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>
---
Documentation/hwmon/max31722 | 34 +++++
drivers/hwmon/Kconfig | 11 ++
drivers/hwmon/Makefile | 1 +
drivers/hwmon/max31722.c | 304 +++++++++++++++++++++++++++++++++++++++++++
4 files changed, 350 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 5c2d13a..714be75 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -821,6 +821,17 @@ 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
+ select REGMAP_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 58cc3ac..2ef5b7c 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -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
diff --git a/drivers/hwmon/max31722.c b/drivers/hwmon/max31722.c
new file mode 100644
index 0000000..13ba906
--- /dev/null
+++ b/drivers/hwmon/max31722.c
@@ -0,0 +1,304 @@
+/*
+ * 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/kernel.h>
+#include <linux/acpi.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+
+#define MAX31722_REG_CFG 0x00
+#define MAX31722_REG_TEMP_LSB 0x01
+#define MAX31722_REG_TEMP_MSB 0x02
+#define MAX31722_MAX_REG 0x86
+
+#define MAX31722_MODE_CONTINUOUS 0x00
+#define MAX31722_MODE_STANDBY 0x01
+#define MAX31722_RESOLUTION_11BIT 0x02
+
+#define MAX31722_REGMAP_NAME "max31722_regmap"
+
+#define MAX31722_REGFIELD(name) \
+ do { \
+ data->reg_##name = \
+ devm_regmap_field_alloc(&spi->dev, regmap, \
+ max31722_reg_field_##name); \
+ if (IS_ERR(data->reg_##name)) { \
+ dev_err(&spi->dev, "reg field alloc failed.\n"); \
+ return PTR_ERR(data->reg_##name); \
+ } \
+ } while (0)
+
+struct max31722_data {
+ struct spi_device *spi_device;
+ struct device *hwmon_dev;
+ struct regmap *regmap;
+ struct regmap_field *reg_state;
+ struct regmap_field *reg_resolution;
+};
+
+/*
+ * This is a negative exponent value lookup table (as millidegree units)
+ * for calculating LSB values. The value corresponding to the fourth LSB
+ * bit is missing, as it is not used.
+ */
+static const int max31722_milli_table[3] = {
+ 500, 250, 125
+};
+
+static const struct reg_field max31722_reg_field_state =
+ REG_FIELD(MAX31722_REG_CFG, 0, 0);
+static const struct reg_field max31722_reg_field_resolution =
+ REG_FIELD(MAX31722_REG_CFG, 1, 2);
+
+static bool max31722_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+ switch (reg) {
+ case MAX31722_REG_TEMP_LSB:
+ case MAX31722_REG_TEMP_MSB:
+ return true;
+ default:
+ return false;
+ }
+}
+
+static bool max31722_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+ switch (reg) {
+ case MAX31722_REG_TEMP_LSB:
+ case MAX31722_REG_TEMP_MSB:
+ return false;
+ default:
+ return true;
+ }
+}
+
+static struct regmap_config max31722_regmap_config = {
+ .name = MAX31722_REGMAP_NAME,
+ .reg_bits = 8,
+ .val_bits = 8,
+
+ .max_register = MAX31722_MAX_REG,
+ .cache_type = REGCACHE_RBTREE,
+
+ .volatile_reg = max31722_is_volatile_reg,
+ .writeable_reg = max31722_is_writeable_reg,
+
+ .read_flag_mask = 0x00,
+ .write_flag_mask = 0x80,
+};
+
+static int max31722_set_mode(struct max31722_data *data, u8 mode)
+{
+ int ret;
+ struct spi_device *spi = data->spi_device;
+
+ ret = regmap_field_write(data->reg_state, mode);
+ if (ret < 0)
+ dev_err(&spi->dev, "failed to set sensor mode.\n");
+
+ return ret;
+}
+
+static ssize_t max31722_show_name(struct device *dev,
+ struct device_attribute *devattr,
+ char *buf)
+{
+ return sprintf(buf, "%s\n", to_spi_device(dev)->modalias);
+}
+
+static ssize_t max31722_show_temperature(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int i;
+ int ret;
+ u8 lsb;
+ s16 val;
+ u16 temp;
+ struct max31722_data *data = dev_get_drvdata(dev);
+
+ ret = regmap_bulk_read(data->regmap, MAX31722_REG_TEMP_LSB, &temp, 2);
+ if (ret < 0) {
+ dev_err(&data->spi_device->dev,
+ "failed to read temperature register\n");
+ return ret;
+ }
+ /*
+ * The MSB contains the integer part of the temperature value
+ * (signed), while the LSB contains the fractional part as
+ * negative powers of 2, e.g.: bit 0 is 2^-1, bit 1 is 2^-2, etc.
