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ad7386/7/8(-4) single-ended parts have a 2:1 mux in front of each ADC.
>From an IIO point of view, all inputs are exported, i.e ad7386/7/8
export 4 channels and ad7386-4/7-4/8-4 export 8 channels. First inputs
of muxes correspond to the first half of IIO channels (i.e 0-1 or 0-3)
and second inputs correspond to second half (i.e 2-3 or 4-7)
Currently, the driver supports only sampling first half OR second half of
the IIO channels. To enable sampling all channels simultaneously, these
parts have an internal sequencer that automatically cycles through the
mux entries.
When enabled, the maximum throughput is divided by two. Moreover, the ADCs
need additional settling time, so we add an extra CS toggle to correctly
propagate setting, and an additional spi transfer to read the second
half.
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20240731-ad7380-add-single-ended-chips-v2-6-cd63bf05744c@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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Adding ad7386/7/8 (16/14/12 bits) unsigned, dual simultaneous sampling,
single-ended compatible parts, and the corresponding ad7386-4/7-4/8-4
4 channels.
These parts have a 2:1 multiplexer in front of each ADC. They also include
additional configuration registers that allow for either manual selection
or automatic switching (sequencer mode), of the multiplexer inputs.
This commit focus on integrating manual selection. Sequencer mode will
be implemented later.
>From an IIO point of view, all inputs are exported, i.e ad7386/7/8
export 4 channels and ad7386-4/7-4/8-4 export 8 channels.
Inputs AinX0 of multiplexers correspond to the first half of IIO channels
(i.e 0-1 or 0-3) and inputs AinX1 correspond to second half (i.e 2-3 or
4-7). Example for AD7386/7/8 (2 channels parts):
IIO | AD7386/7/8
| +----------------------------
| | _____ ______
| | | | | |
voltage0 | AinA0 --|--->| | | |
| | | mux |----->| ADCA |---
voltage2 | AinA1 --|--->| | | |
| | |_____| |_____ |
| | _____ ______
| | | | | |
voltage1 | AinB0 --|--->| | | |
| | | mux |----->| ADCB |---
voltage3 | AinB1 --|--->| | | |
| | |_____| |______|
| |
| +----------------------------
When switching channel, the ADC require an additional settling time.
According to the datasheet, data is valid on the third CS low. We already
have an extra toggle before each read (either direct reads or buffered
reads) to sample correct data, so we just add a single CS toggle at the
end of the register write.
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20240731-ad7380-add-single-ended-chips-v2-5-cd63bf05744c@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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ad738x family contains single-ended parts that have a 2:1 mux in front
of ADC, so the number of IIO channels is different from the number of
simultaneous channels that can be sampled.
To prepare the support for single-ended parts, introduce a new
num_simultaneous_channels variable. For currently supported parts,
num_simultaneous_channels is equal to num_channels minus 1 (the
timestamps channel)
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20240731-ad7380-add-single-ended-chips-v2-4-cd63bf05744c@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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Add missing trailing commas in iio_scan_type structures
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20240731-ad7380-add-single-ended-chips-v2-3-cd63bf05744c@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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ad7380x(-4) parts are able to do oversampling to increase accuracy.
This chips supports a normal oversampling mode and a rolling mode and
also allows enabling and disabling extra resolution bits when
oversampling is enabled.
We have intentionally left out the rolling mode for now as there is not
a compelling use case for it. User can process a captured data buffer
to get the same effect.
We are also currently not supporting changing the oversampling mode
independently of the resolution bits. The resolution boost feature
can only be enabled when oversampling is enabled and oversampling is
not as useful without the resolution boost. So for now we consider the
features tightly coupled. When oversampling is enabled, the resolution
boost is enabled and when oversampling is disabled, the resolution
boost is disabled.
Since the resolution boost feature causes 16-bit chips to now have
18-bit data which means the storagebits has to change from 16 to 32
bits, we use the new ext_scan_type feature to allow changing the
scan_type at runtime based on if the resolution boost is enabled or
not.
SPI message optimization has to be moved since now some of the xfer
parameters change based on the resolution boost mode.
A few neighboring comments are also fixed up while we are touching this
code.
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Co-developed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240530-iio-add-support-for-multiple-scan-types-v3-5-cbc4acea2cfa@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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This changes the AD7380 to use spi_optimize_message() to optimize
buffered reads.
This changes both direct reads and buffered reads to use the same
spi_message. This has some (welcome) side effects. The first is that
in buffered reads, the timestamp will now correspond to the same sample
rather than the previous sample. The second is that direct reads now
use the same SPI bus speed as buffered reads.
This reduces CPU usage of the IRQ thread from around 25% to around 20%
when sampling at 10 kHz on a ZedBoard.
Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240530-iio-add-support-for-multiple-scan-types-v3-4-cbc4acea2cfa@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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Add support for ad7380/1/2/3-4 parts which are 4 channels
variants from ad7380/1/2/3
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Link: https://lore.kernel.org/r/20240528-adding-new-ad738x-driver-v7-7-4cd70a4c12c8@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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The current driver supports only parts with 2 channels.
In order to prepare the support of new compatible ADCs with more
channels, this commit:
- defines MAX_NUM_CHANNEL to specify the maximum number of
channels currently supported by the driver
- adds available_scan_mask member in ad7380_chip_info structure
- fixes spi xfer struct len depending on number of channels
- fixes scan_data.raw buffer size to handle more channels
- adds a timing specifications structure in ad7380_chip_info structure
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Link: https://lore.kernel.org/r/20240528-adding-new-ad738x-driver-v7-5-4cd70a4c12c8@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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Add support for AD7383, AD7384 pseudo-differential compatible parts.
Pseudo differential parts require common mode voltage supplies so add
the support for them and add the support of IIO_CHAN_INFO_OFFSET to
retrieve the offset
Signed-off-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Link: https://lore.kernel.org/r/20240528-adding-new-ad738x-driver-v7-4-4cd70a4c12c8@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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This adds a new driver for the AD7380 family ADCs.
The driver currently implements basic support for the AD7380, AD7381,
2-channel differential ADCs. Support for additional single-ended,
pseudo-differential and 4-channel chips that use the same register map
as well as additional features of the chip will be added in future patches.
[Julien Stephan: fix rx/tx buffer for regmap access]
[Julien Stephan: fix scale issue]
[Julien Stephan: use the new iio_device_claim_direct_scoped
instead of iio_device_claim_direct_mode]
Co-developed-by: Stefan Popa <stefan.popa@analog.com>
Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Signed-off-by: David Lechner <dlechner@baylibre.com>
[Julien Stephan: add datasheet links of supported parts]
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Link: https://lore.kernel.org/r/20240528-adding-new-ad738x-driver-v7-2-4cd70a4c12c8@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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