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iio: humidty: add HDC100x support

PATCH Superseded Matt Ranostay 2 participants 4 messages Sep 2, 2015 – Sep 6, 2015 IIO

v3 of 4 Superseded Latest is v4 →

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#0 lore raw

v3 cover iio: humidty: add HDC100x support

Changes from v2:
* Change 4.2 reference to 4.3
* Removed rogue newline
* Make sure adc_int_us isn't updated on error
* Allow an reading of 0 to be returned from hdc100x_read_measurement

Matt Ranostay (1):
iio: humidity: add HDC100x support

 .../ABI/testing/sysfs-bus-iio-humidity-hdc100x     |   9 +
 drivers/iio/humidity/Kconfig                       |  10 +
 drivers/iio/humidity/Makefile                      |   1 +
 drivers/iio/humidity/hdc100x.c                     | 317 +++++++++++++++++++++
 4 files changed, 337 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-humidity-hdc100x
 create mode 100644 drivers/iio/humidity/hdc100x.c
Signature · 1 line
1.9.1
#1 lore raw

PATCH v3 1/1 iio: humidity: add HDC100x support

Add support for the HDC100x temperature and humidity sensors including the resistive heater element.

---
 .../ABI/testing/sysfs-bus-iio-humidity-hdc100x     |   9 +
 drivers/iio/humidity/Kconfig                       |  10 +
 drivers/iio/humidity/Makefile                      |   1 +
 drivers/iio/humidity/hdc100x.c                     | 317 +++++++++++++++++++++
 4 files changed, 337 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-humidity-hdc100x
 create mode 100644 drivers/iio/humidity/hdc100x.c
Documentation/ABI/testing/sysfs-bus-iio-humidity-hdc100x new file +9 -0
new file mode 100644
index 0000000..b72bb62
@@ -0,0 +1,9 @@
+What:		/sys/bus/iio/devices/iio:deviceX/out_current_heater_raw
+What:		/sys/bus/iio/devices/iio:deviceX/out_current_heater_raw_available
+KernelVersion:	4.3
+Contact:	[email protected]
+Description:
+		Controls the heater device within the humidity sensor to get
+		rid of excess condensation.
+
+		Valid control values are 0 = OFF, and 1 = ON.
drivers/iio/humidity/Kconfig +10 -0
index 688c0d1..353ee9a 100644
@@ -12,6 +12,16 @@ config DHT11
 	  Other sensors should work as well as long as they speak the
 	  same protocol.
 
+config HDC100X
+	tristate "TI HDC100x relative humidity and temperature sensor"
+	depends on I2C
+	help
+	 Say yes here to build support for the TI HDC100x series of
+	 relative humidity and temperature sensors.
+
+	 To compile this driver as a module, choose M here: the module
+	 will be called hdc100x.
+
 config SI7005
 	tristate "SI7005 relative humidity and temperature sensor"
 	depends on I2C
drivers/iio/humidity/Makefile +1 -0
index 86e2d26..3e62c0a 100644
@@ -3,5 +3,6 @@
 #
 
 obj-$(CONFIG_DHT11) += dht11.o
+obj-$(CONFIG_HDC100X) += hdc100x.o
 obj-$(CONFIG_SI7005) += si7005.o
 obj-$(CONFIG_SI7020) += si7020.o
drivers/iio/humidity/hdc100x.c new file +317 -0

317 lines not on this page · raw message

Signature · 1 line
1.9.1
maintainer
#2 lore raw

Re: [PATCH v3] iio: humidity: add HDC100x support

Quoted 4 lines · Matt Ranostay

Add support for the HDC100x temperature and humidity sensors including the resistive heater element.

Just a couple of corners of program flow that I think could be cleaned up slightly (I'd have probably let it go as is, but we are very early in the cycle, so might as well aim for perfection!)

