Re: [PATCH v7 2/2] iio: adc: Add MAX1241 driver

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On Fri, Apr 3, 2020 at 3:09 PM Alexandru Lazar <alazar@xxxxxxxxxxxxx> wrote:
>
> Add driver for the Maxim MAX1241 12-bit, single-channel ADC.
>

FWIW,
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>

> Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1240-MAX1241.pdf

>

No blank line, but this can be fixed by maintainer, I think.

> Reviewed-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx>
> Signed-off-by: Alexandru Lazar <alazar@xxxxxxxxxxxxx>
> ---
>  drivers/iio/adc/Kconfig   |  10 ++
>  drivers/iio/adc/Makefile  |   1 +
>  drivers/iio/adc/max1241.c | 227 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 238 insertions(+)
>  create mode 100644 drivers/iio/adc/max1241.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 5d8540b7b427..55f6462cd93f 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -566,6 +566,16 @@ config MAX1118
>           To compile this driver as a module, choose M here: the module will be
>           called max1118.
>
> +config MAX1241
> +       tristate "Maxim max1241 ADC driver"
> +       depends on SPI_MASTER
> +       help
> +         Say yes here to build support for Maxim max1241 12-bit, single-channel
> +         ADC.
> +
> +         To compile this driver as a module, choose M here: the module will be
> +         called max1241.
> +
>  config MAX1363
>         tristate "Maxim max1363 ADC driver"
>         depends on I2C
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index a1f1fbec0f87..37d6f17559dc 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -54,6 +54,7 @@ obj-$(CONFIG_LTC2497) += ltc2497.o
>  obj-$(CONFIG_MAX1027) += max1027.o
>  obj-$(CONFIG_MAX11100) += max11100.o
>  obj-$(CONFIG_MAX1118) += max1118.o
> +obj-$(CONFIG_MAX1241) += max1241.o
>  obj-$(CONFIG_MAX1363) += max1363.o
>  obj-$(CONFIG_MAX9611) += max9611.o
>  obj-$(CONFIG_MCP320X) += mcp320x.o
> diff --git a/drivers/iio/adc/max1241.c b/drivers/iio/adc/max1241.c
> new file mode 100644
> index 000000000000..541939c7abca
> --- /dev/null
> +++ b/drivers/iio/adc/max1241.c
> @@ -0,0 +1,227 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * MAX1241 low-power, 12-bit serial ADC
> + *
> + * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1240-MAX1241.pdf
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +
> +#define MAX1241_VAL_MASK GENMASK(11, 0)
> +#define MAX1241_SHUTDOWN_DELAY_USEC 4
> +
> +enum max1241_id {
> +       max1241,
> +};
> +
> +struct max1241 {
> +       struct spi_device *spi;
> +       struct mutex lock;
> +       struct regulator *vdd;
> +       struct regulator *vref;
> +       struct gpio_desc *shutdown;
> +
> +       __be16 data ____cacheline_aligned;
> +};
> +
> +static const struct iio_chan_spec max1241_channels[] = {
> +       {
> +               .type = IIO_VOLTAGE,
> +               .indexed = 1,
> +               .channel = 0,
> +               .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +                               BIT(IIO_CHAN_INFO_SCALE),
> +       },
> +};
> +
> +static int max1241_read(struct max1241 *adc)
> +{
> +       struct spi_transfer xfers[] = {
> +               /*
> +                * Begin conversion by bringing /CS low for at least
> +                * tconv us.
> +                */
> +               {
> +                       .len = 0,
> +                       .delay.value = 8,
> +                       .delay.unit = SPI_DELAY_UNIT_USECS,
> +               },
> +               /*
> +                * Then read two bytes of data in our RX buffer.
> +                */
> +               {
> +                       .rx_buf = &adc->data,
> +                       .len = 2,
> +               },
> +       };
> +
> +       return spi_sync_transfer(adc->spi, xfers, ARRAY_SIZE(xfers));
> +}
> +
> +static int max1241_read_raw(struct iio_dev *indio_dev,
> +                       struct iio_chan_spec const *chan,
> +                       int *val, int *val2, long mask)
> +{
> +       int ret, vref_uV;
> +       struct max1241 *adc = iio_priv(indio_dev);
> +
> +       switch (mask) {
> +       case IIO_CHAN_INFO_RAW:
> +               mutex_lock(&adc->lock);
> +
> +               if (adc->shutdown) {
> +                       gpiod_set_value(adc->shutdown, 0);
> +                       udelay(MAX1241_SHUTDOWN_DELAY_USEC);
> +                       ret = max1241_read(adc);
> +                       gpiod_set_value(adc->shutdown, 1);
> +               } else
> +                       ret = max1241_read(adc);
> +
> +               if (ret) {
