iio: adc: stm32-adc: Replace deprecated strncpy() with strscpy()

strncpy() is deprecated for use on NUL-terminated destination strings [1].

We should prefer more robust and less ambiguous string interfaces.

We expect adc->chan_name[val] to be NUL-terminated based on ch_name's
use within functions that expect NUL-terminated strings like strncmp and
printf-likes:
| if (!strncmp(stm32_adc_ic[i].name, ch_name, STM32_ADC_CH_SZ)) {
| /* Check internal channel availability */
| switch (i) {
| case STM32_ADC_INT_CH_VDDCORE:
| if (!adc->cfg->regs->or_vddcore.reg)
| dev_warn(&indio_dev->dev,
| "%s channel not available\n", ch_name);
...

There is no evidence that NUL-padding is needed either.

Considering the above, a suitable replacement is strscpy() [2] due to
the fact that it guarantees NUL-termination on the destination buffer
without unnecessarily NUL-padding. If, for any reason, NUL-padding _is_
required we should go for `strscpy_pad`.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230921-strncpy-drivers-iio-adc-stm32-adc-c-v1-1-c50eca098597@google.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: 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/20230919174931.1417681-22-u.kleine-koenig@pengutronix.de
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: add debug info if dt uses legacy channel config

Since nearly all stm32 dt's are using the legacy adc channel config,
we should warn users about using it.

Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Link: https://lore.kernel.org/r/20230421083858.2613289-1-sean@geanix.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: skip adc-channels setup if none is present

If only adc differential channels are defined driver will fail with
stm32-adc: probe of 48003000.adc:adc@0 failed with error -22

Fix this by skipping the initialization if no channels are defined.

This applies only to the legacy way of initializing adc channels.

Fixes: d7705f35448a ("iio: adc: stm32-adc: convert to device properties")
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Reviewed-by: Olivier Moysan <olivier.moysan@foss.st.com>
Link: https://lore.kernel.org/r/20230503162029.3654093-2-sean@geanix.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: skip adc-diff-channels setup if none is present

If no adc differential channels are defined driver will fail with EINVAL:
stm32-adc: probe of 48003000.adc:adc@0 failed with error -22

Fix this by skipping the initialization if no channels are defined.

This applies only to the legacy way of initializing adc channels.

Fixes: d7705f35448a ("iio: adc: stm32-adc: convert to device properties")
Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Link: https://lore.kernel.org/r/20230503162029.3654093-1-sean@geanix.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: set some stm32-adc.c variables storage-class-specifier to static

smatch reports several warnings
drivers/iio/adc/stm32-adc.c:2591:20: warning:
symbol 'stm32_adc_min_ts_h7' was not declared. Should it be static?
drivers/iio/adc/stm32-adc.c:2610:20: warning:
symbol 'stm32_adc_min_ts_mp1' was not declared. Should it be static?
drivers/iio/adc/stm32-adc.c:2630:20: warning:
symbol 'stm32_adc_min_ts_mp13' was not declared. Should it be static?

These variables are only used in stm32-adc.c, so they should be static

Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20230312161733.470617-1-trix@redhat.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: add debugfs to read raw calibration result

Add debugfs to read linear ADC STM32 self calibration results.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20221115103124.70074-4-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: improve calibration error log

Add more information in calibration error log to differentiate
single-ended and differential calibration.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20221115103124.70074-3-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: smart calibration support

Add smart calibration support for STM32MP1.
- STM32MP15x: both linear & offset calibration are supported
- STM32MP13x: Only offset calibration is supported

Linear calibration:
Linear calibration is SoC dependent and does not change over time
so it can be done only once.
Linear calibration may have already been done in u-boot.
Skip calibration execution if calibration data are already available.
Save calibration factors in private data and restore them from private
data on next ADC start.

Offset calibration:
This calibration may vary over time, depending on temperature or voltage.
Run offset single-ended and differential calibration on each ADC start,
as it is not time consuming. This calibration do not need to be saved.
So, remove calfact_s and calfact_d value and bitfields that are no
longer used.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20221115103124.70074-2-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32: manage min sampling time on all internal channels

Force minimum sampling time for all internal channels according
to datasheet requirement. This value can be increased through
DT st,min-sample-time-ns property.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20221012142205.13041-5-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: add stm32mp13 support

Add STM32 ADC support for STM32MP13x SOCs family.

