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@xxxxxxxxx>
---
Changes since v2:
- addressed Guenter's comments
---
Documentation/hwmon/max31722 | 34 +++++++++
drivers/hwmon/Kconfig | 10 +++
drivers/hwmon/Makefile | 1 +
drivers/hwmon/max31722.c | 167 +++++++++++++++++++++++++++++++++++++++++++
4 files changed, 212 insertions(+)
create mode 100644 Documentation/hwmon/max31722
create mode 100644 drivers/hwmon/max31722.c
diff --git a/Documentation/hwmon/max31722 b/Documentation/hwmon/max31722
new file mode 100644
index 0000000..090da845
--- /dev/null
+++ b/Documentation/hwmon/max31722
@@ -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@xxxxxxxxx>
+
+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.
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 60fb80b..00dbe08 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -807,6 +807,16 @@ 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
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 30c94df..689afe9 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -111,6 +111,7 @@ 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
diff --git a/drivers/hwmon/max31722.c b/drivers/hwmon/max31722.c
new file mode 100644
index 0000000..f36846b
--- /dev/null
+++ b/drivers/hwmon/max31722.c
@@ -0,0 +1,167 @@
+/*
+ * 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
+#define MAX31722_12BIT_SCALE (125 / 32)
+
+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) * MAX31722_12BIT_SCALE);
+}
+
+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@xxxxxxxxx>");
+MODULE_DESCRIPTION("max31722 sensor driver");
+MODULE_LICENSE("GPL v2");
--
1.9.1
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