1/*
2 * mpl115.c - Support for Freescale MPL115A2 pressure/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 0x60)
11 *
12 * TODO: shutdown pin
13 *
14 */
15
16#include <linux/module.h>
17#include <linux/i2c.h>
18#include <linux/iio/iio.h>
19#include <linux/delay.h>
20
21#define MPL115_PADC 0x00 /* pressure ADC output value, MSB first, 10 bit */
22#define MPL115_TADC 0x02 /* temperature ADC output value, MSB first, 10 bit */
23#define MPL115_A0 0x04 /* 12 bit integer, 3 bit fraction */
24#define MPL115_B1 0x06 /* 2 bit integer, 13 bit fraction */
25#define MPL115_B2 0x08 /* 1 bit integer, 14 bit fraction */
26#define MPL115_C12 0x0a /* 0 bit integer, 13 bit fraction */
27#define MPL115_CONVERT 0x12 /* convert temperature and pressure */
28
29struct mpl115_data {
30	struct i2c_client *client;
31	struct mutex lock;
32	s16 a0;
33	s16 b1, b2;
34	s16 c12;
35};
36
37static int mpl115_request(struct mpl115_data *data)
38{
39	int ret = i2c_smbus_write_byte_data(data->client, MPL115_CONVERT, 0);
40	if (ret < 0)
41		return ret;
42
43	usleep_range(3000, 4000);
44
45	return 0;
46}
47
48static int mpl115_comp_pressure(struct mpl115_data *data, int *val, int *val2)
49{
50	int ret;
51	u16 padc, tadc;
52	int a1, y1, pcomp;
53	unsigned kpa;
54
55	mutex_lock(&data->lock);
56	ret = mpl115_request(data);
57	if (ret < 0)
58		goto done;
59
60	ret = i2c_smbus_read_word_swapped(data->client, MPL115_PADC);
61	if (ret < 0)
62		goto done;
63	padc = ret >> 6;
64
65	ret = i2c_smbus_read_word_swapped(data->client, MPL115_TADC);
66	if (ret < 0)
67		goto done;
68	tadc = ret >> 6;
69
70	/* see Freescale AN3785 */
71	a1 = data->b1 + ((data->c12 * tadc) >> 11);
72	y1 = (data->a0 << 10) + a1 * padc;
73
74	/* compensated pressure with 4 fractional bits */
75	pcomp = (y1 + ((data->b2 * (int) tadc) >> 1)) >> 9;
76
77	kpa = pcomp * (115 - 50) / 1023 + (50 << 4);
78	*val = kpa >> 4;
79	*val2 = (kpa & 15) * (1000000 >> 4);
80done:
81	mutex_unlock(&data->lock);
82	return ret;
83}
84
85static int mpl115_read_temp(struct mpl115_data *data)
86{
87	int ret;
88
89	mutex_lock(&data->lock);
90	ret = mpl115_request(data);
91	if (ret < 0)
92		goto done;
93	ret = i2c_smbus_read_word_swapped(data->client, MPL115_TADC);
94done:
95	mutex_unlock(&data->lock);
96	return ret;
97}
98
99static int mpl115_read_raw(struct iio_dev *indio_dev,
100			    struct iio_chan_spec const *chan,
101			    int *val, int *val2, long mask)
102{
103	struct mpl115_data *data = iio_priv(indio_dev);
104	int ret;
105
106	switch (mask) {
107	case IIO_CHAN_INFO_PROCESSED:
108		ret = mpl115_comp_pressure(data, val, val2);
109		if (ret < 0)
110			return ret;
111		return IIO_VAL_INT_PLUS_MICRO;
112	case IIO_CHAN_INFO_RAW:
113		/* temperature -5.35 C / LSB, 472 LSB is 25 C */
114		ret = mpl115_read_temp(data);
115		if (ret < 0)
116			return ret;
117		*val = ret >> 6;
118		return IIO_VAL_INT;
119	case IIO_CHAN_INFO_OFFSET:
120		*val = 605;
121		*val2 = 750000;
122		return IIO_VAL_INT_PLUS_MICRO;
123	case IIO_CHAN_INFO_SCALE:
124		*val = -186;
125		*val2 = 915888;
126		return IIO_VAL_INT_PLUS_MICRO;
127	}
128	return -EINVAL;
129}
130
131static const struct iio_chan_spec mpl115_channels[] = {
132	{
133		.type = IIO_PRESSURE,
134		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
135	},
136	{
137		.type = IIO_TEMP,
138		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
139			BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_SCALE),
140	},
141};
142
143static const struct iio_info mpl115_info = {
144	.read_raw = &mpl115_read_raw,
145	.driver_module = THIS_MODULE,
146};
147
148static int mpl115_probe(struct i2c_client *client,
149			 const struct i2c_device_id *id)
150{
151	struct mpl115_data *data;
152	struct iio_dev *indio_dev;
153	int ret;
154
155	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
156		return -ENODEV;
157
158	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
159	if (!indio_dev)
160		return -ENOMEM;
161
162	data = iio_priv(indio_dev);
163	data->client = client;
164	mutex_init(&data->lock);
165
166	i2c_set_clientdata(client, indio_dev);
167	indio_dev->info = &mpl115_info;
168	indio_dev->name = id->name;
169	indio_dev->dev.parent = &client->dev;
170	indio_dev->modes = INDIO_DIRECT_MODE;
171	indio_dev->channels = mpl115_channels;
172	indio_dev->num_channels = ARRAY_SIZE(mpl115_channels);
173
174	ret = i2c_smbus_read_word_swapped(data->client, MPL115_A0);
175	if (ret < 0)
176		return ret;
177	data->a0 = ret;
178	ret = i2c_smbus_read_word_swapped(data->client, MPL115_B1);
179	if (ret < 0)
180		return ret;
181	data->b1 = ret;
182	ret = i2c_smbus_read_word_swapped(data->client, MPL115_B2);
183	if (ret < 0)
184		return ret;
185	data->b2 = ret;
186	ret = i2c_smbus_read_word_swapped(data->client, MPL115_C12);
187	if (ret < 0)
188		return ret;
189	data->c12 = ret;
190
191	return devm_iio_device_register(&client->dev, indio_dev);
192}
193
194static const struct i2c_device_id mpl115_id[] = {
195	{ "mpl115", 0 },
196	{ }
197};
198MODULE_DEVICE_TABLE(i2c, mpl115_id);
199
200static struct i2c_driver mpl115_driver = {
201	.driver = {
202		.name	= "mpl115",
203	},
204	.probe = mpl115_probe,
205	.id_table = mpl115_id,
206};
207module_i2c_driver(mpl115_driver);
208
209MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
210MODULE_DESCRIPTION("Freescale MPL115 pressure/temperature driver");
211MODULE_LICENSE("GPL");
212