On STM32MP13x, each ADC peripheral has a single ADC block.
These ADC peripherals, ADC1 and ADC2, are fully independent.
This introduces changes in common registers handling.

Some features such as boost mode, channel preselection and
linear calibration are not supported by the STM32MP13x ADC.
Add diversity management for these features.

The STM32MP13x ADC introduces registers and bitfield variants
on existing features such as calibration factors and internal
channels. Add register diversity management.

Add also support for new internal channels VDDCPU and VDDQ_DDR.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20221012142205.13041-4-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: fix channel sampling time init

Fix channel init for ADC generic channel bindings.
In generic channel initialization, stm32_adc_smpr_init() is called to
initialize channel sampling time. The "st,min-sample-time-ns" property
is an optional property. If it is not defined, stm32_adc_smpr_init() is
currently skipped.
However stm32_adc_smpr_init() must always be called, to force a minimum
sampling time for the internal channels, as the minimum sampling time is
known. Make stm32_adc_smpr_init() call unconditional.

Fixes: 796e5d0b1e9b ("iio: adc: stm32-adc: use generic binding for sample-time")
Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20221012142205.13041-2-olivier.moysan@foss.st.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: convert to device properties

Make the conversion to firmware agnostic device properties. As part of
the conversion the IIO inkern interface 'of_xlate()' is also converted to
'fwnode_xlate()'. The goal is to completely drop 'of_xlate' and hence OF
dependencies from IIO.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Tested-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20220715122903.332535-14-nuno.sa@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: disable adc before calibration

The calibration is launched from prepare callback.
The ADC state when entering this function may be unknown as the
ADC may have been left enabled by boot stage.
One prerequisite for ADC calibration is to have ADC in disabled state.
If the calibration is started when ADC is still enabled, the behavior is
unpredictable, and the calibration may fail with a timeout error.

Force ADC to disabled state in stm32h7_adc_selfcalib().
ADC enabling is ensured by stm32h7_adc_enable() call,
before leaving prepare callback.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20220620154738.801706-3-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: make safe adc disable

From ADC reference manual the software is allowed to write the
control bit ADDIS of the ADC_CR register only if the ADC is enabled.
Return immediately from stm32h7_adc_disable() if ADC is already disabled.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20220620154738.801706-2-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32: fix vrefint wrong calibration value handling

If the vrefint calibration is zero, the vrefint channel output value
cannot be computed. Currently, in such case, the raw conversion value
is returned, which is not relevant.
Do not expose the vrefint channel when the output value cannot be
computed, instead.

Fixes: 0e346b2cfa85 ("iio: adc: stm32-adc: add vrefint calibration support")
Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20220609095856.376961-1-olivier.moysan@foss.st.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32: Fix IRQs on STM32F4 by removing custom spurious IRQs message

The check for spurious IRQs introduced in 695e2f5c289bb assumed that the bits
in the control and status registers are aligned. This is true for the H7 and MP1
version, but not the F4. The interrupt was then never handled on the F4.

Instead of increasing the complexity of the comparison and check each bit specifically,
we remove this check completely and rely on the generic handler for spurious IRQs.

Fixes: 695e2f5c289b ("iio: adc: stm32-adc: fix a regression when using dma and irq")
Signed-off-by: Yannick Brosseau <yannick.brosseau@gmail.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20220516203939.3498673-3-yannick.brosseau@gmail.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio:adc:stm32:Switch from CONFIG_PM guards to pm_ptr()

Letting the compiler remove these functions when the kernel is built
without CONFIG_PM support is simpler and less error prone than the
use of #ifdef based config guards.

Removing instances of this approach from IIO also stops them being
copied into new drivers.

The new DEFINE_RUNTIME_DEV_PM_OPS() macro reduces boilerplate.

Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20220130193147.279148-45-jic23@kernel.org

iio: adc: stm32-adc: Fix of_node_put() issue in stm32-adc

Fix following coccicheck warning:
./drivers/iio/adc/stm32-adc.c:2014:1-33: WARNING: Function
for_each_available_child_of_node should have of_node_put() before return.

Early exits from for_each_available_child_of_node should decrement the
node reference counter. Replace return by goto here.

Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Link: https://lore.kernel.org/r/20211021121826.6339-1-wanjiabing@vivo.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32: fix null pointer on defer_probe error

dev_err_probe() calls __device_set_deferred_probe_reason()
on -EPROBE_DEFER error. If device pointer to driver core
private structure is not initialized, an null pointer error occurs.
This pointer is set on iio_device_register() call for iio device.

dev_err_probe() must be called with the device which is probing.
Replace iio device by its parent device.

Fixes: 0e346b2cfa85 ("iio: adc: stm32-adc: add vrefint calibration support")
Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.kernel.org/r/20211122143809.2332-1-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32: fix a current leak by resetting pcsel before disabling vdda

Some I/Os are connected to ADC input channels, when the corresponding bit
in PCSEL register are set on STM32H7 and STM32MP15. This is done in the
prepare routine of stm32-adc driver.
There are constraints here, as PCSEL shouldn't be set when VDDA supply
is disabled. Enabling/disabling of VDDA supply in done via stm32-adc-core
runtime PM routines (before/after ADC is enabled/disabled).

Currently, PCSEL remains set when disabling ADC. Later on, PM runtime
can disable the VDDA supply. This creates some conditions on I/Os that
can start to leak current.
So PCSEL needs to be cleared when disabling the ADC.

Fixes: 95e339b6e85d ("iio: adc: stm32: add support for STM32H7")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Reviewed-by: Olivier Moysan <olivier.moysan@foss.st.com>
Link: https://lore.kernel.org/r/1634905169-23762-1-git-send-email-fabrice.gasnier@foss.st.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: use generic binding for sample-time

Add st,min-sample-time-nsecs to channel generic binding.
Sample time can be defined par channel node. If a channel
is configured as differential, the same sample time applies
for both inputs.
Keep support of legacy st,min-sample-time-nsecs property
for backward compatibility.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20211014131228.4692-8-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: add vrefint calibration support

Add support of vrefint calibration.
If a channel is labeled as vrefint, get vrefint calibration
from non volatile memory for this channel.
vrefint channel is exposed as a processed channel returning
the actual value of vrefp:
vrefp = 3.3 x vrefint_cal / vrefint_data

A conversion on vrefint channel allows to update scale
factor according to vrefint deviation, compared to vrefint
calibration value.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20211014131228.4692-7-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: add support of internal channels

Add support of ADC2 internal channels VDDCORE, VREFINT and VBAT.
The reserved label name "vddcore", "vrefint" and "vbat" must
be used in Device Tree channel node, to enable the corresponding
internal channel.

Note: This patch does not provide support of internal channels
for F4 and H7.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20211014131228.4692-6-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: add support of generic channels binding

Add support of generic IIO channel binding:
./devicetree/bindings/iio/adc/adc.yaml
Keep support of st,adc-channels and st,adc-diff-channels
for backward compatibility.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20211014131228.4692-5-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: split channel init into several routines

Split stm32_adc_chan_of_init channel initialization function into
several routines to increase readability and prepare channel
generic binding handling.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20211014131228.4692-4-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: 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/20210509113354.660190-15-jic23@kernel.org

iio: adc: stm32-adc: Fix docs wrongly marked as kernel-doc

W=1 highlights these two cases that are obviously not in kernel-doc
format.

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>

iio: adc: stm32-adc: enable timestamping for non-DMA usage

For non-DMA usage, we have an easy way to associate a timestamp with a
sample: iio_pollfunc_store_time stores a timestamp in the primary
trigger IRQ handler and stm32_adc_trigger_handler runs in the IRQ thread
to push out the buffer along with the timestamp.

For this to work, the driver needs to register an IIO_TIMESTAMP channel.
Do this.

