iio: adc: ad9467: convert to backend framework

Convert the driver to use the new IIO backend framework. The device
functionality is expected to be the same (meaning no added or removed
features).

Also note this patch effectively breaks ABI and that's needed so we can
properly support this device and add needed features making use of the
new IIO framework.

Given the lack of features (and devices supported) in the ad9467 driver
compared with the ADI out of tree version, we don't expect any user of
the upstream driver so no one should notice the ABI breakage. However,
if someone is affected by this, ADI will happily support transitioning
to the backend framework.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240210-iio-backend-v11-6-f5242a5fb42a@analog.com
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: ad9467: use the more common !val NULL check

Check !val instead of directing checking for NULL (val == NULL).
No functional changes intended.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20231207-iio-backend-prep-v2-7-a4a33bc4d70e@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: ad9467: use chip_info variables instead of array

Instead of having an array and keeping IDs for each entry of the array,
just have a chip_info struct per device.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20231207-iio-backend-prep-v2-6-a4a33bc4d70e@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: ad9467: use spi_get_device_match_data()

Make use of spi_get_device_match_data() to simplify things.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20231207-iio-backend-prep-v2-5-a4a33bc4d70e@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: ad9467: fix scale setting

When reading in_voltage_scale we can get something like:

root@analog:/sys/bus/iio/devices/iio:device2# cat in_voltage_scale
0.038146

However, when reading the available options:

root@analog:/sys/bus/iio/devices/iio:device2# cat
in_voltage_scale_available
2000.000000 2100.000006 2200.000007 2300.000008 2400.000009 2500.000010

which does not make sense. Moreover, when trying to set a new scale we
get an error because there's no call to __ad9467_get_scale() to give us
values as given when reading in_voltage_scale. Fix it by computing the
available scales during probe and properly pass the list when
.read_available() is called.

While at it, change to use .read_available() from iio_info. Also note
that to properly fix this, adi-axi-adc.c has to be changed accordingly.

Fixes: ad6797120238 ("iio: adc: ad9467: add support AD9467 ADC")
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20231207-iio-backend-prep-v2-4-a4a33bc4d70e@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: ad9467: add mutex to struct ad9467_state

When calling ad9467_set_scale(), multiple calls to ad9467_spi_write()
are done which means we need to properly protect the whole operation so
we are sure we will be in a sane state if two concurrent calls occur.

Fixes: ad6797120238 ("iio: adc: ad9467: add support AD9467 ADC")
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20231207-iio-backend-prep-v2-3-a4a33bc4d70e@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: ad9467: don't ignore error codes

Make sure functions that return errors are not ignored.

Fixes: ad6797120238 ("iio: adc: ad9467: add support AD9467 ADC")
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20231207-iio-backend-prep-v2-2-a4a33bc4d70e@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: ad9467: fix reset gpio handling

The reset gpio was being handled with inverted polarity. This means that
as far as gpiolib is concerned we were actually leaving the pin asserted
(in theory, this would mean reset). However, inverting the polarity in
devicetree made things work. Fix it by doing it the proper way and how
gpiolib expects it to be done.

While at it, moved the handling to it's own function and dropped
'reset_gpio' from the 'struct ad9467_state' as we only need it during
probe. On top of that, refactored things so that we now request the gpio
asserted (i.e in reset) and then de-assert it. Also note that we now use
gpiod_set_value_cansleep() instead of gpiod_direction_output() as we
already request the pin as output.

Fixes: ad6797120238 ("iio: adc: ad9467: add support AD9467 ADC")
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20231207-iio-backend-prep-v2-1-a4a33bc4d70e@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: Explicitly include correct DT includes

The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.

Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20230714174628.4057920-1-robh@kernel.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: ad9467: Silence no spi_device_id warnings

SPI devices use the spi_device_id for module autoloading even on
systems using device tree, after commit 5fa6863ba692 ("spi: Check
we have a spi_device_id for each DT compatible"), kernel warns as
follows since the spi_device_id is missing:

SPI driver ad9467 has no spi_device_id for adi,ad9265
SPI driver ad9467 has no spi_device_id for adi,ad9434

Add spi_device_id entries to silence the warnings, and ensure driver
module autoloading works.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Link: https://lore.kernel.org/r/20220921163620.805879-4-weiyongjun@huaweicloud.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: ad9467: Benefit from devm_clk_get_enabled() to simplify

Make use of devm_clk_get_enabled() to replace some code that effectively
open codes this new function.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20220808204740.307667-3-u.kleine-koenig@pengutronix.de
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: adi-axi: Move exported symbols into IIO_ADI_AXI namespace.

