Add a helper function for validating a scan mask for devices where exactly one
channel must be selected during sampling. This is a common case among devices
which have scan mask restrictions so it makes sense to provide this function in
the core.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

This is useful for cases where the number of valid scan masks grows
exponentially, but it is rather easy to check whether a mask is valid or not
programmatically.

An example of such a case is a device with multiple ADCs where each ADC has a
upstream MUX, which allows to select from a number of physical channels.

  +-------+   +-------+
  |       |   |       | --- Channel 1
  | ADC 1 |---| MUX 1 | ---   ...
  |       |   |       | --- Channel M
  +-------+   +-------+

     .            .            .
     .            .            .
     .            .            .

  +-------+   +-------+
  |       |   |       | --- Channel M * N + 1
  | ADC N |---| MUX N | ---       ...
  |       |   |       | --- Channel M * N + M
  +-------+   +-------+

The number of necessary scan masks for this case is (M+1)**N - 1, on the other
hand it is easy to check whether subsets for each ADC of the scanmask have only
one bit set.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

It is not always the case that all channels can be used in buffered mode. This
patch allows channels, which can not be used in buffered mode, to set their scan
index to a negative number, which will cause iio_buffer_register to ignore the
channel.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Acked-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

iio_scan_mask_match() returns NULL if the passed in scan mask is empty. This
will happen if no channel has been selected and buffer is enabled.
iio_sw_buffer_preenable() will assign NULL to indio_dev->active_scan_mask in
this case. As a result iio_update_demux() will cause a NULL pointer deref,
because it expects active_scan_mask to be non-NULL.

Since it does not make much sense to start data capture if there is no data to
capture this patch updates the code to fail gracefully in iio_scan_mask_match()
instead of crashing the kernel.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Acked-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Replace open-coded instances of getting a iio_dev struct from a device struct
with dev_to_iio_dev().
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Acked-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Take the core support + the kfifo buffer implentation out of
staging.  Whilst we are far from done in improving this subsystem
it is now at a stage where the userspae interfaces (provided by
the core) can be considered stable.

Drivers will follow over a longer time scale.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Step 1 in moving the IIO core out of staging.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This will come in handy again when we move to multiple buffers
so lets pull it out into a little utility function now.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This will be needed when multiple buffer support is added.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This is just a locally cached value that is device specific (rather
than buffer specific.) Hence it wants to come out of the buffer before
we add multiple buffer support.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Principal reason is to make later patches more coherent and easier to review
but this set in itself separates a logical entity out nicely wihin the code.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The core must not modify available_scan_mask, because it causes problems
with drivers where multiple instances of the driver share the same mask set.
So make this explicit by marking available scan masks as const.

The max1363 driver needs some minor adjustment to accommodate this change.
Pull scan mask allocation into a separate function.
Signed-off-by: NMichael Hennerich <michael.hennerich@analog.com>
Acked-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

These callbacks are currently used by the individual buffer implementations to
ensure that the request_update callback is not issued while the buffer is in use.
But the core already provides sufficient measures to prevent this from happening
in the first place. So it is safe to remove them.

There is one functional change due to this patch. Since the buffer is no longer
marked as in use when the chrdev is opened, it is now possible to enable the
buffer while it is opened. This did not work before, because mark_param_change
did fail if the buffer was marked as in use.
Acked-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Right now we have a mark_param_change callback in the buffer access
functions struct, which should be called whenever the parameters (length,
bytes per datum) of the buffer change. But it is only called when the user
changes the buffer size, not when the bytes per datum change. Additionally each
buffer implementation already keeps track internally whether its parameters
have changed, making the call to mark_param_change after changing the buffer
length redundant. Since each buffer implementation knows best when one of its
parameters has changed just make tracking of this internal and drop the
mark_param_change callback.
Acked-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The flag is only cleared, never set or tested, so it is safe to remove it.
Acked-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The buffer buffer storage is only update when enabling the buffer. Changing the
buffer size while the buffer is enabled will confuse the buffer in regard to
its actual buffer size and can cause potential memory corruption. Thus it is
only safe to modify the buffer size when the buffer is disabled.
Acked-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Currently we only disallow changing the scan elements, while the buffer is
enabled, in triggered buffer mode. This patch changes it to disallow it for all
buffered modes. Disabling or enabling scan elements while the buffer is enabled
will cause undefined behavior since the reader will not be able to tell samples
with the new and old scan element set apart and thus wont be able to extract
any meaningful data from the buffer.
Acked-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Acked-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Fixes the following warning:
	drivers/staging/iio/industrialio-buffer.c: In function ‘iio_scan_mask_query’:
	drivers/staging/iio/industrialio-buffer.c:620: warning: unused variable ‘mask’
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

