Add a driver for the MAX6675 thermocouple converter. This
device interfaces with K-type thermocouples and provides
cold-junction compensated temperature readings via a
SPI interface.
Signed-off-by: Matt Porter <mporter@xxxxxxxxxxxx>
---
drivers/iio/temperature/Kconfig | 11 +++
drivers/iio/temperature/Makefile | 1 +
drivers/iio/temperature/max6675.c | 155 ++++++++++++++++++++++++++++++++++++++
3 files changed, 167 insertions(+)
create mode 100644 drivers/iio/temperature/max6675.c
diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig
index 21feaa4..b73fbf4 100644
--- a/drivers/iio/temperature/Kconfig
+++ b/drivers/iio/temperature/Kconfig
@@ -3,6 +3,17 @@
#
menu "Temperature sensors"
+config MAX6675
+ tristate "MAX6675 thermocouple converter"
+ depends on SPI
+ help
+ If you say yes here you get support for the Maxim
+ MAX6675 thermocouple converter connected with SPI.
+
+ This driver can also be built as a module. If so, the module will
+ be called max6675.
+
+
config MLX90614
tristate "MLX90614 contact-less infrared sensor"
depends on I2C
diff --git a/drivers/iio/temperature/Makefile b/drivers/iio/temperature/Makefile
index 40710a8..d67ef40 100644
--- a/drivers/iio/temperature/Makefile
+++ b/drivers/iio/temperature/Makefile
@@ -2,5 +2,6 @@
# Makefile for industrial I/O temperature drivers
#
+obj-$(CONFIG_MAX6675) += max6675.o
obj-$(CONFIG_MLX90614) += mlx90614.o
obj-$(CONFIG_TMP006) += tmp006.o
diff --git a/drivers/iio/temperature/max6675.c b/drivers/iio/temperature/max6675.c
new file mode 100644
index 0000000..2d1fda2
--- /dev/null
+++ b/drivers/iio/temperature/max6675.c
@@ -0,0 +1,155 @@
+/*
+ * max6675.c - MAX6675 thermocouple converter driver
+ *
+ * Copyright (C) 2015 Konsulko Group, Matt Porter <mporter@xxxxxxxxxxxx>
+ *
+ * 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/acpi.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/iio/iio.h>
+#include <linux/spi/spi.h>
+
+struct max6675_state {
+ struct spi_device *spi;
+};
+
+static const struct iio_chan_spec max6675_channels[] = {
+ {
+ .type = IIO_TEMP,
+ .info_mask_separate =
+ BIT(IIO_CHAN_INFO_RAW) |
+ BIT(IIO_CHAN_INFO_SCALE),
+ },
+};
+
+static int max6675_read(struct max6675_state *st, int *val)
+{
+ int ret;
+
+ ret = spi_read(st->spi, val, 2);
+ if (ret < 0)
+ return ret;
+
+ /* Temperature is bits 14..3 */
+ *val = (*val >> 3) & 0xfff;
+
+ return ret;
+}
+
+static int max6675_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val,
+ int *val2,
+ long m)
+{
+ struct max6675_state *st = iio_priv(indio_dev);
+ int ret;
+
+ if (m == IIO_CHAN_INFO_RAW) {
+ *val2 = 0;
+ ret = max6675_read(st, val);
+ if (ret)
+ return ret;
+ } else if (m == IIO_CHAN_INFO_SCALE) {
+ *val = 250;
+ *val2 = 0;
+ } else
+ return -EINVAL;
+
+ return IIO_VAL_INT;
+}
+
+static const struct iio_info max6675_info = {
+ .driver_module = THIS_MODULE,
+ .read_raw = &max6675_read_raw,
+};
+
+static int max6675_probe(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev;
+ struct max6675_state *st;
+ int ret = 0;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ st = iio_priv(indio_dev);
+ st->spi = spi;
+
+ spi->mode = SPI_MODE_1;
+ spi->bits_per_word = 16;
+
+ spi_set_drvdata(spi, indio_dev);
+
+ indio_dev->dev.parent = &spi->dev;
+ indio_dev->name = spi_get_device_id(spi)->name;
+ indio_dev->channels = max6675_channels;
+ indio_dev->num_channels = ARRAY_SIZE(max6675_channels);
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->info = &max6675_info;
+
+ ret = iio_device_register(indio_dev);
+ if (ret < 0)
+ dev_err(&spi->dev, "unable to register device\n");
+
+ return ret;
+}
+
+static int max6675_remove(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev = spi_get_drvdata(spi);
+
+ iio_device_unregister(indio_dev);
+
+ return 0;
+}
+
+static const struct acpi_device_id max6675_acpi_ids[] = {
+ { "MXIM6675", 0 },
+ {},
+};
+MODULE_DEVICE_TABLE(acpi, max6675_acpi_ids);
+
+static const struct of_device_id max6675_dt_ids[] = {
+ { .compatible = "maxim,max6675" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, max6675_dt_ids);
+
+static const struct spi_device_id max6675_spi_ids[] = {
+ {"max6675", 0},
+ {},
+};
+MODULE_DEVICE_TABLE(spi, max6675_spi_ids);
+
+static struct spi_driver max6675_driver = {
+ .driver = {
+ .name = "max6675",
+ .owner = THIS_MODULE,
+ .acpi_match_table = ACPI_PTR(max6675_acpi_ids),
+ .of_match_table = of_match_ptr(max6675_dt_ids),
+ },
+ .probe = max6675_probe,
+ .remove = max6675_remove,
+ .id_table = max6675_spi_ids,
+};
+module_spi_driver(max6675_driver);
+
+MODULE_AUTHOR("Matt Porter <mporter@xxxxxxxxxxxx>");
+MODULE_DESCRIPTION("MAX6675 thermocouple converter driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("spi:max6675");
--
2.1.4
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