[PATCH v6] iio: temperature: Add driver support for Maxim MAX30208
From: Rajat Khandelwal
Date: Mon Oct 24 2022 - 15:18:41 EST
Maxim MAX30208 is a digital temperature sensor with 0.1°C accuracy.
Add support for max30208 driver in iio subsystem.
Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX30208.pdf
Signed-off-by: Rajat Khandelwal <rajat.khandelwal@xxxxxxxxxxxxxxx>
---
v6: Converted usleep_range to msleep as delay is quite large
v5:
1. Fixed comment position in max30208_request
2. Use of local u8 variable to build register values
3. Using u8 instead of s8 in data_count
4. Removed global MAX30208_RES_MILLICELCIUS
5. Removed 'comma' on NULL terminators
v4: Version comments go below line separator of signed-off-by
v3: Release the mutex lock after error gets returned
v2:
1. Removed TODO
2. Removed unnecessary blank spaces
3. Corrected MC->MILLICELCIUS
4. Comments added wherever required
5. dev_err on i2c fails
6. Rearranged some flows
7. Removed PROCESSED
8. int error return on gpio setup
9. device_register at the end of probe
10. Return on unsuccessful reset
11. acpi_match_table and of_match_table added
12. Minor quirks
MAINTAINERS | 6 +
drivers/iio/temperature/Kconfig | 10 +
drivers/iio/temperature/Makefile | 1 +
drivers/iio/temperature/max30208.c | 323 +++++++++++++++++++++++++++++
4 files changed, 340 insertions(+)
create mode 100644 drivers/iio/temperature/max30208.c
diff --git a/MAINTAINERS b/MAINTAINERS
index f1390b8270b2..7f1fd2e31b94 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12373,6 +12373,12 @@ S: Maintained
F: Documentation/devicetree/bindings/regulator/maxim,max20086.yaml
F: drivers/regulator/max20086-regulator.c
+MAXIM MAX30208 TEMPERATURE SENSOR DRIVER
+M: Rajat Khandelwal <rajat.khandelwal@xxxxxxxxxxxxxxx>
+L: linux-iio@xxxxxxxxxxxxxxx
+S: Maintained
+F: drivers/iio/temperature/max30208.c
+
MAXIM MAX77650 PMIC MFD DRIVER
M: Bartosz Golaszewski <brgl@xxxxxxxx>
L: linux-kernel@xxxxxxxxxxxxxxx
diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig
index e8ed849e3b76..ed384f33e0c7 100644
--- a/drivers/iio/temperature/Kconfig
+++ b/drivers/iio/temperature/Kconfig
@@ -128,6 +128,16 @@ config TSYS02D
This driver can also be built as a module. If so, the module will
be called tsys02d.
+config MAX30208
+ tristate "Maxim MAX30208 digital temperature sensor"
+ depends on I2C
+ help
+ If you say yes here you get support for Maxim MAX30208
+ digital temperature sensor connected via I2C.
+
+ This driver can also be built as a module. If so, the module
+ will be called max30208.
+
config MAX31856
tristate "MAX31856 thermocouple sensor"
depends on SPI
diff --git a/drivers/iio/temperature/Makefile b/drivers/iio/temperature/Makefile
index dd08e562ffe0..dfec8c6d3019 100644
--- a/drivers/iio/temperature/Makefile
+++ b/drivers/iio/temperature/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_IQS620AT_TEMP) += iqs620at-temp.o
obj-$(CONFIG_LTC2983) += ltc2983.o
obj-$(CONFIG_HID_SENSOR_TEMP) += hid-sensor-temperature.o
obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o
+obj-$(CONFIG_MAX30208) += max30208.o
obj-$(CONFIG_MAX31856) += max31856.o
obj-$(CONFIG_MAX31865) += max31865.o
obj-$(CONFIG_MLX90614) += mlx90614.o
diff --git a/drivers/iio/temperature/max30208.c b/drivers/iio/temperature/max30208.c
new file mode 100644
index 000000000000..41b26755ce27
--- /dev/null
+++ b/drivers/iio/temperature/max30208.c
@@ -0,0 +1,323 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Copyright (c) Rajat Khandelwal <rajat.khandelwal@xxxxxxxxxxxxxxx>
+ *
+ * Maxim MAX30208 digital temperature sensor with 0.1°C accuracy
+ * (7-bit I2C slave address (0x50 - 0x53))
+ *
+ * Note: This driver sets GPIO1 to behave as input for temperature
+ * conversion and GPIO0 to act as interrupt for temperature conversion.
