linux/drivers/iio/adc/ltc2497.c

280 lines
6.8 KiB
C

/*
* ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC
*
* Copyright (C) 2017 Analog Devices Inc.
*
* Licensed under the GPL-2.
*
* Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf
*/
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/regulator/consumer.h>
#define LTC2497_ENABLE 0xA0
#define LTC2497_SGL BIT(4)
#define LTC2497_DIFF 0
#define LTC2497_SIGN BIT(3)
#define LTC2497_CONFIG_DEFAULT LTC2497_ENABLE
#define LTC2497_CONVERSION_TIME_MS 150ULL
struct ltc2497_st {
struct i2c_client *client;
struct regulator *ref;
ktime_t time_prev;
u8 addr_prev;
/*
* DMA (thus cache coherency maintenance) requires the
* transfer buffers to live in their own cache lines.
*/
__be32 buf ____cacheline_aligned;
};
static int ltc2497_wait_conv(struct ltc2497_st *st)
{
s64 time_elapsed;
time_elapsed = ktime_ms_delta(ktime_get(), st->time_prev);
if (time_elapsed < LTC2497_CONVERSION_TIME_MS) {
/* delay if conversion time not passed
* since last read or write
*/
if (msleep_interruptible(
LTC2497_CONVERSION_TIME_MS - time_elapsed))
return -ERESTARTSYS;
return 0;
}
if (time_elapsed - LTC2497_CONVERSION_TIME_MS <= 0) {
/* We're in automatic mode -
* so the last reading is stil not outdated
*/
return 0;
}
return 1;
}
static int ltc2497_read(struct ltc2497_st *st, u8 address, int *val)
{
struct i2c_client *client = st->client;
int ret;
ret = ltc2497_wait_conv(st);
if (ret < 0)
return ret;
if (ret || st->addr_prev != address) {
ret = i2c_smbus_write_byte(st->client,
LTC2497_ENABLE | address);
if (ret < 0)
return ret;
st->addr_prev = address;
if (msleep_interruptible(LTC2497_CONVERSION_TIME_MS))
return -ERESTARTSYS;
}
ret = i2c_master_recv(client, (char *)&st->buf, 3);
if (ret < 0) {
dev_err(&client->dev, "i2c_master_recv failed\n");
return ret;
}
st->time_prev = ktime_get();
/* convert and shift the result,
* and finally convert from offset binary to signed integer
*/
*val = (be32_to_cpu(st->buf) >> 14) - (1 << 17);
return ret;
}
static int ltc2497_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct ltc2497_st *st = iio_priv(indio_dev);
int ret;
switch (mask) {
case IIO_CHAN_INFO_RAW:
mutex_lock(&indio_dev->mlock);
ret = ltc2497_read(st, chan->address, val);
mutex_unlock(&indio_dev->mlock);
if (ret < 0)
return ret;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
ret = regulator_get_voltage(st->ref);
if (ret < 0)
return ret;
*val = ret / 1000;
*val2 = 17;
return IIO_VAL_FRACTIONAL_LOG2;
default:
return -EINVAL;
}
}
#define LTC2497_CHAN(_chan, _addr) { \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = (_chan), \
.address = (_addr | (_chan / 2) | ((_chan & 1) ? LTC2497_SIGN : 0)), \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
}
#define LTC2497_CHAN_DIFF(_chan, _addr) { \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 1 : 0), \
.channel2 = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 0 : 1),\
.address = (_addr | _chan), \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
.differential = 1, \
}
static const struct iio_chan_spec ltc2497_channel[] = {
LTC2497_CHAN(0, LTC2497_SGL),
