160 lines
3.5 KiB
C
160 lines
3.5 KiB
C
/*
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* Driver for Linear Technology LTC2471 and LTC2473 voltage monitors
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* The LTC2473 is identical to the 2471, but reports a differential signal.
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*
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* Copyright (C) 2017 Topic Embedded Products
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* Author: Mike Looijmans <mike.looijmans@topic.nl>
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*
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* License: GPLv2
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*/
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#include <linux/err.h>
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#include <linux/i2c.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/sysfs.h>
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enum ltc2471_chips {
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ltc2471,
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ltc2473,
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};
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struct ltc2471_data {
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struct i2c_client *client;
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};
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/* Reference voltage is 1.25V */
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#define LTC2471_VREF 1250
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/* Read two bytes from the I2C bus to obtain the ADC result */
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static int ltc2471_get_value(struct i2c_client *client)
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{
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int ret;
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__be16 buf;
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ret = i2c_master_recv(client, (char *)&buf, sizeof(buf));
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if (ret < 0)
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return ret;
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if (ret != sizeof(buf))
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return -EIO;
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/* MSB first */
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return be16_to_cpu(buf);
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}
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static int ltc2471_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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int *val, int *val2, long info)
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{
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struct ltc2471_data *data = iio_priv(indio_dev);
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int ret;
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switch (info) {
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case IIO_CHAN_INFO_RAW:
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ret = ltc2471_get_value(data->client);
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if (ret < 0)
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return ret;
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*val = ret;
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return IIO_VAL_INT;
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case IIO_CHAN_INFO_SCALE:
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if (chan->differential)
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/* Output ranges from -VREF to +VREF */
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*val = 2 * LTC2471_VREF;
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else
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/* Output ranges from 0 to VREF */
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*val = LTC2471_VREF;
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*val2 = 16; /* 16 data bits */
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return IIO_VAL_FRACTIONAL_LOG2;
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case IIO_CHAN_INFO_OFFSET:
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/* Only differential chip has this property */
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*val = -LTC2471_VREF;
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return IIO_VAL_INT;
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default:
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return -EINVAL;
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}
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}
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static const struct iio_chan_spec ltc2471_channel[] = {
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{
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.type = IIO_VOLTAGE,
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
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.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
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},
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};
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static const struct iio_chan_spec ltc2473_channel[] = {
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{
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.type = IIO_VOLTAGE,
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
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.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
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BIT(IIO_CHAN_INFO_OFFSET),
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.differential = 1,
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},
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};
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static const struct iio_info ltc2471_info = {
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.read_raw = ltc2471_read_raw,
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};
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static int ltc2471_i2c_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct iio_dev *indio_dev;
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struct ltc2471_data *data;
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int ret;
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
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return -EOPNOTSUPP;
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indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
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if (!indio_dev)
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return -ENOMEM;
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data = iio_priv(indio_dev);
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data->client = client;
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indio_dev->dev.parent = &client->dev;
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indio_dev->name = id->name;
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indio_dev->info = <c2471_info;
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indio_dev->modes = INDIO_DIRECT_MODE;
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if (id->driver_data == ltc2473)
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indio_dev->channels = ltc2473_channel;
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else
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indio_dev->channels = ltc2471_channel;
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indio_dev->num_channels = 1;
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/* Trigger once to start conversion and check if chip is there */
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ret = ltc2471_get_value(client);
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if (ret < 0) {
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dev_err(&client->dev, "Cannot read from device.\n");
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return ret;
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}
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return devm_iio_device_register(&client->dev, indio_dev);
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}
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static const struct i2c_device_id ltc2471_i2c_id[] = {
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{ "ltc2471", ltc2471 },
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{ "ltc2473", ltc2473 },
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{}
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};
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MODULE_DEVICE_TABLE(i2c, ltc2471_i2c_id);
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static struct i2c_driver ltc2471_i2c_driver = {
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.driver = {
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.name = "ltc2471",
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},
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.probe = ltc2471_i2c_probe,
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.id_table = ltc2471_i2c_id,
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};
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module_i2c_driver(ltc2471_i2c_driver);
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MODULE_DESCRIPTION("LTC2471/LTC2473 ADC driver");
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MODULE_AUTHOR("Topic Embedded Products");
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MODULE_LICENSE("GPL v2");
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