iio: Add LTC2471/LTC2473 driver (1d3eacbf) · Commits · e / devices / android_kernel_fairphone_FP5

drivers/iio/adc/Kconfig

+10 −0

Original line number	Diff line number	Diff line
		@@ -362,6 +362,16 @@ config LPC32XX_ADC
		activate only one via device tree selection. Provides direct access
		via sysfs.

		config LTC2471
		tristate "Linear Technology LTC2471 and LTC2473 ADC driver"
		depends on I2C
		help
		Say yes here to build support for Linear Technology LTC2471 and
		LTC2473 16-bit I2C ADC.

		This driver can also be built as a module. If so, the module will
		be called ltc2471.

		config LTC2485
		tristate "Linear Technology LTC2485 ADC driver"
		depends on I2C

drivers/iio/adc/Makefile

+1 −0

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		@@ -34,6 +34,7 @@ obj-$(CONFIG_INA2XX_ADC) += ina2xx-adc.o
		obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
		obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
		obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
		obj-$(CONFIG_LTC2471) += ltc2471.o
		obj-$(CONFIG_LTC2485) += ltc2485.o
		obj-$(CONFIG_LTC2497) += ltc2497.o
		obj-$(CONFIG_MAX1027) += max1027.o

drivers/iio/adc/ltc2471.c

0 → 100644

+160 −0

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		/*
		* Driver for Linear Technology LTC2471 and LTC2473 voltage monitors
		* The LTC2473 is identical to the 2471, but reports a differential signal.
		*
		* Copyright (C) 2017 Topic Embedded Products
		* Author: Mike Looijmans <mike.looijmans@topic.nl>
		*
		* License: GPLv2
		*/

		#include <linux/err.h>
		#include <linux/i2c.h>
		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <linux/iio/iio.h>
		#include <linux/iio/sysfs.h>

		enum ltc2471_chips {
		ltc2471,
		ltc2473,
		};

		struct ltc2471_data {
		struct i2c_client *client;
		};

		/* Reference voltage is 1.25V */
		#define LTC2471_VREF 1250

		/* Read two bytes from the I2C bus to obtain the ADC result */
		static int ltc2471_get_value(struct i2c_client *client)
		{
		int ret;
		__be16 buf;

		ret = i2c_master_recv(client, (char *)&buf, sizeof(buf));
		if (ret < 0)
		return ret;
		if (ret != sizeof(buf))
		return -EIO;

		/* MSB first */
		return be16_to_cpu(buf);
		}

		static int ltc2471_read_raw(struct iio_dev *indio_dev,
		struct iio_chan_spec const *chan,
		int val, int val2, long info)
		{
		struct ltc2471_data *data = iio_priv(indio_dev);
		int ret;

		switch (info) {
		case IIO_CHAN_INFO_RAW:
		ret = ltc2471_get_value(data->client);
		if (ret < 0)
		return ret;
		*val = ret;
		return IIO_VAL_INT;

		case IIO_CHAN_INFO_SCALE:
		if (chan->differential)
		/* Output ranges from -VREF to +VREF */
		val = 2 LTC2471_VREF;
		else
		/* Output ranges from 0 to VREF */
		*val = LTC2471_VREF;
		val2 = 16; / 16 data bits */
		return IIO_VAL_FRACTIONAL_LOG2;

		case IIO_CHAN_INFO_OFFSET:
		/* Only differential chip has this property */
		*val = -LTC2471_VREF;
		return IIO_VAL_INT;

		default:
		return -EINVAL;
		}
		}

		static const struct iio_chan_spec ltc2471_channel[] = {
		{
		.type = IIO_VOLTAGE,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
		},
		};

		static const struct iio_chan_spec ltc2473_channel[] = {
		{
		.type = IIO_VOLTAGE,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \|
		BIT(IIO_CHAN_INFO_OFFSET),
		.differential = 1,
		},
		};

		static const struct iio_info ltc2471_info = {
		.read_raw = ltc2471_read_raw,
		.driver_module = THIS_MODULE,
		};

		static int ltc2471_i2c_probe(struct i2c_client *client,
		const struct i2c_device_id *id)
		{
		struct iio_dev *indio_dev;
		struct ltc2471_data *data;
		int ret;

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

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

		data = iio_priv(indio_dev);
		data->client = client;

		indio_dev->dev.parent = &client->dev;
		indio_dev->name = id->name;
		indio_dev->info = &ltc2471_info;
		indio_dev->modes = INDIO_DIRECT_MODE;
		if (id->driver_data == ltc2473)
		indio_dev->channels = ltc2473_channel;
		else
		indio_dev->channels = ltc2471_channel;
		indio_dev->num_channels = 1;

		/* Trigger once to start conversion and check if chip is there */
		ret = ltc2471_get_value(client);
		if (ret < 0) {
		dev_err(&client->dev, "Cannot read from device.\n");
		return ret;
		}

		return devm_iio_device_register(&client->dev, indio_dev);
		}

		static const struct i2c_device_id ltc2471_i2c_id[] = {
		{ "ltc2471", ltc2471 },
		{ "ltc2473", ltc2473 },
		{}
		};
		MODULE_DEVICE_TABLE(i2c, ltc2471_i2c_id);

		static struct i2c_driver ltc2471_i2c_driver = {
		.driver = {
		.name = "ltc2471",
		},
		.probe = ltc2471_i2c_probe,
		.id_table = ltc2471_i2c_id,
		};

		module_i2c_driver(ltc2471_i2c_driver);

		MODULE_DESCRIPTION("LTC2471/LTC2473 ADC driver");
		MODULE_AUTHOR("Topic Embedded Products");
		MODULE_LICENSE("GPL v2");