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hwmon: (max31722) Add support for MAX31722/MAX31723 temperature sensors

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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: Tiberiu Breana <tiberiu.a.breana@intel.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Tiberiu Breana 2016-03-30 19:16:24 +03:00 committed by Guenter Roeck
parent 7a18afe809
commit 04e1e70afe
4 changed files with 210 additions and 0 deletions
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34
Documentation/hwmon/max31722 Normal file
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@ -0,0 +1,34 @@
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.

10
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

1
drivers/hwmon/Makefile
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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

165
drivers/hwmon/max31722.c Normal file
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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");