Commit 8a80a71d authored by Alexandru Lazar's avatar Alexandru Lazar Committed by Jonathan Cameron
Browse files

iio: adc: Add MAX1241 driver 

Add driver for the Maxim MAX1241 12-bit, single-channel ADC.

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


Reviewed-by: default avatarAlexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: default avatarAlexandru Lazar <alazar@startmail.com>
Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent fc20a26a

drivers/iio/adc/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -630,6 +630,16 @@ 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

drivers/iio/adc/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ 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_MAX1241) += max1241.o

obj-$(CONFIG_MAX1363) += max1363.o

obj-$(CONFIG_MAX9611) += max9611.o

obj-$(CONFIG_MCP320X) += mcp320x.o

drivers/iio/adc/max1241.c

0 → 100644
+227 −0
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// 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@startmail.com>");

MODULE_DESCRIPTION("MAX1241 ADC driver");

MODULE_LICENSE("GPL v2");