drivers/iio/adc/mcp3422.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * mcp3422.c - driver for the Microchip mcp3421/2/3/4/5/6/7/8 chip family
  *
  * Copyright (C) 2013, Angelo Compagnucci
  * Author: Angelo Compagnucci <angelo.compagnucci@gmail.com>
  *
  * Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/22088b.pdf
  *            https://ww1.microchip.com/downloads/en/DeviceDoc/22226a.pdf
  *            https://ww1.microchip.com/downloads/en/DeviceDoc/22072b.pdf
  *
  * This driver exports the value of analog input voltage to sysfs, the
  * voltage unit is nV.
  */

 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/delay.h>
 #include <linux/sysfs.h>
 #include <asm/unaligned.h>

 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>

 /* Masks */
 #define MCP3422_CHANNEL_MASK	0x60
 #define MCP3422_PGA_MASK	0x03
 #define MCP3422_SRATE_MASK	0x0C
 #define MCP3422_SRATE_240	0x0
 #define MCP3422_SRATE_60	0x1
 #define MCP3422_SRATE_15	0x2
 #define MCP3422_SRATE_3	0x3
 #define MCP3422_PGA_1	0
 #define MCP3422_PGA_2	1
 #define MCP3422_PGA_4	2
 #define MCP3422_PGA_8	3
 #define MCP3422_CONT_SAMPLING	0x10

 #define MCP3422_CHANNEL(config)	(((config) & MCP3422_CHANNEL_MASK) >> 5)
 #define MCP3422_PGA(config)	((config) & MCP3422_PGA_MASK)
 #define MCP3422_SAMPLE_RATE(config)	(((config) & MCP3422_SRATE_MASK) >> 2)

 #define MCP3422_CHANNEL_VALUE(value) (((value) << 5) & MCP3422_CHANNEL_MASK)
 #define MCP3422_PGA_VALUE(value) ((value) & MCP3422_PGA_MASK)
 #define MCP3422_SAMPLE_RATE_VALUE(value) ((value << 2) & MCP3422_SRATE_MASK)

 #define MCP3422_CHAN(_index) \
 	{ \
 		.type = IIO_VOLTAGE, \
 		.indexed = 1, \
 		.channel = _index, \
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
 				| BIT(IIO_CHAN_INFO_SCALE), \
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
 	}

 static const int mcp3422_scales[4][4] = {
 	{ 1000000, 500000, 250000, 125000 },
 	{ 250000,  125000, 62500,  31250  },
 	{ 62500,   31250,  15625,  7812   },
 	{ 15625,   7812,   3906,   1953   } };

 /* Constant msleep times for data acquisitions */
 static const int mcp3422_read_times[4] = {
 	[MCP3422_SRATE_240] = 1000 / 240,
 	[MCP3422_SRATE_60] = 1000 / 60,
 	[MCP3422_SRATE_15] = 1000 / 15,
 	[MCP3422_SRATE_3] = 1000 / 3 };

 /* sample rates to integer conversion table */
 static const int mcp3422_sample_rates[4] = {
 	[MCP3422_SRATE_240] = 240,
 	[MCP3422_SRATE_60] = 60,
 	[MCP3422_SRATE_15] = 15,
 	[MCP3422_SRATE_3] = 3 };

 /* sample rates to sign extension table */
 static const int mcp3422_sign_extend[4] = {
 	[MCP3422_SRATE_240] = 11,
 	[MCP3422_SRATE_60] = 13,
 	[MCP3422_SRATE_15] = 15,
 	[MCP3422_SRATE_3] = 17 };

 /* Client data (each client gets its own) */
 struct mcp3422 {
 	struct i2c_client *i2c;
 	u8 id;
 	u8 config;
 	u8 pga[4];
 	struct mutex lock;
 };

 static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig)
 {
 	int ret;

 	ret = i2c_master_send(adc->i2c, &newconfig, 1);
 	if (ret > 0) {
 		adc->config = newconfig;
 		ret = 0;
 	}

 	return ret;
 }

 static int mcp3422_read(struct mcp3422 *adc, int *value, u8 *config)
 {
 	int ret = 0;
 	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
 	u8 buf[4] = {0, 0, 0, 0};
 	u32 temp;

 	if (sample_rate == MCP3422_SRATE_3) {
 		ret = i2c_master_recv(adc->i2c, buf, 4);
 		temp = get_unaligned_be24(&buf[0]);
 		*config = buf[3];
 	} else {
 		ret = i2c_master_recv(adc->i2c, buf, 3);
 		temp = get_unaligned_be16(&buf[0]);
 		*config = buf[2];
 	}

