RE: [PATCH v2 2/2] iio: adc: add max11205 adc driver

[Bolboaca, Ramona]

> On Wed, Aug 31, 2022 at 4:36 PM Ramona Bolboaca
> <ramona.bolboaca@xxxxxxxxxx> wrote:
> >
> > Adding support for max11205 16-bit single-channel ultra-low power
> > delta-sigma adc.
> > The MAX11205 is compatible with the 2-wire interface and uses
> > SCLK and RDY/DOUT for serial communications. In this mode, all
> > controls are implemented by timing the high or low phase of the SCLK.
> > The 2-wire serial interface only allows for data to be read out through
> > the RDY/DOUT output.
> 
> Couple of minor comments, if you are going to address them,
> Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> 
> > Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX11205.pdf
> > Signed-off-by: Ramona Bolboaca <ramona.bolboaca@xxxxxxxxxx>
> > ---
> > changes in v2:
> >  - add chip_info null pointer check
> >  - add support for probing with ACPI table
> >  - remove function for module removal
> >  - remove irq flag from max11205_sigma_delta_info
> >  - add missing commas and missing spaces
> >  - remove redundant blank line
> >  - wrap text to 75-80 chars
> >  - removed typos in commit message
> >  drivers/iio/adc/Kconfig    |  14 +++
> >  drivers/iio/adc/Makefile   |   1 +
> >  drivers/iio/adc/max11205.c | 183 +++++++++++++++++++++++++++++++++++++
> >  3 files changed, 198 insertions(+)
> >  create mode 100644 drivers/iio/adc/max11205.c
> >
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> > index 7fe5930891e0..0c8f376b65d8 100644
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -653,6 +653,20 @@ config MAX1118
> >           To compile this driver as a module, choose M here: the module will be
> >           called max1118.
> >
> > +config MAX11205
> > +       tristate "Maxim max11205 ADC driver"
> > +       depends on SPI
> > +       select AD_SIGMA_DELTA
> > +       select IIO_BUFFER
> > +       select IIO_TRIGGERED_BUFFER
> > +
> > +       help
> > +         Say yes here to build support for Maxim max11205 16-bit, single-channel
> > +         ultra-low power delta-sigma ADC.
> > +
> > +         To compile this driver as a module, choose M here: the module will be
> > +         called max11205.
> > +
> >  config MAX1241
> >         tristate "Maxim max1241 ADC driver"
> >         depends on SPI_MASTER
> > diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> > index 1772a549a3c8..bb681844e497 100644
> > --- a/drivers/iio/adc/Makefile
> > +++ b/drivers/iio/adc/Makefile
> > @@ -61,6 +61,7 @@ obj-$(CONFIG_LTC2497) += ltc2497.o ltc2497-core.o
> >  obj-$(CONFIG_MAX1027) += max1027.o
> >  obj-$(CONFIG_MAX11100) += max11100.o
> >  obj-$(CONFIG_MAX1118) += max1118.o
> > +obj-$(CONFIG_MAX11205) += max11205.o
> >  obj-$(CONFIG_MAX1241) += max1241.o
> >  obj-$(CONFIG_MAX1363) += max1363.o
> >  obj-$(CONFIG_MAX9611) += max9611.o
> > diff --git a/drivers/iio/adc/max11205.c b/drivers/iio/adc/max11205.c
> > new file mode 100644
> > index 000000000000..68e6082e70e5
> > --- /dev/null
> > +++ b/drivers/iio/adc/max11205.c
> > @@ -0,0 +1,183 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * max11205 16-Bit Delta-Sigma ADC
> 
> Can you spell the vendor and part number verbosely?
> Something like "Maxim MAX11205" or similar.
> 
> > + *
> > + * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1240-max11205.pdf
> > + * Copyright (C) 2022 Analog Devices, Inc.
> > + * Author: Ramona Bolboaca <ramona.bolboaca@xxxxxxxxxx>
> > + */
> > +
> > +#include <linux/device.h>
> > +#include <linux/module.h>
> > +#include <linux/regulator/consumer.h>
> > +#include <linux/spi/spi.h>
> > +
> > +#include <linux/iio/iio.h>
> > +#include <linux/iio/adc/ad_sigma_delta.h>
> > +
> > +#define MAX11205_BIT_SCALE     15
> > +#define MAX11205A_OUT_DATA_RATE        116
> > +#define MAX11205B_OUT_DATA_RATE        13
> > +
> > +enum chip_type {
> > +       TYPE_MAX11205A,
> > +       TYPE_MAX11205B,
> > +};
> > +
> > +struct chip_info {
> > +       unsigned int    out_data_rate;
> > +       const char      *name;
> > +};
> > +
> > +struct max11205_state {
> > +       const struct chip_info  *chip_info;
> > +       struct regulator        *vref;
> > +       struct ad_sigma_delta   sd;
> > +};
> > +
> > +static const struct ad_sigma_delta_info max11205_sigma_delta_info = {
> > +       .has_registers = false,
> > +};
> > +
> > +static int max11205_read_raw(struct iio_dev *indio_dev,
> > +                            struct iio_chan_spec const *chan,
> > +                            int *val, int *val2, long mask)
> > +{
> > +       struct max11205_state *st = iio_priv(indio_dev);
> > +       int reg_mv;
> > +
> > +       switch (mask) {
> > +       case IIO_CHAN_INFO_RAW:
> > +               return ad_sigma_delta_single_conversion(indio_dev, chan, val);
> > +       case IIO_CHAN_INFO_SCALE:
> > +               reg_mv = regulator_get_voltage(st->vref);
> > +               if (reg_mv < 0)
> > +                       return reg_mv;
> > +               reg_mv /= 1000;
> > +               *val = reg_mv;
