Jonathan writes:

First round of new device support, features and cleanups for IIO in the 4.11 cycle.

It's shaping to be another fairly busy cycle. Lots more on the way!

New device support
* ads7950
  - new driver supporting ads7950, ads7951, ads7952, ads7953, ads7954,
  ads7955, ads7956, ads7957, ads7958, ads7959, ads7960, and ads7961 ADCs.
* cm3605
  - New driver for this light sensor and proximity sensor  which is an
  analog part with some additional digital controls.
* hx711
  - New driver.

Core new stuff
* Gravity sensor type.  This is a processed datastream in which the device
will try to work out which way is down.
* Split the buffer.h file into two parts. One provides the interface to 'use'
a buffer, the second provides the internals of the buffer functionality as
needed by implementations of buffers.
  - Move documentation inline so as to allow use of private: tag when
  generating documentation.
  - Add some utility functions for the few things that are directly done
  with the buffers.
  - Stop exporting functions that no-one uses outside of the core code.
  - Push docs down by the code in the c file where they should have always
  been.
  - Fix typo in kernel-doc for buffer.
  - push down some includes that were previously happening implicitly.
  - stop enabling the timestamp of the dummy device.

Features and cleanups
* ad5592r
  - ACPI support
* ad5593r
  -ACPI support.
* ad5933
  - Fix a false comment about size of a particular register.
* ad7150
  - replace S_IRUGO | S_IWUSR with 0644.  I'm not that keen on these patches
  in general, but as it was nicely presented I took this one anyway. As a
  general rule will only take these as part of a larger driver cleanup.
  - don't eat an error but rather reutnr it in the write_event_config callback.
* ad7606
  - replace non standard range attibute with _scale
* ade7753
  - use usleep_range for short sleeps
* ade7754
  - use usleep_range for short sleeps
* ade7758
  - use usleep_range for short sleeps
* ade7759
  - use usleep_range for short sleeps
* ade7854
  - use usleep_range for short sleeps
* adis16201
  - fix description
* adis16203
  - fix description
  - fix copyright year
* adis16209
  - fix description
* adt7316
  - Add braces to arms of if else statement (for consistency)
  - Alignment fixes.
* axp288
  - Fix up an issue with accidental overwrites of data.
* bmi160
  - add deivce tables for i2c and spi to support correctly identifying the
  full dt name (including manufacturer).
  - device tree binding.
* bmp280
  - use usleep_range for short sleeps.
* cm3232
  - return error from cm3232_reg_init rather than eating it if the last write
  fails.
* dummy driver
  - remove a semicolor found at end of a function defintition.
* exynos-adc
  - use usleep_range for short sleeps.
* hid-sensor (accel)
  - Add timestamp support.  The hardware can provide timestamps so lets support
  them. If not fall back to timestamps estimated in kernel.
* hid-sensor (light)
  - Add a duplicate ID for the light channels so as to keep existing interface
  whilst also using the more standard IIO interface.
* hts221
  - acpi probing
* imx25-gcq
  - Add a macro call to allow this driver to be automatically loaded.
* isl29028
  - reorganise code to avoid deep nesting of if statements.
  - move chip test and default regs into a function suitable or sharing with
  power management code.
  - tidy up some code alignment.
* lidar-lite-v3
  - introduce compatible strings that make it clear Garmin have consideral
  friends.
* mma8452
  - avoid returning signed value when unsigned is appropriate
* spmi-vadc
  - Update function for generic voltage conversion to take into account that
  different channels on this device should be handled differently.
  - Rework code to allow per channel voltage scaling and support the standard
  options for this hardware.
  - Fixup three minor issues with the above patches for this part. These all
  effect test builds rather than the native builds for the part, but good to
  clean them up anyway.
* st_sensors
  - support device matching from the ACPI DST tables.
  - acpi based probing for accelerometers
  - acpi based probing for pressure sensors
  - Allow pressure sensors to read negative values.
  - Export sampling frequency for lps25h and lps331ap.
  - Add support for the old DT bindings from the period when these deivces
  were often supported through windows.