 	*value = sign_extend32(temp, mcp3422_sign_extend[sample_rate]);

 	return ret;
 }

 static int mcp3422_read_channel(struct mcp3422 *adc,
 				struct iio_chan_spec const *channel, int *value)
 {
 	int ret;
 	u8 config;
 	u8 req_channel = channel->channel;

 	mutex_lock(&adc->lock);

 	if (req_channel != MCP3422_CHANNEL(adc->config)) {
 		config = adc->config;
 		config &= ~MCP3422_CHANNEL_MASK;
 		config |= MCP3422_CHANNEL_VALUE(req_channel);
 		config &= ~MCP3422_PGA_MASK;
 		config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
 		ret = mcp3422_update_config(adc, config);
 		if (ret < 0) {
 			mutex_unlock(&adc->lock);
 			return ret;
 		}
 		msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
 	}

 	ret = mcp3422_read(adc, value, &config);

 	mutex_unlock(&adc->lock);

 	return ret;
 }

 static int mcp3422_read_raw(struct iio_dev *iio,
 			struct iio_chan_spec const *channel, int *val1,
 			int *val2, long mask)
 {
 	struct mcp3422 *adc = iio_priv(iio);
 	int err;

 	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
 	u8 pga		 = MCP3422_PGA(adc->config);

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		err = mcp3422_read_channel(adc, channel, val1);
 		if (err < 0)
 			return -EINVAL;
 		return IIO_VAL_INT;

 	case IIO_CHAN_INFO_SCALE:

 		*val1 = 0;
 		*val2 = mcp3422_scales[sample_rate][pga];
 		return IIO_VAL_INT_PLUS_NANO;

 	case IIO_CHAN_INFO_SAMP_FREQ:
 		*val1 = mcp3422_sample_rates[MCP3422_SAMPLE_RATE(adc->config)];
 		return IIO_VAL_INT;

 	default:
 		break;
 	}

 	return -EINVAL;
 }

 static int mcp3422_write_raw(struct iio_dev *iio,
 			struct iio_chan_spec const *channel, int val1,
 			int val2, long mask)
 {
 	struct mcp3422 *adc = iio_priv(iio);
 	u8 temp;
 	u8 config = adc->config;
 	u8 req_channel = channel->channel;
 	u8 sample_rate = MCP3422_SAMPLE_RATE(config);
 	u8 i;

 	switch (mask) {
 	case IIO_CHAN_INFO_SCALE:
 		if (val1 != 0)
 			return -EINVAL;

 		for (i = 0; i < ARRAY_SIZE(mcp3422_scales[0]); i++) {
 			if (val2 == mcp3422_scales[sample_rate][i]) {
 				adc->pga[req_channel] = i;

 				config &= ~MCP3422_CHANNEL_MASK;
 				config |= MCP3422_CHANNEL_VALUE(req_channel);
 				config &= ~MCP3422_PGA_MASK;
 				config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);

 				return mcp3422_update_config(adc, config);
 			}
 		}
 		return -EINVAL;

 	case IIO_CHAN_INFO_SAMP_FREQ:
 		switch (val1) {
 		case 240:
 			temp = MCP3422_SRATE_240;
 			break;
 		case 60:
 			temp = MCP3422_SRATE_60;
 			break;
 		case 15:
 			temp = MCP3422_SRATE_15;
 			break;
 		case 3:
 			if (adc->id > 4)
 				return -EINVAL;
 			temp = MCP3422_SRATE_3;
 			break;
 		default:
 			return -EINVAL;
 		}

 		config &= ~MCP3422_CHANNEL_MASK;
 		config |= MCP3422_CHANNEL_VALUE(req_channel);
 		config &= ~MCP3422_SRATE_MASK;
 		config |= MCP3422_SAMPLE_RATE_VALUE(temp);

 		return mcp3422_update_config(adc, config);

 	default:
 		break;
 	}

 	return -EINVAL;
 }

 static int mcp3422_write_raw_get_fmt(struct iio_dev *indio_dev,
 		struct iio_chan_spec const *chan, long mask)
 {
 	switch (mask) {
 	case IIO_CHAN_INFO_SCALE:
 		return IIO_VAL_INT_PLUS_NANO;
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		return IIO_VAL_INT_PLUS_MICRO;
 	default:
 		return -EINVAL;
 	}
 }

