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