Re: [PATCH v2 3/3] iio: adc: ad7380: new driver for AD7380 ADCs

From: David Lechner <dlechner@baylibre.com>
To: "Nuno Sá" <noname.nuno@gmail.com>
Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org,
	"Rob Herring" <robh+dt@kernel.org>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
	"Conor Dooley" <conor+dt@kernel.org>,
	"Jonathan Cameron" <jic23@kernel.org>,
	"Michael Hennerich" <michael.hennerich@analog.com>,
	"Nuno Sá" <nuno.sa@analog.com>,
	"Liam Girdwood" <lgirdwood@gmail.com>,
	"Mark Brown" <broonie@kernel.org>,
	linux-kernel@vger.kernel.org,
	"Stefan Popa" <stefan.popa@analog.com>
Subject: Re: [PATCH v2 3/3] iio: adc: ad7380: new driver for AD7380 ADCs
Date: Wed, 13 Dec 2023 14:47:16 +0100	[thread overview]
Message-ID: <CAMknhBE6mPepiE=EYBj0ScU8SHXMhpO+D_kKBKFj6W+go_Jrxg@mail.gmail.com> (raw)
In-Reply-To: <5f7a1c60ccebe13ba6cdfa5d8f9632bc9b838137.camel@gmail.com>

On Wed, Dec 13, 2023 at 1:18 PM Nuno Sá <noname.nuno@gmail.com> wrote:
>
> On Wed, 2023-12-13 at 05:21 -0600, David Lechner wrote:
> > This adds a new driver for the AD7380 family ADCs.
> >
> > The driver currently implements basic support for the AD7380, AD7381,
> > AD7383, and AD7384 2-channel differential ADCs. Support for additional
> > single-ended and 4-channel chips that use the same register map as well
> > as additional features of the chip will be added in future patches.
> >
> > Co-developed-by: Stefan Popa <stefan.popa@analog.com>
> > Signed-off-by: Stefan Popa <stefan.popa@analog.com>
> > Signed-off-by: David Lechner <dlechner@baylibre.com>
> > ---
> >
> > v2 changes:
> > - Fixed CONFIG_AD7380 in Makefile
> > - rx_buf = st->scan_data.raw instead of rx_buf = &st->scan_data
> > - Moved iio_push_to_buffers_with_timestamp() outside of if statement
> > - Removed extra blank lines
> > - Renamed regulator disable function
> > - Dropped checking of adi,sdo-mode property (regardless of the actual
> >         wiring, we can always use 1-wire mode)
> > - Added available_scan_masks (we always sample two channels at the same time
> >   so we need to let userspace know this)
> > - Added check for missing driver match data
> >
> >  MAINTAINERS              |   1 +
> >  drivers/iio/adc/Kconfig  |  16 ++
> >  drivers/iio/adc/Makefile |   1 +
> >  drivers/iio/adc/ad7380.c | 464 +++++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 482 insertions(+)
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index e2a998be5879..5a54620a31b8 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -438,6 +438,7 @@ S:  Supported
> >  W:
> > https://wiki.analog.com/resources/tools-software/linux-drivers/iio-adc/ad738x
> >  W:     https://ez.analog.com/linux-software-drivers
> >  F:     Documentation/devicetree/bindings/iio/adc/adi,ad7380.yaml
> > +F:     drivers/iio/adc/ad7380.c
> >
> >  AD7877 TOUCHSCREEN DRIVER
> >  M:     Michael Hennerich <michael.hennerich@analog.com>
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> > index 35f9867da12c..cbfd626712e3 100644
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -122,6 +122,22 @@ config AD7298
> >           To compile this driver as a module, choose M here: the
> >           module will be called ad7298.
> >
> > +config AD7380
> > +       tristate "Analog Devices AD7380 ADC driver"
> > +       depends on SPI_MASTER
> > +       select IIO_BUFFER
> > +       select IIO_TRIGGER
> > +       select IIO_TRIGGERED_BUFFER
> > +       help
> > +         AD7380 is a family of simultaneous sampling ADCs that share the same
> > +         SPI register map and have similar pinouts.
> > +
> > +         Say yes here to build support for Analog Devices AD7380 ADC and
> > +         similar chips.
> > +
> > +         To compile this driver as a module, choose M here: the module will be
> > +         called ad7380.
> > +
> >  config AD7476
> >         tristate "Analog Devices AD7476 1-channel ADCs driver and other similar
> > devices from AD and TI"
> >         depends on SPI
> > diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> > index bee11d442af4..9c921c497655 100644
> > --- a/drivers/iio/adc/Makefile
> > +++ b/drivers/iio/adc/Makefile
> > @@ -16,6 +16,7 @@ obj-$(CONFIG_AD7291) += ad7291.o
> >  obj-$(CONFIG_AD7292) += ad7292.o
