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 *  http://www.meas-spec.com/downloads/MS5607-02BA03.pdf
13 *
14 */
15
16#include <linux/module.h>
17#include <linux/iio/iio.h>
18#include <linux/delay.h>
19
20#include "ms5611.h"
21
22static bool ms5611_prom_is_valid(u16 *prom, size_t len)
23{
24	int i, j;
25	uint16_t crc = 0, crc_orig = prom[7] & 0x000F;
26
27	prom[7] &= 0xFF00;
28
29	for (i = 0; i < len * 2; i++) {
30		if (i % 2 == 1)
31			crc ^= prom[i >> 1] & 0x00FF;
32		else
33			crc ^= prom[i >> 1] >> 8;
34
35		for (j = 0; j < 8; j++) {
36			if (crc & 0x8000)
37				crc = (crc << 1) ^ 0x3000;
38			else
39				crc <<= 1;
40		}
41	}
42
43	crc = (crc >> 12) & 0x000F;
44
45	return crc_orig != 0x0000 && crc == crc_orig;
46}
47
48static int ms5611_read_prom(struct iio_dev *indio_dev)
49{
50	int ret, i;
51	struct ms5611_state *st = iio_priv(indio_dev);
52
53	for (i = 0; i < MS5611_PROM_WORDS_NB; i++) {
54		ret = st->read_prom_word(&indio_dev->dev,
55					 i, &st->chip_info->prom[i]);
56		if (ret < 0) {
57			dev_err(&indio_dev->dev,
58				"failed to read prom at %d\n", i);
59			return ret;
60		}
61	}
62
63	if (!ms5611_prom_is_valid(st->chip_info->prom, MS5611_PROM_WORDS_NB)) {
64		dev_err(&indio_dev->dev, "PROM integrity check failed\n");
65		return -ENODEV;
66	}
67
68	return 0;
69}
70
71static int ms5611_read_temp_and_pressure(struct iio_dev *indio_dev,
72					 s32 *temp, s32 *pressure)
73{
74	int ret;
75	struct ms5611_state *st = iio_priv(indio_dev);
76
77	ret = st->read_adc_temp_and_pressure(&indio_dev->dev, temp, pressure);
78	if (ret < 0) {
79		dev_err(&indio_dev->dev,
80			"failed to read temperature and pressure\n");
81		return ret;
82	}
83
84	return st->chip_info->temp_and_pressure_compensate(st->chip_info,
85							   temp, pressure);
86}
87
88static int ms5611_temp_and_pressure_compensate(struct ms5611_chip_info *chip_info,
89					       s32 *temp, s32 *pressure)
90{
91	s32 t = *temp, p = *pressure;
92	s64 off, sens, dt;
93
94	dt = t - (chip_info->prom[5] << 8);
95	off = ((s64)chip_info->prom[2] << 16) + ((chip_info->prom[4] * dt) >> 7);
96	sens = ((s64)chip_info->prom[1] << 15) + ((chip_info->prom[3] * dt) >> 8);
97
98	t = 2000 + ((chip_info->prom[6] * dt) >> 23);
99	if (t < 2000) {
100		s64 off2, sens2, t2;
101
102		t2 = (dt * dt) >> 31;
103		off2 = (5 * (t - 2000) * (t - 2000)) >> 1;
104		sens2 = off2 >> 1;
105
106		if (t < -1500) {
107			s64 tmp = (t + 1500) * (t + 1500);
108
109			off2 += 7 * tmp;
110			sens2 += (11 * tmp) >> 1;
111		}
112
113		t -= t2;
114		off -= off2;
115		sens -= sens2;
116	}
117
118	*temp = t;
119	*pressure = (((p * sens) >> 21) - off) >> 15;
120
121	return 0;
122}
123
124static int ms5607_temp_and_pressure_compensate(struct ms5611_chip_info *chip_info,
125					       s32 *temp, s32 *pressure)
126{
127	s32 t = *temp, p = *pressure;
128	s64 off, sens, dt;
129
130	dt = t - (chip_info->prom[5] << 8);
131	off = ((s64)chip_info->prom[2] << 17) + ((chip_info->prom[4] * dt) >> 6);
132	sens = ((s64)chip_info->prom[1] << 16) + ((chip_info->prom[3] * dt) >> 7);
133
134	t = 2000 + ((chip_info->prom[6] * dt) >> 23);
135	if (t < 2000) {
136		s64 off2, sens2, t2;
