iio: adc: ltc2485: add support for Linear Technology LTC2485 ADC (8c9e7b1b) · Commits · 戴 / test

drivers/iio/adc/Kconfig

+9 −0

Original line number	Diff line number	Diff line
		@@ -264,6 +264,15 @@ config LPC18XX_ADC
		To compile this driver as a module, choose M here: the module will be
		called lpc18xx_adc.

		config LTC2485
		tristate "Linear Technology LTC2485 ADC driver"
		depends on I2C
		help
		Say yes here to build support for Linear Technology LTC2485 ADC.

		To compile this driver as a module, choose M here: the module will be
		called ltc2485.

		config MAX1027
		tristate "Maxim max1027 ADC driver"
		depends on SPI

drivers/iio/adc/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -27,6 +27,7 @@ obj-$(CONFIG_IMX7D_ADC) += imx7d_adc.o
		obj-$(CONFIG_INA2XX_ADC) += ina2xx-adc.o
		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-$(CONFIG_MAX1363) += max1363.o
		obj-$(CONFIG_MCP320X) += mcp320x.o

drivers/iio/adc/ltc2485.c

0 → 100644

+148 −0

Original line number	Diff line number	Diff line
		/*
		* ltc2485.c - Driver for Linear Technology LTC2485 ADC
		*
		* Copyright (C) 2016 Alison Schofield <amsfield22@gmail.com>
		*
		* 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.
		*
		* Datasheet: http://cds.linear.com/docs/en/datasheet/2485fd.pdf
		*/

		#include <linux/delay.h>
		#include <linux/i2c.h>
		#include <linux/module.h>

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

		/* Power-on configuration: rejects both 50/60Hz, operates at 1x speed */
		#define LTC2485_CONFIG_DEFAULT 0

		struct ltc2485_data {
		struct i2c_client *client;
		ktime_t time_prev; /* last conversion */
		};

		static void ltc2485_wait_conv(struct ltc2485_data *data)
		{
		const unsigned int conv_time = 147; /* conversion time ms */
		unsigned int time_elapsed;

		/* delay if conversion time not passed since last read or write */
		time_elapsed = ktime_ms_delta(ktime_get(), data->time_prev);

		if (time_elapsed < conv_time)
		msleep(conv_time - time_elapsed);
		}

		static int ltc2485_read(struct ltc2485_data data, int val)
		{
		struct i2c_client *client = data->client;
		__be32 buf = 0;
		int ret;

		ltc2485_wait_conv(data);

		ret = i2c_master_recv(client, (char *)&buf, 4);
		if (ret < 0) {
		dev_err(&client->dev, "i2c_master_recv failed\n");
		return ret;
		}
		data->time_prev = ktime_get();
		*val = sign_extend32(be32_to_cpu(buf) >> 6, 24);

		return ret;
		}

		static int ltc2485_read_raw(struct iio_dev *indio_dev,
		struct iio_chan_spec const *chan,
		int val, int val2, long mask)
		{
		struct ltc2485_data *data = iio_priv(indio_dev);
		int ret;

		if (mask == IIO_CHAN_INFO_RAW) {
		ret = ltc2485_read(data, val);
		if (ret < 0)
		return ret;

		return IIO_VAL_INT;

		} else if (mask == IIO_CHAN_INFO_SCALE) {
		val = 5000; / on board vref millivolts */
		val2 = 25; / 25 (24 + sign) data bits */
		return IIO_VAL_FRACTIONAL_LOG2;

		} else {
		return -EINVAL;
		}
		}

		static const struct iio_chan_spec ltc2485_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_info ltc2485_info = {
		.read_raw = ltc2485_read_raw,
		.driver_module = THIS_MODULE,
		};

		static int ltc2485_probe(struct i2c_client *client,
		const struct i2c_device_id *id)
		{
		struct iio_dev *indio_dev;
		struct ltc2485_data *data;
		int ret;

		if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C \|
		I2C_FUNC_SMBUS_WRITE_BYTE))
		return -EOPNOTSUPP;

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

		data = iio_priv(indio_dev);
		i2c_set_clientdata(client, indio_dev);
		data->client = client;

		indio_dev->dev.parent = &client->dev;
		indio_dev->name = id->name;
		indio_dev->info = &ltc2485_info;
		indio_dev->modes = INDIO_DIRECT_MODE;
		indio_dev->channels = ltc2485_channel;
		indio_dev->num_channels = ARRAY_SIZE(ltc2485_channel);

		ret = i2c_smbus_write_byte(data->client, LTC2485_CONFIG_DEFAULT);
		if (ret < 0)
		return ret;

		data->time_prev = ktime_get();

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

		static const struct i2c_device_id ltc2485_id[] = {
		{ "ltc2485", 0 },
		{ }
		};
		MODULE_DEVICE_TABLE(i2c, ltc2485_id);

		static struct i2c_driver ltc2485_driver = {
		.driver = {
		.name = "ltc2485",
		},
		.probe = ltc2485_probe,
		.id_table = ltc2485_id,
		};
		module_i2c_driver(ltc2485_driver);

		MODULE_AUTHOR("Alison Schofield <amsfield22@gmail.com>");
		MODULE_DESCRIPTION("Linear Technology LTC2485 ADC driver");
		MODULE_LICENSE("GPL v2");

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