For DMA, it's not as easy, because we don't push the buffers out of
stm32_adc_trigger, but out of stm32_adc_dma_buffer_done, which runs in
a tasklet scheduled after a DMA completion.

Preferably, the DMA controller would copy us the timestamp into that buffer
as well. Until this is implemented, restrict timestamping support to
only PIO. For low-frequency sampling, PIO is probably good enough.

Cc: Holger Assmann <has@pengutronix.de>
Acked-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.kernel.org/r/20210125194824.30549-1-a.fatoum@pengutronix.de
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: Remove redundant null check before clk_prepare_enable/clk_disable_unprepare

Because clk_prepare_enable() and clk_disable_unprepare() already checked
NULL clock parameter, so the additional checks are unnecessary, just
remove them.

Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Acked-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20201218093512.871-1-vulab@iscas.ac.cn
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: dma transfers cleanup

- Remove processing related to DMA in irq handler as this
data transfer is managed directly in DMA callback.
- Update comment in stm32_adc_set_watermark() function.

Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Link: https://lore.kernel.org/r/20201105142941.27301-1-olivier.moysan@st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: fix a regression when using dma and irq

Since overrun interrupt support has been added, there's a regression when
two ADCs are used at the same time, with:
- an ADC configured to use IRQs. EOCIE bit is set. The handler is normally
called in this case.
- an ADC configured to use DMA. EOCIE bit isn't set. EOC triggers the DMA
request. It's then automatically cleared by DMA read. But the handler
gets called due to status bit is temporarily set (IRQ triggered by the
other ADC).

This is a regression as similar issue had been fixed earlier by
commit dcb10920179a ("iio: adc: stm32-adc:
fix a race when using several adcs with dma and irq").
Issue is that stm32_adc_eoc_enabled() returns non-zero value (always)
since OVR bit has been added and enabled for both DMA and IRQ case.

Remove OVR mask in IER register, and rely only on CSR status for overrun.
To avoid subsequent calls to interrupt routine on overrun, CSR OVR bit has
to be cleared. CSR OVR bit cannot be cleared directly by software.
To do this ADC must be stopped first, and OVR bit in ADC ISR has
to be cleared.
Also add a check in ADC IRQ handler to report spurious IRQs.

Fixes: cc06e67d8fa5 ("iio: adc: stm32-adc: Add check on overrun interrupt")
Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201021085313.5335-1-olivier.moysan@st.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: Move attach/detach of the poll func to the core

All devices using a triggered buffer need to attach and detach the trigger
to the device in order to properly work. Instead of doing this in each and
every driver by hand move this into the core.

At this point in time, all drivers should have been resolved to
attach/detach the poll-function in the same order.

This patch removes all explicit calls of iio_triggered_buffer_postenable()
& iio_triggered_buffer_predisable() in all drivers, since the core handles
now the pollfunc attach/detach.

The more peculiar change is for the 'at91-sama5d2_adc' driver, since it's
not immediately obvious that removing the hooks doesn't break anything.
Eugen was able to test on at91-sama5d2-adc driver, sama5d2-xplained board.
All seems to be fine.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Tested-by: Eugen Hristev <eugen.hristev@microchip.com> #for at91-sama5d2-adc
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: remove explicit IIO device parent assignment

This patch applies the semantic patch:
@@
expression I, P, SP;
@@
I = devm_iio_device_alloc(P, SP);
...
- I->dev.parent = P;

It updates 302 files and does 307 deletions.
This semantic patch also removes some comments like
'/* Establish that the iio_dev is a child of the i2c device */'

But this is is only done in case where the block is left empty.

The patch does not seem to cover all cases. It looks like in some cases a
different variable is used in some cases to assign the parent, but it
points to the same reference.
In other cases, the block covered by ... may be just too big to be covered
by the semantic patch.

However, this looks pretty good as well, as it does cover a big bulk of the
drivers that should remove the parent assignment.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: stm32-adc: remove usage of iio_priv_to_dev() helper

We may want to get rid of the iio_priv_to_dev() helper. The reason is that
we will hide some of the members of the iio_dev structure (to prevent
drivers from accessing them directly), and that will also mean hiding the
implementation of the iio_priv_to_dev() helper inside the IIO core.