Jonathan

Quoted 221 lines
---
 .../ABI/testing/sysfs-bus-iio-humidity-hdc100x     |   9 +
 drivers/iio/humidity/Kconfig                       |  10 +
 drivers/iio/humidity/Makefile                      |   1 +
 drivers/iio/humidity/hdc100x.c                     | 317 +++++++++++++++++++++
 4 files changed, 337 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-humidity-hdc100x
 create mode 100644 drivers/iio/humidity/hdc100x.c
Documentation/ABI/testing/sysfs-bus-iio-humidity-hdc100x new file +9 -0
new file mode 100644
index 0000000..b72bb62
@@ -0,0 +1,9 @@
+What:		/sys/bus/iio/devices/iio:deviceX/out_current_heater_raw
+What:		/sys/bus/iio/devices/iio:deviceX/out_current_heater_raw_available
+KernelVersion:	4.3
+Contact:	[email protected]
+Description:
+		Controls the heater device within the humidity sensor to get
+		rid of excess condensation.
+
+		Valid control values are 0 = OFF, and 1 = ON.
drivers/iio/humidity/Kconfig +10 -0
index 688c0d1..353ee9a 100644
@@ -12,6 +12,16 @@ config DHT11
 	  Other sensors should work as well as long as they speak the
 	  same protocol.
 
+config HDC100X
+	tristate "TI HDC100x relative humidity and temperature sensor"
+	depends on I2C
+	help
+	 Say yes here to build support for the TI HDC100x series of
+	 relative humidity and temperature sensors.
+
+	 To compile this driver as a module, choose M here: the module
+	 will be called hdc100x.
+
 config SI7005
 	tristate "SI7005 relative humidity and temperature sensor"
 	depends on I2C
drivers/iio/humidity/Makefile +1 -0
index 86e2d26..3e62c0a 100644
@@ -3,5 +3,6 @@
 #
 
 obj-$(CONFIG_DHT11) += dht11.o
+obj-$(CONFIG_HDC100X) += hdc100x.o
 obj-$(CONFIG_SI7005) += si7005.o
 obj-$(CONFIG_SI7020) += si7020.o
drivers/iio/humidity/hdc100x.c new file +159 -0
new file mode 100644
index 0000000..591bd92
@@ -0,0 +1,317 @@
+/*
+ * hdc100x.c - Support for the TI HDC100x temperature + humidity sensors
+ *
+ * Copyright (C) 2015 Matt Ranostay <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define HDC100X_REG_TEMP			0x00
+#define HDC100X_REG_HUMIDITY			0x01
+
+#define HDC100X_REG_CONFIG			0x02
+#define HDC100X_REG_CONFIG_HEATER_EN		BIT(13)
+
+struct hdc100x_data {
+	struct i2c_client *client;
+	struct mutex lock;
+	u16 config;
+
+	/* integration time of the sensor */
+	int adc_int_us[2];
+};
+
+/* integration time in us */
+static const int hdc100x_int_time[][3] = {
+	{ 6350, 3650, 0 },	/* IIO_TEMP channel*/
+	{ 6500, 3850, 2500 },	/* IIO_HUMIDITYRELATIVE channel */
+};
+
+/* HDC100X_REG_CONFIG shift and mask values */
+static const struct {
+	int shift;
+	int mask;
+} hdc100x_resolution_shift[2] = {
+	{ /* IIO_TEMP channel */
+		.shift = 10,
+		.mask = 1
+	},
+	{ /* IIO_HUMIDITYRELATIVE channel */
+		.shift = 8,
+		.mask = 2,
+	},
+};
+
+static IIO_CONST_ATTR(temp_integration_time_available,
+		"0.00365 0.00635");
+
+static IIO_CONST_ATTR(humidityrelative_integration_time_available,
+		"0.0025 0.00385 0.0065");
+
+static IIO_CONST_ATTR(out_current_heater_raw_available,
+		"0 1");
+
+static struct attribute *hdc100x_attributes[] = {
+	&iio_const_attr_temp_integration_time_available.dev_attr.attr,
+	&iio_const_attr_humidityrelative_integration_time_available.dev_attr.attr,
+	&iio_const_attr_out_current_heater_raw_available.dev_attr.attr,
+	NULL
+};
+
+static struct attribute_group hdc100x_attribute_group = {
+	.attrs = hdc100x_attributes,
+};
+
+static const struct iio_chan_spec hdc100x_channels[] = {
+	{
+		.type = IIO_TEMP,
+		.address = HDC100X_REG_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE) |
+			BIT(IIO_CHAN_INFO_INT_TIME) |
+			BIT(IIO_CHAN_INFO_OFFSET),
+	},
+	{
+		.type = IIO_HUMIDITYRELATIVE,
+		.address = HDC100X_REG_HUMIDITY,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE) |
+			BIT(IIO_CHAN_INFO_INT_TIME)
+	},
+	{
+		.type = IIO_CURRENT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.extend_name = "heater",
+		.output = 1,
+	},
+};
+
+static int hdc100x_update_config(struct hdc100x_data *data, int mask, int val)
+{
+	int tmp = (~mask & data->config) | val;
+	int ret;
+
+	ret = i2c_smbus_write_word_swapped(data->client,
+						HDC100X_REG_CONFIG, tmp);
+	if (!ret)
+		data->config = tmp;
+
+	return ret;
+}
+
+static int hdc100x_set_it_time(struct hdc100x_data *data, int chan, int val2)
+{
+	int shift = hdc100x_resolution_shift[chan].shift;
+	int ret = -EINVAL;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(hdc100x_int_time[chan]); i++) {
+		if (val2 && val2 == hdc100x_int_time[chan][i]) {
+			ret = hdc100x_update_config(data,
+				hdc100x_resolution_shift[chan].mask << shift,
+				i << shift);
+			if (!ret)
+				data->adc_int_us[chan] = val2;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static int hdc100x_get_measurement(struct hdc100x_data *data,
+				   struct iio_chan_spec const *chan)
+{
+	struct i2c_client *client = data->client;
+	int delay = data->adc_int_us[chan->address];
+	int ret;
+	int val;
+
+	/* start measurement */
+	ret = i2c_smbus_write_byte(client, chan->address);
+	if (ret < 0) {
+		dev_err(&client->dev, "cannot start measurement");
+		return ret;
+	}
+
+	/* wait for integration time to pass */
+	usleep_range(delay, delay + 1000);
+
+	ret = i2c_smbus_read_byte(client);
+	if (ret < 0) {
+		dev_err(&client->dev, "cannot read high byte measurement");