When updating the scan mask we have to check the actual scan mask for if the
channel is already enabled, not the matching scan mask from the available
scan masks. The bit will already be set there and as a result the actual
scan mask will not get updated and the channel stays disabled.

Also fix the return value of iio_scan_el_store which would return 1 instead of
the number of bytes written if the channel was already active in the scan mask.
Acked-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

In all existing cases, the calls are coming from a location where
the indio_dev is already available.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Obviously drivers should only use this for pushing to buffers.
They need buffer->scan_mask for pulling from them post demux.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

These callbacks should not be buffer instance specific.
Hence move them out of the buffer.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

There are no known reasons why userspace should want this value.
It can be established from the buffer description anyway.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This gives you only what you ask for which is handy
for some devices with weird scan combinations.

Routes all data flow through a core utility function.
That and this demuxing support will be needed to do
demuxing to multiple destinations in kernel.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>
Tested-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Also introduces active_scan_mask storage to tell the core what is
really being currently captured from the device (different from
what is desired as often has bonus channels).
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>
Tested-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Basically avoids looking it up lots of times.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The advantage of kcalloc is, that will prevent integer overflows which could
result from the multiplication of number of elements and size and it is also
a bit nicer to read.

The semantic patch that makes this change is available
in https://lkml.org/lkml/2011/11/25/107Signed-off-by: NThomas Meyer <thomas@m3y3r.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Issue brought up by Lars-Peter Clausen. This is a varient of what
he suggested.

io/iio.h for driver stuff (has to include types.h)
	Sub files for the bits drivers may or may not use
	iio/sysfs.h
	iio/buffer.h (contents of current buffer_generic.h)
	(obviously anything offering events will need events.h as well)
iio/types.h for the enums that matter to both
	iio_chan_type, iio_modifier
iio/events.h for the event code stuff
	IIO_EVENT_CODE and friends.  + everything in chrdev.h  So this
	is the stuff that userspace cares about.
	Also include iio_event_type, iio_event_direction

Thus iio drivers include iio.h + as required
events.h
sysfs.h
buffer.h

in kernel users (once that interface is merged) will need inkern.h
which will pull in types.h

Userspace will need just events.h (which pulls in types.h) to get
everything they need to know about.  Buffer userspace access doesn't
currently need any core defines. All information about the data
format is passed through sysfs.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Logic bug meant the chrdev would fail to open if there was no buffer support
in a driver or in the core. This meant the ioctl to get the event chrdev
would fail and hence events were not available.

V2: change error to -EINVAL to mark as unsuitable for reading rather than
not there.  Both are true depending on how you look at it.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Lots of drivers have in the past expected the presence of basic things
like THIS_MODULE and EXPORT_SYMBOL.  With the header cleanup, they wont
have these.  Call out the include explicitly.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

We had a random missmatch of these two.  Lets pick the most common
and get rid of the other.  This patch covers the core.  Others
will clean up the drivers.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Unsuprisingly this symbol isn't defined on big endian systems.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Silly bug introduced during the chrdev merge series.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

They aren't always ring buffers, so just use buffer for all naming.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Nothing in this file is specific to RING buffers so rename it.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

also, IIO_RING_HARDWARE_BUFFER -> IIO_BUFFER_HARDWARE

These aren't always rings so the naming should not imply that.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This set also includes quite a number of bug fixes of particularly
remove functions.

Necessary due to issue pointed out in Bart Van Assche's patch:
docs/driver-model: Document device.groups

V2: Rebase due to patch reordering.
V3: Pull various error fixes and cleanups out into their own patches.
Signed-off-by: NJonathan Cameron <jic23@cam.ac.uk>
Acked-by: NMichael Hennerich <Michael.Hennerich@analog.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>