1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * maxim_thermocouple.c  - Support for Maxim thermocouple chips
4 *
5 * Copyright (C) 2016-2018 Matt Ranostay
6 * Author: <matt.ranostay@konsulko.com>
7 */
8
9#include <linux/module.h>
10#include <linux/init.h>
11#include <linux/mutex.h>
12#include <linux/err.h>
13#include <linux/of.h>
14#include <linux/of_device.h>
15#include <linux/spi/spi.h>
16#include <linux/iio/iio.h>
17#include <linux/iio/sysfs.h>
18#include <linux/iio/trigger.h>
19#include <linux/iio/buffer.h>
20#include <linux/iio/triggered_buffer.h>
21#include <linux/iio/trigger_consumer.h>
22
23#define MAXIM_THERMOCOUPLE_DRV_NAME	"maxim_thermocouple"
24
25enum {
26	MAX6675,
27	MAX31855,
28	MAX31855K,
29	MAX31855J,
30	MAX31855N,
31	MAX31855S,
32	MAX31855T,
33	MAX31855E,
34	MAX31855R,
35};
36
37static const char maxim_tc_types[] = {
38	'K', '?', 'K', 'J', 'N', 'S', 'T', 'E', 'R'
39};
40
41static const struct iio_chan_spec max6675_channels[] = {
42	{	/* thermocouple temperature */
43		.type = IIO_TEMP,
44		.info_mask_separate =
45			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) |
46			BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE),
47		.scan_index = 0,
48		.scan_type = {
49			.sign = 's',
50			.realbits = 13,
51			.storagebits = 16,
52			.shift = 3,
53			.endianness = IIO_BE,
54		},
55	},
56	IIO_CHAN_SOFT_TIMESTAMP(1),
57};
58
59static const struct iio_chan_spec max31855_channels[] = {
60	{	/* thermocouple temperature */
61		.type = IIO_TEMP,
62		.address = 2,
63		.info_mask_separate =
64			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) |
65			BIT(IIO_CHAN_INFO_THERMOCOUPLE_TYPE),
66		.scan_index = 0,
67		.scan_type = {
68			.sign = 's',
69			.realbits = 14,
70			.storagebits = 16,
71			.shift = 2,
72			.endianness = IIO_BE,
73		},
74	},
75	{	/* cold junction temperature */
76		.type = IIO_TEMP,
77		.address = 0,
78		.channel2 = IIO_MOD_TEMP_AMBIENT,
79		.modified = 1,
80		.info_mask_separate =
81			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
82		.scan_index = 1,
83		.scan_type = {
84			.sign = 's',
85			.realbits = 12,
86			.storagebits = 16,
87			.shift = 4,
88			.endianness = IIO_BE,
89		},
90	},
91	IIO_CHAN_SOFT_TIMESTAMP(2),
92};
93
94static const unsigned long max31855_scan_masks[] = {0x3, 0};
95
96struct maxim_thermocouple_chip {
97	const struct iio_chan_spec *channels;
98	const unsigned long *scan_masks;
99	u8 num_channels;
100	u8 read_size;
101
102	/* bit-check for valid input */
103	u32 status_bit;
104};
105
106static const struct maxim_thermocouple_chip maxim_thermocouple_chips[] = {
107	[MAX6675] = {
108			.channels = max6675_channels,
109			.num_channels = ARRAY_SIZE(max6675_channels),
110			.read_size = 2,
111			.status_bit = BIT(2),
112		},
113	[MAX31855] = {
114			.channels = max31855_channels,
115			.num_channels = ARRAY_SIZE(max31855_channels),
116			.read_size = 4,
117			.scan_masks = max31855_scan_masks,
118			.status_bit = BIT(16),
119		},
120};
121
122struct maxim_thermocouple_data {
123	struct spi_device *spi;
124	const struct maxim_thermocouple_chip *chip;
125
126	u8 buffer[16] ____cacheline_aligned;
127	char tc_type;
128};
129
130static int maxim_thermocouple_read(struct maxim_thermocouple_data *data,
131				   struct iio_chan_spec const *chan, int *val)
132{
133	unsigned int storage_bytes = data->chip->read_size;
134	unsigned int shift = chan->scan_type.shift + (chan->address * 8);
135	__be16 buf16;
136	__be32 buf32;
137	int ret;
138
139	switch (storage_bytes) {
140	case 2:
141		ret = spi_read(data->spi, (void *)&buf16, storage_bytes);
142		*val = be16_to_cpu(buf16);
143		break;
144	case 4:
145		ret = spi_read(data->spi, (void *)&buf32, storage_bytes);
146		*val = be32_to_cpu(buf32);
147		break;
148	default:
149		ret = -EINVAL;
150	}
151
152	if (ret)
153		return ret;
154
155	/* check to be sure this is a valid reading */
156	if (*val & data->chip->status_bit)
157		return -EINVAL;
158
159	*val = sign_extend32(*val >> shift, chan->scan_type.realbits - 1);
160
161	return 0;
162}
163
164static irqreturn_t maxim_thermocouple_trigger_handler(int irq, void *private)
165{
166	struct iio_poll_func *pf = private;
167	struct iio_dev *indio_dev = pf->indio_dev;