drivers/iio/humidity/hdc100x.c line 169

Quoted 10 lines
drivers/iio/humidity/hdc100x.c new file +10 -0
+		return ret;
+	}
+	val = ret << 6;
+
+	ret = i2c_smbus_read_byte(client);
+	if (ret < 0) {
+		dev_err(&client->dev, "cannot read low byte measurement");
+		return ret;
+	}
+	val |= ret >> 2;

If you can't use a read word here I'd like docs to say why (presumably starts / stops are wrong for what the device expects?)

Quoted 20 lines
drivers/iio/humidity/hdc100x.c new file +20 -0
+
+	return val;
+}
+
+static int hdc100x_get_heater_status(struct hdc100x_data *data)
+{
+	return !!(data->config & HDC100X_REG_CONFIG_HEATER_EN);
+}
+
+static int hdc100x_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int *val,
+			    int *val2, long mask)
+{
+	struct hdc100x_data *data = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&data->lock);
+		if (chan->type == IIO_CURRENT) {

drivers/iio/humidity/hdc100x.c

Quoted 10 lines
drivers/iio/humidity/hdc100x.c new file +10 -0
+			*val = hdc100x_get_heater_status(data);
+			ret = IIO_VAL_INT;
+		} else {
+			ret = hdc100x_get_measurement(data, chan);
+			if (ret >= 0) {
+				*val = ret;
+				ret = IIO_VAL_INT;
+			}
+		}
+		mutex_unlock(&data->lock);r

I'd return ret here to have consistency across different parts of this function.

drivers/iio/humidity/hdc100x.c line 208

Quoted 9 lines
drivers/iio/humidity/hdc100x.c new file +9 -0
+		break;
+	case IIO_CHAN_INFO_INT_TIME:
+		*val = 0;
+		*val2 = data->adc_int_us[chan->address];
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_SCALE:
+		if (chan->type == IIO_TEMP) {
+			*val = 165;
+			*val2 = 65536 >> 2;

return directly in both these cases.

drivers/iio/humidity/hdc100x.c line 219

Quoted 11 lines
drivers/iio/humidity/hdc100x.c new file +11 -0
+			ret = IIO_VAL_FRACTIONAL;
+		} else {
+			*val = 0;
+			*val2 = 10000;
+			ret = IIO_VAL_INT_PLUS_MICRO;
+		}
+		break;
+	case IIO_CHAN_INFO_OFFSET:
+		*val = -40;
+		return IIO_VAL_INT;
+	default:

return -EINVAL; and you can loose the outer parts of this function.

