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![Arnd Bergmann](/assets/img/avatar_default.png)
As found by gcc -Wmaybe-uninitialized, having a storage_bytes value other than 2 or 4 will result in undefined behavior: drivers/iio/temperature/maxim_thermocouple.c: In function 'maxim_thermocouple_read': drivers/iio/temperature/maxim_thermocouple.c:141:5: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized] This probably cannot happen, but returning -EINVAL here is appropriate and makes gcc happy and the code more robust. Fixes:231147ee77
("iio: maxim_thermocouple: Align 16 bit big endian value of raw reads") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Jonathan Cameron <jic23@kernel.org> (cherry picked from commit32cb7d27e6
) Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
285 lines
6.7 KiB
C
285 lines
6.7 KiB
C
/*
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* maxim_thermocouple.c - Support for Maxim thermocouple chips
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*
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* Copyright (C) 2016 Matt Ranostay <mranostay@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/mutex.h>
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#include <linux/err.h>
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#include <linux/spi/spi.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/trigger.h>
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#include <linux/iio/buffer.h>
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#include <linux/iio/triggered_buffer.h>
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#include <linux/iio/trigger_consumer.h>
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#define MAXIM_THERMOCOUPLE_DRV_NAME "maxim_thermocouple"
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enum {
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MAX6675,
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MAX31855,
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};
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static const struct iio_chan_spec max6675_channels[] = {
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{ /* thermocouple temperature */
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.type = IIO_TEMP,
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.info_mask_separate =
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BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
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.scan_index = 0,
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.scan_type = {
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.sign = 's',
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.realbits = 13,
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.storagebits = 16,
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.shift = 3,
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.endianness = IIO_BE,
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},
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},
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IIO_CHAN_SOFT_TIMESTAMP(1),
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};
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static const struct iio_chan_spec max31855_channels[] = {
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{ /* thermocouple temperature */
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.type = IIO_TEMP,
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.address = 2,
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.info_mask_separate =
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BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
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.scan_index = 0,
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.scan_type = {
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.sign = 's',
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.realbits = 14,
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.storagebits = 16,
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.shift = 2,
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.endianness = IIO_BE,
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},
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},
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{ /* cold junction temperature */
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.type = IIO_TEMP,
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.address = 0,
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.channel2 = IIO_MOD_TEMP_AMBIENT,
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.modified = 1,
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.info_mask_separate =
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BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
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.scan_index = 1,
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.scan_type = {
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.sign = 's',
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.realbits = 12,
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.storagebits = 16,
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.shift = 4,
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.endianness = IIO_BE,
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},
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},
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IIO_CHAN_SOFT_TIMESTAMP(2),
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};
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static const unsigned long max31855_scan_masks[] = {0x3, 0};
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struct maxim_thermocouple_chip {
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const struct iio_chan_spec *channels;
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const unsigned long *scan_masks;
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u8 num_channels;
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u8 read_size;
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/* bit-check for valid input */
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u32 status_bit;
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};
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static const struct maxim_thermocouple_chip maxim_thermocouple_chips[] = {
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[MAX6675] = {
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.channels = max6675_channels,
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.num_channels = ARRAY_SIZE(max6675_channels),
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.read_size = 2,
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.status_bit = BIT(2),
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},
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[MAX31855] = {
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.channels = max31855_channels,
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.num_channels = ARRAY_SIZE(max31855_channels),
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.read_size = 4,
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.scan_masks = max31855_scan_masks,
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.status_bit = BIT(16),
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},
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};
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struct maxim_thermocouple_data {
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struct spi_device *spi;
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const struct maxim_thermocouple_chip *chip;
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u8 buffer[16] ____cacheline_aligned;
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};
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static int maxim_thermocouple_read(struct maxim_thermocouple_data *data,
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struct iio_chan_spec const *chan, int *val)
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{
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unsigned int storage_bytes = data->chip->read_size;
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unsigned int shift = chan->scan_type.shift + (chan->address * 8);
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__be16 buf16;
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__be32 buf32;
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int ret;
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switch (storage_bytes) {
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case 2:
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ret = spi_read(data->spi, (void *)&buf16, storage_bytes);
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*val = be16_to_cpu(buf16);
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break;
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case 4:
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ret = spi_read(data->spi, (void *)&buf32, storage_bytes);
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*val = be32_to_cpu(buf32);
