diff options
Diffstat (limited to 'drivers/iio/adc/ltc2471.c')
| -rw-r--r-- | drivers/iio/adc/ltc2471.c | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/drivers/iio/adc/ltc2471.c b/drivers/iio/adc/ltc2471.c new file mode 100644 index 000000000000..29b7ed60cdb0 --- /dev/null +++ b/drivers/iio/adc/ltc2471.c @@ -0,0 +1,160 @@ +/* + * Driver for Linear Technology LTC2471 and LTC2473 voltage monitors + * The LTC2473 is identical to the 2471, but reports a differential signal. + * + * Copyright (C) 2017 Topic Embedded Products + * Author: Mike Looijmans <mike.looijmans@topic.nl> + * + * License: GPLv2 + */ + +#include <linux/err.h> +#include <linux/i2c.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/iio/iio.h> +#include <linux/iio/sysfs.h> + +enum ltc2471_chips { + ltc2471, + ltc2473, +}; + +struct ltc2471_data { + struct i2c_client *client; +}; + +/* Reference voltage is 1.25V */ +#define LTC2471_VREF 1250 + +/* Read two bytes from the I2C bus to obtain the ADC result */ +static int ltc2471_get_value(struct i2c_client *client) +{ + int ret; + __be16 buf; + + ret = i2c_master_recv(client, (char *)&buf, sizeof(buf)); + if (ret < 0) + return ret; + if (ret != sizeof(buf)) + return -EIO; + + /* MSB first */ + return be16_to_cpu(buf); +} + +static int ltc2471_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long info) +{ + struct ltc2471_data *data = iio_priv(indio_dev); + int ret; + + switch (info) { + case IIO_CHAN_INFO_RAW: + ret = ltc2471_get_value(data->client); + if (ret < 0) + return ret; + *val = ret; + return IIO_VAL_INT; + + case IIO_CHAN_INFO_SCALE: + if (chan->differential) + /* Output ranges from -VREF to +VREF */ + *val = 2 * LTC2471_VREF; + else + /* Output ranges from 0 to VREF */ + *val = LTC2471_VREF; + *val2 = 16; /* 16 data bits */ + return IIO_VAL_FRACTIONAL_LOG2; + + case IIO_CHAN_INFO_OFFSET: + /* Only differential chip has this property */ + *val = -LTC2471_VREF; + return IIO_VAL_INT; + + default: + return -EINVAL; + } +} + +static const struct iio_chan_spec ltc2471_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_chan_spec ltc2473_channel[] = { + { + .type = IIO_VOLTAGE, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | + BIT(IIO_CHAN_INFO_OFFSET), + .differential = 1, + }, +}; + +static const struct iio_info ltc2471_info = { + .read_raw = ltc2471_read_raw, + .driver_module = THIS_MODULE, +}; + +static int ltc2471_i2c_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct iio_dev *indio_dev; + struct ltc2471_data *data; + int ret; + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) + return -EOPNOTSUPP; + + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); + if (!indio_dev) + return -ENOMEM; + + data = iio_priv(indio_dev); + data->client = client; + + indio_dev->dev.parent = &client->dev; + indio_dev->name = id->name; + indio_dev->info = <c2471_info; + indio_dev->modes = INDIO_DIRECT_MODE; + if (id->driver_data == ltc2473) + indio_dev->channels = ltc2473_channel; + else + indio_dev->channels = ltc2471_channel; + indio_dev->num_channels = 1; + + /* Trigger once to start conversion and check if chip is there */ + ret = ltc2471_get_value(client); + if (ret < 0) { + dev_err(&client->dev, "Cannot read from device.\n"); + return ret; + } + + return devm_iio_device_register(&client->dev, indio_dev); +} + +static const struct i2c_device_id ltc2471_i2c_id[] = { + { "ltc2471", ltc2471 }, + { "ltc2473", ltc2473 }, + {} +}; +MODULE_DEVICE_TABLE(i2c, ltc2471_i2c_id); + +static struct i2c_driver ltc2471_i2c_driver = { + .driver = { + .name = "ltc2471", + }, + .probe = ltc2471_i2c_probe, + .id_table = ltc2471_i2c_id, +}; + +module_i2c_driver(ltc2471_i2c_driver); + +MODULE_DESCRIPTION("LTC2471/LTC2473 ADC driver"); +MODULE_AUTHOR("Topic Embedded Products"); +MODULE_LICENSE("GPL v2"); |