linux-toradex.git/include/linux/iio/adc/ad_sigma_delta.h, branch v6.4

iio: adc: ad_sigma_delta: Add sequencer support

2022-04-04T08:11:25+00:00

Some sigma-delta chips support sampling of multiple
channels in continuous mode.

When the operating with more than one channel enabled,
the channel sequencer cycles through the enabled channels
in sequential order, from first channel to the last one.
If a channel is disabled, it is skipped by the sequencer.

If more than one channel is used in continuous mode,
instruct the device to append the status to the SPI transfer
(1 extra byte) every time we receive a sample.
All sigma-delta chips possessing a sampling sequencer have
this ability. Inside the status register there will be
the number of the converted channel. In this way, even
if the CPU won't keep up with the sampling rate, it won't
send to userspace wrong channel samples.

When multiple channels are enabled in continuous mode,
the device needs to perform a measurement on all slots
before we can push to userspace the sample.

If, during sequencing and data reading, a channel measurement
is lost, a desync occurred. In this case, ad_sigma_delta drops
the incomplete sample and waits for the device to send the
measurement on the first active slot.

Co-developed-by: Alexandru Tachici 
Signed-off-by: Alexandru Tachici 
Signed-off-by: Lars-Peter Clausen 
Link: https://lore.kernel.org/r/20220322105029.86389-5-alexandru.tachici@analog.com
Signed-off-by: Jonathan Cameron

iio: adc: ad_sigma_delta: remove ad_sd_{setup,cleanup}_buffer_and_trigger()

2021-06-13T16:00:17+00:00

Since all AD Sigma-Delta drivers now use the
devm_ad_sd_setup_buffer_and_trigger() function, we can remove the old
ad_sd_{setup,cleanup}_buffer_and_trigger() functions.

This way we can discourage new drivers that use the ad_sigma_delta
lib-driver to use these (older functions).

Signed-off-by: Alexandru Ardelean 
Link: https://lore.kernel.org/r/20210513120752.90074-13-aardelean@deviqon.com
Signed-off-by: Jonathan Cameron

iio: adc: ad_sigma_delta: introduct devm_ad_sd_setup_buffer_and_trigger()

2021-06-13T16:00:16+00:00

This is a version of ad_sd_setup_buffer_and_trigger() with all underlying
functions (that are used) being replaced with their device-managed
variants.

One thing to take care here is with {devm_}iio_trigger_alloc(), where both
functions take a parent-device object as the first parameter.

To make sure nothing quirky is happening, the devm_ad_sd_probe_trigger()
function is checking that the provided 'dev' reference is the same as the
one stored on the 'struct ad_sigma_delta' driver data.

Signed-off-by: Alexandru Ardelean 
Link: https://lore.kernel.org/r/20210513120752.90074-6-aardelean@deviqon.com
Signed-off-by: Jonathan Cameron

iio: ad_sigma_delta: Don't put SPI transfer buffer on the stack

2020-12-03T19:32:40+00:00

Use a heap allocated memory for the SPI transfer buffer. Using stack memory
can corrupt stack memory when using DMA on some systems.

This change moves the buffer from the stack of the trigger handler call to
the heap of the buffer of the state struct. The size increases takes into
account the alignment for the timestamp, which is 8 bytes.

The 'data' buffer is split into 'tx_buf' and 'rx_buf', to make a clearer
separation of which part of the buffer should be used for TX & RX.

Fixes: af3008485ea03 ("iio:adc: Add common code for ADI Sigma Delta devices")
Signed-off-by: Lars-Peter Clausen 
Signed-off-by: Alexandru Ardelean 
Link: https://lore.kernel.org/r/20201124123807.19717-1-alexandru.ardelean@analog.com
Cc: 
Signed-off-by: Jonathan Cameron

iio: ad_sigma_delta: remove unused IIO channel macros

2020-04-19T15:56:11+00:00

Now that all channel SigmaDelta IIO channel macros have been localized,
remove the generic ones.

Signed-off-by: Alexandru Ardelean 
Signed-off-by: Jonathan Cameron

iio: adc: ad-sigma-delta: Allow custom IRQ flags

2020-01-18T11:43:16+00:00

Before this patch the ad_sigma_delta implementation hardcoded
the irq trigger type to low, assuming that all Sigma-Delta ADCs
have the same interrupt-type.

This patch allows all drivers using the ad_sigma_delta layer to set the
irq trigger type to the one specified in the datasheet.

Signed-off-by: Alexandru Tachici 
Signed-off-by: Jonathan Cameron

iio: adc: ad_sigma_delta: Export ad_sd_calibrate

2019-09-08T09:35:31+00:00

This patch exports the ad_sd_calibrate function in order to be able to
call it from outside ad_sigma_delta.

There are cases where the option to calibrate one channel at a time is
necessary (ex. system calibration for zero scale and full scale).

Signed-off-by: Mircea Caprioru 
Signed-off-by: Jonathan Cameron

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 177

2019-05-30T18:29:19+00:00

Based on 1 normalized pattern(s):

  licensed under the gpl 2

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 135 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Reviewed-by: Richard Fontana 
Reviewed-by: Alexios Zavras 
Reviewed-by: Steve Winslow 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190528170026.071193225@linutronix.de
Signed-off-by: Greg Kroah-Hartman

iio: ad_sigma_delta: Properly handle SPI bus locking vs CS assertion

2019-04-04T19:21:15+00:00

For devices from the SigmaDelta family we need to keep CS low when doing a
conversion, since the device will use the MISO line as a interrupt to
indicate that the conversion is complete.

This is why the driver locks the SPI bus and when the SPI bus is locked
keeps as long as a conversion is going on. The current implementation gets
one small detail wrong though. CS is only de-asserted after the SPI bus is
unlocked. This means it is possible for a different SPI device on the same
bus to send a message which would be wrongfully be addressed to the
SigmaDelta device as well. Make sure that the last SPI transfer that is
done while holding the SPI bus lock de-asserts the CS signal.

Signed-off-by: Lars-Peter Clausen 
Signed-off-by: Alexandru Ardelean 
Signed-off-by: Jonathan Cameron

iio: ad_sigma_delta: Allow to provide custom data register address

2018-11-17T16:30:00+00:00

Some newer devices from the Sigma-Delta ADC family do have their data
register at a different address than the current default address. Add a
parameter to the ad_sigma_delta_info struct which allows to override the
default address.

Signed-off-by: Lars-Peter Clausen 
Signed-off-by: Stefan Popa 
Signed-off-by: Jonathan Cameron