1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * mpl115.c - Support for Freescale MPL115A pressure/temperature sensor
4 *
5 * Copyright (c) 2014 Peter Meerwald <pmeerw@pmeerw.net>
6 *
7 * TODO: shutdown pin
8 */
9
10#include <linux/module.h>
11#include <linux/iio/iio.h>
12#include <linux/delay.h>
13
14#include "mpl115.h"
15
16#define MPL115_PADC 0x00 /* pressure ADC output value, MSB first, 10 bit */
17#define MPL115_TADC 0x02 /* temperature ADC output value, MSB first, 10 bit */
18#define MPL115_A0 0x04 /* 12 bit integer, 3 bit fraction */
19#define MPL115_B1 0x06 /* 2 bit integer, 13 bit fraction */
20#define MPL115_B2 0x08 /* 1 bit integer, 14 bit fraction */
21#define MPL115_C12 0x0a /* 0 bit integer, 13 bit fraction */
22#define MPL115_CONVERT 0x12 /* convert temperature and pressure */
23
24struct mpl115_data {
25	struct device *dev;
26	struct mutex lock;
27	s16 a0;
28	s16 b1, b2;
29	s16 c12;
30	const struct mpl115_ops *ops;
31};
32
33static int mpl115_request(struct mpl115_data *data)
34{
35	int ret = data->ops->write(data->dev, MPL115_CONVERT, 0);
36
37	if (ret < 0)
38		return ret;
39
40	usleep_range(3000, 4000);
41
42	return 0;
43}
44
45static int mpl115_comp_pressure(struct mpl115_data *data, int *val, int *val2)
46{
47	int ret;
48	u16 padc, tadc;
49	int a1, y1, pcomp;
50	unsigned kpa;
51
52	mutex_lock(&data->lock);
53	ret = mpl115_request(data);
54	if (ret < 0)
55		goto done;
56
57	ret = data->ops->read(data->dev, MPL115_PADC);
58	if (ret < 0)
59		goto done;
60	padc = ret >> 6;
61
62	ret = data->ops->read(data->dev, MPL115_TADC);
63	if (ret < 0)
64		goto done;
65	tadc = ret >> 6;
66
67	/* see Freescale AN3785 */
68	a1 = data->b1 + ((data->c12 * tadc) >> 11);
69	y1 = (data->a0 << 10) + a1 * padc;
70
71	/* compensated pressure with 4 fractional bits */
72	pcomp = (y1 + ((data->b2 * (int) tadc) >> 1)) >> 9;
73
74	kpa = pcomp * (115 - 50) / 1023 + (50 << 4);
75	*val = kpa >> 4;
76	*val2 = (kpa & 15) * (1000000 >> 4);
77done:
78	mutex_unlock(&data->lock);
79	return ret;
80}
81
82static int mpl115_read_temp(struct mpl115_data *data)
83{
84	int ret;
85
86	mutex_lock(&data->lock);
87	ret = mpl115_request(data);
88	if (ret < 0)
89		goto done;
90	ret = data->ops->read(data->dev, MPL115_TADC);
91done:
92	mutex_unlock(&data->lock);
93	return ret;
94}
95
96static int mpl115_read_raw(struct iio_dev *indio_dev,
97			    struct iio_chan_spec const *chan,
98			    int *val, int *val2, long mask)
99{
100	struct mpl115_data *data = iio_priv(indio_dev);
101	int ret;
102
103	switch (mask) {
104	case IIO_CHAN_INFO_PROCESSED:
105		ret = mpl115_comp_pressure(data, val, val2);
106		if (ret < 0)
107			return ret;
108		return IIO_VAL_INT_PLUS_MICRO;
109	case IIO_CHAN_INFO_RAW:
110		/* temperature -5.35 C / LSB, 472 LSB is 25 C */
111		ret = mpl115_read_temp(data);
112		if (ret < 0)
113			return ret;
114		*val = ret >> 6;
115		return IIO_VAL_INT;
116	case IIO_CHAN_INFO_OFFSET:
117		*val = -605;
118		*val2 = 750000;
119		return IIO_VAL_INT_PLUS_MICRO;
120	case IIO_CHAN_INFO_SCALE:
121		*val = -186;
122		*val2 = 915888;
123		return IIO_VAL_INT_PLUS_MICRO;
124	}
125	return -EINVAL;
126}
127
128static const struct iio_chan_spec mpl115_channels[] = {
129	{
130		.type = IIO_PRESSURE,
131		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
132	},
133	{
134		.type = IIO_TEMP,
135		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
136		.info_mask_shared_by_type =
137			BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_SCALE),
138	},
139};
140
141static const struct iio_info mpl115_info = {
142	.read_raw = &mpl115_read_raw,
143};
144
145int mpl115_probe(struct device *dev, const char *name,
146			const struct mpl115_ops *ops)
147{
148	struct mpl115_data *data;
149	struct iio_dev *indio_dev;
150	int ret;
151
152	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
153	if (!indio_dev)
154		return -ENOMEM;
155
156	data = iio_priv(indio_dev);
157	data->dev = dev;
158	data->ops = ops;
159	mutex_init(&data->lock);
160
161	indio_dev->info = &mpl115_info;
162	indio_dev->name = name;
163	indio_dev->modes = INDIO_DIRECT_MODE;
164	indio_dev->channels = mpl115_channels;
165	indio_dev->num_channels = ARRAY_SIZE(mpl115_channels);
166
167	ret = data->ops->init(data->dev);
168	if (ret)
169		return ret;
170
171	ret = data->ops->read(data->dev, MPL115_A0);
172	if (ret < 0)
173		return ret;
174	data->a0 = ret;
175	ret = data->ops->read(data->dev, MPL115_B1);
176	if (ret < 0)
177		return ret;
178	data->b1 = ret;
179	ret = data->ops->read(data->dev, MPL115_B2);
180	if (ret < 0)
181		return ret;
182	data->b2 = ret;
183	ret = data->ops->read(data->dev, MPL115_C12);
184	if (ret < 0)
185		return ret;
186	data->c12 = ret;
187
188	return devm_iio_device_register(dev, indio_dev);
189}
190EXPORT_SYMBOL_GPL(mpl115_probe);
191
192MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
193MODULE_DESCRIPTION("Freescale MPL115 pressure/temperature driver");
194MODULE_LICENSE("GPL");
195