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

[Nuno Sá]

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@xxxxxxxxxx>
> Signed-off-by: Stefan Popa <stefan.popa@xxxxxxxxxx>
> Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx>
> ---
> 
> 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@xxxxxxxxxx>
> 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@xxxxxxxxxx>


- Nuno Sá