summaryrefslogtreecommitdiff
path: root/drivers/iio/pressure/mpl115.c
blob: a0d7deeac62f78dfc416bf597e0b894436c75a8c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
/*
 * mpl115.c - Support for Freescale MPL115A2 pressure/temperature sensor
 *
 * Copyright (c) 2014 Peter Meerwald <pmeerw@pmeerw.net>
 *
 * This file is subject to the terms and conditions of version 2 of
 * the GNU General Public License.  See the file COPYING in the main
 * directory of this archive for more details.
 *
 * (7-bit I2C slave address 0x60)
 *
 * TODO: shutdown pin
 *
 */

#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#include <linux/delay.h>

#define MPL115_PADC 0x00 /* pressure ADC output value, MSB first, 10 bit */
#define MPL115_TADC 0x02 /* temperature ADC output value, MSB first, 10 bit */
#define MPL115_A0 0x04 /* 12 bit integer, 3 bit fraction */
#define MPL115_B1 0x06 /* 2 bit integer, 13 bit fraction */
#define MPL115_B2 0x08 /* 1 bit integer, 14 bit fraction */
#define MPL115_C12 0x0a /* 0 bit integer, 13 bit fraction */
#define MPL115_CONVERT 0x12 /* convert temperature and pressure */

struct mpl115_data {
	struct i2c_client *client;
	struct mutex lock;
	s16 a0;
	s16 b1, b2;
	s16 c12;
};

static int mpl115_request(struct mpl115_data *data)
{
	int ret = i2c_smbus_write_byte_data(data->client, MPL115_CONVERT, 0);
	if (ret < 0)
		return ret;

	usleep_range(3000, 4000);

	return 0;
}

static int mpl115_comp_pressure(struct mpl115_data *data, int *val, int *val2)
{
	int ret;
	u16 padc, tadc;
	int a1, y1, pcomp;
	unsigned kpa;

	mutex_lock(&data->lock);
	ret = mpl115_request(data);
	if (ret < 0)
		goto done;

	ret = i2c_smbus_read_word_swapped(data->client, MPL115_PADC);
	if (ret < 0)
		goto done;
	padc = ret >> 6;

	ret = i2c_smbus_read_word_swapped(data->client, MPL115_TADC);
	if (ret < 0)
		goto done;
	tadc = ret >> 6;

	/* see Freescale AN3785 */
	a1 = data->b1 + ((data->c12 * tadc) >> 11);
	y1 = (data->a0 << 10) + a1 * padc;

	/* compensated pressure with 4 fractional bits */
	pcomp = (y1 + ((data->b2 * (int) tadc) >> 1)) >> 9;

	kpa = pcomp * (115 - 50) / 1023 + (50 << 4);
	*val = kpa >> 4;
	*val2 = (kpa & 15) * (1000000 >> 4);
done:
	mutex_unlock(&data->lock);
	return ret;
}

static int mpl115_read_temp(struct mpl115_data *data)
{
	int ret;

	mutex_lock(&data->lock);
	ret = mpl115_request(data);
	if (ret < 0)
		goto done;
	ret = i2c_smbus_read_word_swapped(data->client, MPL115_TADC);
done:
	mutex_unlock(&data->lock);
	return ret;
}

static int mpl115_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int *val, int *val2, long mask)
{
	struct mpl115_data *data = iio_priv(indio_dev);
	int ret;

	switch (mask) {
	case IIO_CHAN_INFO_PROCESSED:
		ret = mpl115_comp_pressure(data, val, val2);
		if (ret < 0)
			return ret;
		return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_RAW:
		/* temperature -5.35 C / LSB, 472 LSB is 25 C */
		ret = mpl115_read_temp(data);
		if (ret < 0)
			return ret;
		*val = ret >> 6;
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_OFFSET:
		*val = -605;
		*val2 = 750000;
		return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_SCALE:
		*val = -186;
		*val2 = 915888;
		return IIO_VAL_INT_PLUS_MICRO;
	}
	return -EINVAL;
}

static const struct iio_chan_spec mpl115_channels[] = {
	{
		.type = IIO_PRESSURE,
		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
	},
	{
		.type = IIO_TEMP,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
			BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_SCALE),
	},
};

static const struct iio_info mpl115_info = {
	.read_raw = &mpl115_read_raw,
	.driver_module = THIS_MODULE,
};

static int mpl115_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct mpl115_data *data;
	struct iio_dev *indio_dev;
	int ret;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
		return -ENODEV;

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
	if (!indio_dev)
		return -ENOMEM;

	data = iio_priv(indio_dev);
	data->client = client;
	mutex_init(&data->lock);

	i2c_set_clientdata(client, indio_dev);
	indio_dev->info = &mpl115_info;
	indio_dev->name = id->name;
	indio_dev->dev.parent = &client->dev;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = mpl115_channels;
	indio_dev->num_channels = ARRAY_SIZE(mpl115_channels);

	ret = i2c_smbus_read_word_swapped(data->client, MPL115_A0);
	if (ret < 0)
		return ret;
	data->a0 = ret;
	ret = i2c_smbus_read_word_swapped(data->client, MPL115_B1);
	if (ret < 0)
		return ret;
	data->b1 = ret;
	ret = i2c_smbus_read_word_swapped(data->client, MPL115_B2);
	if (ret < 0)
		return ret;
	data->b2 = ret;
	ret = i2c_smbus_read_word_swapped(data->client, MPL115_C12);
	if (ret < 0)
		return ret;
	data->c12 = ret;

	return devm_iio_device_register(&client->dev, indio_dev);
}

static const struct i2c_device_id mpl115_id[] = {
	{ "mpl115", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, mpl115_id);

static struct i2c_driver mpl115_driver = {
	.driver = {
		.name	= "mpl115",
	},
	.probe = mpl115_probe,
	.id_table = mpl115_id,
};
module_i2c_driver(mpl115_driver);

MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
MODULE_DESCRIPTION("Freescale MPL115 pressure/temperature driver");
MODULE_LICENSE("GPL");