICS 2049 Level     cxl-afu0.0-err
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

If an AFU has a hardware bug that causes it to acknowledge a context
terminate or remove while that context has outstanding transactions, it
is possible for the kernel to receive an interrupt for that context
after we have removed it from the context list.

The kernel will not be able to demultiplex the interrupt (or worse - if
we have already reallocated the process handle we could mis-attribute it
to the new context), and printed a big scary warning.

It did not acknowledge the interrupt, which would effectively halt
further translation fault processing on the PSL.

This patch makes the warning clearer about the likely cause of the issue
(i.e. hardware bug) to make it obvious to future AFU designers of what
needs to be fixed. It also prints out the process handle which can then
be matched up with hardware and software traces for debugging.

It also acknowledges the interrupt to the PSL with either an address
error or acknowledge, so that the PSL can continue with other
translations.
Signed-off-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This is the core of the cxl driver.

It adds support for using cxl cards in the powernv environment only (ie POWER8
bare metal). It allows access to cxl accelerators by userspace using the
/dev/cxl/afuM.N char devices.

The kernel driver has no knowledge of the function implemented by the
accelerator. It provides services to userspace via the /dev/cxl/afuM.N
devices. When a program opens this device and runs the start work IOCTL, the
accelerator will have coherent access to that processes memory using the same
virtual addresses. That process may mmap the device to access any MMIO space
the accelerator provides.  Also, reads on the device will allow interrupts to
be received. These services are further documented in a later patch in
Documentation/powerpc/cxl.txt.

Documentation of the cxl hardware architecture and userspace API is provided in
subsequent patches.
Signed-off-by: NIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>