Docs fixup:
* typo in sysfs-bus-iio

The LIS3LV02 has a special bit that need to be set to get the
read values left aligned. Before this patch we get gibberish
like this:

iio_generic_buffer -a -c10 -n lis3lv02dl_accel
(...)
0.000000 -0.010042 -0.642688 19155832931907
0.000000 -0.010042 -0.642688 19155858751073

Which is because we read a raw value for 1g as 64 which is
the nominal 1024 for 1g shifted 4 bits to the left by being
right-aligned rather than left aligned.

Since all other sensors are left aligned, add some code to
set the special DAS (data alignment setting) bit to 1 so that
the right value is now read like this:

iio_generic_buffer -a -c10 -n lis3lv02dl_accel
(...)
0.000000 -0.147095 -10.120135 24761614364956
-0.029419 -0.176514 -10.120135 24761631624540

The scaling was weird as well: we have a gain of 1000 for 1g
and 3000 for 6g. I don't even remember how I came up with the
old values but they are wrong.

Fixes: 3acddf74f807 ("iio: st-sensors: add support for lis3lv02d accelerometer")
Cc: Lorenzo Bianconi <lorenzo.bianconi@st.com>
Cc: Giuseppe Barba <giuseppe.barba@st.com>
Cc: Denis Ciocca <denis.ciocca@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Add support to match st sensors using information passed from ACPI DST
tables.

Signed-off-by: Shrirang Bagul <shrirang.bagul@canonical.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Leonard Crestez observed the following phenomenon: when using
hard interrupt triggers (the DRDY line coming out of an ST
sensor) sometimes a new value would arrive while reading the
previous value, due to latencies in the system.

We discovered that the ST hardware as far as can be observed
is designed for level interrupts: the DRDY line will be held
asserted as long as there are new values coming. The interrupt
handler should be re-entered until we're out of values to
handle from the sensor.

If interrupts were handled as occurring on the edges (usually
low-to-high) new values could appear and the line be held
asserted after that, and these values would be missed, the
interrupt handler would also lock up as new data was
available, but as no new edges occurs on the DRDY signal,
nothing happens: the edge detector only detects edges.

To counter this, do the following:

- Accept interrupt lines to be flagged as level interrupts
  using IRQF_TRIGGER_HIGH and IRQF_TRIGGER_LOW. If the line
  is marked like this (in the device tree node or ACPI
  table or similar) it will be utilized as a level IRQ.
  We mark the line with IRQF_ONESHOT and mask the IRQ
  while processing a sample, then the top half will be
  entered again if new values are available.

- If we are flagged as using edge interrupts with
  IRQF_TRIGGER_RISING or IRQF_TRIGGER_FALLING: remove
  IRQF_ONESHOT so that the interrupt line is not
  masked while running the thread part of the interrupt.
  This way we will never miss an interrupt, then introduce
  a loop that polls the data ready registers repeatedly
  until no new samples are available, then exit the
  interrupt handler. This way we know no new values are
  available when the interrupt handler exits and
  new (edge) interrupts will be triggered when data arrives.
  Take some extra care to update the timestamp in the poll
  loop if this happens. The timestamp will not be 100%
  perfect, but it will at least be closer to the actual
  events. Usually the extra poll loop will handle the new
  samples, but once in a blue moon, we get a new IRQ
  while exiting the loop, before returning from the
  thread IRQ bottom half with IRQ_HANDLED. On these rare
  occasions, the removal of IRQF_ONESHOT means the
  interrupt will immediately fire again.

- If no interrupt type is indicated from the DT/ACPI,
  choose IRQF_TRIGGER_RISING as default, as this is necessary
  for legacy boards.

Tested successfully on the LIS331DL and L3G4200D by setting
sampling frequency to 400Hz/800Hz and stressing the system:
extra reads in the threaded interrupt handler occurs.

