Commit a8e7e88d authored by Jacopo Mondi's avatar Jacopo Mondi Committed by Jonathan Cameron
Browse files

iio: adc: Add Maxim MAX11100 driver 



Add iio driver for Maxim MAX11100 single-channel ADC.

Signed-off-by: default avatarJacopo Mondi <jacopo+renesas@jmondi.org>
Tested-by: default avatarMarek Vasut <marek.vasut@gmail.com>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent 2d3f956e

drivers/iio/adc/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -326,6 +326,15 @@ config MAX1027 
	  To compile this driver as a module, choose M here: the module will be

	  called max1027.



config MAX11100

	tristate "Maxim max11100 ADC driver"

	depends on SPI_MASTER

	help

	  Say yes here to build support for Maxim max11100 SPI ADC



	  To compile this driver as a module, choose M here: the module will be

	  called max11100.



config MAX1363

	tristate "Maxim max1363 ADC driver"

	depends on I2C

drivers/iio/adc/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o 
obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o

obj-$(CONFIG_LTC2485) += ltc2485.o

obj-$(CONFIG_MAX1027) += max1027.o

obj-$(CONFIG_MAX11100) += max11100.o

obj-$(CONFIG_MAX1363) += max1363.o

obj-$(CONFIG_MCP320X) += mcp320x.o

obj-$(CONFIG_MCP3422) += mcp3422.o

drivers/iio/adc/max11100.c

0 → 100644
+192 −0
Original line number Diff line number Diff line 
/*

 * iio/adc/max11100.c

 * Maxim max11100 ADC Driver with IIO interface

 *

 * Copyright (C) 2016-17 Renesas Electronics Corporation

 * Copyright (C) 2016-17 Jacopo Mondi

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */

#include <linux/delay.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/regulator/consumer.h>

#include <linux/spi/spi.h>



#include <linux/iio/iio.h>

#include <linux/iio/driver.h>



/*

 * LSB is the ADC single digital step

 * 1 LSB = (vref_mv / 2 ^ 16)

 *

 * LSB is used to calculate analog voltage value

 * from the number of ADC steps count

 *

 * Ain = (count * LSB)

 */

#define MAX11100_LSB_DIV		(1 << 16)



struct max11100_state {

	const struct max11100_chip_desc *desc;

	struct regulator *vref_reg;

	struct spi_device *spi;



	/*

	 * DMA (thus cache coherency maintenance) requires the

	 * transfer buffers to live in their own cache lines.

	 */

	u8 buffer[3] ____cacheline_aligned;

};



static struct iio_chan_spec max11100_channels[] = {

	{ /* [0] */

		.type = IIO_VOLTAGE,

		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |

				      BIT(IIO_CHAN_INFO_SCALE),

	},

};



static struct max11100_chip_desc {

	unsigned int num_chan;

	const struct iio_chan_spec *channels;

} max11100_desc = {

	.num_chan = ARRAY_SIZE(max11100_channels),

	.channels = max11100_channels,

};



static int max11100_read_single(struct iio_dev *indio_dev, int *val)

{

	int ret;

	struct max11100_state *state = iio_priv(indio_dev);



	ret = spi_read(state->spi, state->buffer, sizeof(state->buffer));

	if (ret) {

		dev_err(&indio_dev->dev, "SPI transfer failed\n");

		return ret;

	}



	/* the first 8 bits sent out from ADC must be 0s */

	if (state->buffer[0]) {

		dev_err(&indio_dev->dev, "Invalid value: buffer[0] != 0\n");

		return -EINVAL;

	}



	*val = (state->buffer[1] << 8) | state->buffer[2];



	return 0;

}



static int max11100_read_raw(struct iio_dev *indio_dev,

			     struct iio_chan_spec const *chan,

			     int *val, int *val2, long info)

{

	int ret, vref_uv;

	struct max11100_state *state = iio_priv(indio_dev);



	switch (info) {

	case IIO_CHAN_INFO_RAW:

		ret = max11100_read_single(indio_dev, val);

		if (ret)

			return ret;



		return IIO_VAL_INT;



	case IIO_CHAN_INFO_SCALE:

		vref_uv = regulator_get_voltage(state->vref_reg);

		if (vref_uv < 0)

			/* dummy regulator "get_voltage" returns -EINVAL */

			return -EINVAL;



		*val =  vref_uv / 1000;

		*val2 = MAX11100_LSB_DIV;

		return IIO_VAL_FRACTIONAL;

	}



	return -EINVAL;

}



static const struct iio_info max11100_info = {

	.driver_module = THIS_MODULE,

	.read_raw = max11100_read_raw,

};



static int max11100_probe(struct spi_device *spi)

{

	int ret;

	struct iio_dev *indio_dev;

	struct max11100_state *state;



	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));

	if (!indio_dev)

		return -ENOMEM;



	spi_set_drvdata(spi, indio_dev);



	state = iio_priv(indio_dev);

	state->spi = spi;

	state->desc = &max11100_desc;



	indio_dev->dev.parent = &spi->dev;

	indio_dev->dev.of_node = spi->dev.of_node;

	indio_dev->name = "max11100";

	indio_dev->info = &max11100_info;

	indio_dev->modes = INDIO_DIRECT_MODE;

	indio_dev->channels = state->desc->channels;

	indio_dev->num_channels = state->desc->num_chan;



	state->vref_reg = devm_regulator_get(&spi->dev, "vref");

	if (IS_ERR(state->vref_reg))

		return PTR_ERR(state->vref_reg);



	ret = regulator_enable(state->vref_reg);

	if (ret)

		return ret;



	ret = iio_device_register(indio_dev);

	if (ret)

		goto disable_regulator;



	return 0;



disable_regulator:

	regulator_disable(state->vref_reg);



	return ret;

}



static int max11100_remove(struct spi_device *spi)

{

	struct iio_dev *indio_dev = spi_get_drvdata(spi);

	struct max11100_state *state = iio_priv(indio_dev);



	regulator_disable(state->vref_reg);



	iio_device_unregister(indio_dev);



	return 0;

}



static const struct of_device_id max11100_ids[] = {

	{.compatible = "maxim,max11100"},

	{ },

};

MODULE_DEVICE_TABLE(of, max11100_ids);



static struct spi_driver max11100_driver = {

	.driver = {

		.name	= "max11100",

		.owner	= THIS_MODULE,

		.of_match_table = of_match_ptr(max11100_ids),

	},

	.probe		= max11100_probe,

	.remove		= max11100_remove,

};



module_spi_driver(max11100_driver);



MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>");

MODULE_DESCRIPTION("Maxim max11100 ADC Driver");

MODULE_LICENSE("GPL v2");