 static ssize_t mcp3422_show_samp_freqs(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));

 	if (adc->id > 4)
 		return sprintf(buf, "240 60 15\n");

 	return sprintf(buf, "240 60 15 3\n");
 }

 static ssize_t mcp3422_show_scales(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
 	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);

 	return sprintf(buf, "0.%09u 0.%09u 0.%09u 0.%09u\n",
 		mcp3422_scales[sample_rate][0],
 		mcp3422_scales[sample_rate][1],
 		mcp3422_scales[sample_rate][2],
 		mcp3422_scales[sample_rate][3]);
 }

 static IIO_DEVICE_ATTR(sampling_frequency_available, S_IRUGO,
 		mcp3422_show_samp_freqs, NULL, 0);
 static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
 		mcp3422_show_scales, NULL, 0);

 static struct attribute *mcp3422_attributes[] = {
 	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
 	&iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
 	NULL,
 };

 static const struct attribute_group mcp3422_attribute_group = {
 	.attrs = mcp3422_attributes,
 };

 static const struct iio_chan_spec mcp3421_channels[] = {
 	MCP3422_CHAN(0),
 };

 static const struct iio_chan_spec mcp3422_channels[] = {
 	MCP3422_CHAN(0),
 	MCP3422_CHAN(1),
 };

 static const struct iio_chan_spec mcp3424_channels[] = {
 	MCP3422_CHAN(0),
 	MCP3422_CHAN(1),
 	MCP3422_CHAN(2),
 	MCP3422_CHAN(3),
 };

 static const struct iio_info mcp3422_info = {
 	.read_raw = mcp3422_read_raw,
 	.write_raw = mcp3422_write_raw,
 	.write_raw_get_fmt = mcp3422_write_raw_get_fmt,
 	.attrs = &mcp3422_attribute_group,
 };

 static int mcp3422_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
 	struct iio_dev *indio_dev;
 	struct mcp3422 *adc;
 	int err;
 	u8 config;

 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 		return -EOPNOTSUPP;

 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*adc));
 	if (!indio_dev)
 		return -ENOMEM;

 	adc = iio_priv(indio_dev);
 	adc->i2c = client;
 	adc->id = (u8)(id->driver_data);

 	mutex_init(&adc->lock);

 	indio_dev->name = dev_name(&client->dev);
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->info = &mcp3422_info;

 	switch (adc->id) {
 	case 1:
 	case 5:
 		indio_dev->channels = mcp3421_channels;
 		indio_dev->num_channels = ARRAY_SIZE(mcp3421_channels);
 		break;
 	case 2:
 	case 3:
 	case 6:
 	case 7:
 		indio_dev->channels = mcp3422_channels;
 		indio_dev->num_channels = ARRAY_SIZE(mcp3422_channels);
 		break;
 	case 4:
 	case 8:
 		indio_dev->channels = mcp3424_channels;
 		indio_dev->num_channels = ARRAY_SIZE(mcp3424_channels);
 		break;
 	}

 	/* meaningful default configuration */
 	config = (MCP3422_CONT_SAMPLING
 		| MCP3422_CHANNEL_VALUE(0)
 		| MCP3422_PGA_VALUE(MCP3422_PGA_1)
 		| MCP3422_SAMPLE_RATE_VALUE(MCP3422_SRATE_240));
 	err = mcp3422_update_config(adc, config);
 	if (err < 0)
 		return err;

 	err = devm_iio_device_register(&client->dev, indio_dev);
 	if (err < 0)
 		return err;

 	i2c_set_clientdata(client, indio_dev);

 	return 0;
 }

 static const struct i2c_device_id mcp3422_id[] = {
 	{ "mcp3421", 1 },
 	{ "mcp3422", 2 },
 	{ "mcp3423", 3 },
 	{ "mcp3424", 4 },
 	{ "mcp3425", 5 },
 	{ "mcp3426", 6 },
 	{ "mcp3427", 7 },
 	{ "mcp3428", 8 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, mcp3422_id);

 static const struct of_device_id mcp3422_of_match[] = {
 	{ .compatible = "mcp3422" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, mcp3422_of_match);

 static struct i2c_driver mcp3422_driver = {
 	.driver = {
 		.name = "mcp3422",
 		.of_match_table = mcp3422_of_match,
 	},
 	.probe = mcp3422_probe,
 	.id_table = mcp3422_id,
 };
 module_i2c_driver(mcp3422_driver);

 MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
 MODULE_DESCRIPTION("Microchip mcp3421/2/3/4/5/6/7/8 driver");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* mcp3422.c - driver for the Microchip mcp3421/2/3/4/5/6/7/8 chip family
	*
	* Copyright (C) 2013, Angelo Compagnucci
	* Author: Angelo Compagnucci <angelo.compagnucci@gmail.com>
	*
	* Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/22088b.pdf
	* https://ww1.microchip.com/downloads/en/DeviceDoc/22226a.pdf
	* https://ww1.microchip.com/downloads/en/DeviceDoc/22072b.pdf
	*
	* This driver exports the value of analog input voltage to sysfs, the
	* voltage unit is nV.
	*/

	#include <linux/err.h>
	#include <linux/i2c.h>
	#include <linux/module.h>
	#include <linux/mod_devicetable.h>
	#include <linux/delay.h>
	#include <linux/sysfs.h>
	#include <asm/unaligned.h>

	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>

	/* Masks */
	#define MCP3422_CHANNEL_MASK 0x60
	#define MCP3422_PGA_MASK 0x03
	#define MCP3422_SRATE_MASK 0x0C
	#define MCP3422_SRATE_240 0x0
	#define MCP3422_SRATE_60 0x1
	#define MCP3422_SRATE_15 0x2
	#define MCP3422_SRATE_3 0x3
	#define MCP3422_PGA_1 0
	#define MCP3422_PGA_2 1
	#define MCP3422_PGA_4 2
	#define MCP3422_PGA_8 3
	#define MCP3422_CONT_SAMPLING 0x10

	#define MCP3422_CHANNEL(config) (((config) & MCP3422_CHANNEL_MASK) >> 5)
	#define MCP3422_PGA(config) ((config) & MCP3422_PGA_MASK)
	#define MCP3422_SAMPLE_RATE(config) (((config) & MCP3422_SRATE_MASK) >> 2)

	#define MCP3422_CHANNEL_VALUE(value) (((value) << 5) & MCP3422_CHANNEL_MASK)
	#define MCP3422_PGA_VALUE(value) ((value) & MCP3422_PGA_MASK)
	#define MCP3422_SAMPLE_RATE_VALUE(value) ((value << 2) & MCP3422_SRATE_MASK)

	#define MCP3422_CHAN(_index) \
	{ \
	.type = IIO_VOLTAGE, \
	.indexed = 1, \
	.channel = _index, \
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
	\| BIT(IIO_CHAN_INFO_SCALE), \
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
	}

	static const int mcp3422_scales[4][4] = {
	{ 1000000, 500000, 250000, 125000 },
	{ 250000, 125000, 62500, 31250 },
	{ 62500, 31250, 15625, 7812 },
	{ 15625, 7812, 3906, 1953 } };

	/* Constant msleep times for data acquisitions */
	static const int mcp3422_read_times[4] = {
	[MCP3422_SRATE_240] = 1000 / 240,
	[MCP3422_SRATE_60] = 1000 / 60,
	[MCP3422_SRATE_15] = 1000 / 15,
	[MCP3422_SRATE_3] = 1000 / 3 };

	/* sample rates to integer conversion table */
	static const int mcp3422_sample_rates[4] = {
	[MCP3422_SRATE_240] = 240,
	[MCP3422_SRATE_60] = 60,
	[MCP3422_SRATE_15] = 15,
	[MCP3422_SRATE_3] = 3 };

	/* sample rates to sign extension table */
	static const int mcp3422_sign_extend[4] = {
	[MCP3422_SRATE_240] = 11,
	[MCP3422_SRATE_60] = 13,
	[MCP3422_SRATE_15] = 15,
	[MCP3422_SRATE_3] = 17 };

	/* Client data (each client gets its own) */
	struct mcp3422 {
	struct i2c_client *i2c;
	u8 id;
	u8 config;
	u8 pga[4];
	struct mutex lock;
	};

	static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig)
	{
	int ret;

	ret = i2c_master_send(adc->i2c, &newconfig, 1);
	if (ret > 0) {
	adc->config = newconfig;
	ret = 0;
	}

	return ret;
	}

	static int mcp3422_read(struct mcp3422 adc, int value, u8 *config)
	{
	int ret = 0;
	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
	u8 buf[4] = {0, 0, 0, 0};
	u32 temp;

	if (sample_rate == MCP3422_SRATE_3) {
	ret = i2c_master_recv(adc->i2c, buf, 4);
	temp = get_unaligned_be24(&buf[0]);
	*config = buf[3];
	} else {
	ret = i2c_master_recv(adc->i2c, buf, 3);
	temp = get_unaligned_be16(&buf[0]);
	*config = buf[2];
	}

