[linux-2.6-block.git] / drivers / hwmon / htu21.c

/*
 * Measurement Specialties HTU21D humidity and temperature sensor driver
 *
 * Copyright (C) 2013 William Markezana <william.markezana@meas-spec.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.
 *
 */

#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/jiffies.h>

/* HTU21 Commands */
#define HTU21_T_MEASUREMENT_HM	0xE3
#define HTU21_RH_MEASUREMENT_HM	0xE5

struct htu21 {
	struct i2c_client *client;
	struct mutex lock;
	bool valid;
	unsigned long last_update;
	int temperature;
	int humidity;
};

static inline int htu21_temp_ticks_to_millicelsius(int ticks)
{
	ticks &= ~0x0003; /* clear status bits */
	/*
	 * Formula T = -46.85 + 175.72 * ST / 2^16 from datasheet p14,
	 * optimized for integer fixed point (3 digits) arithmetic
	 */
	return ((21965 * ticks) >> 13) - 46850;
}

static inline int htu21_rh_ticks_to_per_cent_mille(int ticks)
{
	ticks &= ~0x0003; /* clear status bits */
	/*
	 * Formula RH = -6 + 125 * SRH / 2^16 from datasheet p14,
	 * optimized for integer fixed point (3 digits) arithmetic
	 */
	return ((15625 * ticks) >> 13) - 6000;
}

static int htu21_update_measurements(struct device *dev)
{
	struct htu21 *htu21 = dev_get_drvdata(dev);
	struct i2c_client *client = htu21->client;
	int ret = 0;

	mutex_lock(&htu21->lock);

	if (time_after(jiffies, htu21->last_update + HZ / 2) ||
	    !htu21->valid) {
		ret = i2c_smbus_read_word_swapped(client,
						  HTU21_T_MEASUREMENT_HM);
		if (ret < 0)
			goto out;
		htu21->temperature = htu21_temp_ticks_to_millicelsius(ret);
		ret = i2c_smbus_read_word_swapped(client,
						  HTU21_RH_MEASUREMENT_HM);
		if (ret < 0)
			goto out;
		htu21->humidity = htu21_rh_ticks_to_per_cent_mille(ret);
		htu21->last_update = jiffies;
		htu21->valid = true;
	}
out:
	mutex_unlock(&htu21->lock);

	return ret >= 0 ? 0 : ret;
}

static ssize_t htu21_show_temperature(struct device *dev,
				      struct device_attribute *attr, char *buf)
{
	struct htu21 *htu21 = dev_get_drvdata(dev);
	int ret;

	ret = htu21_update_measurements(dev);
	if (ret < 0)
		return ret;
	return sprintf(buf, "%d\n", htu21->temperature);
}

static ssize_t htu21_show_humidity(struct device *dev,
				   struct device_attribute *attr, char *buf)
{
	struct htu21 *htu21 = dev_get_drvdata(dev);
	int ret;

	ret = htu21_update_measurements(dev);
	if (ret < 0)
		return ret;
	return sprintf(buf, "%d\n", htu21->humidity);
}

static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
			  htu21_show_temperature, NULL, 0);
static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO,
			  htu21_show_humidity, NULL, 0);

static struct attribute *htu21_attrs[] = {
	&sensor_dev_attr_temp1_input.dev_attr.attr,
	&sensor_dev_attr_humidity1_input.dev_attr.attr,
	NULL
};

ATTRIBUTE_GROUPS(htu21);

static int htu21_probe(struct i2c_client *client,
		       const struct i2c_device_id *id)
{
	struct device *dev = &client->dev;
	struct htu21 *htu21;
	struct device *hwmon_dev;

	if (!i2c_check_functionality(client->adapter,
				     I2C_FUNC_SMBUS_READ_WORD_DATA)) {
		dev_err(&client->dev,
			"adapter does not support SMBus word transactions\n");
		return -ENODEV;
	}

	htu21 = devm_kzalloc(dev, sizeof(*htu21), GFP_KERNEL);
	if (!htu21)
		return -ENOMEM;

	htu21->client = client;
	mutex_init(&htu21->lock);

	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
							   htu21,
							   htu21_groups);
	return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id htu21_id[] = {
	{ "htu21", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, htu21_id);

static struct i2c_driver htu21_driver = {
	.class = I2C_CLASS_HWMON,
	.driver = {
		.name	= "htu21",
	},
	.probe       = htu21_probe,
	.id_table    = htu21_id,
};

module_i2c_driver(htu21_driver);

