diff options
Diffstat (limited to 'drivers/iio/adc/ltc2485.c')
| -rw-r--r-- | drivers/iio/adc/ltc2485.c | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/drivers/iio/adc/ltc2485.c b/drivers/iio/adc/ltc2485.c new file mode 100644 index 0000000000..859e4314cf --- /dev/null +++ b/drivers/iio/adc/ltc2485.c @@ -0,0 +1,143 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * ltc2485.c - Driver for Linear Technology LTC2485 ADC + * + * Copyright (C) 2016 Alison Schofield <amsfield22@gmail.com> + * + * 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, +}; + +static int ltc2485_probe(struct i2c_client *client) +{ + const struct i2c_device_id *id = i2c_client_get_device_id(client); + 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->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"); |