commit 1bdc0293901cbea23c6dc29432e81919d4719844 upstream.

Change return value to 0 if no device is bound since
unsigned int cannot support negative error codes.

Fixes: f18e7a068 ("iio: Return -ENODEV for file operations if the
device has been unregistered")

Signed-off-by: Cristina Opriceana <cristina.opriceana@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In hardware mode we can not use the software demuxer, this means that the
selected scan mask needs to match one of the available scan masks exactly.

It also means that all attached buffers need to use the same scan mask.
Given that when operating in hardware mode there is typically only a single
buffer attached to the device this not an issue. Add a sanity check to make
sure that only a single buffer is attached in hardware mode nevertheless.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

For each buffer type specify the supported device modes for this buffer.
This allows us for devices which support multiple different operating modes
to pick the correct operating mode based on the modes supported by the
attached buffers.

It also prevents that buffers with conflicting modes are attached
to a device at the same time or that a buffer with a non-supported mode is
attached to a device (e.g. in-kernel callback buffer to a device only
supporting hardware mode).

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Even if no userspace consumer buffer is attached to the IIO device at
registration we still need to compute the masklength, since it is possible
that a in-kernel consumer buffer is going to get attached to the device at
a later point.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

The same code is executed regardless ret value, so this test
can be removed.
Also fix coverity scan CID 1268786.

Signed-off-by: Laurent Navet <laurent.navet@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Currently when something goes wrong at some step when disabling the buffers
we immediately abort. This has the effect that the enable/disable calls are
no longer balanced. So make sure that even if one step in the disable
sequence fails the other steps are still executed.

The other issue is that when either enable or disable fails buffers that
were active at that time stay active while the device itself is disabled.
This leaves things in a inconsistent state and can cause unbalanced
enable/disable calls. Furthermore when enable fails we restore the old scan
mask, but still keeps things disabled.

Given that verification of the configuration was performed earlier and it
is valid at the point where we try to enable/disable the most likely reason
of failure is a communication failure with the device or maybe a
out-of-memory situation. There is not really a good recovery strategy in
such a case, so it makes sense to leave the device disabled, but we should
still leave it in a consistent state.

What the patch does if disable/enable fails is to deactivate all buffers
and make sure that the device will be in the same state as if all buffers
had been manually disabled.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

__iio_update_buffers is already a rather large function with many different
error paths and it is going to get even larger. This patch factors out the
device enable and device disable paths into separate helper functions.

The patch also re-implements iio_disable_all_buffers() using the new
iio_disable_buffers() function removing a fair bit of redundant code.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Currently __iio_update_buffers() verifies whether the new configuration
will work in the middle of the update sequence. This means if the new
configuration is invalid we need to rollback the changes already made. This
patch moves the validation of the new configuration at the beginning of
__iio_update_buffers() and will not start to make any changes if the new
configuration is invalid.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

We only have to call the request_update() callback for a newly inserted
buffer. The configuration of the already previously active buffers will not
have changed.

This also allows us to move the request_update() call to the beginning of
__iio_update_buffers(), before any currently active buffers are stopped.
This makes the error handling a lot easier since no changes were made to
the buffer list and no rollback needs to be performed.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Add a small helper function iio_free_scan_mask() that takes a mask and
frees its memory if the scan masks for the device are dynamically
allocated, otherwise does nothing. This means we don't have to open-code
the same check over and over again in __iio_update_buffers.

Also free compound_mask as soon a we are done using it. This constrains its
usage to a specific region of the function will make further refactoring
and splitting the function into smaller sub-parts more easier.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>