iio: adc: stm32-dfsdm-core: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.
To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new() which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230919174931.1417681-24-u.kleine-koenig@pengutronix.de
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: stm32-dfsdm: add id registers support

Add support of identification registers to STM32 DFSDM
to allow hardware capabilities discovery and configuration check.
The number of filters and channels, are read from registers,
when they are available.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Link: https://lore.kernel.org/r/20230105125331.328275-1-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio:adc:stm32*: Use pm[_sleep]_ptr() etc to avoid need to make pm __maybe_unused

The combinations of either
* pm_sleep_ptr() and DEFINE_SIMPLE_DEV_PM_OPS()
* pm_ptr() and RUNTIME_PM_OPS()/SYSTEM_SLEEP_PM_OPS
Make sure the functions are always visible to the compiler and removed by
it rather than requring #ifdef magic.

This removes the need to mark the functions as __maybe_unused and saves
additional space with some build options as the dev_pm_ops structure
itself can be dropped automatically if CONFIG_PM is not enabled.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Olivier Moysan <olivier.moysan@st.com>
Cc: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20220130193147.279148-51-jic23@kernel.org

iio: adc: stm32-dfsdm: Use pm_runtime_resume_and_get() to replace open coding.

Found using coccicheck script under review at:
https://lore.kernel.org/lkml/20210427141946.2478411-1-Julia.Lawall@inria.fr/

This is a prequel to taking a closer look at the runtime pm in IIO drivers
in general.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/20210509113354.660190-16-jic23@kernel.org

iio: adc: stm32-dfsdm: Remove redundant null check before clk_disable_unprepare

ecause clk_disable_unprepare() already checked NULL clock parameter,
so the additional check is unnecessary, just remove it.

Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Link: https://lore.kernel.org/r/20201231085322.24398-1-vulab@iscas.ac.cn
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-dfsdm: Use devm_platform_get_and_ioremap_resource()

Make use of devm_platform_get_and_ioremap_resource() provided by
driver core platform instead of duplicated analogue, dev_err() is
removed because it has been done in devm_ioremap_resource().

Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Link: https://lore.kernel.org/r/20200918083142.32816-1-bobo.shaobowang@huawei.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32: Simplify with dev_err_probe()

Common pattern of handling deferred probe can be simplified with
dev_err_probe(). Less code and also it prints the error value.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20200829064726.26268-8-krzk@kernel.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-dfsdm: missing error case during probe

During probe, check the devm_ioremap_resource() error value.
Also return the devm_clk_get() error value instead of -EINVAL.

Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Acked-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-dfsdm: add PM support

Add PM and runtime PM support to STM32 DFSDM drivers:
- stm32-dfsdm-core: manage clocks.
- stm32-dfsdm-adc: restore channels configuration upon resume. Also stop
restart everything in case of buffer mode.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-dfsdm: make spi_master_freq more accurate

Current ckout divider may be set to a value that makes ckout to exceed
spi-max-frequency. Rather use lower value (e.g. round up divider when
ckout isn't accurate).

Also when the SPI clock isn't accurate, 'spi_master_freq' is filled in
with expected frequency. Use computed value instead to be more accurate:
- e.g. source clock / (CKOUTDIV + 1)

Enforce checks on the divider: ckoutdiv range can be from 1-255 to provide
divider of 2-256.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-dfsdm: Add support for stm32mp1

Add support for DFSDM (Digital Filter For Sigma Delta Modulators)
to STM32MP1. This variant is close to STM32H7 DFSDM, it implements
6 filter instances. Registers map is also increased.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-dfsdm: add check on spi-max-frequency

spi-max-frequency is requested for SPI master mode (only), to tune output
clock. It may happen requested frequency isn't reachable.
Add explicit check, so probe fails with error in this case. Otherwise,
output clock may simply be silently turned off (conversions fail).

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-dfsdm: fix clock source selection

Add missing clock source selection. In case "audio" clock is provided,
it's unused currently: "dfsdm" clock is wrongly used by default.

Fixes: bed73904e76f ("IIO: ADC: add stm32 DFSDM core support")

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Acked-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-dfsdm: fix compatible data use

Fix use of compatible data: stm32h7 regmap configuration is statically
used. Rather use regmap_cfg from compatible data.

Fixes: bed73904e76f ("IIO: ADC: add stm32 DFSDM core support")

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Acked-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

IIO: ADC: stm32-dfsdm: remove unused variable again

The merge between commit abaca806fd13 ("IIO: ADC: stm32-dfsdm: code
optimization") and commit 2353758bc2d4 ("IIO: ADC: stm32-dfsdm: avoid
unused-variable warning") left one variable behind that is no longer
needed and can be removed, as shown by the gcc warning:

drivers/iio/adc/stm32-dfsdm-core.c: In function 'stm32_dfsdm_probe':
drivers/iio/adc/stm32-dfsdm-core.c:245:29: error: unused variable 'of_id' [-Werror=unused-variable]

Fixes: d84b4c7c706f ("Merge branch 'topic/iio' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into asoc-st-dfsdm")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

IIO: ADC: stm32-dfsdm: code optimization

Use of_device_get_match_data to optimize the source code.
No check is needed on dev_data as match table is defined in driver.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

IIO: ADC: stm32-dfsdm: avoid unused-variable warning

Building with CONFIG_OF disabled produces a compiler warning:

drivers/iio/adc/stm32-dfsdm-core.c: In function 'stm32_dfsdm_probe':
drivers/iio/adc/stm32-dfsdm-core.c:245:22: error: unused variable 'pnode' [-Werror=unused-variable]

This removes the variable and open-codes it in the only place
it gets used to avoid that warning.

Fixes: bed73904e76f ("IIO: ADC: add stm32 DFSDM core support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

IIO: ADC: stm32-dfsdm: avoid unused-variable warning

Building with CONFIG_OF disabled produces a compiler warning:

drivers/iio/adc/stm32-dfsdm-core.c: In function 'stm32_dfsdm_probe':
drivers/iio/adc/stm32-dfsdm-core.c:245:22: error: unused variable 'pnode' [-Werror=unused-variable]

This removes the variable and open-codes it in the only place
it gets used to avoid that warning.

Fixes: bed73904e76f ("IIO: ADC: add stm32 DFSDM core support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

IIO: ADC: add stm32 DFSDM core support

Add driver for stm32 DFSDM pheripheral. Its converts a sigma delta
stream in n bit samples through a low pass filter and an integrator.
stm32-dfsdm-core driver is the core part supporting the filter
instances dedicated to sigma-delta ADC or audio PDM microphone purpose.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Mark Brown <broonie@kernel.org>