Quoted 23 lines
drivers/iio/humidity/hdc100x.c new file +23 -0
+		break;
+	}
+
+	return ret;
+}
+
+static int hdc100x_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct hdc100x_data *data = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_INT_TIME:
+		if (val != 0)
+			return -EINVAL;
+
+		mutex_lock(&data->lock);
+		ret = hdc100x_set_it_time(data, chan->address, val2);
+		mutex_unlock(&data->lock);
+		break;
+	case IIO_CHAN_INFO_RAW:

drivers/iio/humidity/hdc100x.c line 252

Quoted 10 lines
drivers/iio/humidity/hdc100x.c new file +10 -0
+		if (chan->type == IIO_CURRENT) {
+			if (val2 != 0)
+				return -EINVAL;
+
+			mutex_lock(&data->lock);
+			ret = hdc100x_update_config(data,
+					HDC100X_REG_CONFIG_HEATER_EN,
+					val ? HDC100X_REG_CONFIG_HEATER_EN : 0);
+			mutex_unlock(&data->lock);
+		}

This return ret is different from the other case for no particular reason. If it makes sense to return here, it makes sense there as well.

I think I'd martinally prefer if you inverted the logic to check if the channel isn't IIO_CURRENT and return -EINVAL directly if it isn't. Drops a level of indentation. You could the use a default:
statement returning -EINVAL to drop the return below and seeing of a default value for ret above. Makes for slightly longer but simpler code.

Quoted 66 lines
drivers/iio/humidity/hdc100x.c new file +65 -0
+		return ret;
+	}
+
+	return ret;
+}
+
+static const struct iio_info hdc100x_info = {
+	.read_raw = hdc100x_read_raw,
+	.write_raw = hdc100x_write_raw,
+	.attrs = &hdc100x_attribute_group,
+	.driver_module = THIS_MODULE,
+};
+
+static int hdc100x_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct iio_dev *indio_dev;
+	struct hdc100x_data *data;
+
+	if (!i2c_check_functionality(client->adapter,
+				I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BYTE))
+		return -ENODEV;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+	mutex_init(&data->lock);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->name = dev_name(&client->dev);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &hdc100x_info;
+
+	indio_dev->channels = hdc100x_channels;
+	indio_dev->num_channels = ARRAY_SIZE(hdc100x_channels);
+
+	/* be sure we are in a known state */
+	hdc100x_set_it_time(data, 0, hdc100x_int_time[0][0]);
+	hdc100x_set_it_time(data, 1, hdc100x_int_time[1][0]);
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id hdc100x_id[] = {
+	{ "hdc100x", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, hdc100x_id);
+
+static struct i2c_driver hdc100x_driver = {
+	.driver = {
+		.name	= "hdc100x",
+	},
+	.probe = hdc100x_probe,
+	.id_table = hdc100x_id,
+};
+module_i2c_driver(hdc100x_driver);
+
+MODULE_AUTHOR("Matt Ranostay <[email protected]>");
+MODULE_DESCRIPTION("TI HDC100x humidity and temperature sensor driver");
+MODULE_LICENSE("GPL");
#3 lore raw

Re: [PATCH v3] iio: humidity: add HDC100x support

Quoted 235 lines · Jonathan Cameron
Quoted 4 lines · Matt Ranostay

Add support for the HDC100x temperature and humidity sensors including the resistive heater element.

Just a couple of corners of program flow that I think could be cleaned up slightly (I'd have probably let it go as is, but we are very early in the cycle, so might as well aim for perfection!)

Jonathan

Quoted 225 lines
---
 .../ABI/testing/sysfs-bus-iio-humidity-hdc100x     |   9 +
 drivers/iio/humidity/Kconfig                       |  10 +
 drivers/iio/humidity/Makefile                      |   1 +
 drivers/iio/humidity/hdc100x.c                     | 317 +++++++++++++++++++++
 4 files changed, 337 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-humidity-hdc100x
 create mode 100644 drivers/iio/humidity/hdc100x.c
Documentation/ABI/testing/sysfs-bus-iio-humidity-hdc100x new file +9 -0
new file mode 100644
index 0000000..b72bb62
@@ -0,0 +1,9 @@
+What:                /sys/bus/iio/devices/iio:deviceX/out_current_heater_raw
+What:                /sys/bus/iio/devices/iio:deviceX/out_current_heater_raw_available
+KernelVersion:       4.3
+Contact:     [email protected]
+Description:
+             Controls the heater device within the humidity sensor to get
+             rid of excess condensation.
+
+             Valid control values are 0 = OFF, and 1 = ON.
drivers/iio/humidity/Kconfig +10 -0
index 688c0d1..353ee9a 100644
@@ -12,6 +12,16 @@ config DHT11
        Other sensors should work as well as long as they speak the
        same protocol.
 