168	struct maxim_thermocouple_data *data = iio_priv(indio_dev);
169	int ret;
170
171	ret = spi_read(data->spi, data->buffer, data->chip->read_size);
172	if (!ret) {
173		iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
174						   iio_get_time_ns(indio_dev));
175	}
176
177	iio_trigger_notify_done(indio_dev->trig);
178
179	return IRQ_HANDLED;
180}
181
182static int maxim_thermocouple_read_raw(struct iio_dev *indio_dev,
183				       struct iio_chan_spec const *chan,
184				       int *val, int *val2, long mask)
185{
186	struct maxim_thermocouple_data *data = iio_priv(indio_dev);
187	int ret = -EINVAL;
188
189	switch (mask) {
190	case IIO_CHAN_INFO_RAW:
191		ret = iio_device_claim_direct_mode(indio_dev);
192		if (ret)
193			return ret;
194
195		ret = maxim_thermocouple_read(data, chan, val);
196		iio_device_release_direct_mode(indio_dev);
197
198		if (!ret)
199			return IIO_VAL_INT;
200
201		break;
202	case IIO_CHAN_INFO_SCALE:
203		switch (chan->channel2) {
204		case IIO_MOD_TEMP_AMBIENT:
205			*val = 62;
206			*val2 = 500000; /* 1000 * 0.0625 */
207			ret = IIO_VAL_INT_PLUS_MICRO;
208			break;
209		default:
210			*val = 250; /* 1000 * 0.25 */
211			ret = IIO_VAL_INT;
212		}
213		break;
214	case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
215		*val = data->tc_type;
216		ret = IIO_VAL_CHAR;
217		break;
218	}
219
220	return ret;
221}
222
223static const struct iio_info maxim_thermocouple_info = {
224	.read_raw = maxim_thermocouple_read_raw,
225};
226
227static int maxim_thermocouple_probe(struct spi_device *spi)
228{
229	const struct spi_device_id *id = spi_get_device_id(spi);
230	struct iio_dev *indio_dev;
231	struct maxim_thermocouple_data *data;
232	const int chip_type = (id->driver_data == MAX6675) ? MAX6675 : MAX31855;
233	const struct maxim_thermocouple_chip *chip =
234		&maxim_thermocouple_chips[chip_type];
235	int ret;
236
237	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
238	if (!indio_dev)
239		return -ENOMEM;
240
241	indio_dev->info = &maxim_thermocouple_info;
242	indio_dev->name = MAXIM_THERMOCOUPLE_DRV_NAME;
243	indio_dev->channels = chip->channels;
244	indio_dev->available_scan_masks = chip->scan_masks;
245	indio_dev->num_channels = chip->num_channels;
246	indio_dev->modes = INDIO_DIRECT_MODE;
247
248	data = iio_priv(indio_dev);
249	data->spi = spi;
250	data->chip = chip;
251	data->tc_type = maxim_tc_types[id->driver_data];
252
253	ret = devm_iio_triggered_buffer_setup(&spi->dev,
254				indio_dev, NULL,
255				maxim_thermocouple_trigger_handler, NULL);
256	if (ret)
257		return ret;
258
259	if (id->driver_data == MAX31855)
260		dev_warn(&spi->dev, "generic max31855 ID is deprecated\nplease use more specific part type");
261
262	return devm_iio_device_register(&spi->dev, indio_dev);
263}
264
265static const struct spi_device_id maxim_thermocouple_id[] = {
266	{"max6675", MAX6675},
267	{"max31855", MAX31855},
268	{"max31855k", MAX31855K},
269	{"max31855j", MAX31855J},
270	{"max31855n", MAX31855N},
271	{"max31855s", MAX31855S},
272	{"max31855t", MAX31855T},
273	{"max31855e", MAX31855E},
274	{"max31855r", MAX31855R},
275	{},
276};
277MODULE_DEVICE_TABLE(spi, maxim_thermocouple_id);
278
279static const struct of_device_id maxim_thermocouple_of_match[] = {
280        { .compatible = "maxim,max6675" },
281        { .compatible = "maxim,max31855" },
282	{ .compatible = "maxim,max31855k" },
283	{ .compatible = "maxim,max31855j" },
284	{ .compatible = "maxim,max31855n" },
285	{ .compatible = "maxim,max31855s" },
286	{ .compatible = "maxim,max31855t" },
287	{ .compatible = "maxim,max31855e" },
288	{ .compatible = "maxim,max31855r" },
289        { },
290};
291MODULE_DEVICE_TABLE(of, maxim_thermocouple_of_match);
292
293static struct spi_driver maxim_thermocouple_driver = {
294	.driver = {
295		.name	= MAXIM_THERMOCOUPLE_DRV_NAME,
296		.of_match_table = maxim_thermocouple_of_match,
297	},
298	.probe		= maxim_thermocouple_probe,
299	.id_table	= maxim_thermocouple_id,
300};
301module_spi_driver(maxim_thermocouple_driver);
302
303MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
304MODULE_DESCRIPTION("Maxim thermocouple sensors");
305MODULE_LICENSE("GPL");
306