Cc: Giuseppe Barba <giuseppe.barba@st.com>
Cc: Denis Ciocca <denis.ciocca@st.com>
Tested-by: Crestez Dan Leonard <cdleonard@gmail.com>
Reported-by: Crestez Dan Leonard <cdleonard@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

We want the fixes in here, and we can resolve a merge issue in
drivers/iio/industrialio-trigger.c

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 98ad8b41f58dff6b30713d7f09ae3834b8df7ded
("iio: st_sensors: verify interrupt event to status") caused
a regression when reading ST sensors from a HRTimer trigger
rather than the intrinsic interrupts: the HRTimer may
trigger faster than the sensor provides new values, and
as the check against new values available as a cause of
the interrupt trigger was done in the poll function,
this would bail out of the HRTimer interrupt with
IRQ_NONE.

So clearly we need to only check the new values available
from the proper interrupt handler and not from the poll
function, which should rather just read the raw values
from the registers, put them into the buffer and be happy.

To achieve this: switch the ST Sensors over to using a true
threaded interrupt handler.

In the interrupt thread, check if new values are available,
else yield to the (potential) next device on the same
interrupt line to check the registers. If the interrupt
was ours, proceed to poll the values.

Instead of relying on iio_trigger_generic_data_rdy_poll() as
a top half to wake up the thread that polls the sensor for
new data, have the thread call iio_trigger_poll_chained()
after determining that is is the proper source of the
interrupt. This is modelled on drivers/iio/accel/mma8452.c
which is already using a properly threaded interrupt handler.

In order to get the same precision in timestamps as
previously, where samples would be timestamped in the
poll function pf->timestamp when calling
iio_trigger_generic_data_rdy_poll() we introduce a
local timestamp in the sensor data, set it in the top half
(fastpath) of the interrupt handler and provide that to the
core when calling iio_push_to_buffers_with_timestamp().

Additionally: if the active scanmask is not set for the
sensor no IRQs should be enabled and we need to bail out
with IRQ_NONE. This can happen if spurious IRQs fire when
installing the threaded interrupt handler.

Tested with hard interrupt triggers on LIS331DL, then also
tested with hrtimers on the same sensor by creating a 75Hz
HRTimer and using it to poll the sensor.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Giuseppe Barba <giuseppe.barba@st.com>
Cc: Denis Ciocca <denis.ciocca@st.com>
Reported-by: Crestez Dan Leonard <cdleonard@gmail.com>
Tested-by: Crestez Dan Leonard <cdleonard@gmail.com>
Tested-by: Jonathan Cameron <jic23@kernel.org>
Fixes: 97865fe41322 ("iio: st_sensors: verify interrupt event to status")
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Ensure failure to enable power regulators is properly handled.

Signed-off-by: Gregor Boirie <gregor.boirie@parrot.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Remove st_sensors_get_buffer_element symbol export since not explicitly
used outside of st_sensors driver.

Signed-off-by: Gregor Boirie <gregor.boirie@parrot.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Some types of ST Sensors can be connected to the same IRQ line
as other peripherals using open drain. Add a device tree binding
and a sensor data property to flip the right bit in the interrupt
control register to enable open drain mode on the INT line.

If the line is set to be open drain, also tag on IRQF_SHARED
to the IRQ flags when requesting the interrupt, as the whole
point of using open drain interrupt lines is to share them with
more than one peripheral (wire-or).

Cc: devicetree@vger.kernel.org
Cc: Giuseppe Barba <giuseppe.barba@st.com>
Cc: Denis Ciocca <denis.ciocca@st.com>
Acked-by: Rob Herring <rob@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

This makes all ST sensor drivers check that they actually have
new data available for the requested channel(s) before claiming
an IRQ, by reading the status register (which is conveniently
the same for all ST sensors) and check that the channel has new
data before proceeding to read it and fill the buffer.

This way sensors can share an interrupt line: it can be flaged
as shared and then the sensor that did not fire will return
NO_IRQ, and the sensor that fired will handle the IRQ and
return IRQ_HANDLED.

Cc: Giuseppe Barba <giuseppe.barba@st.com>
Cc: Denis Ciocca <denis.ciocca@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>