MODULE_AUTHOR("William Markezana <william.markezana@meas-spec.com>");
MODULE_DESCRIPTION("MEAS HTU21D humidity and temperature sensor driver");
MODULE_LICENSE("GPL");
Commit	Line	Data
f060c658 WM	1	/*
	2	* Measurement Specialties HTU21D humidity and temperature sensor driver
	3	*
	4	* Copyright (C) 2013 William Markezana <william.markezana@meas-spec.com>
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	*/
	17
	18	#include <linux/module.h>
	19	#include <linux/init.h>
	20	#include <linux/slab.h>
	21	#include <linux/i2c.h>
	22	#include <linux/hwmon.h>
	23	#include <linux/hwmon-sysfs.h>
	24	#include <linux/err.h>
	25	#include <linux/mutex.h>
	26	#include <linux/device.h>
	27	#include <linux/jiffies.h>
	28
	29	/* HTU21 Commands */
	30	#define HTU21_T_MEASUREMENT_HM 0xE3
	31	#define HTU21_RH_MEASUREMENT_HM 0xE5
	32
	33	struct htu21 {
fa0efc40	34	struct i2c_client *client;
f060c658 WM	35	struct mutex lock;
	36	bool valid;
	37	unsigned long last_update;
	38	int temperature;
	39	int humidity;
	40	};
	41
	42	static inline int htu21_temp_ticks_to_millicelsius(int ticks)
	43	{
	44	ticks &= ~0x0003; /* clear status bits */
	45	/*
	46	* Formula T = -46.85 + 175.72 * ST / 2^16 from datasheet p14,
	47	* optimized for integer fixed point (3 digits) arithmetic
	48	*/
	49	return ((21965 * ticks) >> 13) - 46850;
	50	}
	51
	52	static inline int htu21_rh_ticks_to_per_cent_mille(int ticks)
	53	{
	54	ticks &= ~0x0003; /* clear status bits */
	55	/*
	56	* Formula RH = -6 + 125 * SRH / 2^16 from datasheet p14,
	57	* optimized for integer fixed point (3 digits) arithmetic
	58	*/
	59	return ((15625 * ticks) >> 13) - 6000;
	60	}
	61
fa0efc40	62	static int htu21_update_measurements(struct device *dev)
f060c658	63	{
fa0efc40 AL	64	struct htu21 *htu21 = dev_get_drvdata(dev);
fa0efc40 AL	65	struct i2c_client *client = htu21->client;
f060c658	66	int ret = 0;
f060c658 WM	67
	68	mutex_lock(&htu21->lock);
	69
	70	if (time_after(jiffies, htu21->last_update + HZ / 2) \|\|
	71	!htu21->valid) {
	72	ret = i2c_smbus_read_word_swapped(client,
	73	HTU21_T_MEASUREMENT_HM);
	74	if (ret < 0)
	75	goto out;
	76	htu21->temperature = htu21_temp_ticks_to_millicelsius(ret);
	77	ret = i2c_smbus_read_word_swapped(client,
	78	HTU21_RH_MEASUREMENT_HM);
	79	if (ret < 0)
	80	goto out;
	81	htu21->humidity = htu21_rh_ticks_to_per_cent_mille(ret);
	82	htu21->last_update = jiffies;
	83	htu21->valid = true;
	84	}
	85	out:
	86	mutex_unlock(&htu21->lock);
	87
	88	return ret >= 0 ? 0 : ret;
	89	}
	90
	91	static ssize_t htu21_show_temperature(struct device *dev,
	92	struct device_attribute attr, char buf)
	93	{
fa0efc40 AL	94	struct htu21 *htu21 = dev_get_drvdata(dev);
	95	int ret;
	96
	97	ret = htu21_update_measurements(dev);
f060c658 WM	98	if (ret < 0)
	99	return ret;
	100	return sprintf(buf, "%d\n", htu21->temperature);
	101	}
	102
	103	static ssize_t htu21_show_humidity(struct device *dev,
	104	struct device_attribute attr, char buf)
	105	{
fa0efc40 AL	106	struct htu21 *htu21 = dev_get_drvdata(dev);
	107	int ret;
	108
	109	ret = htu21_update_measurements(dev);
f060c658 WM	110	if (ret < 0)
	111	return ret;
	112	return sprintf(buf, "%d\n", htu21->humidity);
	113	}
	114
	115	static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
	116	htu21_show_temperature, NULL, 0);
	117	static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO,
	118	htu21_show_humidity, NULL, 0);
	119
fa0efc40	120	static struct attribute *htu21_attrs[] = {
f060c658 WM	121	&sensor_dev_attr_temp1_input.dev_attr.attr,
	122	&sensor_dev_attr_humidity1_input.dev_attr.attr,
	123	NULL
	124	};
	125
fa0efc40	126	ATTRIBUTE_GROUPS(htu21);
f060c658 WM	127
	128	static int htu21_probe(struct i2c_client *client,
	129	const struct i2c_device_id *id)
	130	{
fa0efc40	131	struct device *dev = &client->dev;
f060c658	132	struct htu21 *htu21;
fa0efc40	133	struct device *hwmon_dev;
f060c658 WM	134
	135	if (!i2c_check_functionality(client->adapter,
	136	I2C_FUNC_SMBUS_READ_WORD_DATA)) {
	137	dev_err(&client->dev,
	138	"adapter does not support SMBus word transactions\n");
	139	return -ENODEV;
	140	}
	141
fa0efc40	142	htu21 = devm_kzalloc(dev, sizeof(*htu21), GFP_KERNEL);
f060c658 WM	143	if (!htu21)
	144	return -ENOMEM;
	145
fa0efc40	146	htu21->client = client;
f060c658 WM	147	mutex_init(&htu21->lock);
f060c658 WM	148
fa0efc40 AL	149	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
	150	htu21,
	151	htu21_groups);
	152	return PTR_ERR_OR_ZERO(hwmon_dev);
f060c658 WM	153	}
	154
	155	static const struct i2c_device_id htu21_id[] = {
	156	{ "htu21", 0 },
	157	{ }
	158	};
	159	MODULE_DEVICE_TABLE(i2c, htu21_id);
	160
	161	static struct i2c_driver htu21_driver = {
	162	.class = I2C_CLASS_HWMON,
	163	.driver = {
	164	.name = "htu21",
	165	},
	166	.probe = htu21_probe,
f060c658 WM	167	.id_table = htu21_id,
	168	};
	169
	170	module_i2c_driver(htu21_driver);
	171
	172	MODULE_AUTHOR("William Markezana <william.markezana@meas-spec.com>");
	173	MODULE_DESCRIPTION("MEAS HTU21D humidity and temperature sensor driver");
	174	MODULE_LICENSE("GPL");