1 files changed, 305 insertions, 0 deletions
diff --git a/drivers/iio/temperature/maxim_thermocouple.c b/drivers/iio/temperature/maxim_thermocouple.c
new file mode 100644
index 000000000..0297e215b
--- /dev/null
+++ b/drivers/iio/temperature/maxim_thermocouple.c
@@ -0,0 +1,305 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * maxim_thermocouple.c  - Support for Maxim thermocouple chips
+ *
+ * Copyright (C) 2016-2018 Matt Ranostay
+ * Author: <matt.ranostay@konsulko.com>
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/mutex.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/spi/spi.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.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,
+	MAX31855K,
+	MAX31855J,
+	MAX31855N,
+	MAX31855S,
+	MAX31855T,
+	MAX31855E,
+	MAX31855R,
+};
+
+static const char maxim_tc_types[] = {
+	'K', '?', 'K', 'J', 'N', 'S', 'T', 'E', 'R'
+};
+
+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) |
+			BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE),
+		.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) |
+			BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE),
+		.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;
+	char tc_type;
+};
+
+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);
+	__be16 buf16;
+	__be32 buf32;
+	int ret;
+
+	switch (storage_bytes) {
+	case 2:
+		ret = spi_read(data->spi, (void *)&buf16, storage_bytes);
+		*val = be16_to_cpu(buf16);
+		break;
+	case 4:
+		ret = spi_read(data->spi, (void *)&buf32, storage_bytes);
+		*val = be32_to_cpu(buf32);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	if (ret)
+		return ret;
+
+	/* 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;
+	case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
+		*val = data->tc_type;
+		ret = IIO_VAL_CHAR;
+		break;
+	}
+
+	return ret;
+}
+
+static const struct iio_info maxim_thermocouple_info = {
+	.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 int chip_type = (id->driver_data == MAX6675) ? MAX6675 : MAX31855;
+	const struct maxim_thermocouple_chip *chip =
+		&maxim_thermocouple_chips[chip_type];
+	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;
+	data->tc_type = maxim_tc_types[id->driver_data];
+
+	ret = devm_iio_triggered_buffer_setup(&spi->dev,
+				indio_dev, NULL,
+				maxim_thermocouple_trigger_handler, NULL);
+	if (ret)
+		return ret;
+
+	if (id->driver_data == MAX31855)
+		dev_warn(&spi->dev, "generic max31855 ID is deprecated\nplease use more specific part type");
+
+	return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static const struct spi_device_id maxim_thermocouple_id[] = {
+	{"max6675", MAX6675},
+	{"max31855", MAX31855},
+	{"max31855k", MAX31855K},
+	{"max31855j", MAX31855J},
+	{"max31855n", MAX31855N},
+	{"max31855s", MAX31855S},
+	{"max31855t", MAX31855T},
+	{"max31855e", MAX31855E},
+	{"max31855r", MAX31855R},
+	{},
+};
+MODULE_DEVICE_TABLE(spi, maxim_thermocouple_id);
+
+static const struct of_device_id maxim_thermocouple_of_match[] = {
+        { .compatible = "maxim,max6675" },
+        { .compatible = "maxim,max31855" },
+	{ .compatible = "maxim,max31855k" },
+	{ .compatible = "maxim,max31855j" },
+	{ .compatible = "maxim,max31855n" },
+	{ .compatible = "maxim,max31855s" },
+	{ .compatible = "maxim,max31855t" },
+	{ .compatible = "maxim,max31855e" },
+	{ .compatible = "maxim,max31855r" },
+        { },
+};
+MODULE_DEVICE_TABLE(of, maxim_thermocouple_of_match);
+
+static struct spi_driver maxim_thermocouple_driver = {
+	.driver = {
+		.name	= MAXIM_THERMOCOUPLE_DRV_NAME,
+		.of_match_table = maxim_thermocouple_of_match,
+	},
+	.probe		= maxim_thermocouple_probe,
+	.id_table	= maxim_thermocouple_id,
+};
+module_spi_driver(maxim_thermocouple_driver);
+
+MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
+MODULE_DESCRIPTION("Maxim thermocouple sensors");
+MODULE_LICENSE("GPL");