summaryrefslogtreecommitdiff
path: root/drivers/iio/temperature/maxim_thermocouple.c
blob: d70e2e53d6a78cc5ab8ee073a7e01e5f635483d1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
/*
 * maxim_thermocouple.c  - Support for Maxim thermocouple chips
 *
 * Copyright (C) 2016 Matt Ranostay <mranostay@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/err.h>
#include <linux/spi/spi.h>
#include <linux/iio/iio.h>
#include <linux/iio/trigger.h>
#include <linux/iio/buffer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/trigger_consumer.h>

#define MAXIM_THERMOCOUPLE_DRV_NAME	"maxim_thermocouple"

enum {
	MAX6675,
	MAX31855,
};

static const struct iio_chan_spec max6675_channels[] = {
	{	/* thermocouple temperature */
		.type = IIO_TEMP,
		.info_mask_separate =
			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
		.scan_index = 0,
		.scan_type = {
			.sign = 's',
			.realbits = 13,
			.storagebits = 16,
			.shift = 3,
			.endianness = IIO_BE,
		},
	},
	IIO_CHAN_SOFT_TIMESTAMP(1),
};

static const struct iio_chan_spec max31855_channels[] = {
	{	/* thermocouple temperature */
		.type = IIO_TEMP,
		.address = 2,
		.info_mask_separate =
			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
		.scan_index = 0,
		.scan_type = {
			.sign = 's',
			.realbits = 14,
			.storagebits = 16,
			.shift = 2,
			.endianness = IIO_BE,
		},
	},
	{	/* cold junction temperature */
		.type = IIO_TEMP,
		.address = 0,
		.channel2 = IIO_MOD_TEMP_AMBIENT,
		.modified = 1,
		.info_mask_separate =
			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
		.scan_index = 1,
		.scan_type = {
			.sign = 's',
			.realbits = 12,
			.storagebits = 16,
			.shift = 4,
			.endianness = IIO_BE,
		},
	},
	IIO_CHAN_SOFT_TIMESTAMP(2),
};

static const unsigned long max31855_scan_masks[] = {0x3, 0};

struct maxim_thermocouple_chip {
	const struct iio_chan_spec *channels;
	const unsigned long *scan_masks;
	u8 num_channels;
	u8 read_size;

	/* bit-check for valid input */
	u32 status_bit;
};

static const struct maxim_thermocouple_chip maxim_thermocouple_chips[] = {
	[MAX6675] = {
			.channels = max6675_channels,
			.num_channels = ARRAY_SIZE(max6675_channels),
			.read_size = 2,
			.status_bit = BIT(2),
		},
	[MAX31855] = {
			.channels = max31855_channels,
			.num_channels = ARRAY_SIZE(max31855_channels),
			.read_size = 4,
			.scan_masks = max31855_scan_masks,
			.status_bit = BIT(16),
		},
};

struct maxim_thermocouple_data {
	struct spi_device *spi;
	const struct maxim_thermocouple_chip *chip;

	u8 buffer[16] ____cacheline_aligned;
};

static int maxim_thermocouple_read(struct maxim_thermocouple_data *data,
				   struct iio_chan_spec const *chan, int *val)
{
	unsigned int storage_bytes = data->chip->read_size;
	unsigned int shift = chan->scan_type.shift + (chan->address * 8);
	__be16 buf16;
	__be32 buf32;
	int ret;

	switch (storage_bytes) {
	case 2:
		ret = spi_read(data->spi, (void *)&buf16, storage_bytes);
		*val = be16_to_cpu(buf16);
		break;
	case 4:
		ret = spi_read(data->spi, (void *)&buf32, storage_bytes);
		*val = be32_to_cpu(buf32);
		break;
	default:
		ret = -EINVAL;
	}

	if (ret)
		return ret;

	/* check to be sure this is a valid reading */
	if (*val & data->chip->status_bit)
		return -EINVAL;

