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Commit 04e1e70a authored by Tiberiu Breana's avatar Tiberiu Breana Committed by Guenter Roeck
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hwmon: (max31722) Add support for MAX31722/MAX31723 temperature sensors 

Add basic support for the Maxim Integrated MAX31722/MAX31723 SPI
temperature sensors / thermostats.

Includes:
    - ACPI support;
    - raw temperature readings;
    - power management

Datasheet:
https://datasheets.maximintegrated.com/en/ds/MAX31722-MAX31723.pdf



Signed-off-by: default avatarTiberiu Breana <tiberiu.a.breana@intel.com>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 7a18afe8

Documentation/hwmon/max31722

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Kernel driver max31722

======================



Supported chips:

  * Maxim Integrated MAX31722

    Prefix: 'max31722'

    ACPI ID: MAX31722

    Addresses scanned: -

    Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX31722-MAX31723.pdf

  * Maxim Integrated MAX31723

    Prefix: 'max31723'

    ACPI ID: MAX31723

    Addresses scanned: -

    Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX31722-MAX31723.pdf



Author: Tiberiu Breana <tiberiu.a.breana@intel.com>



Description

-----------



This driver adds support for the Maxim Integrated MAX31722/MAX31723 thermometers

and thermostats running over an SPI interface.



Usage Notes

-----------



This driver uses ACPI to auto-detect devices. See ACPI IDs in the above section.



Sysfs entries

-------------



The following attribute is supported:



temp1_input		Measured temperature. Read-only.

drivers/hwmon/Kconfig

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@@ -821,6 +821,16 @@ config SENSORS_MAX197 
	  This driver can also be built as a module. If so, the module

	  will be called max197.



config SENSORS_MAX31722

tristate "MAX31722 temperature sensor"

	depends on SPI

	help

	  Support for the Maxim Integrated MAX31722/MAX31723 digital

	  thermometers/thermostats operating over an SPI interface.



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

	  will be called max31722.



config SENSORS_MAX6639

	tristate "Maxim MAX6639 sensor chip"

	depends on I2C

drivers/hwmon/Makefile

+1 −0
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@@ -112,6 +112,7 @@ obj-$(CONFIG_SENSORS_MAX16065) += max16065.o 
obj-$(CONFIG_SENSORS_MAX1619)	+= max1619.o

obj-$(CONFIG_SENSORS_MAX1668)	+= max1668.o

obj-$(CONFIG_SENSORS_MAX197)	+= max197.o

obj-$(CONFIG_SENSORS_MAX31722)	+= max31722.o

obj-$(CONFIG_SENSORS_MAX6639)	+= max6639.o

obj-$(CONFIG_SENSORS_MAX6642)	+= max6642.o

obj-$(CONFIG_SENSORS_MAX6650)	+= max6650.o

drivers/hwmon/max31722.c

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/*

 * max31722 - hwmon driver for Maxim Integrated MAX31722/MAX31723 SPI

 * digital thermometer and thermostats.

 *

 * Copyright (c) 2016, Intel Corporation.

 *

 * This file is subject to the terms and conditions of version 2 of

 * the GNU General Public License. See the file COPYING in the main

 * directory of this archive for more details.

 */



#include <linux/acpi.h>

#include <linux/hwmon.h>

#include <linux/hwmon-sysfs.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/spi/spi.h>



#define MAX31722_REG_CFG				0x00

#define MAX31722_REG_TEMP_LSB				0x01



#define MAX31722_MODE_CONTINUOUS			0x00

#define MAX31722_MODE_STANDBY				0x01

#define MAX31722_MODE_MASK				0xFE

#define MAX31722_RESOLUTION_12BIT			0x06

#define MAX31722_WRITE_MASK				0x80



struct max31722_data {

	struct device *hwmon_dev;

	struct spi_device *spi_device;

	u8 mode;

};



static int max31722_set_mode(struct max31722_data *data, u8 mode)