Avoid unnecessary pollution of the global symbol namespace by
moving library functions in to a specific namespace and import
that into the drivers that make use of the functions.

For more info: https://lwn.net/Articles/760045/

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Nuno Sá <nuno.sa@analog.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220220173701.502331-5-jic23@kernel.org

iio: adc: remove unused private data assigned with spi_set_drvdata()

These were usually used before the conversion to devm_ functions, so that
the remove hook would be able to retrieve the pointer and do cleanups on
remove.
When the conversion happened, they should have been removed, but were
omitted.

Some drivers were copied from drivers that fit the criteria described
above. In any case, in order to prevent more drivers from being used as
example (and have spi_set_drvdata() needlessly set), this change removes it
from the IIO ADC group.

Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com>
Link: https://lore.kernel.org/r/20210513111035.77950-1-aardelean@deviqon.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: ad9467: add support for AD9265 high-speed ADC

The AD9265 is a 16-bit, 125 MSPS analog-to-digital converter (ADC). The
AD9265 is designed to support communications applications where high
performance combined with low cost, small size, and versatility is
desired.

The ADC core features a multistage, differential pipelined architecture
with integrated output error correction logic to provide 16-bit accuracy at
125 MSPS data rates and guarantees no missing codes over the full operating
temperature range.

The ADC features a wide bandwidth differential sample-and-hold analog input
amplifier supporting a variety of user-selectable input ranges. It is
suitable for multiplexed systems that switch full-scale voltage levels in
successive channels and for sampling single-channel inputs at frequencies
well beyond the Nyquist rate. Combined with power and cost savings over
previously available ADCs, the AD9265 is suitable for applications in
communications, instrumentation and medical imaging.

Link: https://www.analog.com/media/en/technical-documentation/data-sheets/AD9434.pdf

The driver supports the same register set as the AD9467, so the support for
this chip is added to the 'ad9467' driver.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20200924080518.96410-4-alexandru.ardelean@analog.com

iio: adc: ad9467: add support for AD9434 high-speed ADC

The AD9434 is a 12-bit monolithic sampling analog-to-digital converter
(ADC) optimized for high performance, low power, and ease of use. The part
operates at up to a 500 MSPS conversion rate and is optimized for
outstanding dynamic performance in wideband carrier and broadband systems.

All necessary functions, including a sample-and-hold and voltage reference,
are included on the chip to provide a complete signal conversion solution.
The VREF pin can be used to monitor the internal reference or provide an
external voltage reference (external reference mode must be enabled through
the SPI port).

The ADC requires a 1.8 V analog voltage supply and a differential clock
for full performance operation. The digital outputs are LVDS (ANSI-644)
compatible and support twos complement, offset binary format, or Gray code.
A data clock output is available for proper output data timing.

Link: https://www.analog.com/media/en/technical-documentation/data-sheets/AD9434.pdf

The driver supports the same register set as the AD9467, so the support for
this chip is added to the 'ad9467' driver.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20200924080518.96410-3-alexandru.ardelean@analog.com

iio: adc: ad9467: wrap a axi-adc chip-info into a ad9467_chip_info type

There are 2 chip constants that can be added to the chip-info part. The
default output-mode and the VREF mask.

When adding new chips to this driver, these can be easily omitted, because
these also need to be updated in 2 switch statements.

However, if adding them in the chip-info constants, they are updated in a
single place and propagated in both switch statements.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20200924080518.96410-2-alexandru.ardelean@analog.com

iio: adc: ad9467: return ENODEV vs EINVAL in ad9467_setup()

The proper error code should be ENODEV (vs EINVAL) in case the chip ID
isn't recognized.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20200916082221.72851-1-alexandru.ardelean@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: ad9467: refine mismatch vs unknown chip-id messages

We should probably print what the expected chip-ID is. We already have
that information available, based on the device specified via
device-tree.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20200916083128.73729-1-alexandru.ardelean@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: ad9467: add support AD9467 ADC

The AD9467 is a 16-bit, monolithic, IF sampling analog-to-digital converter
(ADC). It is optimized for high performanceover wide bandwidths and ease of
use. The product operates at a 250 MSPS conversion rate and is designed for
wireless receivers, instrumentation, and test equipment that require a high
dynamic range. The ADC requires 1.8 V and 3.3 V power supplies and a low
voltage differential input clock for full performance operation. No
external reference or driver components are required for many applications.
Data outputs are LVDS compatible (ANSI-644 compatible) and include the
means to reduce the overall current needed for short trace distances.

Since the chip can operate at such high sample-rates (much higher than
classical interfaces), it requires that a DMA controller be used to
interface directly to the chip and push data into memory.
Typically, the AXI ADC IP core is used to interface with it.

Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/AD9467.pdf

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>