+ * Temperature is exported in millidegrees Celsius.
+ */
+ val = (temp >> 8) * 1000;
+ lsb = (temp << 8) >> 13; /* We only need the first 3 LSB bits. */
+ i = 0;
+ while (i < 3) {
+ if ((lsb >> (3 - i - 1)) & 0x01)
+ val += max31722_milli_table[i];
+ i++;
+ }
+
+ return sprintf(buf, "%d\n", val);
+}
+
+static DEVICE_ATTR(name, S_IRUGO, max31722_show_name, NULL);
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
+ max31722_show_temperature, NULL, 0);
+
+static struct attribute *max31722_attributes[] = {
+ &dev_attr_name.attr,
+ &sensor_dev_attr_temp1_input.dev_attr.attr,
+ NULL,
+};
+
+static const struct attribute_group max31722_group = {
+ .attrs = max31722_attributes,
+};
+
+static int max31722_init(struct max31722_data *data)
+{
+ int ret = 0;
+ struct spi_device *spi = data->spi_device;
+ struct regmap *regmap;
+
+ /* Initialize the regmap */
+ regmap = devm_regmap_init_spi(spi, &max31722_regmap_config);
+ if (IS_ERR(regmap)) {
+ dev_err(&spi->dev, "regmap initialization failed.\n");
+ return PTR_ERR(regmap);
+ }
+ data->regmap = regmap;
+
+ MAX31722_REGFIELD(state);
+ MAX31722_REGFIELD(resolution);
+
+ /* Set SD bit to 0 so we can have continuous measurements. */
+ ret = regmap_field_write(data->reg_state, MAX31722_MODE_CONTINUOUS);
+ if (ret < 0)
+ goto err;
+ /*
+ * Set resolution to 11 bits (3 decimals) so we can have the maximum
+ * precision in the exported millidegree range.
+ */
+ ret = regmap_field_write(data->reg_resolution,
+ MAX31722_RESOLUTION_11BIT);
+ if (ret < 0)
+ goto err;
+
+ return 0;
+
+err:
+ dev_err(&spi->dev, "sensor configuration failed.\n");
+ return ret;
+}
+
+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;
+
+ ret = max31722_init(data);
+ if (ret < 0)
+ goto err_standby;
+
+ ret = sysfs_create_group(&spi->dev.kobj, &max31722_group);
+ if (ret < 0)
+ goto err_standby;
+
+ data->hwmon_dev = hwmon_device_register(&spi->dev);
+ if (IS_ERR(data->hwmon_dev)) {
+ ret = PTR_ERR(data->hwmon_dev);
+ goto err_remove_group;
+ }
+
+ return 0;
+
+err_remove_group:
+ sysfs_remove_group(&spi->dev.kobj, &max31722_group);
+err_standby:
+ max31722_set_mode(data, MAX31722_MODE_STANDBY);
+ return ret;
+}
+
+static int max31722_remove(struct spi_device *spi)
+{
+ struct max31722_data *data = spi_get_drvdata(spi);
+
+ hwmon_device_unregister(data->hwmon_dev);
+ sysfs_remove_group(&spi->dev.kobj, &max31722_group);
+
+ return max31722_set_mode(data, MAX31722_MODE_STANDBY);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int 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 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);
+
+#define MAX31722_PM_OPS (&max31722_pm_ops)
+#else
+#define MAX31722_PM_OPS NULL
+#endif
+
+static const struct spi_device_id max31722_spi_id[] = {
+ {"max31722", 0},
+ {"max31723", 0},
+ {}
+};
+
+static const struct acpi_device_id 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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