/* * maxim_thermocouple.c - Support for Maxim thermocouple chips * * Copyright (C) 2016 Matt Ranostay * * 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 #include #include #include #include #include #include #include #include #include #define MAXIM_THERMOCOUPLE_DRV_NAME "maxim_thermocouple" enum { MAX6675, MAX31855, }; 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), }; 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; }; 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 "); MODULE_DESCRIPTION("Maxim thermocouple sensors"); MODULE_LICENSE("GPL");