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: Tiberiu Breana <tiberiu.a.breana@intel.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/Documentation/hwmon/max31722 b/Documentation/hwmon/max31722
new file mode 100644 (file)
index 0000000..090da84
--- /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@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.

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 5c2d13a687aab5c1367429c567ac5cf118508c7d..bdfa394089964b209a120ad0222fa996ddaf2e94 100644 (file)
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -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

diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 58cc3acba7e7bc1141c8133c08ba0c4b55428cb1..2ef5b7c4c54ffad958eedcadd0ef225cc93989ec 100644 (file)
--- 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 (file)
index 0000000..30a100e
--- /dev/null
+++ b/drivers/hwmon/max31722.c
@@ -0,0 +1,165 @@
+/*
+ * 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");