{

	int ret;

	struct spi_device *spi = data->spi_device;

	u8 buf[2] = {

		MAX31722_REG_CFG | MAX31722_WRITE_MASK,

		(data->mode & MAX31722_MODE_MASK) | mode

	};



	ret = spi_write(spi, &buf, sizeof(buf));

	if (ret < 0) {

		dev_err(&spi->dev, "failed to set sensor mode.\n");

		return ret;

	}

	data->mode = (data->mode & MAX31722_MODE_MASK) | mode;



	return 0;

}



static ssize_t max31722_show_temp(struct device *dev,

				  struct device_attribute *attr,

				  char *buf)

{

	ssize_t ret;

	struct max31722_data *data = dev_get_drvdata(dev);



	ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB);

	if (ret < 0)

		return ret;

	/* Keep 12 bits and multiply by the scale of 62.5 millidegrees/bit. */

	return sprintf(buf, "%d\n", (s16)le16_to_cpu(ret) * 125 / 32);

}



static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,

			  max31722_show_temp, NULL, 0);



static struct attribute *max31722_attrs[] = {

	&sensor_dev_attr_temp1_input.dev_attr.attr,

	NULL,

};



ATTRIBUTE_GROUPS(max31722);



static int max31722_probe(struct spi_device *spi)

{

	int ret;

	struct max31722_data *data;



	data = devm_kzalloc(&spi->dev, sizeof(*data), GFP_KERNEL);

	if (!data)

		return -ENOMEM;



	spi_set_drvdata(spi, data);

	data->spi_device = spi;

	/*

	 * Set SD bit to 0 so we can have continuous measurements.

	 * Set resolution to 12 bits for maximum precision.

	 */

	data->mode = MAX31722_MODE_CONTINUOUS | MAX31722_RESOLUTION_12BIT;

	ret = max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);

	if (ret < 0)

		return ret;



	data->hwmon_dev = hwmon_device_register_with_groups(&spi->dev,

							    spi->modalias,

							    data,

							    max31722_groups);

	if (IS_ERR(data->hwmon_dev)) {

		max31722_set_mode(data, MAX31722_MODE_STANDBY);

		return PTR_ERR(data->hwmon_dev);

	}



	return 0;

}



static int max31722_remove(struct spi_device *spi)

{

	struct max31722_data *data = spi_get_drvdata(spi);



	hwmon_device_unregister(data->hwmon_dev);



	return max31722_set_mode(data, MAX31722_MODE_STANDBY);

}



static int __maybe_unused max31722_suspend(struct device *dev)

{

	struct spi_device *spi_device = to_spi_device(dev);

	struct max31722_data *data = spi_get_drvdata(spi_device);



	return max31722_set_mode(data, MAX31722_MODE_STANDBY);

}



static int __maybe_unused max31722_resume(struct device *dev)

{

	struct spi_device *spi_device = to_spi_device(dev);

	struct max31722_data *data = spi_get_drvdata(spi_device);



	return max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);

}



static SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume);



static const struct spi_device_id max31722_spi_id[] = {

	{"max31722", 0},

	{"max31723", 0},

	{}

};



static const struct acpi_device_id __maybe_unused max31722_acpi_id[] = {

	{"MAX31722", 0},

	{"MAX31723", 0},

	{}

};



MODULE_DEVICE_TABLE(spi, max31722_spi_id);



static struct spi_driver max31722_driver = {

	.driver = {

		.name = "max31722",

		.pm = &max31722_pm_ops,

		.acpi_match_table = ACPI_PTR(max31722_acpi_id),

	},

	.probe =            max31722_probe,

	.remove =           max31722_remove,

	.id_table =         max31722_spi_id,

};



module_spi_driver(max31722_driver);



MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");

MODULE_DESCRIPTION("max31722 sensor driver");

MODULE_LICENSE("GPL v2");