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-rw-r--r--drivers/hwmon/max31722.c155
1 files changed, 155 insertions, 0 deletions
diff --git a/drivers/hwmon/max31722.c b/drivers/hwmon/max31722.c
new file mode 100644
index 000000000..9a31ef388
--- /dev/null
+++ b/drivers/hwmon/max31722.c
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * max31722 - hwmon driver for Maxim Integrated MAX31722/MAX31723 SPI
+ * digital thermometer and thermostats.
+ *
+ * Copyright (c) 2016, Intel Corporation.
+ */
+
+#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_temp_show(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_RO(temp1_input, max31722_temp, 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 void max31722_remove(struct spi_device *spi)
+{
+ struct max31722_data *data = spi_get_drvdata(spi);
+ int ret;
+
+ hwmon_device_unregister(data->hwmon_dev);
+
+ ret = max31722_set_mode(data, MAX31722_MODE_STANDBY);
+ if (ret)
+ /* There is nothing we can do about this ... */
+ dev_warn(&spi->dev, "Failed to put device in stand-by mode\n");
+}
+
+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 DEFINE_SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume);
+
+static const struct spi_device_id max31722_spi_id[] = {
+ {"max31722", 0},
+ {"max31723", 0},
+ {}
+};
+MODULE_DEVICE_TABLE(spi, max31722_spi_id);
+
+static struct spi_driver max31722_driver = {
+ .driver = {
+ .name = "max31722",
+ .pm = pm_sleep_ptr(&max31722_pm_ops),
+ },
+ .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");