+config HDC100X
+     tristate "TI HDC100x relative humidity and temperature sensor"
+     depends on I2C
+     help
+      Say yes here to build support for the TI HDC100x series of
+      relative humidity and temperature sensors.
+
+      To compile this driver as a module, choose M here: the module
+      will be called hdc100x.
+
 config SI7005
      tristate "SI7005 relative humidity and temperature sensor"
      depends on I2C
drivers/iio/humidity/Makefile +1 -0
index 86e2d26..3e62c0a 100644
@@ -3,5 +3,6 @@
 #
 
 obj-$(CONFIG_DHT11) += dht11.o
+obj-$(CONFIG_HDC100X) += hdc100x.o
 obj-$(CONFIG_SI7005) += si7005.o
 obj-$(CONFIG_SI7020) += si7020.o
drivers/iio/humidity/hdc100x.c new file +163 -0
new file mode 100644
index 0000000..591bd92
@@ -0,0 +1,317 @@
+/*
+ * hdc100x.c - Support for the TI HDC100x temperature + humidity sensors
+ *
+ * Copyright (C) 2015 Matt Ranostay <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define HDC100X_REG_TEMP                     0x00
+#define HDC100X_REG_HUMIDITY                 0x01
+
+#define HDC100X_REG_CONFIG                   0x02
+#define HDC100X_REG_CONFIG_HEATER_EN         BIT(13)
+
+struct hdc100x_data {
+     struct i2c_client *client;
+     struct mutex lock;
+     u16 config;
+
+     /* integration time of the sensor */
+     int adc_int_us[2];
+};
+
+/* integration time in us */
+static const int hdc100x_int_time[][3] = {
+     { 6350, 3650, 0 },      /* IIO_TEMP channel*/
+     { 6500, 3850, 2500 },   /* IIO_HUMIDITYRELATIVE channel */
+};
+
+/* HDC100X_REG_CONFIG shift and mask values */
+static const struct {
+     int shift;
+     int mask;
+} hdc100x_resolution_shift[2] = {
+     { /* IIO_TEMP channel */
+             .shift = 10,
+             .mask = 1
+     },
+     { /* IIO_HUMIDITYRELATIVE channel */
+             .shift = 8,
+             .mask = 2,
+     },
+};
+
+static IIO_CONST_ATTR(temp_integration_time_available,
+             "0.00365 0.00635");
+
+static IIO_CONST_ATTR(humidityrelative_integration_time_available,
+             "0.0025 0.00385 0.0065");
+
+static IIO_CONST_ATTR(out_current_heater_raw_available,
+             "0 1");
+
+static struct attribute *hdc100x_attributes[] = {
+     &iio_const_attr_temp_integration_time_available.dev_attr.attr,
+     &iio_const_attr_humidityrelative_integration_time_available.dev_attr.attr,
+     &iio_const_attr_out_current_heater_raw_available.dev_attr.attr,
+     NULL
+};
+
+static struct attribute_group hdc100x_attribute_group = {
+     .attrs = hdc100x_attributes,
+};
+
+static const struct iio_chan_spec hdc100x_channels[] = {
+     {
+             .type = IIO_TEMP,
+             .address = HDC100X_REG_TEMP,
+             .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+                     BIT(IIO_CHAN_INFO_SCALE) |
+                     BIT(IIO_CHAN_INFO_INT_TIME) |
+                     BIT(IIO_CHAN_INFO_OFFSET),
+     },
+     {
+             .type = IIO_HUMIDITYRELATIVE,
+             .address = HDC100X_REG_HUMIDITY,
+             .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+                     BIT(IIO_CHAN_INFO_SCALE) |
+                     BIT(IIO_CHAN_INFO_INT_TIME)
+     },
+     {
+             .type = IIO_CURRENT,
+             .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+             .extend_name = "heater",
+             .output = 1,
+     },
+};
+
+static int hdc100x_update_config(struct hdc100x_data *data, int mask, int val)
+{
+     int tmp = (~mask & data->config) | val;
+     int ret;
+
+     ret = i2c_smbus_write_word_swapped(data->client,
+                                             HDC100X_REG_CONFIG, tmp);
+     if (!ret)
+             data->config = tmp;
+
+     return ret;
+}
+
+static int hdc100x_set_it_time(struct hdc100x_data *data, int chan, int val2)
+{
+     int shift = hdc100x_resolution_shift[chan].shift;
+     int ret = -EINVAL;
+     int i;
+
+     for (i = 0; i < ARRAY_SIZE(hdc100x_int_time[chan]); i++) {
+             if (val2 && val2 == hdc100x_int_time[chan][i]) {
+                     ret = hdc100x_update_config(data,
+                             hdc100x_resolution_shift[chan].mask << shift,
+                             i << shift);
+                     if (!ret)
+                             data->adc_int_us[chan] = val2;
+                     break;
+             }
+     }
+
+     return ret;
+}
+
+static int hdc100x_get_measurement(struct hdc100x_data *data,
+                                struct iio_chan_spec const *chan)
+{
+     struct i2c_client *client = data->client;
+     int delay = data->adc_int_us[chan->address];
+     int ret;
+     int val;
+
+     /* start measurement */
+     ret = i2c_smbus_write_byte(client, chan->address);
+     if (ret < 0) {
+             dev_err(&client->dev, "cannot start measurement");
+             return ret;
+     }
+
+     /* wait for integration time to pass */
+     usleep_range(delay, delay + 1000);
+
+     ret = i2c_smbus_read_byte(client);
+     if (ret < 0) {
+             dev_err(&client->dev, "cannot read high byte measurement");
+             return ret;
+     }
+     val = ret << 6;
+
Quoted 8 lines