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break;
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default:
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ret = -EINVAL;
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}
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if (ret)
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return ret;
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/* check to be sure this is a valid reading */
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if (*val & data->chip->status_bit)
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return -EINVAL;
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*val = sign_extend32(*val >> shift, chan->scan_type.realbits - 1);
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return 0;
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}
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static irqreturn_t maxim_thermocouple_trigger_handler(int irq, void *private)
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{
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struct iio_poll_func *pf = private;
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struct iio_dev *indio_dev = pf->indio_dev;
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struct maxim_thermocouple_data *data = iio_priv(indio_dev);
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int ret;
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ret = spi_read(data->spi, data->buffer, data->chip->read_size);
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if (!ret) {
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iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
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iio_get_time_ns(indio_dev));
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}
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iio_trigger_notify_done(indio_dev->trig);
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return IRQ_HANDLED;
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}
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static int maxim_thermocouple_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 maxim_thermocouple_data *data = iio_priv(indio_dev);
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int ret = -EINVAL;
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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ret = iio_device_claim_direct_mode(indio_dev);
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if (ret)
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return ret;
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ret = maxim_thermocouple_read(data, chan, val);
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iio_device_release_direct_mode(indio_dev);
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if (!ret)
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return IIO_VAL_INT;
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break;
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case IIO_CHAN_INFO_SCALE:
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switch (chan->channel2) {
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case IIO_MOD_TEMP_AMBIENT:
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*val = 62;
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*val2 = 500000; /* 1000 * 0.0625 */
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ret = IIO_VAL_INT_PLUS_MICRO;
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break;
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default:
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*val = 250; /* 1000 * 0.25 */
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ret = IIO_VAL_INT;
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};
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break;
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}
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return ret;
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}
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static const struct iio_info maxim_thermocouple_info = {
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.driver_module = THIS_MODULE,
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.read_raw = maxim_thermocouple_read_raw,
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};
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static int maxim_thermocouple_probe(struct spi_device *spi)
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{
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const struct spi_device_id *id = spi_get_device_id(spi);
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struct iio_dev *indio_dev;
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struct maxim_thermocouple_data *data;
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const struct maxim_thermocouple_chip *chip =
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&maxim_thermocouple_chips[id->driver_data];
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int ret;
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indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
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if (!indio_dev)
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return -ENOMEM;
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indio_dev->info = &maxim_thermocouple_info;
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indio_dev->name = MAXIM_THERMOCOUPLE_DRV_NAME;
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indio_dev->channels = chip->channels;
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indio_dev->available_scan_masks = chip->scan_masks;
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indio_dev->num_channels = chip->num_channels;
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indio_dev->modes = INDIO_DIRECT_MODE;
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data = iio_priv(indio_dev);
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data->spi = spi;
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data->chip = chip;
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ret = iio_triggered_buffer_setup(indio_dev, NULL,
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maxim_thermocouple_trigger_handler, NULL);
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if (ret)
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return ret;
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ret = iio_device_register(indio_dev);
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if (ret)
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goto error_unreg_buffer;
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return 0;
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error_unreg_buffer:
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iio_triggered_buffer_cleanup(indio_dev);
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return ret;
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}
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static int maxim_thermocouple_remove(struct spi_device *spi)
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{
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struct iio_dev *indio_dev = spi_get_drvdata(spi);
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iio_device_unregister(indio_dev);
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iio_triggered_buffer_cleanup(indio_dev);
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return 0;
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}
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static const struct spi_device_id maxim_thermocouple_id[] = {
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{"max6675", MAX6675},
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{"max31855", MAX31855},
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{},
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};
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MODULE_DEVICE_TABLE(spi, maxim_thermocouple_id);
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static struct spi_driver maxim_thermocouple_driver = {
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.driver = {
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.name = MAXIM_THERMOCOUPLE_DRV_NAME,
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},
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.probe = maxim_thermocouple_probe,
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.remove = maxim_thermocouple_remove,
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.id_table = maxim_thermocouple_id,
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};
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module_spi_driver(maxim_thermocouple_driver);
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MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
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MODULE_DESCRIPTION("Maxim thermocouple sensors");
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MODULE_LICENSE("GPL");
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