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
21static 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
47static 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
69static 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
114static 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
130static 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
163static 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
176static const struct iio_info ms5611_info = {
177	.read_raw = &ms5611_read_raw,
178	.driver_module = THIS_MODULE,
179};
180
181static 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
192int 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}
211EXPORT_SYMBOL(ms5611_probe);
212
213MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
214MODULE_DESCRIPTION("MS5611 core driver");
215MODULE_LICENSE("GPL v2");
216