280 lines
6.8 KiB
C
280 lines
6.8 KiB
C
/*
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* ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC
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*
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* Copyright (C) 2017 Analog Devices Inc.
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*
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* Licensed under the GPL-2.
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*
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* Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.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/iio/iio.h>
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#include <linux/iio/sysfs.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/regulator/consumer.h>
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#define LTC2497_ENABLE 0xA0
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#define LTC2497_SGL BIT(4)
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#define LTC2497_DIFF 0
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#define LTC2497_SIGN BIT(3)
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#define LTC2497_CONFIG_DEFAULT LTC2497_ENABLE
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#define LTC2497_CONVERSION_TIME_MS 150ULL
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struct ltc2497_st {
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struct i2c_client *client;
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struct regulator *ref;
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ktime_t time_prev;
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u8 addr_prev;
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/*
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* DMA (thus cache coherency maintenance) requires the
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* transfer buffers to live in their own cache lines.
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*/
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__be32 buf ____cacheline_aligned;
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};
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static int ltc2497_wait_conv(struct ltc2497_st *st)
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{
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s64 time_elapsed;
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time_elapsed = ktime_ms_delta(ktime_get(), st->time_prev);
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if (time_elapsed < LTC2497_CONVERSION_TIME_MS) {
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/* delay if conversion time not passed
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* since last read or write
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*/
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if (msleep_interruptible(
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LTC2497_CONVERSION_TIME_MS - time_elapsed))
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return -ERESTARTSYS;
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return 0;
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}
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if (time_elapsed - LTC2497_CONVERSION_TIME_MS <= 0) {
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/* We're in automatic mode -
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* so the last reading is stil not outdated
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*/
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return 0;
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}
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return 1;
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}
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static int ltc2497_read(struct ltc2497_st *st, u8 address, int *val)
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{
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struct i2c_client *client = st->client;
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int ret;
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ret = ltc2497_wait_conv(st);
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if (ret < 0)
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return ret;
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if (ret || st->addr_prev != address) {
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ret = i2c_smbus_write_byte(st->client,
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LTC2497_ENABLE | address);
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if (ret < 0)
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return ret;
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st->addr_prev = address;
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if (msleep_interruptible(LTC2497_CONVERSION_TIME_MS))
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return -ERESTARTSYS;
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}
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ret = i2c_master_recv(client, (char *)&st->buf, 3);
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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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st->time_prev = ktime_get();
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/* convert and shift the result,
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* and finally convert from offset binary to signed integer
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*/
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*val = (be32_to_cpu(st->buf) >> 14) - (1 << 17);
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return ret;
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}
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static int ltc2497_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 ltc2497_st *st = iio_priv(indio_dev);
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int ret;
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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mutex_lock(&indio_dev->mlock);
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ret = ltc2497_read(st, chan->address, val);
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mutex_unlock(&indio_dev->mlock);
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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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case IIO_CHAN_INFO_SCALE:
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ret = regulator_get_voltage(st->ref);
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if (ret < 0)
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return ret;
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*val = ret / 1000;
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*val2 = 17;
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return IIO_VAL_FRACTIONAL_LOG2;
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default:
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return -EINVAL;
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}
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}
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#define LTC2497_CHAN(_chan, _addr) { \
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.type = IIO_VOLTAGE, \
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.indexed = 1, \
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.channel = (_chan), \
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.address = (_addr | (_chan / 2) | ((_chan & 1) ? LTC2497_SIGN : 0)), \
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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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#define LTC2497_CHAN_DIFF(_chan, _addr) { \
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.type = IIO_VOLTAGE, \
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.indexed = 1, \
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.channel = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 1 : 0), \
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.channel2 = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 0 : 1),\
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.address = (_addr | _chan), \
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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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.differential = 1, \
