[v10] iio: temperature: Add driver support for Maxim MAX30208

Message ID 20221118153729.762018-1-rajat.khandelwal@linux.intel.com
State New
Headers
Series [v10] iio: temperature: Add driver support for Maxim MAX30208 |

Commit Message

Rajat Khandelwal Nov. 18, 2022, 3:37 p.m. UTC
  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@linux.intel.com>
---

v10: Correcting the overflow logic

v9: Repositioning register data

v8:
1. Returning time out if conversion fails to happen
2. Setting rollover bit to '1' to allow FIFO overwriting
3. Dropping ACPI_PTR

v7:
1. Dropped GPIOs use for now
2. Driver name string directly used
3. Mutex lock description added
4. Removed noisy errors and only kept errors on larger code blocks
5. dev_warn -> dev_err for temperature conversion failure
6. Improvised the logic of popping out values
7. Fixed line breaks
8. module_i2c_driver

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 | 252 +++++++++++++++++++++++++++++
 4 files changed, 269 insertions(+)
 create mode 100644 drivers/iio/temperature/max30208.c
  

Comments

Jonathan Cameron Nov. 17, 2022, 4:30 p.m. UTC | #1
On Fri, 18 Nov 2022 21:07:29 +0530
Rajat Khandelwal <rajat.khandelwal@linux.intel.com> wrote:

> Maxim MAX30208 is a digital temperature sensor with 0.1°C accuracy.
> 
> Add support for max30208 driver in iio subsystem.

Blank line here.

> Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX30208.pdf
> 
Datasheet part of the tags block, so no blank line between that and the SoB.
That makes life easy for tools parsing git messages.

> Signed-off-by: Rajat Khandelwal <rajat.khandelwal@linux.intel.com>

One query inline.  Basically boils down to what we do after
overflow occurs.  I assume you are right and the first reading is the most recent, but
I think we still want to flush the whole fifo in that case to get back to
a sane state for future reads.

Jonathan

> +/**
> + * 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--;
> +	}
Hmm. Given you've been poking this a lot, I guess this works and the part is
as just odd. Just to check one last case... Does max30208_request() guarantee we can't
get...

1. Read first time, overflow set so we read latest result - leaving
   31 ancient values in the fifo.
2. Read again really quickly and get those ancient values.
?

Perhaps we should flush out those unwanted values from the fifo, so after
overflow we get back to a normal state rather than immediately overflowing again.

More than possible that I still don't understand how this device works though!

> +
> +unlock:
> +	mutex_unlock(&data->lock);
> +	return ret;
> +}
> +
  
Jonathan Cameron Nov. 21, 2022, 4:42 p.m. UTC | #2
On Fri, 18 Nov 2022 18:27:10 +0530
Rajat Khandelwal <rajat.khandelwal@linux.intel.com> wrote:

> Have provided inline comments.
> Please provide your comments for me to spin a v11 :)
> 
> On 11/17/2022 10:00 PM, Jonathan Cameron wrote:
> > On Fri, 18 Nov 2022 21:07:29 +0530
> > Rajat Khandelwal<rajat.khandelwal@linux.intel.com>  wrote:
> >  
> >> Maxim MAX30208 is a digital temperature sensor with 0.1°C accuracy.
> >>
> >> Add support for max30208 driver in iio subsystem.  
> > Blank line here.
> >  
> >> Datasheet:https://datasheets.maximintegrated.com/en/ds/MAX30208.pdf
> >>  
> > Datasheet part of the tags block, so no blank line between that and the SoB.
> > That makes life easy for tools parsing git messages.  
> 
> - Got it. Will do that.
> 
> >  
> >> Signed-off-by: Rajat Khandelwal<rajat.khandelwal@linux.intel.com>  
> > One query inline.  Basically boils down to what we do after
> > overflow occurs.  I assume you are right and the first reading is the most recent, but
> > I think we still want to flush the whole fifo in that case to get back to
> > a sane state for future reads.
> >
> > Jonathan
> >  
> >> +/**
> >> + * 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--;
> >> +	}  
> > Hmm. Given you've been poking this a lot, I guess this works and the part is
> > as just odd. Just to check one last case... Does max30208_request() guarantee we can't
> > get...
> >
> > 1. Read first time, overflow set so we read latest result - leaving
> >     31 ancient values in the fifo.
> > 2. Read again really quickly and get those ancient values.
> > ?
> >
> > Perhaps we should flush out those unwanted values from the fifo, so after
> > overflow we get back to a normal state rather than immediately overflowing again.
> >
> > More than possible that I still don't understand how this device works though!  
> 
> - Ok, so whenever user wants a temperature reading, conversion first takes place and then
> the reading gets returned. So, user will always get the latest converted reading despite
> the number of ancient readings.
> Flushing everytime we get an overflow is not required I think because even though overflow
> could happen again, user still gets the latest updated reading. Also, I plan to incorporate
> buffered flow in IIO. Even though, I think let FIFO remain intact because it doesn't impact
> the recent readings.

Fair enough. Sounds like yes, we are guaranteed there will always be a new reading before
we start popping entries off the fifo again. If that's the case, all is fine as is - was
just really hard to figure that out from the code / datasheet, so I wanted to check.

Jonathan

> 
> >> +
> >> +unlock:
> >> +	mutex_unlock(&data->lock);
> >> +	return ret;
> >> +}
> >> +
  

Patch

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@linux.intel.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	drivers/iio/temperature/max30208.c
+
 MAXIM MAX77650 PMIC MFD DRIVER
 M:	Bartosz Golaszewski <brgl@bgdev.pl>
 L:	linux-kernel@vger.kernel.org
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..c85c21474711
--- /dev/null
+++ b/drivers/iio/temperature/max30208.c
@@ -0,0 +1,252 @@ 
+// 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");