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  1. 01 Mar, 2014 2 commits
    • Lars-Peter Clausen's avatar
      iio:adc: Add Xilinx XADC driver · bdc8cda1
      Lars-Peter Clausen authored 
      The Xilinx XADC is a ADC that can be found in the series 7 FPGAs from Xilinx.
The XADC has a DRP interface for communication. Currently two different
frontends for the DRP interface exist. One that is only available on the ZYNQ
family as a hardmacro in the SoC portion of the ZYNQ. The other one is available
on all series 7 platforms and is a softmacro with a AXI interface. This driver
supports both interfaces and internally has a small abstraction layer that hides
the specifics of these interfaces from the main driver logic.

The ADC has a couple of internal channels which are used for voltage and
temperature monitoring of the FPGA as well as one primary and up to 16 channels
auxiliary channels for measuring external voltages. The external auxiliary
channels can either be directly connected each to one physical pin on the FPGA
or they can make use of an external multiplexer which is responsible for
multiplexing the external signals onto one pair of physical pins.

The voltage and temperature monitoring channels also have an event capability
which allows to generate a interrupt when their value falls below or raises
above a set threshold.

Buffered sampling mode is supported by the driver, but only for AXI-XADC since
the ZYNQ XADC interface does not have capabilities for supporting buffer mode
(no end-of-conversion interrupt). If buffered mode is supported the driver will
register two triggers. One "xadc-samplerate" trigger which will generate samples
with the configured samplerate. And one "xadc-convst" trigger which will
generate one sample each time the CONVST (conversion start) signal is asserted.
Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
      bdc8cda1
    • Lars-Peter Clausen's avatar
      devicetree: Add Xilinx XADC binding documentation · 588858c4
      Lars-Peter Clausen authored 
      The Xilinx XADC is a ADC that can be found in the series 7 FPGAs from Xilinx.
The XADC has a DRP interface for communication. Currently two different
frontends for the DRP interface exist. One that is only available on the ZYNQ
family as a hardmacro in the SoC portion of the ZYNQ. The other one is available
on all series 7 platforms and is a softmacro with a AXI interface. This binding
document describes the bindings for both of them since the bindings are very
similar.

Each of them needs:
	* A address range where the registers are mapped
	* An interrupt number for the device interrupt
	* A clock. For the the ZYNQ hardmacro interface this is the modules PCAP
	  clock, for the AXI softmacro it is the AXI bus interface clock.

Additionally the bindings specify whether an external multiplexer is used and in
which mode it is used. The devicetree bindings also describe which external
channels are connected and in which configuration.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
      588858c4
  3. 25 Feb, 2014 1 commit
  5. 23 Feb, 2014 2 commits
    • Greg Kroah-Hartman's avatar
      Merge tag 'iio-for-3.15b' of... · aa256f8d
      Greg Kroah-Hartman authored 
      Merge tag 'iio-for-3.15b' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-next

Jonathan writes:

Second round of IIO new driver, functionality and cleanups for the 3.15 series.

There are a few fixes in here that might, earlier in a cycle, have gone
to Greg as fixes. Given they are either minor or have never actually
been observed as causing trouble (the locking bug in the event code) and
are invasive, I have included them in this pull request, targeting the
3.15 merge window instead.

The rest are pretty uncontroversial new drivers, a handy little tool for
the example code in our documentation and little cleanups.

New drivers
* Freescale Vybrid and i.MX6SLX ADC driver.
* HID Sensor hub proximity sensors.
* HID Sensor hub pressure sensors.
* LPS25H Pressure sensors added to the ST micro pressure sensor driver.

New functionality
* lsiio tool.  This is added to the staging tree as we haven't yet moved
  the example code it sits with out.  Moving this code out is now a reasonably
  high priority but holding up this tool in the meantime did not seem
  worthwhile.
* mag3110 - add missing scale factor for temperature output to userspace.

Cleanups
* Fix a bug in the event reporting in which a spin lock might be held over
  when a sleep occured.  A similar bug was found by Lars in the buffer code.
  It has not to our knowledge been observed as actually occuring and is
  a little too invasive to push out as a fix.
* Drop the IIO_ST macro after clearing out all users.  This macro was a very
  bad idea leading to a number of bugs after it stopped covering all elements
  of the structure being assigned and people started making assumptions about
  what it did cover.  Glad to see it go!
* Avoid applying extended name to shared attributes as it makes no sense.
  No in tree drivers were using the combination, hence not pushed out as
  a fix.
* ad799x - move to devm_request_threaded_irq to reduce boilerplate clean up.
* bma180 - make the low_pass_filter_3db_frequency info element shared rather
  than per attribute.  The old approach was valid but not as clean as it might
  be and was setting a bad example.  Hence the cleanup.
* mxs-lradc - propogate the error code form a platform_get_irq call rather than
  eating it up by returning -EINVAL on all errors.
* ad799x - typo fix in the copyright message. Either that or Michael was
  asserting a copyright that moved backwards in time by about a thousand years.
* ad799x - use a regulator for vref rather than platform data.  The driver
  dates from just as the regulator framework was coming into common use so
  provides an alternative way of specifying the reference voltage.  We no
  longer need that approach so drop it in favour of a regulator only approach.
* max1363 - some internal vref values were out by a small amount.  The effect
  would have been tiny and no one noticed hence not pushing this through as
  a fix.
* core - replace some pointless goto error_ret (with no clean up) lines with
  direct returns.  This is my bad coding style so I'm glad to see it cleaned
  up.
* core - avoid a kasprintf that just directly prints a string with no
  formatting elements.  This has always been there but Lars just noticed it.
  Oops.
      aa256f8d
    • Lars-Peter Clausen's avatar
      iio:event: Fix and cleanup locking · b91accaf
      Lars-Peter Clausen authored 
      The event code currently holds a spinlock with IRQs disabled while calling
kfifo_to_user(). kfifo_to_user() can generate a page fault though, which means
we have to be able to sleep, which is not possible if the interrupts are
disabled. The good thing is that kfifo handles concurrent read and write access
just fine as long as there is only one reader and one writer, so we do not any
locking to protect against concurrent access from the read and writer thread. It
is possible though that userspace is trying to read from the event FIFO from
multiple concurrent threads, so we need to add locking to protect against this.
This is done using a mutex. The mutex will only protect the kfifo_to_user()
call, it will not protect the waitqueue. This means that multiple threads can be
waiting for new data and once a new event is added to the FIFO all waiting
threads will be woken up. If one of those threads is unable to read any data
(because another thread already read all the data) it will go back to sleep. The
only remaining issue is that now that the clearing of the BUSY flag and the
emptying of the FIFO does no longer happen in one atomic step it is possible
that a event is added to the FIFO after it has been emptied and this sample will
be visible the next time a new event file descriptor is created. To avoid this
rather move the emptying of the FIFO from iio_event_chrdev_release to
iio_event_getfd().
Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
      b91accaf
  7. 22 Feb, 2014 3 commits
  9. 21 Feb, 2014 16 commits
  11. 18 Feb, 2014 16 commits
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