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}
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static const struct iio_chan_spec ltc2497_channel[] = {
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LTC2497_CHAN(0, LTC2497_SGL),
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LTC2497_CHAN(1, LTC2497_SGL),
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LTC2497_CHAN(2, LTC2497_SGL),
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LTC2497_CHAN(3, LTC2497_SGL),
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LTC2497_CHAN(4, LTC2497_SGL),
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LTC2497_CHAN(5, LTC2497_SGL),
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LTC2497_CHAN(6, LTC2497_SGL),
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LTC2497_CHAN(7, LTC2497_SGL),
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LTC2497_CHAN(8, LTC2497_SGL),
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LTC2497_CHAN(9, LTC2497_SGL),
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LTC2497_CHAN(10, LTC2497_SGL),
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LTC2497_CHAN(11, LTC2497_SGL),
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LTC2497_CHAN(12, LTC2497_SGL),
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LTC2497_CHAN(13, LTC2497_SGL),
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LTC2497_CHAN(14, LTC2497_SGL),
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LTC2497_CHAN(15, LTC2497_SGL),
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LTC2497_CHAN_DIFF(0, LTC2497_DIFF),
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LTC2497_CHAN_DIFF(1, LTC2497_DIFF),
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LTC2497_CHAN_DIFF(2, LTC2497_DIFF),
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LTC2497_CHAN_DIFF(3, LTC2497_DIFF),
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LTC2497_CHAN_DIFF(4, LTC2497_DIFF),
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LTC2497_CHAN_DIFF(5, LTC2497_DIFF),
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LTC2497_CHAN_DIFF(6, LTC2497_DIFF),
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LTC2497_CHAN_DIFF(7, LTC2497_DIFF),
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LTC2497_CHAN_DIFF(0, LTC2497_DIFF | LTC2497_SIGN),
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LTC2497_CHAN_DIFF(1, LTC2497_DIFF | LTC2497_SIGN),
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LTC2497_CHAN_DIFF(2, LTC2497_DIFF | LTC2497_SIGN),
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LTC2497_CHAN_DIFF(3, LTC2497_DIFF | LTC2497_SIGN),
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LTC2497_CHAN_DIFF(4, LTC2497_DIFF | LTC2497_SIGN),
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LTC2497_CHAN_DIFF(5, LTC2497_DIFF | LTC2497_SIGN),
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LTC2497_CHAN_DIFF(6, LTC2497_DIFF | LTC2497_SIGN),
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LTC2497_CHAN_DIFF(7, LTC2497_DIFF | LTC2497_SIGN),
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};
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static const struct iio_info ltc2497_info = {
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.read_raw = ltc2497_read_raw,
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.driver_module = THIS_MODULE,
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};
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static int ltc2497_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 ltc2497_st *st;
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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(*st));
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if (!indio_dev)
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return -ENOMEM;
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st = iio_priv(indio_dev);
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i2c_set_clientdata(client, indio_dev);
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st->client = client;
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indio_dev->dev.parent = &client->dev;
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indio_dev->name = id->name;
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indio_dev->info = <c2497_info;
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->channels = ltc2497_channel;
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indio_dev->num_channels = ARRAY_SIZE(ltc2497_channel);
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st->ref = devm_regulator_get(&client->dev, "vref");
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if (IS_ERR(st->ref))
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return PTR_ERR(st->ref);
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ret = regulator_enable(st->ref);
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if (ret < 0)
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return ret;
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ret = i2c_smbus_write_byte(st->client, LTC2497_CONFIG_DEFAULT);
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if (ret < 0)
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goto err_regulator_disable;
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st->addr_prev = LTC2497_CONFIG_DEFAULT;
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st->time_prev = ktime_get();
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ret = iio_device_register(indio_dev);
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if (ret < 0)
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goto err_regulator_disable;
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return 0;
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err_regulator_disable:
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regulator_disable(st->ref);
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return ret;
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}
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static int ltc2497_remove(struct i2c_client *client)
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{
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struct iio_dev *indio_dev = i2c_get_clientdata(client);
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struct ltc2497_st *st = iio_priv(indio_dev);
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iio_device_unregister(indio_dev);
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regulator_disable(st->ref);
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return 0;
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}
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static const struct i2c_device_id ltc2497_id[] = {
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{ "ltc2497", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, ltc2497_id);
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static const struct of_device_id ltc2497_of_match[] = {
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{ .compatible = "lltc,ltc2497", },
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{},
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};
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MODULE_DEVICE_TABLE(of, ltc2497_of_match);
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static struct i2c_driver ltc2497_driver = {
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.driver = {
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.name = "ltc2497",
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.of_match_table = of_match_ptr(ltc2497_of_match),
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},
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.probe = ltc2497_probe,
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.remove = ltc2497_remove,
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.id_table = ltc2497_id,
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};
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module_i2c_driver(ltc2497_driver);
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MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
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MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver");
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MODULE_LICENSE("GPL v2");
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