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
24 struct 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
mpl115_request(struct mpl115_data * data)33 static 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
mpl115_comp_pressure(struct mpl115_data * data,int * val,int * val2)45 static 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);
77 done:
78 mutex_unlock(&data->lock);
79 return ret;
80 }
81
mpl115_read_temp(struct mpl115_data * data)82 static 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);
91 done:
92 mutex_unlock(&data->lock);
93 return ret;
94 }
95
mpl115_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)96 static 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
128 static 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
141 static const struct iio_info mpl115_info = {
142 .read_raw = &mpl115_read_raw,
143 };
144
mpl115_probe(struct device * dev,const char * name,const struct mpl115_ops * ops)145 int 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 }
190 EXPORT_SYMBOL_NS_GPL(mpl115_probe, IIO_MPL115);
191
192 MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
193 MODULE_DESCRIPTION("Freescale MPL115 pressure/temperature driver");
194 MODULE_LICENSE("GPL");
195