Hiding the implementation of iio_priv_to_dev() implies that some fast-paths
may not be fast anymore, so a general idea is to try to get rid of the
iio_priv_to_dev() altogether.
The iio_priv() helper won't be affected by the rework, as the iio_dev
struct will keep a reference to the private information.

For this driver, not using iio_priv_to_dev(), means reworking some paths to
pass the iio device and using iio_priv() to access the private information.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Acked-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: fix device used to request dma

DMA channel request should use device struct from platform device struct.
Currently it's using iio device struct. But at this stage when probing,
device struct isn't yet registered (e.g. device_register is done in
iio_device_register). Since commit 71723a96b8b1 ("dmaengine: Create
symlinks between DMA channels and slaves"), a warning message is printed
as the links in sysfs can't be created, due to device isn't yet registered:
- Cannot create DMA slave symlink
- Cannot create DMA dma:rx symlink

Fix this by using device struct from platform device to request dma chan.

Fixes: 2763ea0585c99 ("iio: adc: stm32: add optional dma support")

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: fix sleep in atomic context

This commit fixes the following error:
"BUG: sleeping function called from invalid context at kernel/irq/chip.c"

In DMA mode suppress the trigger irq handler, and make the buffer
transfers directly in DMA callback, instead.

Fixes: 2763ea0585c9 ("iio: adc: stm32: add optional dma support")
Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Acked-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: Use dma_request_chan() instead dma_request_slave_channel()

dma_request_slave_channel() is a wrapper on top of dma_request_chan()
eating up the error code.

By using dma_request_chan() directly the driver can support deferred
probing against DMA.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: Add check on overrun interrupt

Enable overrun interrupt on STM32 ADC. In case data register hasn't been
read (by CPU or DMA), overrun condition is detected when there's new
conversion data available. Stop grabbing data and log an error message.
Use a threaded irq to avoid printing the error message from hard irq
context.

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

iio: adc: stm32-adc: fix stopping dma

There maybe a race when using dmaengine_terminate_all(). The predisable
routine may call iio_triggered_buffer_predisable() prior to a pending DMA
callback.
Adopt dmaengine_terminate_sync() to ensure there's no pending DMA request
before calling iio_triggered_buffer_predisable().

Fixes: 2763ea0585c9 ("iio: adc: stm32: add optional dma support")

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: fix kernel-doc warnings

Fix the following warnings when documentation is built:
drivers/iio/adc/stm32-adc-core.c:62: warning: cannot understand function
prototype: 'struct stm32_adc_common_regs '
drivers/iio/adc/stm32-adc-core.c:78: warning: cannot understand function
prototype: 'struct stm32_adc_priv_cfg '
drivers/iio/adc/stm32-adc-core.c:123: warning: Function parameter or
member 'pdev' not described in 'stm32f4_adc_clk_sel'
drivers/iio/adc/stm32-adc.c:219: warning: cannot understand function
prototype: 'struct stm32_adc_regs '
drivers/iio/adc/stm32-adc.c:237: warning: cannot understand function
prototype: 'struct stm32_adc_regspec '
drivers/iio/adc/stm32-adc.c:264: warning: cannot understand function
prototype: 'struct stm32_adc_cfg '
drivers/iio/adc/stm32-adc.c:323: warning: Function parameter or member
'difsel' not described in 'N'
drivers/iio/adc/stm32-adc.c:323: warning: Function parameter or member
'pcsel' not described in 'stm32_adc'
drivers/iio/adc/stm32-adc.c:371: warning: cannot understand function
prototype: 'const struct stm32_adc_regs stm32f4_sq[STM32_ADC_MAX_SQ + 1]
drivers/iio/adc/stm32-adc.c:417: warning: cannot understand function
prototype: 'const struct stm32_adc_regs stm32f4_smp_bits[] = '
drivers/iio/adc/stm32-adc.c:508: warning: cannot understand function
prototype: 'const struct stm32_adc_regs stm32h7_smp_bits[] = '
drivers/iio/adc/stm32-adc.c:1112: warning: Function parameter or member
'indio_dev' not described in 'stm32_adc_get_trig_extsel'
drivers/iio/adc/stm32-adc.c:1420: warning: Function parameter or member
'indio_dev' not described in 'stm32_adc_debugfs_reg_access'
drivers/iio/adc/stm32-adc.c:1420: warning: Function parameter or member
'reg' not described in 'stm32_adc_debugfs_reg_access'
drivers/iio/adc/stm32-adc.c:1420: warning: Function parameter or member
'writeval' not described in 'stm32_adc_debugfs_reg_access'
drivers/iio/adc/stm32-adc.c:1420: warning: Function parameter or member
'readval' not described in 'stm32_adc_debugfs_reg_access'

