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Diffstat (limited to 'drivers/iio/temperature/maxim_thermocouple.c')
-rw-r--r--drivers/iio/temperature/maxim_thermocouple.c281
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");