iio: temperature: add support for Maxim thermocouple chips (1f25ca11) · Commits · e / devices / android_kernel_oneplus_sm7250

Documentation/devicetree/bindings/iio/temperature/maxim_thermocouple.txt

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		Maxim thermocouple support

		* https://datasheets.maximintegrated.com/en/ds/MAX6675.pdf
		* https://datasheets.maximintegrated.com/en/ds/MAX31855.pdf

		Required properties:

		- compatible: must be "maxim,max31855" or "maxim,max6675"
		- reg: SPI chip select number for the device
		- spi-max-frequency: must be 4300000
		- spi-cpha: must be defined for max6675 to enable SPI mode 1

		Refer to spi/spi-bus.txt for generic SPI slave bindings.

		Example:

		max31855@0 {
		compatible = "maxim,max31855";
		reg = <0>;
		spi-max-frequency = <4300000>;
		};

drivers/iio/temperature/Kconfig

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		@@ -3,6 +3,20 @@
		#
		menu "Temperature sensors"

		config MAXIM_THERMOCOUPLE
		tristate "Maxim thermocouple sensors"
		depends on SPI
		help
		If you say yes here you get support for the Maxim series of
		thermocouple sensors connected via SPI.

		Supported sensors:
		* MAX6675
		* MAX31855

		This driver can also be built as a module. If so, the module will
		be called maxim_thermocouple.

		config MLX90614
		tristate "MLX90614 contact-less infrared sensor"
		depends on I2C

drivers/iio/temperature/Makefile

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		@@ -2,6 +2,7 @@
		# Makefile for industrial I/O temperature drivers
		#

		obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o
		obj-$(CONFIG_MLX90614) += mlx90614.o
		obj-$(CONFIG_TMP006) += tmp006.o
		obj-$(CONFIG_TSYS01) += tsys01.o

drivers/iio/temperature/maxim_thermocouple.c

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		/*
		* 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,
		};

		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 <mranostay@gmail.com>");
		MODULE_DESCRIPTION("Maxim thermocouple sensors");
		MODULE_LICENSE("GPL");