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

iio: adc: stm32-adc: move registers definitions

Move STM32 ADC registers definitions to common header.
This is precursor patch to:
- iio: adc: stm32-adc: fix a race when using several adcs with dma and irq

It keeps registers definitions as a whole block, to ease readability and
allow simple access path to EOC bits (readl) in stm32-adc-core driver.

Fixes: 2763ea0585c9 ("iio: adc: stm32: add optional dma support")

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: Remove dev_err() usage after platform_get_irq()

We don't need dev_err() messages when platform_get_irq() fails now that
platform_get_irq() prints an error message itself when something goes
wrong. Let's remove these prints with a simple semantic patch.

// <smpl>
@@
expression ret;
struct platform_device *E;
@@

ret =
(
platform_get_irq(E, ...)
|
platform_get_irq_byname(E, ...)
);

if ( \( ret < 0 \| ret <= 0 \) )
{
(
-if (ret != -EPROBE_DEFER)
-{ ...
-dev_err(...);
-... }
|
...
-dev_err(...);
)
...
}
// </smpl>

While we're here, remove braces on if statements that only have one
statement (manually).

Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Cc: linux-iio@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32-adc: switch off running adc when going to low power

Switch off ADC when going to low power mode, in case it has been left
running in buffer mode. Then re-enable it when resuming.

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

iio: adc: stm32-adc: add power management support

Add support for runtime PM & sleep. Move all regulator and clock management
to dedicated HW start/stop routines. Then rely on (runtime) PM OPS to
call them.

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

iio: adc: stm32-adc: move self-calibration to prepare routine

Move self-calibration routine to prepare routine.
- This is precursor patch to ease power management handling.
- This also allow to factorize few error cases (error handling).

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

iio: adc: stm32-adc: add support for STM32MP1

Add support for STM32MP1 ADC. It's quite similar to STM32H7 ADC.
Introduce new compatible to handle variants of this hardware such as
vregready flag, trigger list, interrupts, clock rate.

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

iio: adc: stm32: fix stm32h7_adc_enable error handling

Error handling in stm32h7_adc_enable routine doesn't unwind enable
sequence correctly. ADEN can only be cleared by hardware (e.g. by
writing one to ADDIS).
It's also better to clear ADRDY just after it's been set by hardware.

Fixes: 95e339b6e85d ("iio: adc: stm32: add support for STM32H7")

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32: fix scan of multiple channels with DMA

By default, watermark is set to '1'. Watermark is used to fine tune
cyclic dma buffer period. In case watermark is left untouched (e.g. 1)
and several channels are being scanned, buffer period is wrongly set
(e.g. to 1 sample). As a consequence, data is never pushed to upper layer.
Fix buffer period size, by taking scan channels number into account.

Fixes: 2763ea0585c9 ("iio: adc: stm32: add optional dma support")

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

iio: stm32: Adopt SPDX identifier

Add SPDX identifier in stm32's files in IIO directory

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Acked-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Acked-by: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

iio: adc: stm32: add support for differential channels

STM32H7 ADC channels can be configured either as single ended or
differential with 'st,adc-channels' or 'st,adc-diff-channels'
(positive and negative input pair: <vinp vinn>, ...).

Differential channels have different offset and scale, from spec:
raw value = (full_scale / 2) * (1 + (vinp - vinn) / vref).
Add offset attribute.

Differential channels are selected by DIFSEL register. Negative
inputs must be added to pre-selected channels as well (PCSEL).

