1/*
2 * si7005.c - Support for Silabs Si7005 humidity and temperature sensor
3 *
4 * Copyright (c) 2014 Peter Meerwald <pmeerw@pmeerw.net>
5 *
6 * This file is subject to the terms and conditions of version 2 of
7 * the GNU General Public License.  See the file COPYING in the main
8 * directory of this archive for more details.
9 *
10 * (7-bit I2C slave address 0x40)
11 *
12 * TODO: heater, fast mode, processed mode (temp. / linearity compensation)
13 */
14
15#include <linux/err.h>
16#include <linux/i2c.h>
17#include <linux/delay.h>
18#include <linux/module.h>
19#include <linux/pm.h>
20
21#include <linux/iio/iio.h>
22#include <linux/iio/sysfs.h>
23
24#define SI7005_STATUS 0x00
25#define SI7005_DATA 0x01 /* 16-bit, MSB */
26#define SI7005_CONFIG 0x03
27#define SI7005_ID 0x11
28
29#define SI7005_STATUS_NRDY BIT(0)
30#define SI7005_CONFIG_TEMP BIT(4)
31#define SI7005_CONFIG_START BIT(0)
32
33#define SI7005_ID_7005 0x50
34#define SI7005_ID_7015 0xf0
35
36struct si7005_data {
37	struct i2c_client *client;
38	struct mutex lock;
39	u8 config;
40};
41
42static int si7005_read_measurement(struct si7005_data *data, bool temp)
43{
44	int tries = 50;
45	int ret;
46
47	mutex_lock(&data->lock);
48
49	ret = i2c_smbus_write_byte_data(data->client, SI7005_CONFIG,
50		data->config | SI7005_CONFIG_START |
51		(temp ? SI7005_CONFIG_TEMP : 0));
52	if (ret < 0)
53		goto done;
54
55	while (tries-- > 0) {
56		msleep(20);
57		ret = i2c_smbus_read_byte_data(data->client, SI7005_STATUS);
58		if (ret < 0)
59			goto done;
60		if (!(ret & SI7005_STATUS_NRDY))
61			break;
62	}
63	if (tries < 0) {
64		ret = -EIO;
65		goto done;
66	}
67
68	ret = i2c_smbus_read_word_swapped(data->client, SI7005_DATA);
69
70done:
71	mutex_unlock(&data->lock);
72
73	return ret;
74}
75
76static int si7005_read_raw(struct iio_dev *indio_dev,
77			    struct iio_chan_spec const *chan, int *val,
78			    int *val2, long mask)
79{
80	struct si7005_data *data = iio_priv(indio_dev);
81	int ret;
82
83	switch (mask) {
84	case IIO_CHAN_INFO_RAW:
85		ret = si7005_read_measurement(data, chan->type == IIO_TEMP);
86		if (ret < 0)
87			return ret;
88		*val = ret;
89		return IIO_VAL_INT;
90	case IIO_CHAN_INFO_SCALE:
91		if (chan->type == IIO_TEMP) {
92			*val = 7;
93			*val2 = 812500;
94		} else {
95			*val = 3;
96			*val2 = 906250;
97		}
98		return IIO_VAL_INT_PLUS_MICRO;
99	case IIO_CHAN_INFO_OFFSET:
100		if (chan->type == IIO_TEMP)
101			*val = -50 * 32 * 4;
102		else
103			*val = -24 * 16 * 16;
104		return IIO_VAL_INT;
105	default:
106		break;
107	}
108
109	return -EINVAL;
110}
111
112static const struct iio_chan_spec si7005_channels[] = {
113	{
114		.type = IIO_HUMIDITYRELATIVE,
115		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
116			BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
117	},
118	{
119		.type = IIO_TEMP,
120		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
121			BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
122	}
123};
124
125static const struct iio_info si7005_info = {
126	.read_raw = si7005_read_raw,
127	.driver_module = THIS_MODULE,
128};
129
130static int si7005_probe(struct i2c_client *client,
131			 const struct i2c_device_id *id)
132{
133	struct iio_dev *indio_dev;
134	struct si7005_data *data;
135	int ret;
136
137	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
138		return -ENODEV;
139
140	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
141	if (!indio_dev)
142		return -ENOMEM;
143
144	data = iio_priv(indio_dev);
145	i2c_set_clientdata(client, indio_dev);
146	data->client = client;
147	mutex_init(&data->lock);
148
149	indio_dev->dev.parent = &client->dev;
150	indio_dev->name = dev_name(&client->dev);
151	indio_dev->modes = INDIO_DIRECT_MODE;
152	indio_dev->info = &si7005_info;
153
154	indio_dev->channels = si7005_channels;
155	indio_dev->num_channels = ARRAY_SIZE(si7005_channels);
156
157	ret = i2c_smbus_read_byte_data(client, SI7005_ID);
158	if (ret < 0)
159		return ret;
160	if (ret != SI7005_ID_7005 && ret != SI7005_ID_7015)
161		return -ENODEV;
162
163	ret = i2c_smbus_read_byte_data(client, SI7005_CONFIG);
164	if (ret < 0)
165		return ret;
166	data->config = ret;
167
168	return devm_iio_device_register(&client->dev, indio_dev);
169}
170
171static const struct i2c_device_id si7005_id[] = {
172	{ "si7005", 0 },
173	{ }
174};
175MODULE_DEVICE_TABLE(i2c, si7005_id);
176
177static struct i2c_driver si7005_driver = {
178	.driver = {
179		.name	= "si7005",
180		.owner	= THIS_MODULE,
181	},
182	.probe = si7005_probe,
183	.id_table = si7005_id,
184};
185module_i2c_driver(si7005_driver);
186
187MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
188MODULE_DESCRIPTION("Silabs Si7005 humidity and temperature sensor driver");
189MODULE_LICENSE("GPL");
190