[lm-sensors] [PATCH] hwmon: Honeywell Humidicon HIH-6130/HIH-6131 humidity and temperature sensor dr

[Iain Paton <ipaton0@gmail.com>]

Hi,

This is a new driver for the Honeywell Humidicon HIH-6130 humidity sensor.

I don't claim originality, the driver is mostly identical to the existing Sensiron sht21 
driver with the necessary changes to the probe, update_measurements and conversion functions
necessary to use the Honeywell sensors.

My first kernel patch, please go easy on me as I'm bound to be doing something stupid :)


diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 6f1d167..2b13375 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -433,6 +433,16 @@ config SENSORS_GPIO_FAN
 	  This driver can also be built as a module.  If so, the module
 	  will be called gpio-fan.
 
+config SENSORS_HIH613X
+	tristate "Honeywell Humidicon HIH-613x humidity/temperature sensor"
+	depends on I2C
+	help
+	  If you say yes here you get support for Honeywell HIH-613x
+	  Humidicon humidity sensors.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called hih613x.
+
 config SENSORS_CORETEMP
 	tristate "Intel Core/Core2/Atom temperature sensor"
 	depends on X86 && PCI && EXPERIMENTAL
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index e1eeac1..b92447c 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -58,6 +58,7 @@ obj-$(CONFIG_SENSORS_G760A)	+= g760a.o
 obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
 obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o
 obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
+obj-$(CONFIG_SENSORS_HIH613X)	+= hih613x.o
 obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
 obj-$(CONFIG_SENSORS_I5K_AMB)	+= i5k_amb.o
 obj-$(CONFIG_SENSORS_IBMAEM)	+= ibmaem.o
diff --git a/drivers/hwmon/hih613x.c b/drivers/hwmon/hih613x.c
new file mode 100644
index 0000000..0c8693c
--- /dev/null
+++ b/drivers/hwmon/hih613x.c
@@ -0,0 +1,297 @@
+/* Honeywell HIH-613x humidity and temperature sensor driver
+ *
+ * Copyright (C) 2012 Iain Paton <ipaton0@gmail.com>
+ *
+ * heavily based on the sht21 driver
+ * Copyright (C) 2010 Urs Fleisch <urs.fleisch@sensirion.com>
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Data sheets available (6/2012) at
+ * http://sensing.honeywell.com/index.php?ci_id106&la_id=1&defIdD872
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+
+/**
+ * struct hih613x - HIH-613x device specific data
+ * @hwmon_dev: device registered with hwmon
+ * @lock: mutex to protect measurement values
+ * @valid: only 0 before first measurement is taken
+ * @last_update: time of last update (jiffies)
+ * @temperature: cached temperature measurement value
+ * @humidity: cached humidity measurement value
+ */
+struct hih613x {
+	struct device *hwmon_dev;
+	struct mutex lock;
+	char valid;
+	unsigned long last_update;
+	int temperature;
+	int humidity;
+};
+
+/**
+ * hih613x_temp_ticks_to_millicelsius() - convert raw temperature ticks to
+ * milli celsius
+ * @ticks: temperature ticks value received from sensor
+ */
+static inline int hih613x_temp_ticks_to_millicelsius(int ticks)
+{
+
+	ticks &= ~0x0003; /* clear unused bits */
+	ticks = ticks >> 2;
+	/*
+	 * Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -40 from data sheet section 5.0,
+	 */
+	return ((ticks * 165000) / 16382) - 40000;
+}
+
+/**
+ * hih613x_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to
+ * one-thousandths of a percent relative humidity
+ * @ticks: humidity ticks value received from sensor
+ */
+static inline int hih613x_rh_ticks_to_per_cent_mille(int ticks)
+{
+
+	ticks &= ~0xC000; /* clear status bits */
+	/*
+	 * Formula RH = ( ticks / ( 2^14 -2 ) ) * 100 from data sheet section 4.0,
+	 */
+	return (ticks * 100000) / 16382;
+}
+
+/**
+ * hih613x_update_measurements() - get updated measurements from device
+ * @client: I2C client device
+ *
+ * Returns 0 on success, else negative errno.
+ */
+static int hih613x_update_measurements(struct i2c_client *client)
+{
+	int ret = 0;
+	int t;
+	struct hih613x *hih613x = i2c_get_clientdata(client);
+
+	unsigned char tmp[4];
+	struct i2c_msg msgs[1] = {
+		{
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = 4,
+			.buf = tmp,
+		}
+	};
+
+	mutex_lock(&hih613x->lock);
+
+	/*
+	 * Unlike the SHT2x the HIH-613x datasheet doesn't give limits on the number of
+	 * measurements per second we can make. However it makes no sense to allow polling
+	 * for humidity or temperature more than a couple of times a second anyway.
+	 */
+	if (time_after(jiffies, hih613x->last_update + HZ / 2) || !hih613x->valid) {
+
+		/* write to slave address, no data, to request a measurement */
+		ret = i2c_master_send(client, tmp, 0);
+		if (ret < 0)
+			goto out;
+
