--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Copyright (c) Rajat Khandelwal <rajat.khandelwal@linux.intel.com>
+ *
+ * Maxim MAX30208 digital temperature sensor with 0.1°C accuracy
+ * (7-bit I2C slave address (0x50 - 0x53))
+ */
+
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/iio/iio.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+#define MAX30208_STATUS 0x00
+#define MAX30208_STATUS_TEMP_RDY BIT(0)
+#define MAX30208_INT_ENABLE 0x01
+#define MAX30208_INT_ENABLE_TEMP_RDY BIT(0)
+
+#define MAX30208_FIFO_OVF_CNTR 0x06
+#define MAX30208_FIFO_DATA_CNTR 0x07
+#define MAX30208_FIFO_DATA 0x08
+
+#define MAX30208_FIFO_CONFIG 0x0a
+#define MAX30208_FIFO_CONFIG_RO BIT(1)
+
+#define MAX30208_SYSTEM_CTRL 0x0c
+#define MAX30208_SYSTEM_CTRL_RESET 0x01
+
+#define MAX30208_TEMP_SENSOR_SETUP 0x14
+#define MAX30208_TEMP_SENSOR_SETUP_CONV BIT(0)
+
+struct max30208_data {
+ struct i2c_client *client;
+ struct iio_dev *indio_dev;
+ struct mutex lock; /* Lock to prevent concurrent reads of temperature readings */
+};
+
+static const struct iio_chan_spec max30208_channels[] = {
+ {
+ .type = IIO_TEMP,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+ },
+};
+
+/**
+ * max30208_request() - Request a reading
+ * @data: Struct comprising member elements of the device
+ *
+ * Requests a reading from the device and waits until the conversion is ready.
+ */
+static int max30208_request(struct max30208_data *data)
+{
+ /*
+ * Sensor can take up to 500 ms to respond so execute a total of
+ * 10 retries to give the device sufficient time.
+ */
+ int retries = 10;
+ u8 regval;
+ int ret;
+
+ ret = i2c_smbus_read_byte_data(data->client, MAX30208_TEMP_SENSOR_SETUP);
+ if (ret < 0)
+ return ret;
+
+ regval = ret | MAX30208_TEMP_SENSOR_SETUP_CONV;
+
+ ret = i2c_smbus_write_byte_data(data->client, MAX30208_TEMP_SENSOR_SETUP, regval);
+ if (ret)
+ return ret;
+
+ while (retries--) {
+ ret = i2c_smbus_read_byte_data(data->client, MAX30208_STATUS);
+ if (ret < 0)
+ return ret;
+
+ if (ret & MAX30208_STATUS_TEMP_RDY)
+ return 0;
+
+ msleep(50);
+ }
+ dev_err(&data->client->dev, "Temperature conversion failed\n");
+
+ return -ETIMEDOUT;
+}
+
+static int max30208_update_temp(struct max30208_data *data)
+{
+ u8 data_count;
+ int ret;
+
+ mutex_lock(&data->lock);
+
+ ret = max30208_request(data);
+ if (ret)
+ goto unlock;
+
+ ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_OVF_CNTR);
+ if (ret < 0)
+ goto unlock;
+ else if (!ret) {
+ ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_DATA_CNTR);
+ if (ret < 0)
+ goto unlock;
+
+ data_count = ret;
+ } else
+ data_count = 1;
+
+ while (data_count) {
+ ret = i2c_smbus_read_word_swapped(data->client, MAX30208_FIFO_DATA);
+ if (ret < 0)
+ goto unlock;
+
+ data_count--;
+ }
+
+unlock:
+ mutex_unlock(&data->lock);
+ return ret;
+}
+
+/**
+ * max30208_config_setup() - Set up FIFO configuration register
+ * @data: Struct comprising member elements of the device
+ *
+ * Sets the rollover bit to '1' to enable overwriting FIFO during overflow.
+ */
+static int max30208_config_setup(struct max30208_data *data)
+{
+ u8 regval;
+ int ret;
+
+ ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_CONFIG);
+ if (ret < 0)
+ return ret;
+
+ regval = ret | MAX30208_FIFO_CONFIG_RO;
+
+ ret = i2c_smbus_write_byte_data(data->client, MAX30208_FIFO_CONFIG, regval);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static int max30208_read(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct max30208_data *data = iio_priv(indio_dev);
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ ret = max30208_update_temp(data);
+ if (ret < 0)
+ return ret;
+
+ *val = sign_extend32(ret, 15);
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_SCALE:
+ *val = 5;
+ return IIO_VAL_INT;
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct iio_info max30208_info = {
+ .read_raw = max30208_read,
+};
+
+static int max30208_probe(struct i2c_client *i2c)
+{
+ struct device *dev = &i2c->dev;
+ struct max30208_data *data;
+ struct iio_dev *indio_dev;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ data = iio_priv(indio_dev);
+ data->client = i2c;
+ mutex_init(&data->lock);
+
+ indio_dev->name = "max30208";
+ indio_dev->channels = max30208_channels;
+ indio_dev->num_channels = ARRAY_SIZE(max30208_channels);
+ indio_dev->info = &max30208_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+
+ ret = i2c_smbus_write_byte_data(data->client, MAX30208_SYSTEM_CTRL,
+ MAX30208_SYSTEM_CTRL_RESET);
+ if (ret) {
+ dev_err(dev, "Failure in performing reset\n");
+ return ret;
+ }
+
+ msleep(50);
+
+ ret = max30208_config_setup(data);
+ if (ret)
+ return ret;
+
+ ret = devm_iio_device_register(dev, indio_dev);
+ if (ret) {
+ dev_err(dev, "Failed to register IIO device\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static const struct i2c_device_id max30208_id_table[] = {
+ { "max30208" },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, max30208_id_table);
+
+static const struct acpi_device_id max30208_acpi_match[] = {
+ { "MAX30208" },
+ { }
+};
+MODULE_DEVICE_TABLE(acpi, max30208_acpi_match);
+
+static const struct of_device_id max30208_of_match[] = {
+ { .compatible = "maxim,max30208" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, max30208_of_match);
+
+static struct i2c_driver max30208_driver = {
+ .driver = {
+ .name = "max30208",
+ .of_match_table = max30208_of_match,
+ .acpi_match_table = max30208_acpi_match,
+ },
+ .probe_new = max30208_probe,
+ .id_table = max30208_id_table,
+};
+module_i2c_driver(max30208_driver);
+
+MODULE_AUTHOR("Rajat Khandelwal <rajat.khandelwal@linux.intel.com>");
+MODULE_DESCRIPTION("Maxim MAX30208 digital temperature sensor");
+MODULE_LICENSE("GPL");
projects / linux.git / commitdiff