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/*
* 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 = <c2485_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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