diff options
Diffstat (limited to 'drivers/iio/temperature/maxim_thermocouple.c')
| -rw-r--r-- | drivers/iio/temperature/maxim_thermocouple.c | 281 |
1 files changed, 281 insertions, 0 deletions
diff --git a/drivers/iio/temperature/maxim_thermocouple.c b/drivers/iio/temperature/maxim_thermocouple.c new file mode 100644 index 000000000000..39dd2026ccc9 --- /dev/null +++ b/drivers/iio/temperature/maxim_thermocouple.c @@ -0,0 +1,281 @@ +/* + * maxim_thermocouple.c - Support for Maxim thermocouple chips + * + * Copyright (C) 2016 Matt Ranostay <mranostay@gmail.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/mutex.h> +#include <linux/err.h> +#include <linux/spi/spi.h> +#include <linux/iio/iio.h> +#include <linux/iio/trigger.h> +#include <linux/iio/buffer.h> +#include <linux/iio/triggered_buffer.h> +#include <linux/iio/trigger_consumer.h> + +#define MAXIM_THERMOCOUPLE_DRV_NAME "maxim_thermocouple" + +enum { + MAX6675, + MAX31855, +}; + +static const struct iio_chan_spec max6675_channels[] = { + { /* thermocouple temperature */ + .type = IIO_TEMP, + .info_mask_separate = + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + .scan_index = 0, + .scan_type = { + .sign = 's', + .realbits = 13, + .storagebits = 16, + .shift = 3, + .endianness = IIO_BE, + }, + }, + IIO_CHAN_SOFT_TIMESTAMP(1), +}; + +static const struct iio_chan_spec max31855_channels[] = { + { /* thermocouple temperature */ + .type = IIO_TEMP, + .address = 2, + .info_mask_separate = + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + .scan_index = 0, + .scan_type = { + .sign = 's', + .realbits = 14, + .storagebits = 16, + .shift = 2, + .endianness = IIO_BE, + }, + }, + { /* cold junction temperature */ + .type = IIO_TEMP, + .address = 0, + .channel2 = IIO_MOD_TEMP_AMBIENT, + .modified = 1, + .info_mask_separate = + BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), + .scan_index = 1, + .scan_type = { + .sign = 's', + .realbits = 12, + .storagebits = 16, + .shift = 4, + .endianness = IIO_BE, + }, + }, + IIO_CHAN_SOFT_TIMESTAMP(2), +}; + +static const unsigned long max31855_scan_masks[] = {0x3, 0}; + +struct maxim_thermocouple_chip { + const struct iio_chan_spec *channels; + const unsigned long *scan_masks; + u8 num_channels; + u8 read_size; + + /* bit-check for valid input */ + u32 status_bit; +}; + +static const struct maxim_thermocouple_chip maxim_thermocouple_chips[] = { + [MAX6675] = { + .channels = max6675_channels, + .num_channels = ARRAY_SIZE(max6675_channels), + .read_size = 2, + .status_bit = BIT(2), + }, + [MAX31855] = { + .channels = max31855_channels, + .num_channels = ARRAY_SIZE(max31855_channels), + .read_size = 4, + .scan_masks = max31855_scan_masks, + .status_bit = BIT(16), + }, +}; + +struct maxim_thermocouple_data { + struct spi_device *spi; + const struct maxim_thermocouple_chip *chip; + + u8 buffer[16] ____cacheline_aligned; +}; + +static int maxim_thermocouple_read(struct maxim_thermocouple_data *data, + struct iio_chan_spec const *chan, int *val) +{ + unsigned int storage_bytes = data->chip->read_size; + unsigned int shift = chan->scan_type.shift + (chan->address * 8); + unsigned int buf; + int ret; + + ret = spi_read(data->spi, (void *) &buf, storage_bytes); + if (ret) + return ret; + + switch (storage_bytes) { + case 2: + *val = be16_to_cpu(buf); + break; + case 4: + *val = be32_to_cpu(buf); + break; + } + + /* check