> +                       mutex_unlock(&adc->lock);
> +                       return ret;
> +               }
> +
> +               *val = (be16_to_cpu(adc->data) >> 3) & MAX1241_VAL_MASK;
> +
> +               mutex_unlock(&adc->lock);
> +               return IIO_VAL_INT;
> +       case IIO_CHAN_INFO_SCALE:
> +               vref_uV = regulator_get_voltage(adc->vref);
> +
> +               if (vref_uV < 0)
> +                       return vref_uV;
> +
> +               *val = vref_uV / 1000;
> +               *val2 = 12;
> +
> +               return IIO_VAL_FRACTIONAL_LOG2;
> +       default:
> +               return -EINVAL;
> +       }
> +}
> +
> +static const struct iio_info max1241_info = {
> +       .read_raw = max1241_read_raw,
> +};
> +
> +static void max1241_disable_vdd_action(void *data)
> +{
> +       struct max1241 *adc = data;
> +       struct device *dev = &adc->spi->dev;
> +       int err;
> +
> +       err = regulator_disable(adc->vdd);
> +       if (err)
> +               dev_err(dev, "could not disable vdd regulator.\n");
> +}
> +
> +static void max1241_disable_vref_action(void *data)
> +{
> +       struct max1241 *adc = data;
> +       struct device *dev = &adc->spi->dev;
> +       int err;
> +
> +       err = regulator_disable(adc->vref);
> +       if (err)
> +               dev_err(dev, "could not disable vref regulator.\n");
> +}
> +
> +static int max1241_probe(struct spi_device *spi)
> +{
> +       struct device *dev = &spi->dev;
> +       struct iio_dev *indio_dev;
> +       struct max1241 *adc;
> +       int ret;
> +
> +       indio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
> +       if (!indio_dev)
> +               return -ENOMEM;
> +
> +       adc = iio_priv(indio_dev);
> +       adc->spi = spi;
> +       mutex_init(&adc->lock);
> +
> +       spi_set_drvdata(spi, indio_dev);
> +
> +       adc->vdd = devm_regulator_get(dev, "vdd");
> +       if (IS_ERR(adc->vdd)) {
> +               dev_err(dev, "failed to get vdd regulator\n");
> +               return PTR_ERR(adc->vdd);
> +       }
> +
> +       ret = regulator_enable(adc->vdd);
> +       if (ret)
> +               return ret;
> +
> +       ret = devm_add_action_or_reset(dev, max1241_disable_vdd_action, adc);
> +       if (ret) {
> +               dev_err(dev, "could not set up vdd regulator cleanup action\n");
> +               return ret;
> +       }
> +
> +       adc->vref = devm_regulator_get(dev, "vref");
> +       if (IS_ERR(adc->vref)) {
> +               dev_err(dev, "failed to get vref regulator\n");
> +               return PTR_ERR(adc->vref);
> +       }
> +
> +       ret = regulator_enable(adc->vref);
> +       if (ret)
> +               return ret;
> +
> +       ret = devm_add_action_or_reset(dev, max1241_disable_vref_action, adc);
> +       if (ret) {
> +               dev_err(dev, "could not set up vref regulator cleanup action\n");
> +               return ret;
> +       }
> +
> +       adc->shutdown = devm_gpiod_get_optional(dev, "shutdown",
> +                                               GPIOD_OUT_HIGH);
> +       if (IS_ERR(adc->shutdown))
> +               return PTR_ERR(adc->shutdown);
> +
> +       if (adc->shutdown)
> +               dev_dbg(dev, "shutdown pin passed, low-power mode enabled");
> +       else
> +               dev_dbg(dev, "no shutdown pin passed, low-power mode disabled");
> +
> +       indio_dev->name = spi_get_device_id(spi)->name;
> +       indio_dev->dev.parent = dev;
> +       indio_dev->info = &max1241_info;
> +       indio_dev->modes = INDIO_DIRECT_MODE;
> +       indio_dev->channels = max1241_channels;
> +       indio_dev->num_channels = ARRAY_SIZE(max1241_channels);
> +
> +       return devm_iio_device_register(dev, indio_dev);
> +}
> +
> +static const struct spi_device_id max1241_id[] = {
> +       { "max1241", max1241 },
> +       {}
> +};
> +
> +static const struct of_device_id max1241_dt_ids[] = {
> +       { .compatible = "maxim,max1241" },
> +       {}
> +};
> +MODULE_DEVICE_TABLE(of, max1241_dt_ids);
> +
> +static struct spi_driver max1241_spi_driver = {
> +       .driver = {
> +               .name = "max1241",
> +               .of_match_table = max1241_dt_ids,
> +       },
> +       .probe = max1241_probe,
> +       .id_table = max1241_id,
> +};
> +module_spi_driver(max1241_spi_driver);
> +
> +MODULE_AUTHOR("Alexandru Lazar <alazar@xxxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("MAX1241 ADC driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.20.1
>


-- 
With Best Regards,
Andy Shevchenko



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