drivers/iio/humidity/hdc100x.c line 169

Quoted 6 lines
drivers/iio/humidity/hdc100x.c new file +6 -0
+     ret = i2c_smbus_read_byte(client);
+     if (ret < 0) {
+             dev_err(&client->dev, "cannot read low byte measurement");
+             return ret;
+     }
+     val |= ret >> 2;

If you can't use a read word here I'd like docs to say why (presumably starts / stops are wrong for what the device expects?)

Yeah I'll make this more clear in v3.

Quoted 92 lines
Quoted 20 lines
drivers/iio/humidity/hdc100x.c new file +20 -0
+
+     return val;
+}
+
+static int hdc100x_get_heater_status(struct hdc100x_data *data)
+{
+     return !!(data->config & HDC100X_REG_CONFIG_HEATER_EN);
+}
+
+static int hdc100x_read_raw(struct iio_dev *indio_dev,
+                         struct iio_chan_spec const *chan, int *val,
+                         int *val2, long mask)
+{
+     struct hdc100x_data *data = iio_priv(indio_dev);
+     int ret = -EINVAL;
+
+     switch (mask) {
+     case IIO_CHAN_INFO_RAW:
+             mutex_lock(&data->lock);
+             if (chan->type == IIO_CURRENT) {

drivers/iio/humidity/hdc100x.c

Quoted 10 lines
drivers/iio/humidity/hdc100x.c new file +10 -0
+                     *val = hdc100x_get_heater_status(data);
+                     ret = IIO_VAL_INT;
+             } else {
+                     ret = hdc100x_get_measurement(data, chan);
+                     if (ret >= 0) {
+                             *val = ret;
+                             ret = IIO_VAL_INT;
+                     }
+             }
+             mutex_unlock(&data->lock);r

I'd return ret here to have consistency across different parts of this function.

drivers/iio/humidity/hdc100x.c line 208

Quoted 9 lines
drivers/iio/humidity/hdc100x.c new file +9 -0
+             break;
+     case IIO_CHAN_INFO_INT_TIME:
+             *val = 0;
+             *val2 = data->adc_int_us[chan->address];
+             return IIO_VAL_INT_PLUS_MICRO;
+     case IIO_CHAN_INFO_SCALE:
+             if (chan->type == IIO_TEMP) {
+                     *val = 165;
+                     *val2 = 65536 >> 2;

return directly in both these cases.

drivers/iio/humidity/hdc100x.c line 219

Quoted 11 lines
drivers/iio/humidity/hdc100x.c new file +11 -0
+                     ret = IIO_VAL_FRACTIONAL;
+             } else {
+                     *val = 0;
+                     *val2 = 10000;
+                     ret = IIO_VAL_INT_PLUS_MICRO;
+             }
+             break;
+     case IIO_CHAN_INFO_OFFSET:
+             *val = -40;
+             return IIO_VAL_INT;
+     default:

return -EINVAL; and you can loose the outer parts of this function.