	*value = sign_extend32(temp, mcp3422_sign_extend[sample_rate]);

	return ret;
	}

	static int mcp3422_read_channel(struct mcp3422 *adc,
	struct iio_chan_spec const channel, int value)
	{
	int ret;
	u8 config;
	u8 req_channel = channel->channel;

	mutex_lock(&adc->lock);

	if (req_channel != MCP3422_CHANNEL(adc->config)) {
	config = adc->config;
	config &= ~MCP3422_CHANNEL_MASK;
	config \|= MCP3422_CHANNEL_VALUE(req_channel);
	config &= ~MCP3422_PGA_MASK;
	config \|= MCP3422_PGA_VALUE(adc->pga[req_channel]);
	ret = mcp3422_update_config(adc, config);
	if (ret < 0) {
	mutex_unlock(&adc->lock);
	return ret;
	}
	msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
	}

	ret = mcp3422_read(adc, value, &config);

	mutex_unlock(&adc->lock);

	return ret;
	}

	static int mcp3422_read_raw(struct iio_dev *iio,
	struct iio_chan_spec const channel, int val1,
	int *val2, long mask)
	{
	struct mcp3422 *adc = iio_priv(iio);
	int err;

	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
	u8 pga = MCP3422_PGA(adc->config);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	err = mcp3422_read_channel(adc, channel, val1);
	if (err < 0)
	return -EINVAL;
	return IIO_VAL_INT;

	case IIO_CHAN_INFO_SCALE:

	*val1 = 0;
	*val2 = mcp3422_scales[sample_rate][pga];
	return IIO_VAL_INT_PLUS_NANO;

	case IIO_CHAN_INFO_SAMP_FREQ:
	*val1 = mcp3422_sample_rates[MCP3422_SAMPLE_RATE(adc->config)];
	return IIO_VAL_INT;

	default:
	break;
	}

	return -EINVAL;
	}

	static int mcp3422_write_raw(struct iio_dev *iio,
	struct iio_chan_spec const *channel, int val1,
	int val2, long mask)
	{
	struct mcp3422 *adc = iio_priv(iio);
	u8 temp;
	u8 config = adc->config;
	u8 req_channel = channel->channel;
	u8 sample_rate = MCP3422_SAMPLE_RATE(config);
	u8 i;

	switch (mask) {
	case IIO_CHAN_INFO_SCALE:
	if (val1 != 0)
	return -EINVAL;

	for (i = 0; i < ARRAY_SIZE(mcp3422_scales[0]); i++) {
	if (val2 == mcp3422_scales[sample_rate][i]) {
	adc->pga[req_channel] = i;

	config &= ~MCP3422_CHANNEL_MASK;
	config \|= MCP3422_CHANNEL_VALUE(req_channel);
	config &= ~MCP3422_PGA_MASK;
	config \|= MCP3422_PGA_VALUE(adc->pga[req_channel]);

	return mcp3422_update_config(adc, config);
	}
	}
	return -EINVAL;

	case IIO_CHAN_INFO_SAMP_FREQ:
	switch (val1) {
	case 240:
	temp = MCP3422_SRATE_240;
	break;
	case 60:
	temp = MCP3422_SRATE_60;
	break;
	case 15:
	temp = MCP3422_SRATE_15;
	break;
	case 3:
	if (adc->id > 4)
	return -EINVAL;
	temp = MCP3422_SRATE_3;
	break;
	default:
	return -EINVAL;
	}

	config &= ~MCP3422_CHANNEL_MASK;
	config \|= MCP3422_CHANNEL_VALUE(req_channel);
	config &= ~MCP3422_SRATE_MASK;
	config \|= MCP3422_SAMPLE_RATE_VALUE(temp);

	return mcp3422_update_config(adc, config);

	default:
	break;
	}

	return -EINVAL;
	}

	static int mcp3422_write_raw_get_fmt(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan, long mask)
	{
	switch (mask) {
	case IIO_CHAN_INFO_SCALE:
	return IIO_VAL_INT_PLUS_NANO;
	case IIO_CHAN_INFO_SAMP_FREQ:
	return IIO_VAL_INT_PLUS_MICRO;
	default:
	return -EINVAL;
	}
	}

