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-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: add id registers support

Add support of identification registers to STM32 ADC.

By default the ADC hardware instance number is retrieved from
the compatible configuration data. Get the available ADC number
per ADC block, from hardware configuration register,
when this register exists.

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/20220915135452.1712453-1-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 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 a race when using several adcs with dma and irq

End of conversion may be handled by using IRQ or DMA. There may be a
race when two conversions complete at the same time on several ADCs.
EOC can be read as 'set' for several ADCs, 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 instead. 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).
So both EOC status bit in CSR and EOCIE control bit must be checked
before invoking the interrupt handler (e.g. call ISR only for
IRQ-enabled ADCs).

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: 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: 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 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: 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: Add support for STM32 ADC core

Add core driver for STMicroelectronics STM32 ADC (Analog to Digital
Converter). STM32 ADC can be composed of up to 3 ADCs with shared
resources like clock prescaler, common interrupt line and analog
reference voltage.
This core driver basically manages shared resources.

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