137
138		t2 = (dt * dt) >> 31;
139		off2 = (61 * (t - 2000) * (t - 2000)) >> 4;
140		sens2 = off2 << 1;
141
142		if (t < -1500) {
143			s64 tmp = (t + 1500) * (t + 1500);
144
145			off2 += 15 * tmp;
146			sens2 += (8 * tmp);
147		}
148
149		t -= t2;
150		off -= off2;
151		sens -= sens2;
152	}
153
154	*temp = t;
155	*pressure = (((p * sens) >> 21) - off) >> 15;
156
157	return 0;
158}
159
160static int ms5611_reset(struct iio_dev *indio_dev)
161{
162	int ret;
163	struct ms5611_state *st = iio_priv(indio_dev);
164
165	ret = st->reset(&indio_dev->dev);
166	if (ret < 0) {
167		dev_err(&indio_dev->dev, "failed to reset device\n");
168		return ret;
169	}
170
171	usleep_range(3000, 4000);
172
173	return 0;
174}
175
176static int ms5611_read_raw(struct iio_dev *indio_dev,
177			   struct iio_chan_spec const *chan,
178			   int *val, int *val2, long mask)
179{
180	int ret;
181	s32 temp, pressure;
182	struct ms5611_state *st = iio_priv(indio_dev);
183
184	switch (mask) {
185	case IIO_CHAN_INFO_PROCESSED:
186		mutex_lock(&st->lock);
187		ret = ms5611_read_temp_and_pressure(indio_dev,
188						    &temp, &pressure);
189		mutex_unlock(&st->lock);
190		if (ret < 0)
191			return ret;
192
193		switch (chan->type) {
194		case IIO_TEMP:
195			*val = temp * 10;
196			return IIO_VAL_INT;
197		case IIO_PRESSURE:
198			*val = pressure / 1000;
199			*val2 = (pressure % 1000) * 1000;
200			return IIO_VAL_INT_PLUS_MICRO;
201		default:
202			return -EINVAL;
203		}
204	}
205
206	return -EINVAL;
207}
208
209static struct ms5611_chip_info chip_info_tbl[] = {
210	[MS5611] = {
211		.temp_and_pressure_compensate = ms5611_temp_and_pressure_compensate,
212	},
213	[MS5607] = {
214		.temp_and_pressure_compensate = ms5607_temp_and_pressure_compensate,
215	}
216};
217
218static const struct iio_chan_spec ms5611_channels[] = {
219	{
220		.type = IIO_PRESSURE,
221		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
222	},
223	{
224		.type = IIO_TEMP,
225		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
226	}
227};
228
229static const struct iio_info ms5611_info = {
230	.read_raw = &ms5611_read_raw,
231	.driver_module = THIS_MODULE,
232};
233
234static int ms5611_init(struct iio_dev *indio_dev)
235{
236	int ret;
237
238	ret = ms5611_reset(indio_dev);
239	if (ret < 0)
240		return ret;
241
242	return ms5611_read_prom(indio_dev);
243}
244
245int ms5611_probe(struct iio_dev *indio_dev, struct device *dev, int type)
246{
247	int ret;
248	struct ms5611_state *st = iio_priv(indio_dev);
249
250	mutex_init(&st->lock);
251	st->chip_info = &chip_info_tbl[type];
252	indio_dev->dev.parent = dev;
253	indio_dev->name = dev->driver->name;
254	indio_dev->info = &ms5611_info;
255	indio_dev->channels = ms5611_channels;
256	indio_dev->num_channels = ARRAY_SIZE(ms5611_channels);
257	indio_dev->modes = INDIO_DIRECT_MODE;
258
259	ret = ms5611_init(indio_dev);
260	if (ret < 0)
261		return ret;
262
263	return devm_iio_device_register(dev, indio_dev);
264}
265EXPORT_SYMBOL(ms5611_probe);
266
267MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
268MODULE_DESCRIPTION("MS5611 core driver");
269MODULE_LICENSE("GPL v2");
270