to be sure this is a valid reading */ + if (*val & data->chip->status_bit) + return -EINVAL; + + *val = sign_extend32(*val >> shift, chan->scan_type.realbits - 1); + + return 0; +} + +static irqreturn_t maxim_thermocouple_trigger_handler(int irq, void *private) +{ + struct iio_poll_func *pf = private; + struct iio_dev *indio_dev = pf->indio_dev; + struct maxim_thermocouple_data *data = iio_priv(indio_dev); + int ret; + + ret = spi_read(data->spi, data->buffer, data->chip->read_size); + if (!ret) { + iio_push_to_buffers_with_timestamp(indio_dev, data->buffer, + iio_get_time_ns(indio_dev)); + } + + iio_trigger_notify_done(indio_dev->trig); + + return IRQ_HANDLED; +} + +static int maxim_thermocouple_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct maxim_thermocouple_data *data = iio_priv(indio_dev); + int ret = -EINVAL; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + ret = iio_device_claim_direct_mode(indio_dev); + if (ret) + return ret; + + ret = maxim_thermocouple_read(data, chan, val); + iio_device_release_direct_mode(indio_dev); + + if (!ret) + return IIO_VAL_INT; + + break; + case IIO_CHAN_INFO_SCALE: + switch (chan->channel2) { + case IIO_MOD_TEMP_AMBIENT: + *val = 62; + *val2 = 500000; /* 1000 * 0.0625 */ + ret = IIO_VAL_INT_PLUS_MICRO; + break; + default: + *val = 250; /* 1000 * 0.25 */ + ret = IIO_VAL_INT; + }; + break; + } + + return ret; +} + +static const struct iio_info maxim_thermocouple_info = { + .driver_module = THIS_MODULE, + .read_raw = maxim_thermocouple_read_raw, +}; + +static int maxim_thermocouple_probe(struct spi_device *spi) +{ + const struct spi_device_id *id = spi_get_device_id(spi); + struct iio_dev *indio_dev; + struct maxim_thermocouple_data *data; + const struct maxim_thermocouple_chip *chip = + &maxim_thermocouple_chips[id->driver_data]; + int ret; + + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data)); + if (!indio_dev) + return -ENOMEM; + + indio_dev->info = &maxim_thermocouple_info; + indio_dev->name = MAXIM_THERMOCOUPLE_DRV_NAME; + indio_dev->channels = chip->channels; + indio_dev->available_scan_masks = chip->scan_masks; + indio_dev->num_channels = chip->num_channels; + indio_dev->modes = INDIO_DIRECT_MODE; + + data = iio_priv(indio_dev); + data->spi = spi; + data->chip = chip; + + ret = iio_triggered_buffer_setup(indio_dev, NULL, + maxim_thermocouple_trigger_handler, NULL); + if (ret) + return ret; + + ret = iio_device_register(indio_dev); + if (ret) + goto error_unreg_buffer; + + return 0; + +error_unreg_buffer: + iio_triggered_buffer_cleanup(indio_dev); + + return ret; +} + +static int maxim_thermocouple_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + + iio_device_unregister(indio_dev); + iio_triggered_buffer_cleanup(indio_dev); + + return 0; +} + +static const struct spi_device_id maxim_thermocouple_id[] = { + {"max6675", MAX6675}, + {"max31855", MAX31855}, + {}, +}; +MODULE_DEVICE_TABLE(spi, maxim_thermocouple_id); + +static struct spi_driver maxim_thermocouple_driver = { + .driver = { + .name = MAXIM_THERMOCOUPLE_DRV_NAME, + }, + .probe = maxim_thermocouple_probe, + .remove = maxim_thermocouple_remove, + .id_table = maxim_thermocouple_id, +}; +module_spi_driver(maxim_thermocouple_driver); + +MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>"); +MODULE_DESCRIPTION("Maxim thermocouple sensors"); +MODULE_LICENSE("GPL"); |