> > +               *val2 = MAX11205_BIT_SCALE;
> > +               return IIO_VAL_FRACTIONAL_LOG2;
> > +       case IIO_CHAN_INFO_SAMP_FREQ:
> > +               *val = st->chip_info->out_data_rate;
> > +               return IIO_VAL_INT;
> > +       default:
> > +               return -EINVAL;
> > +       }
> > +}
> > +
> > +static const struct iio_info max11205_iio_info = {
> > +       .read_raw = max11205_read_raw,
> > +       .validate_trigger = ad_sd_validate_trigger,
> > +};
> > +
> > +static const struct iio_chan_spec max11205_channels[] = {
> > +       {
> > +               .type = IIO_VOLTAGE,
> > +               .indexed = 1,
> > +               .scan_type = {
> > +                       .sign = 's',
> > +                       .realbits = 16,
> > +                       .storagebits = 16,
> > +                       .endianness = IIO_BE
> > +               },
> > +               .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > +               BIT(IIO_CHAN_INFO_SAMP_FREQ) |
> > +               BIT(IIO_CHAN_INFO_SCALE),
> > +       },
> > +};
> > +
> > +static const struct chip_info max11205_chip_info[] = {
> > +       [TYPE_MAX11205A] = {
> > +               .out_data_rate = MAX11205A_OUT_DATA_RATE,
> > +               .name = "max11205a",
> > +       },
> > +       [TYPE_MAX11205B] = {
> > +               .out_data_rate = MAX11205B_OUT_DATA_RATE,
> > +               .name = "max11205b",
> > +       },
> > +};
> > +
> > +static void max11205_reg_disable(void *reg)
> > +{
> > +       regulator_disable(reg);
> > +}
> > +
> > +static int max11205_probe(struct spi_device *spi)
> > +{
> > +       struct max11205_state *st;
> > +       struct iio_dev *indio_dev;
> > +       int ret;
> > +
> > +       indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> > +       if (!indio_dev)
> > +               return -ENOMEM;
> > +
> > +       st = iio_priv(indio_dev);
> > +
> > +       ad_sd_init(&st->sd, indio_dev, spi, &max11205_sigma_delta_info);
> 
> > +       st->chip_info = device_get_match_data(&spi->dev);
> 
> > +
> 
> Unneeded blank line.
> 
> > +       if (!st->chip_info)
> > +               st->chip_info = (const struct chip_info *)spi_get_device_id(spi)->driver_data;
> > +
> > +       indio_dev->name = st->chip_info->name;
> > +       indio_dev->modes = INDIO_DIRECT_MODE;
> > +       indio_dev->channels = max11205_channels;
> > +       indio_dev->num_channels = 1;
> > +       indio_dev->info = &max11205_iio_info;
> > +
> > +       st->vref = devm_regulator_get(&spi->dev, "vref");
> 
> devm_regulator_get_enable() ?
I found the patches which implement devm_regulator_get_enable. However, I need to get the voltage of the regulator using regulator_get_voltage(struct regulator *regulator) and if I use devm_regulator_get_enable I do not have access to the regulator pointer. What should I do in this case? Is there an API which works like devm_regulator_get_enable but also gives access to the regulator's pointer?
Thank you for you review!
Kind Regards,
Ramona Bolboaca
> 
> > +       if (IS_ERR(st->vref))
> > +               return dev_err_probe(&spi->dev, PTR_ERR(st->vref),
> > +                                    "Failed to get vref regulator\n");
> > +
> > +       ret = regulator_enable(st->vref);
> > +       if (ret)
> > +               return ret;
> > +
> > +       ret = devm_add_action_or_reset(&spi->dev, max11205_reg_disable, st->vref);
> > +       if (ret)
> > +               return ret;
> > +
> > +       ret = devm_ad_sd_setup_buffer_and_trigger(&spi->dev, indio_dev);
> > +       if (ret)
> > +               return ret;
> > +
> > +       return devm_iio_device_register(&spi->dev, indio_dev);
> > +}
> > +
> > +static const struct spi_device_id max11205_spi_ids[] = {
> > +       { "max11205a", (kernel_ulong_t)&max11205_chip_info[TYPE_MAX11205A] },
> > +       { "max11205b", (kernel_ulong_t)&max11205_chip_info[TYPE_MAX11205B] },
> > +       { }
> > +};
> > +MODULE_DEVICE_TABLE(spi, max11205_spi_ids);
> > +
> > +static const struct of_device_id max11205_dt_ids[] = {
> > +       {
> > +               .compatible = "maxim,max11205a",
> > +               .data = &max11205_chip_info[TYPE_MAX11205A],
> > +       },
> > +       {
> > +               .compatible = "maxim,max11205b",
> > +               .data = &max11205_chip_info[TYPE_MAX11205B],
> > +       },
> > +       { }
> > +};
> > +MODULE_DEVICE_TABLE(of, max11205_dt_ids);
> > +
> > +static struct spi_driver max11205_spi_driver = {
> > +       .driver = {
> > +               .name = "max11205",
> > +               .of_match_table = max11205_dt_ids,
> > +       },
> > +       .probe = max11205_probe,
> > +       .id_table = max11205_spi_ids,
> > +};
> > +module_spi_driver(max11205_spi_driver);
> > +
> > +MODULE_AUTHOR("Ramona Bolboaca <ramona.bolboaca@xxxxxxxxxx>");
> > +MODULE_DESCRIPTION("MAX11205 ADC driver");
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_IMPORT_NS(IIO_AD_SIGMA_DELTA);
> > --
> > 2.25.1
> >
> 
> 
> --
> With Best Regards,
> Andy Shevchenko