LTC2497_CHAN(1, LTC2497_SGL),
LTC2497_CHAN(2, LTC2497_SGL),
LTC2497_CHAN(3, LTC2497_SGL),
LTC2497_CHAN(4, LTC2497_SGL),
LTC2497_CHAN(5, LTC2497_SGL),
LTC2497_CHAN(6, LTC2497_SGL),
LTC2497_CHAN(7, LTC2497_SGL),
LTC2497_CHAN(8, LTC2497_SGL),
LTC2497_CHAN(9, LTC2497_SGL),
LTC2497_CHAN(10, LTC2497_SGL),
LTC2497_CHAN(11, LTC2497_SGL),
LTC2497_CHAN(12, LTC2497_SGL),
LTC2497_CHAN(13, LTC2497_SGL),
LTC2497_CHAN(14, LTC2497_SGL),
LTC2497_CHAN(15, LTC2497_SGL),
LTC2497_CHAN_DIFF(0, LTC2497_DIFF),
LTC2497_CHAN_DIFF(1, LTC2497_DIFF),
LTC2497_CHAN_DIFF(2, LTC2497_DIFF),
LTC2497_CHAN_DIFF(3, LTC2497_DIFF),
LTC2497_CHAN_DIFF(4, LTC2497_DIFF),
LTC2497_CHAN_DIFF(5, LTC2497_DIFF),
LTC2497_CHAN_DIFF(6, LTC2497_DIFF),
LTC2497_CHAN_DIFF(7, LTC2497_DIFF),
LTC2497_CHAN_DIFF(0, LTC2497_DIFF | LTC2497_SIGN),
LTC2497_CHAN_DIFF(1, LTC2497_DIFF | LTC2497_SIGN),
LTC2497_CHAN_DIFF(2, LTC2497_DIFF | LTC2497_SIGN),
LTC2497_CHAN_DIFF(3, LTC2497_DIFF | LTC2497_SIGN),
LTC2497_CHAN_DIFF(4, LTC2497_DIFF | LTC2497_SIGN),
LTC2497_CHAN_DIFF(5, LTC2497_DIFF | LTC2497_SIGN),
LTC2497_CHAN_DIFF(6, LTC2497_DIFF | LTC2497_SIGN),
LTC2497_CHAN_DIFF(7, LTC2497_DIFF | LTC2497_SIGN),
};
static const struct iio_info ltc2497_info = {
.read_raw = ltc2497_read_raw,
.driver_module = THIS_MODULE,
};
static int ltc2497_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct iio_dev *indio_dev;
struct ltc2497_st *st;
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(*st));
if (!indio_dev)
return -ENOMEM;
st = iio_priv(indio_dev);
i2c_set_clientdata(client, indio_dev);
st->client = client;
indio_dev->dev.parent = &client->dev;
indio_dev->name = id->name;
indio_dev->info = &ltc2497_info;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = ltc2497_channel;
indio_dev->num_channels = ARRAY_SIZE(ltc2497_channel);
st->ref = devm_regulator_get(&client->dev, "vref");
if (IS_ERR(st->ref))
return PTR_ERR(st->ref);
ret = regulator_enable(st->ref);
if (ret < 0)
return ret;
ret = i2c_smbus_write_byte(st->client, LTC2497_CONFIG_DEFAULT);
if (ret < 0)
goto err_regulator_disable;
st->addr_prev = LTC2497_CONFIG_DEFAULT;
st->time_prev = ktime_get();
ret = iio_device_register(indio_dev);
if (ret < 0)
goto err_regulator_disable;
return 0;
err_regulator_disable:
regulator_disable(st->ref);
return ret;
}
static int ltc2497_remove(struct i2c_client *client)
{
struct iio_dev *indio_dev = i2c_get_clientdata(client);
struct ltc2497_st *st = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
regulator_disable(st->ref);
return 0;
}
static const struct i2c_device_id ltc2497_id[] = {
{ "ltc2497", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, ltc2497_id);
static const struct of_device_id ltc2497_of_match[] = {
{ .compatible = "lltc,ltc2497", },
{},
};
MODULE_DEVICE_TABLE(of, ltc2497_of_match);
static struct i2c_driver ltc2497_driver = {
.driver = {
.name = "ltc2497",
.of_match_table = of_match_ptr(ltc2497_of_match),
},
.probe = ltc2497_probe,
.remove = ltc2497_remove,
.id_table = ltc2497_id,
};
module_i2c_driver(ltc2497_driver);
MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver");
MODULE_LICENSE("GPL v2");