148 lines
3.5 KiB
C
148 lines
3.5 KiB
C
/*
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* ltc2485.c - Driver for Linear Technology LTC2485 ADC
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*
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* Copyright (C) 2016 Alison Schofield <amsfield22@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Datasheet: http://cds.linear.com/docs/en/datasheet/2485fd.pdf
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*/
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#include <linux/delay.h>
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#include <linux/i2c.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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/* Power-on configuration: rejects both 50/60Hz, operates at 1x speed */
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#define LTC2485_CONFIG_DEFAULT 0
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struct ltc2485_data {
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struct i2c_client *client;
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ktime_t time_prev; /* last conversion */
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};
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static void ltc2485_wait_conv(struct ltc2485_data *data)
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{
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const unsigned int conv_time = 147; /* conversion time ms */
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unsigned int time_elapsed;
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/* delay if conversion time not passed since last read or write */
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time_elapsed = ktime_ms_delta(ktime_get(), data->time_prev);
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if (time_elapsed < conv_time)
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msleep(conv_time - time_elapsed);
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}
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static int ltc2485_read(struct ltc2485_data *data, int *val)
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{
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struct i2c_client *client = data->client;
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__be32 buf = 0;
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int ret;
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ltc2485_wait_conv(data);
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ret = i2c_master_recv(client, (char *)&buf, 4);
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if (ret < 0) {
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dev_err(&client->dev, "i2c_master_recv failed\n");
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return ret;
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}
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data->time_prev = ktime_get();
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*val = sign_extend32(be32_to_cpu(buf) >> 6, 24);
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return ret;
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}
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static int ltc2485_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 mask)
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{
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struct ltc2485_data *data = iio_priv(indio_dev);
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int ret;
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if (mask == IIO_CHAN_INFO_RAW) {
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ret = ltc2485_read(data, val);
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if (ret < 0)
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return ret;
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return IIO_VAL_INT;
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} else if (mask == IIO_CHAN_INFO_SCALE) {
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*val = 5000; /* on board vref millivolts */
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*val2 = 25; /* 25 (24 + sign) data bits */
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return IIO_VAL_FRACTIONAL_LOG2;
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} else {
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return -EINVAL;
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}
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}
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static const struct iio_chan_spec ltc2485_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_info ltc2485_info = {
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.read_raw = ltc2485_read_raw,
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};
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static int ltc2485_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 ltc2485_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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I2C_FUNC_SMBUS_WRITE_BYTE))
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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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i2c_set_clientdata(client, 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 = <c2485_info;
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->channels = ltc2485_channel;
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indio_dev->num_channels = ARRAY_SIZE(ltc2485_channel);
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ret = i2c_smbus_write_byte(data->client, LTC2485_CONFIG_DEFAULT);
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if (ret < 0)
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return ret;
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data->time_prev = ktime_get();
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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 ltc2485_id[] = {
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{ "ltc2485", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, ltc2485_id);
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static struct i2c_driver ltc2485_driver = {
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.driver = {
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.name = "ltc2485",
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},
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.probe = ltc2485_probe,
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.id_table = ltc2485_id,
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};
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module_i2c_driver(ltc2485_driver);
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MODULE_AUTHOR("Alison Schofield <amsfield22@gmail.com>");
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MODULE_DESCRIPTION("Linear Technology LTC2485 ADC driver");
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MODULE_LICENSE("GPL v2");
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