> >  obj-$(CONFIG_AD7298) += ad7298.o
> >  obj-$(CONFIG_AD7923) += ad7923.o
> > +obj-$(CONFIG_AD7380) += ad7380.o
> >  obj-$(CONFIG_AD7476) += ad7476.o
> >  obj-$(CONFIG_AD7606_IFACE_PARALLEL) += ad7606_par.o
> >  obj-$(CONFIG_AD7606_IFACE_SPI) += ad7606_spi.o
> > diff --git a/drivers/iio/adc/ad7380.c b/drivers/iio/adc/ad7380.c
> > new file mode 100644
> > index 000000000000..b8025b636b67
> > --- /dev/null
> > +++ b/drivers/iio/adc/ad7380.c
> > @@ -0,0 +1,464 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Analog Devices AD738x Simultaneous Sampling SAR ADCs
> > + *
> > + * Copyright 2017 Analog Devices Inc.
> > + * Copyright 2023 BayLibre, SAS
> > + */
> > +
> > +#include <linux/bitfield.h>
> > +#include <linux/bitops.h>
> > +#include <linux/cleanup.h>
> > +#include <linux/device.h>
> > +#include <linux/err.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/regmap.h>
> > +#include <linux/regulator/consumer.h>
> > +#include <linux/slab.h>
> > +#include <linux/spi/spi.h>
> > +#include <linux/sysfs.h>
> > +
> > +#include <linux/iio/buffer.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/iio/sysfs.h>
> > +#include <linux/iio/trigger_consumer.h>
> > +#include <linux/iio/triggered_buffer.h>
> > +
>
> ...
>
> >
> > +static int ad7380_probe(struct spi_device *spi)
> > +{
> > +       struct iio_dev *indio_dev;
> > +       struct ad7380_state *st;
> > +       int ret;
> > +
> > +       indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> > +       if (!indio_dev)
> > +               return -ENOMEM;
> > +
> > +       st = iio_priv(indio_dev);
> > +       st->spi = spi;
> > +       st->chip_info = spi_get_device_match_data(spi);
> > +       if (!st->chip_info)
> > +               return dev_err_probe(&spi->dev, -EINVAL, "missing match data\n");
> > +
> > +       st->vref = devm_regulator_get_optional(&spi->dev, "refio");
> > +       if (IS_ERR(st->vref)) {
> > +               /*
> > +                * If there is no REFIO supply, then it means that we are using
> > +                * the internal 2.5V reference.
> > +                */
> > +               if (PTR_ERR(st->vref) == -ENODEV)
> > +                       st->vref = NULL;
> > +               else
> > +                       return dev_err_probe(&spi->dev, PTR_ERR(st->vref),
> > +                                            "Failed to get refio regulator\n");
> > +       }
> > +
> > +       if (st->vref) {
> > +               ret = regulator_enable(st->vref);
> > +               if (ret)
> > +                       return ret;
> > +
> > +               ret = devm_add_action_or_reset(&spi->dev, ad7380_regulator_disable,
> > +                                              st->vref);
> > +               if (ret)
> > +                       return ret;
> > +       }
> > +
> > +       st->regmap = devm_regmap_init(&spi->dev, NULL, st, &ad7380_regmap_config);
> > +       if (IS_ERR(st->regmap))
> > +               return dev_err_probe(&spi->dev, PTR_ERR(st->regmap),
> > +                                    "failed to allocate register map\n");
>
> Still not using a regmap_bus... You could at least argue in the last version why
> you're not doing it rather than ignoring the comment :).
>
> I'm asking for it because it already happened (in IIO) to me and I was asked for
> implementing the bus. You also gain things like regmap core handling endianism and
> formatting the work buffer for you (eg: regmap_bulk_read() could be more efficient),
>
> > +       indio_dev->channels = st->chip_info->channels;
> > +       indio_dev->num_channels = st->chip_info->num_channels;
> > +       indio_dev->dev.parent = &spi->dev;
>
> still not addressed...
>
> With at least the above (for the regmap_bus I'll leave the ultimate decision to
> Jonathan - not a deal breaker for me):
>
> Reviewed-by: Nuno Sa <nuno.sa@analog.com>
>
>
> - Nuno Sá
>

Sorry, I did not mean to ignore these. I just did a bad job of
double-checking that I addressed all comments before sending v2. :-(

If we need a v3, I will look into regmap_bus but at leas
superficially, I don't see much difference for this part, i.e not
really any case where bulk ops make sense and since it uses SPI bus
underneath, endianness isn't an issue.