	*val = sign_extend32(*val >> shift, chan->scan_type.realbits - 1);

	return 0;
}

static irqreturn_t maxim_thermocouple_trigger_handler(int irq, void *private)
{
	struct iio_poll_func *pf = private;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct maxim_thermocouple_data *data = iio_priv(indio_dev);
	int ret;

	ret = spi_read(data->spi, data->buffer, data->chip->read_size);
	if (!ret) {
		iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
						   iio_get_time_ns(indio_dev));
	}

	iio_trigger_notify_done(indio_dev->trig);

	return IRQ_HANDLED;
}

static int maxim_thermocouple_read_raw(struct iio_dev *indio_dev,
				       struct iio_chan_spec const *chan,
				       int *val, int *val2, long mask)
{
	struct maxim_thermocouple_data *data = iio_priv(indio_dev);
	int ret = -EINVAL;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		ret = iio_device_claim_direct_mode(indio_dev);
		if (ret)
			return ret;

		ret = maxim_thermocouple_read(data, chan, val);
		iio_device_release_direct_mode(indio_dev);

		if (!ret)
			return IIO_VAL_INT;

		break;
	case IIO_CHAN_INFO_SCALE:
		switch (chan->channel2) {
		case IIO_MOD_TEMP_AMBIENT:
			*val = 62;
			*val2 = 500000; /* 1000 * 0.0625 */
			ret = IIO_VAL_INT_PLUS_MICRO;
			break;
		default:
			*val = 250; /* 1000 * 0.25 */
			ret = IIO_VAL_INT;
		};
		break;
	}

	return ret;
}

static const struct iio_info maxim_thermocouple_info = {
	.driver_module = THIS_MODULE,
	.read_raw = maxim_thermocouple_read_raw,
};

static int maxim_thermocouple_probe(struct spi_device *spi)
{
	const struct spi_device_id *id = spi_get_device_id(spi);
	struct iio_dev *indio_dev;
	struct maxim_thermocouple_data *data;
	const struct maxim_thermocouple_chip *chip =
			&maxim_thermocouple_chips[id->driver_data];
	int ret;

	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
	if (!indio_dev)
		return -ENOMEM;

	indio_dev->info = &maxim_thermocouple_info;
	indio_dev->name = MAXIM_THERMOCOUPLE_DRV_NAME;
	indio_dev->channels = chip->channels;
	indio_dev->available_scan_masks = chip->scan_masks;
	indio_dev->num_channels = chip->num_channels;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->dev.parent = &spi->dev;

	data = iio_priv(indio_dev);
	data->spi = spi;
	data->chip = chip;

	ret = iio_triggered_buffer_setup(indio_dev, NULL,
				maxim_thermocouple_trigger_handler, NULL);
	if (ret)
		return ret;

	ret = iio_device_register(indio_dev);
	if (ret)
		goto error_unreg_buffer;

	return 0;

error_unreg_buffer:
	iio_triggered_buffer_cleanup(indio_dev);

	return ret;
}

static int maxim_thermocouple_remove(struct spi_device *spi)
{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);

	iio_device_unregister(indio_dev);
	iio_triggered_buffer_cleanup(indio_dev);

	return 0;
}

static const struct spi_device_id maxim_thermocouple_id[] = {
	{"max6675", MAX6675},
	{"max31855", MAX31855},
	{"max31856", MAX31855},
	{},
};
MODULE_DEVICE_TABLE(spi, maxim_thermocouple_id);

static struct spi_driver maxim_thermocouple_driver = {
	.driver = {
		.name	= MAXIM_THERMOCOUPLE_DRV_NAME,
	},
	.probe		= maxim_thermocouple_probe,
	.remove		= maxim_thermocouple_remove,
	.id_table	= maxim_thermocouple_id,
};
module_spi_driver(maxim_thermocouple_driver);

MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
MODULE_DESCRIPTION("Maxim thermocouple sensors");
MODULE_LICENSE("GPL");