	static ssize_t mcp3422_show_samp_freqs(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));

	if (adc->id > 4)
	return sprintf(buf, "240 60 15\n");

	return sprintf(buf, "240 60 15 3\n");
	}

	static ssize_t mcp3422_show_scales(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);

	return sprintf(buf, "0.%09u 0.%09u 0.%09u 0.%09u\n",
	mcp3422_scales[sample_rate][0],
	mcp3422_scales[sample_rate][1],
	mcp3422_scales[sample_rate][2],
	mcp3422_scales[sample_rate][3]);
	}

	static IIO_DEVICE_ATTR(sampling_frequency_available, S_IRUGO,
	mcp3422_show_samp_freqs, NULL, 0);
	static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO,
	mcp3422_show_scales, NULL, 0);

	static struct attribute *mcp3422_attributes[] = {
	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
	&iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
	NULL,
	};

	static const struct attribute_group mcp3422_attribute_group = {
	.attrs = mcp3422_attributes,
	};

	static const struct iio_chan_spec mcp3421_channels[] = {
	MCP3422_CHAN(0),
	};

	static const struct iio_chan_spec mcp3422_channels[] = {
	MCP3422_CHAN(0),
	MCP3422_CHAN(1),
	};

	static const struct iio_chan_spec mcp3424_channels[] = {
	MCP3422_CHAN(0),
	MCP3422_CHAN(1),
	MCP3422_CHAN(2),
	MCP3422_CHAN(3),
	};

	static const struct iio_info mcp3422_info = {
	.read_raw = mcp3422_read_raw,
	.write_raw = mcp3422_write_raw,
	.write_raw_get_fmt = mcp3422_write_raw_get_fmt,
	.attrs = &mcp3422_attribute_group,
	};

	static int mcp3422_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct iio_dev *indio_dev;
	struct mcp3422 *adc;
	int err;
	u8 config;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
	return -EOPNOTSUPP;

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*adc));
	if (!indio_dev)
	return -ENOMEM;

	adc = iio_priv(indio_dev);
	adc->i2c = client;
	adc->id = (u8)(id->driver_data);

	mutex_init(&adc->lock);

	indio_dev->name = dev_name(&client->dev);
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->info = &mcp3422_info;

	switch (adc->id) {
	case 1:
	case 5:
	indio_dev->channels = mcp3421_channels;
	indio_dev->num_channels = ARRAY_SIZE(mcp3421_channels);
	break;
	case 2:
	case 3:
	case 6:
	case 7:
	indio_dev->channels = mcp3422_channels;
	indio_dev->num_channels = ARRAY_SIZE(mcp3422_channels);
	break;
	case 4:
	case 8:
	indio_dev->channels = mcp3424_channels;
	indio_dev->num_channels = ARRAY_SIZE(mcp3424_channels);
	break;
	}

	/* meaningful default configuration */
	config = (MCP3422_CONT_SAMPLING
	\| MCP3422_CHANNEL_VALUE(0)
	\| MCP3422_PGA_VALUE(MCP3422_PGA_1)
	\| MCP3422_SAMPLE_RATE_VALUE(MCP3422_SRATE_240));
	err = mcp3422_update_config(adc, config);
	if (err < 0)
	return err;

	err = devm_iio_device_register(&client->dev, indio_dev);
	if (err < 0)
	return err;

	i2c_set_clientdata(client, indio_dev);

	return 0;
	}

	static const struct i2c_device_id mcp3422_id[] = {
	{ "mcp3421", 1 },
	{ "mcp3422", 2 },
	{ "mcp3423", 3 },
	{ "mcp3424", 4 },
	{ "mcp3425", 5 },
	{ "mcp3426", 6 },
	{ "mcp3427", 7 },
	{ "mcp3428", 8 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, mcp3422_id);

	static const struct of_device_id mcp3422_of_match[] = {
	{ .compatible = "mcp3422" },
	{ }
	};
	MODULE_DEVICE_TABLE(of, mcp3422_of_match);

	static struct i2c_driver mcp3422_driver = {
	.driver = {
	.name = "mcp3422",
	.of_match_table = mcp3422_of_match,
	},
	.probe = mcp3422_probe,
	.id_table = mcp3422_id,
	};
	module_i2c_driver(mcp3422_driver);

	MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
	MODULE_DESCRIPTION("Microchip mcp3421/2/3/4/5/6/7/8 driver");
	MODULE_LICENSE("GPL v2");