Ensure that querying the IIO buffer scan_mask returns a value of
0 or 1. Currently querying the scan mask has the value returned
by test_bit(), which returns either true or false. For some
architectures test_bit() may return -1 for true, which will appear
to return an error when returning from iio_scan_mask_query().

Additionally, it's important for the sysfs interface to consistently
return the same thing when querying the scan_mask.
Signed-off-by: NAlec Berg <alecaberg@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Get rid of obsolete uses of goto error_ret and some empty lines.
Signed-off-by: NHartmut Knaack <knaack.h@gmx.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Currently the IIO buffer interface only allows non-blocking reads. This patch
adds support for blocking IO. In blocking mode the thread will go to sleep if no
data is available and will wait for the buffer implementation to signal that new
data is available by waking up the buffers waitqueue.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

This patch adds a new data_available() callback to the iio_buffer_access_funcs
struct. The callback is used to indicate whether data is available in the buffer
for reading. It is meant to replace the stufftoread flag from the iio_buffer
struct. The reasoning for this is that the buffer implementation usually can
determine whether data is available rather easily based on its state, on the
other hand it can be rather tricky to update the stufftoread flag in a race free
way.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

The functionality implemented by iio_sw_buffer_preenable() is now done directly
in the IIO core and previous users of iio_sw_buffer_preenable() have all been
updated to not use it anymore. It is unused now and can be remove.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Currently a IIO device driver needs to make sure to update the buffer's bytes
per datum after the scan mask has changed. This is usually done in the preenable
callback by invoking iio_sw_buffer_preenable(). This is something that needs to
be done and is done for virtually all devices which support buffers (we
currently have only one exception). Also this a bit of a layering violation
since we have to call the buffer setup ops from the device setup ops. This
requires the device driver to know about the internal requirements of the buffer
(e.g. whether we need to call the set_bytes_per_datum) callback. And especially
with in-kernel buffer consumers, which allows to attach arbitrary buffers to a
device, this is something that the driver can't know.

Moving this to the core allows us to drop the individual calls to
iio_sw_buffer_preenable() from drivers.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Cc: Denis Ciocca <denis.ciocca@st.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Zubair Lutfullah <zubair.lutfullah@gmail.com>
Cc: Jacek Anaszewski <j.anaszewski@samsung.com>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Usually the active scan mask is freed in __iio_update_buffers() when the buffer
is disabled. But when the device is still sampling when it is removed we'll end
up disabling the buffers in iio_disable_all_buffers(). So we also need to free
the active scan mask here, otherwise it will be leaked.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Since the kernel now disables all buffers when a device is unregistered it might
happen that a in-kernel consumer tries to disable that buffer again. So ignore
requests where the buffer already is in the desired state.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

We have the same code to free a IIO device attribute list in multiple place.
This patch adds a new helper function to take care of this and replaces the
custom instances with a call to the helper function. Note that we do not need to
call list_del() for each of the list items since we will never look at any of
the list items nor the list itself again.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

We need to make sure that in-kernel users of iio_update_buffers() do not race
against each other or against unregistration of the device. So we need to take
both the mlock and the info_exist_lock when calling iio_update_buffers() from a
in-kernel consumer.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Once the device has been unregistered there won't be any new data no matter how
long a userspace application waits, so we might as well wake them up and let
them know.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

If the IIO device has been unregistered return -ENODEV for any further file
operations like read() and ioctl(). This avoids userspace being able to grab new
references to the device.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Since the buffer is accessed by userspace we can not just free the buffers
memory once we are done with it in kernel space. There might still be open file
descriptors and userspace still might be accessing the buffer. This patch adds
support for reference counting to the IIO buffers. When a buffer is created and
initialized its initial reference count is set to 1. Instead of freeing the
memory of the buffer the buffer's _free() function will drop that reference
again. But only after the last reference to the buffer has been dropped the
buffer the buffer's memory will be freed. The IIO device will take a reference
to its primary buffer. The patch adds a small helper function for this called
iio_device_attach_buffer() which will get a reference to the buffer and assign
the buffer to the IIO device. This function must be used instead of assigning
the buffer to the device by hand. The reference is only dropped once the IIO
device is freed and we can be sure that there are no more open file handles. A
reference to a buffer will also be taken whenever the buffer is active to avoid
the buffer being freed while data is still being send to it.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Signed-off-by: NPeter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Make sure to stop sampling when the device is removed, otherwise it will
continue to sample forever.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

if device has available_scan_masks set and the buffer is enabled without
any scan_elements enabled, in a NULL pointer is dereferenced in iio_compute_scan_bytes()