+		/* for default 14 bit accuracy the measurement cycle time is ~36.65msec
+		 * we can either simply wait, or could loop polling the status bits
+		 */
+		msleep(40);
+
+		ret = i2c_transfer(client->adapter, msgs, 1);
+		if (ret < 0)
+			goto out;
+
+		if ((tmp[0] & 0xC0) != 0) {
+			dev_err(&client->dev, "Error while reading measurement result\n");
+			ret = -EIO;
+			goto out;
+		}
+
+		t = (tmp[0]<<8) + tmp[1];
+		hih613x->humidity = hih613x_rh_ticks_to_per_cent_mille(t);
+
+		t = (tmp[2]<<8) + tmp[3];
+		hih613x->temperature = hih613x_temp_ticks_to_millicelsius(t);
+
+		hih613x->last_update = jiffies;
+		hih613x->valid = 1;
+
+	}
+out:
+	mutex_unlock(&hih613x->lock);
+
+	return ret >= 0 ? 0 : ret;
+}
+
+/**
+ * hih613x_show_temperature() - show temperature measurement value in sysfs
+ * @dev: device
+ * @attr: device attribute
+ * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
+ *
+ * Will be called on read access to temp1_input sysfs attribute.
+ * Returns number of bytes written into buffer, negative errno on error.
+ */
+static ssize_t hih613x_show_temperature(struct device *dev,
+	struct device_attribute *attr,
+	char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct hih613x *hih613x = i2c_get_clientdata(client);
+	int ret = hih613x_update_measurements(client);
+	if (ret < 0)
+		return ret;
+	return sprintf(buf, "%d\n", hih613x->temperature);
+}
+
+/**
+ * hih613x_show_humidity() - show humidity measurement value in sysfs
+ * @dev: device
+ * @attr: device attribute
+ * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
+ *
+ * Will be called on read access to humidity1_input sysfs attribute.
+ * Returns number of bytes written into buffer, negative errno on error.
+ */
+static ssize_t hih613x_show_humidity(struct device *dev,
+	struct device_attribute *attr,
+	char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct hih613x *hih613x = i2c_get_clientdata(client);
+	int ret = hih613x_update_measurements(client);
+	if (ret < 0)
+		return ret;
+	return sprintf(buf, "%d\n", hih613x->humidity);
+}
+
+/* sysfs attributes */
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, hih613x_show_temperature,
+	NULL, 0);
+static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, hih613x_show_humidity,
+	NULL, 0);
+
+static struct attribute *hih613x_attributes[] = {
+	&sensor_dev_attr_temp1_input.dev_attr.attr,
+	&sensor_dev_attr_humidity1_input.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group hih613x_attr_group = {
+	.attrs = hih613x_attributes,
+};
+
+/**
+ * hih613x_probe() - probe device
+ * @client: I2C client device
+ * @id: device ID
+ *
+ * Called by the I2C core when an entry in the ID table matches a
+ * device's name.
+ * Returns 0 on success.
+ */
+static int __devinit hih613x_probe(struct i2c_client *client,
+	const struct i2c_device_id *id)
+{
+	struct hih613x *hih613x;
+	int err;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_I2C)) {
+		dev_err(&client->dev,
+			"adapter does not support true I2C\n");
+		return -ENODEV;
+	}
+
+	hih613x = devm_kzalloc(&client->dev, sizeof(*hih613x), GFP_KERNEL);
+	if (!hih613x) {
+		dev_dbg(&client->dev, "devm_kzalloc failed\n");
+		return -ENOMEM;
+	}
+
+	i2c_set_clientdata(client, hih613x);
+
+	mutex_init(&hih613x->lock);
+
+	err = sysfs_create_group(&client->dev.kobj, &hih613x_attr_group);
+	if (err) {
+		dev_dbg(&client->dev, "could not create sysfs files\n");
+		return err;
+	}
+
+	hih613x->hwmon_dev = hwmon_device_register(&client->dev);
+	if (IS_ERR(hih613x->hwmon_dev)) {
+		dev_dbg(&client->dev, "unable to register hwmon device\n");
+		err = PTR_ERR(hih613x->hwmon_dev);
+		goto fail_remove_sysfs;
+	}
+
+	dev_info(&client->dev, "initialized\n");
+
+	return 0;
+
+fail_remove_sysfs:
+	sysfs_remove_group(&client->dev.kobj, &hih613x_attr_group);
+	return err;
+}
+
+/**
+ * hih613x_remove() - remove device
+ * @client: I2C client device
+ */
+static int __devexit hih613x_remove(struct i2c_client *client)
+{
+	struct hih613x *hih613x = i2c_get_clientdata(client);
+
+	hwmon_device_unregister(hih613x->hwmon_dev);
+	sysfs_remove_group(&client->dev.kobj, &hih613x_attr_group);
+
+	return 0;
+}
+
+/* Device ID table */
+static const struct i2c_device_id hih613x_id[] = {
+	{ "hih613x", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, hih613x_id);
+
+static struct i2c_driver hih613x_driver = {
+	.driver.name = "hih613x",
+	.probe       = hih613x_probe,
+	.remove      = __devexit_p(hih613x_remove),
+	.id_table    = hih613x_id,
+};
+
+module_i2c_driver(hih613x_driver);
+
+MODULE_AUTHOR("Iain Paton <ipaton0@gmail.com>");
+MODULE_DESCRIPTION("Honeywell HIH-613x humidity and temperature sensor driver");
+MODULE_LICENSE("GPL");

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