Quoted 23 lines
drivers/iio/humidity/hdc100x.c new file +23 -0
+             break;
+     }
+
+     return ret;
+}
+
+static int hdc100x_write_raw(struct iio_dev *indio_dev,
+                          struct iio_chan_spec const *chan,
+                          int val, int val2, long mask)
+{
+     struct hdc100x_data *data = iio_priv(indio_dev);
+     int ret = -EINVAL;
+
+     switch (mask) {
+     case IIO_CHAN_INFO_INT_TIME:
+             if (val != 0)
+                     return -EINVAL;
+
+             mutex_lock(&data->lock);
+             ret = hdc100x_set_it_time(data, chan->address, val2);
+             mutex_unlock(&data->lock);
+             break;
+     case IIO_CHAN_INFO_RAW:

drivers/iio/humidity/hdc100x.c line 252

Quoted 10 lines
drivers/iio/humidity/hdc100x.c new file +10 -0
+             if (chan->type == IIO_CURRENT) {
+                     if (val2 != 0)
+                             return -EINVAL;
+
+                     mutex_lock(&data->lock);
+                     ret = hdc100x_update_config(data,
+                                     HDC100X_REG_CONFIG_HEATER_EN,
+                                     val ? HDC100X_REG_CONFIG_HEATER_EN : 0);
+                     mutex_unlock(&data->lock);
+             }

This return ret is different from the other case for no particular reason. If it makes sense to return here, it makes sense there as well.

Quoted 7 lines

I think I'd martinally prefer if you inverted the logic to check if the channel isn't IIO_CURRENT and return -EINVAL directly if it isn't. Drops a level of indentation. You could the use a default:
statement returning -EINVAL to drop the return below and seeing of a default value for ret above. Makes for slightly longer but simpler code.

Ok will fix!

Quoted 67 lines
Quoted 66 lines
drivers/iio/humidity/hdc100x.c new file +65 -0
+             return ret;
+     }
+
+     return ret;
+}
+
+static const struct iio_info hdc100x_info = {
+     .read_raw = hdc100x_read_raw,
+     .write_raw = hdc100x_write_raw,
+     .attrs = &hdc100x_attribute_group,
+     .driver_module = THIS_MODULE,
+};
+
+static int hdc100x_probe(struct i2c_client *client,
+                      const struct i2c_device_id *id)
+{
+     struct iio_dev *indio_dev;
+     struct hdc100x_data *data;
+
+     if (!i2c_check_functionality(client->adapter,
+                             I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BYTE))
+             return -ENODEV;
+
+     indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+     if (!indio_dev)
+             return -ENOMEM;
+
+     data = iio_priv(indio_dev);
+     i2c_set_clientdata(client, indio_dev);
+     data->client = client;
+     mutex_init(&data->lock);
+
+     indio_dev->dev.parent = &client->dev;
+     indio_dev->name = dev_name(&client->dev);
+     indio_dev->modes = INDIO_DIRECT_MODE;
+     indio_dev->info = &hdc100x_info;
+
+     indio_dev->channels = hdc100x_channels;
+     indio_dev->num_channels = ARRAY_SIZE(hdc100x_channels);
+
+     /* be sure we are in a known state */
+     hdc100x_set_it_time(data, 0, hdc100x_int_time[0][0]);
+     hdc100x_set_it_time(data, 1, hdc100x_int_time[1][0]);
+
+     return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id hdc100x_id[] = {
+     { "hdc100x", 0 },
+     { }
+};
+MODULE_DEVICE_TABLE(i2c, hdc100x_id);
+
+static struct i2c_driver hdc100x_driver = {
+     .driver = {
+             .name   = "hdc100x",
+     },
+     .probe = hdc100x_probe,
+     .id_table = hdc100x_id,
+};
+module_i2c_driver(hdc100x_driver);
+
+MODULE_AUTHOR("Matt Ranostay <[email protected]>");
+MODULE_DESCRIPTION("TI HDC100x humidity and temperature sensor driver");
+MODULE_LICENSE("GPL");