1 /*
2 * MS5611 pressure and temperature sensor driver
3 *
4 * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * Data sheet:
11 * http://www.meas-spec.com/downloads/MS5611-01BA03.pdf
12 *
13 */
14
15 #include <linux/module.h>
16 #include <linux/iio/iio.h>
17 #include <linux/delay.h>
18
19 #include "ms5611.h"
20
ms5611_prom_is_valid(u16 * prom,size_t len)21 static bool ms5611_prom_is_valid(u16 *prom, size_t len)
22 {
23 int i, j;
24 uint16_t crc = 0, crc_orig = prom[7] & 0x000F;
25
26 prom[7] &= 0xFF00;
27
28 for (i = 0; i < len * 2; i++) {
29 if (i % 2 == 1)
30 crc ^= prom[i >> 1] & 0x00FF;
31 else
32 crc ^= prom[i >> 1] >> 8;
33
34 for (j = 0; j < 8; j++) {
35 if (crc & 0x8000)
36 crc = (crc << 1) ^ 0x3000;
37 else
38 crc <<= 1;
39 }
40 }
41
42 crc = (crc >> 12) & 0x000F;
43
44 return crc_orig != 0x0000 && crc == crc_orig;
45 }
46
ms5611_read_prom(struct iio_dev * indio_dev)47 static int ms5611_read_prom(struct iio_dev *indio_dev)
48 {
49 int ret, i;
50 struct ms5611_state *st = iio_priv(indio_dev);
51
52 for (i = 0; i < MS5611_PROM_WORDS_NB; i++) {
53 ret = st->read_prom_word(&indio_dev->dev, i, &st->prom[i]);
54 if (ret < 0) {
55 dev_err(&indio_dev->dev,
56 "failed to read prom at %d\n", i);
57 return ret;
58 }
59 }
60
61 if (!ms5611_prom_is_valid(st->prom, MS5611_PROM_WORDS_NB)) {
62 dev_err(&indio_dev->dev, "PROM integrity check failed\n");
63 return -ENODEV;
64 }
65
66 return 0;
67 }
68
ms5611_read_temp_and_pressure(struct iio_dev * indio_dev,s32 * temp,s32 * pressure)69 static int ms5611_read_temp_and_pressure(struct iio_dev *indio_dev,
70 s32 *temp, s32 *pressure)
71 {
72 int ret;
73 s32 t, p;
74 s64 off, sens, dt;
75 struct ms5611_state *st = iio_priv(indio_dev);
76
77 ret = st->read_adc_temp_and_pressure(&indio_dev->dev, &t, &p);
78 if (ret < 0) {
79 dev_err(&indio_dev->dev,
80 "failed to read temperature and pressure\n");
81 return ret;
82 }
83
84 dt = t - (st->prom[5] << 8);
85 off = ((s64)st->prom[2] << 16) + ((st->prom[4] * dt) >> 7);
86 sens = ((s64)st->prom[1] << 15) + ((st->prom[3] * dt) >> 8);
87
88 t = 2000 + ((st->prom[6] * dt) >> 23);
89 if (t < 2000) {
90 s64 off2, sens2, t2;
91
92 t2 = (dt * dt) >> 31;
93 off2 = (5 * (t - 2000) * (t - 2000)) >> 1;
94 sens2 = off2 >> 1;
95
96 if (t < -1500) {
97 s64 tmp = (t + 1500) * (t + 1500);
98
99 off2 += 7 * tmp;
100 sens2 += (11 * tmp) >> 1;
101 }
102
103 t -= t2;
104 off -= off2;
105 sens -= sens2;
106 }
107
108 *temp = t;
109 *pressure = (((p * sens) >> 21) - off) >> 15;
110
111 return 0;
112 }
113
ms5611_reset(struct iio_dev * indio_dev)114 static int ms5611_reset(struct iio_dev *indio_dev)
115 {
116 int ret;
117 struct ms5611_state *st = iio_priv(indio_dev);
118
119 ret = st->reset(&indio_dev->dev);
120 if (ret < 0) {
121 dev_err(&indio_dev->dev, "failed to reset device\n");
122 return ret;
123 }
124
125 usleep_range(3000, 4000);
126
127 return 0;
128 }
129
ms5611_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)130 static int ms5611_read_raw(struct iio_dev *indio_dev,
131 struct iio_chan_spec const *chan,
132 int *val, int *val2, long mask)
133 {
134 int ret;
135 s32 temp, pressure;
136 struct ms5611_state *st = iio_priv(indio_dev);
137
138 switch (mask) {
139 case IIO_CHAN_INFO_PROCESSED:
140 mutex_lock(&st->lock);
141 ret = ms5611_read_temp_and_pressure(indio_dev,
142 &temp, &pressure);
143 mutex_unlock(&st->lock);
144 if (ret < 0)
145 return ret;
146
147 switch (chan->type) {
148 case IIO_TEMP:
149 *val = temp * 10;
150 return IIO_VAL_INT;
151 case IIO_PRESSURE:
152 *val = pressure / 1000;
153 *val2 = (pressure % 1000) * 1000;
154 return IIO_VAL_INT_PLUS_MICRO;
155 default:
156 return -EINVAL;
157 }
158 }
159
160 return -EINVAL;
161 }
162
163 static const struct iio_chan_spec ms5611_channels[] = {
164 {
165 .type = IIO_PRESSURE,
166 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
167 BIT(IIO_CHAN_INFO_SCALE)
168 },
169 {
170 .type = IIO_TEMP,
171 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
172 BIT(IIO_CHAN_INFO_SCALE)
173 }
174 };
175
176 static const struct iio_info ms5611_info = {
177 .read_raw = &ms5611_read_raw,
178 .driver_module = THIS_MODULE,
179 };
180
ms5611_init(struct iio_dev * indio_dev)181 static int ms5611_init(struct iio_dev *indio_dev)
182 {
183 int ret;
184
185 ret = ms5611_reset(indio_dev);
186 if (ret < 0)
187 return ret;
188
189 return ms5611_read_prom(indio_dev);
190 }
191
ms5611_probe(struct iio_dev * indio_dev,struct device * dev)192 int ms5611_probe(struct iio_dev *indio_dev, struct device *dev)
193 {
194 int ret;
195 struct ms5611_state *st = iio_priv(indio_dev);
196
197 mutex_init(&st->lock);
198 indio_dev->dev.parent = dev;
199 indio_dev->name = dev->driver->name;
200 indio_dev->info = &ms5611_info;
201 indio_dev->channels = ms5611_channels;
202 indio_dev->num_channels = ARRAY_SIZE(ms5611_channels);
203 indio_dev->modes = INDIO_DIRECT_MODE;
204
205 ret = ms5611_init(indio_dev);
206 if (ret < 0)
207 return ret;
208
209 return devm_iio_device_register(dev, indio_dev);
210 }
211 EXPORT_SYMBOL(ms5611_probe);
212
213 MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
214 MODULE_DESCRIPTION("MS5611 core driver");
215 MODULE_LICENSE("GPL v2");
216