[   18.993713] Unable to handle kernel NULL pointer dereference at virtual address 00000000
[   19.002593] pgd = debd4000
[   19.005432] [00000000] *pgd=9ebc0831, *pte=00000000, *ppte=00000000
[   19.012329] Internal error: Oops: 17 [#1] PREEMPT ARM
[   19.017639] Modules linked in:
[   19.020843] CPU: 0    Not tainted  (3.9.11-00036-g75c888a-dirty #207)
[   19.027587] PC is at _find_first_bit_le+0xc/0x2c
[   19.032440] LR is at iio_compute_scan_bytes+0x2c/0xf4
[   19.037719] pc : [<c021dc60>]    lr : [<c03198d0>]    psr: 200d0013
[   19.037719] sp : debd9ed0  ip : 00000000  fp : 000802bc
[   19.049713] r10: 00000000  r9 : 00000000  r8 : deb67250
[   19.055206] r7 : 00000000  r6 : 00000000  r5 : 00000000  r4 : deb67000
[   19.062011] r3 : de96ec00  r2 : 00000000  r1 : 00000004  r0 : 00000000
[   19.068847] Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[   19.076324] Control: 10c5387d  Table: 9ebd4019  DAC: 00000015

problem is the rollback code in iio_update_buffers(), old_mask may be NULL (e.g. on first
call)

I'm not too confident about the fix; works for me...
Signed-off-by: NPeter Meerwald <pmeerw@pmeerw.net>
Reviewed-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

adding one return value check
fix one kerneldoc
Signed-off-by: NPeter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Change the type of the 'data' parameter for iio_push_to_buffers() from 'u8 *' to
'const void *'. Drivers typically use the correct type (e.g. __be16 *) for their
data buffer. When passing the buffer to iio_push_to_buffers() it needs to be
cast to 'u8 *' for the compiler to not complain (and also having to add __force
if we want to keep sparse happy as well). Since the buffer implementation should
not care about the data layout (except the size of one sample) using a void
pointer is the correct thing to do. Also make it const as the buffer
implementations are not supposed to modify it.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Introduce an enum to specify whether the attribute is separate or
shared.

Factor out the bitmap handling for loop into a separate function.

Tidy up error handling and add a NULL assignment to squish a false
positive warning from GCC.

Change ext_info shared type from boolean to enum and update in all
drivers.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Reviewed-by: NLars-Peter Clausen <lars@metafoo.de>

We can skip having to loop through all the device's buffers to see if a certain
buffer is active, if we let the buffer's list head point to itself when the
buffer is inactive.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

1. make messages grepable (in one line)
2. include returned errno in them
Signed-off-by: NMichał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Route all buffer writes through the demux.
Addition or removal of a buffer results in tear down and
setup of all the buffers for a given device.
Signed-off-by: NJonathan Cameron <jic23@kernel.org>
Tested-by: Nsrinivas pandruvada <srinivas.pandruvada@intel.com>

strict_strto* has been deprecated in favor of kstrto*. Use strict_strtouint
respective strict_strtoint, since that is what the functions we pass the
converted values to expect.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Drop timestamp parameter from buffer store_to callback and subsequently from
iio_push_to_buffer. The timestamp parameter is unused and it seems likely that
it will stay unused in the future, so it should be safe to remove it.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

Signed-off-by: NPeter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

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>

The channel set assigned to the iio device is not necessarily the same has the
channel set passed to iio_buffer_register. So to avoid possible complications
always work with the channel set pass to iio_buffer_register and ignore the
channel set assigned to the iio device.
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>