+ */
+
+#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_DRV_NAME "max30208"
+
+#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_SYSTEM_CTRL 0x0c
+#define MAX30208_SYSTEM_CTRL_RESET 0x01
+
+#define MAX30208_TEMP_SENSOR_SETUP 0x14
+#define MAX30208_TEMP_SENSOR_SETUP_CONV BIT(0)
+
+#define MAX30208_GPIO_SETUP 0x20
+#define MAX30208_GPIO1_SETUP GENMASK(7, 6)
+#define MAX30208_GPIO0_SETUP GENMASK(1, 0)
+#define MAX30208_GPIO_CTRL 0x21
+#define MAX30208_GPIO1_CTRL BIT(3)
+#define MAX30208_GPIO0_CTRL BIT(0)
+
+struct max30208_data {
+ struct i2c_client *client;
+ struct iio_dev *indio_dev;
+ struct mutex lock; /* Lock to prevent concurrent reads */
+};
+
+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) {
+ dev_err(&data->client->dev, "Error reading reg temperature setup\n");
+ return ret;
+ }
+
+ regval = ret | MAX30208_TEMP_SENSOR_SETUP_CONV;
+
+ ret = i2c_smbus_write_byte_data(data->client, MAX30208_TEMP_SENSOR_SETUP, regval);
+ if (ret < 0) {
+ dev_err(&data->client->dev, "Error writing reg temperature setup\n");
+ return ret;
+ }
+
+ while (retries--) {
+ ret = i2c_smbus_read_byte_data(data->client, MAX30208_STATUS);
+ if (ret < 0) {
+ dev_err(&data->client->dev, "Error reading reg status\n");
+ goto sleep;
+ }
+
+ if (ret & MAX30208_STATUS_TEMP_RDY)
+ return 0;
+
+ msleep(50);
+ }
+ dev_warn(&data->client->dev, "Temperature conversion failed\n");
+
+ return 0;
+
+sleep:
+ msleep(50);
+ return 0;
+}
+
+static int max30208_update_temp(struct max30208_data *data)
+{
+ u8 data_count;
+ int ret;
+
+ mutex_lock(&data->lock);
+
+ ret = max30208_request(data);
+ if (ret < 0)
+ goto unlock;
+
+ ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_OVF_CNTR);
+ if (ret < 0) {
+ dev_err(&data->client->dev, "Error reading reg FIFO overflow counter\n");
+ goto unlock;
+ } else if (!ret) {
+ ret = i2c_smbus_read_byte_data(data->client,
+ MAX30208_FIFO_DATA_CNTR);
+ if (ret < 0) {
+ dev_err(&data->client->dev, "Error reading reg FIFO data counter\n");
+ goto unlock;
+ }
+ }
+
+ data_count = ret;
+
+ /*
+ * Ideally, counter should decrease by 1 each time a word is read from FIFO.
+ * However, practically, the device behaves erroneously and counter sometimes
+ * decreases by more than 1. Hence, do not loop the counter until it becomes 0
+ * rather, use the exact counter value after each FIFO word is read.
+ * Return the last reading from FIFO as the most recently triggered one.
+ */
+ while (data_count) {
+ ret = i2c_smbus_read_word_swapped(data->client,
+ MAX30208_FIFO_DATA);
+ if (ret < 0) {
+ dev_err(&data->client->dev, "Error reading reg FIFO data\n");
+ goto unlock;
+ }
+
+ data_count = i2c_smbus_read_byte_data(data->client,
+ MAX30208_FIFO_DATA_CNTR);
+ if (data_count < 0) {
+ dev_err(&data->client->dev, "Error reading reg FIFO data counter\n");
+ ret = data_count;
+ goto unlock;
+ }
+ }
+
+unlock:
+ mutex_unlock(&data->lock);
+ return ret;
+}
+
+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 int max30208_gpio_setup(struct max30208_data *data)
+{
+ u8 regval;
+ int ret;
+
+ ret = i2c_smbus_read_byte_data(data->client,
+ MAX30208_GPIO_SETUP);
+ if (ret < 0) {
+ dev_err(&data->client->dev, "Error reading reg GPIO setup\n");
+ return ret;
+ }
+
+ /*
+ * Setting GPIO1 to trigger temperature conversion
+ * when driven low.
+ * Setting GPIO0 to trigger interrupt when temperature
+ * conversion gets completed.
+ */
+ regval = ret | MAX30208_GPIO1_SETUP | MAX30208_GPIO0_SETUP;
+ ret = i2c_smbus_write_byte_data(data->client,
+ MAX30208_GPIO_SETUP, regval);
+ if (ret < 0) {
+ dev_err(&data->client->dev, "Error writing reg GPIO setup\n");
+ return ret;
+ }
+
+ ret = i2c_smbus_read_byte_data(data->client,
+ MAX30208_INT_ENABLE);
+ if (ret < 0) {
+ dev_err(&data->client->dev, "Error reading reg interrupt enable\n");
+ return ret;
+ }
+
+ /* Enabling GPIO0 interrupt */
+ regval = ret | MAX30208_INT_ENABLE_TEMP_RDY;
+ ret = i2c_smbus_write_byte_data(data->client,
+ MAX30208_INT_ENABLE, regval);
+ if (ret < 0) {
+ dev_err(&data->client->dev, "Error writing reg interrupt enable\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+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_DRV_NAME;
+ indio_dev->channels = max30208_channels;
+ indio_dev->num_channels = ARRAY_SIZE(max30208_channels);
+ indio_dev->info = &max30208_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+
+ /* Reset the device initially */
+ 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_gpio_setup(data);
+ if (ret < 0)
+ 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_DRV_NAME,
+ .of_match_table = max30208_of_match,
+ .acpi_match_table = ACPI_PTR(max30208_acpi_match),
+ },
+ .probe_new = max30208_probe,
+ .id_table = max30208_id_table,
+};
+
+static int __init max30208_init(void)
+{
+ return i2c_add_driver(&max30208_driver);
+}
+module_init(max30208_init);
+
+static void __exit max30208_exit(void)
+{
+ i2c_del_driver(&max30208_driver);
+}
+module_exit(max30208_exit);
+
+MODULE_AUTHOR("Rajat Khandelwal <rajat.khandelwal@xxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Maxim MAX30208 digital temperature sensor");
+MODULE_LICENSE("GPL");
--
2.34.1