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

iio: adc: stm32: remove const channel names definition

Remove const array that defines channels. Build channels definition
at probe time, when initializing channels (only for requested ones).
This will ease adding differential channels support.

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

iio: adc: stm32: add tim15 trigger

Add TIM15_TRGO trigger that is now supported on STM32H7.

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

iio: adc: stm32: fix bad error check on max_channels

Fix a bad error check when counting 'st,adc-channels' array elements.
This is seen when all channels are in use simultaneously.

Fixes: 64ad7f643 ("iio: adc: stm32: introduce compatible data cfg")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: stm32: add support for lptimer triggers

STM32 ADC supports hardware triggers like STM32 Low-Power Timer.
For instance, STM32H7 ADC may be triggered by instances 1, 2 or 3.
Add hardware triggered mode so Low-Power Timer Trigger driver can
validate device.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

iio:adc: drop assign iio_info.driver_module and iio_trigger_ops.owner

The equivalent of both of these are now done via macro magic when
the relevant register calls are made. The actual structure
elements will shortly go away.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>

iio: adc: stm32: add optional st,min-sample-time-nsecs

STM32 ADC allows each channel to be sampled with a different sampling time,
by setting SMPR registers. Basically, value depends on local electrical
properties. Selecting correct value for sampling time highly depends on
analog source impedance. There is a manual that may help in this process:
'How to get the best ADC accuracy in STM32...'

This patch allows to configure minimum sampling time via device tree,
either for:
- all channels at once:
st,min-sample-time-nsecs = <10000>;

- independently for each channel (must match "st,adc-channels" list):
st,adc-channels = <0 1>;
st,min-sample-time-nsecs = <5000 10000>;

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

iio: adc: stm32: add support for STM32H7

Add support for STM32H7 Analog to Digital Converter. It has up
to 20 external channels, resolution ranges from 8 to 16bits.
Either bus or asynchronous adc clock may be used.

Add registers & bitfields definition. Also add new configuration
options to enter/exit powerdown and perform self-calibration.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

iio: adc: stm32: make per instance bus clock optional

STM32F4 requires one clock per ADC instance for register access. But,
newer version of ADC hardware block have common bus clock for all
instances (per instance driver isn't responsible for getting it).
So, make it optional by default. Still, enforce it's required on STM32F4.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

iio: adc: stm32: introduce compatible data cfg

Prepare support for stm32h7 adc variant by introducing compatible
configuration data.
Move STM32F4 specific stuff to compatible data structure:
- registers & bit fields
- input channels data
- start/stop procedures
- trigger definitions

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

iio: adc: stm32: add dt option to set resolution

stm32 adc supports several resolution. Add 'assigned-resolution-bits'
dt optional property to set it. Default to maximum resolution in case
it isn't set.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

iio: adc: stm32: add optional dma support

Add DMA optional support to STM32 ADC, as there is a limited number DMA
channels (request lines) that can be assigned to ADC. This way, driver
may fall back using interrupts when all DMA channels are in use for
other IPs.
Use dma cyclic mode with two periods. Allow to tune period length by
using watermark. Coherent memory is used for dma (max buffer size is
fixed to PAGE_SIZE).

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

iio: adc: stm32: add trigger polarity extended attribute

Define extended attribute so that user may choose rising, falling or both
edges for external trigger sources.
Default to rising edge in case it isn't set.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

iio: adc: stm32: Enable use of stm32 timer triggers

STM32 ADC has external timer trigger sources. Use stm32 timer triggers
API (e.g. is_stm32_timer_trigger()) with local ADC lookup table to
validate a trigger can be used.
This also provides correct trigger selection value (e.g. extsel).

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

iio: adc: stm32: add support for triggered buffer mode

STM32 ADC conversions can be launched using hardware triggers.
It can be used to start conversion sequences (group of channels).
Selected channels are select via sequence registers.
Trigger source is selected via 'extsel' (external trigger mux).
Trigger polarity is set to rising edge by default.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

iio: adc: Add support for STM32 ADC

This patch adds support for STMicroelectronics STM32 MCU's analog to
digital converter.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>