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143 lines
3.3 KiB
143 lines
3.3 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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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 <[email protected]> |
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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->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 <[email protected]>"); |
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MODULE_DESCRIPTION("Linear Technology LTC2485 ADC driver"); |
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MODULE_LICENSE("GPL v2");
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