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/types.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
25 enum {
26 MAX6675,
27 MAX31855,
28 MAX31855K,
29 MAX31855J,
30 MAX31855N,
31 MAX31855S,
32 MAX31855T,
33 MAX31855E,
34 MAX31855R,
35 };
36
37 static const char maxim_tc_types[] = {
38 'K', '?', 'K', 'J', 'N', 'S', 'T', 'E', 'R'
39 };
40
41 static 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
59 static 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
94 static const unsigned long max31855_scan_masks[] = {0x3, 0};
95
96 struct 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
106 static 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
122 struct maxim_thermocouple_data {
123 struct spi_device *spi;
124 const struct maxim_thermocouple_chip *chip;
125 char tc_type;
126 /* Buffer for reading up to 2 hardware channels. */
127 struct {
128 union {
129 __be16 raw16;
130 __be32 raw32;
131 __be16 raw[2];
132 };
133 aligned_s64 timestamp;
134 } buffer __aligned(IIO_DMA_MINALIGN);
135 };
136
maxim_thermocouple_read(struct maxim_thermocouple_data * data,struct iio_chan_spec const * chan,int * val)137 static int maxim_thermocouple_read(struct maxim_thermocouple_data *data,
138 struct iio_chan_spec const *chan, int *val)
139 {
140 unsigned int storage_bytes = data->chip->read_size;
141 unsigned int shift = chan->scan_type.shift + (chan->address * 8);
142 int ret;
143
144 switch (storage_bytes) {
145 case 2:
146 ret = spi_read(data->spi, &data->buffer.raw16, storage_bytes);
147 *val = be16_to_cpu(data->buffer.raw16);
148 break;
149 case 4:
150 ret = spi_read(data->spi, &data->buffer.raw32, storage_bytes);
151 *val = be32_to_cpu(data->buffer.raw32);
152 break;
153 default:
154 ret = -EINVAL;
155 }
156
157 if (ret)
158 return ret;
159
160 /* check to be sure this is a valid reading */
161 if (*val & data->chip->status_bit)
162 return -EINVAL;
163
164 *val = sign_extend32(*val >> shift, chan->scan_type.realbits - 1);
165
166 return 0;
167 }
168
maxim_thermocouple_trigger_handler(int irq,void * private)169 static irqreturn_t maxim_thermocouple_trigger_handler(int irq, void *private)
170 {
171 struct iio_poll_func *pf = private;
172 struct iio_dev *indio_dev = pf->indio_dev;
173 struct maxim_thermocouple_data *data = iio_priv(indio_dev);
174 int ret;
175
176 ret = spi_read(data->spi, data->buffer.raw, data->chip->read_size);
177 if (!ret) {
178 iio_push_to_buffers_with_timestamp(indio_dev, &data->buffer,
179 iio_get_time_ns(indio_dev));
180 }
181
182 iio_trigger_notify_done(indio_dev->trig);
183
184 return IRQ_HANDLED;
185 }
186
maxim_thermocouple_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)187 static int maxim_thermocouple_read_raw(struct iio_dev *indio_dev,
188 struct iio_chan_spec const *chan,
189 int *val, int *val2, long mask)
190 {
191 struct maxim_thermocouple_data *data = iio_priv(indio_dev);
192 int ret = -EINVAL;
193
194 switch (mask) {
195 case IIO_CHAN_INFO_RAW:
196 ret = iio_device_claim_direct_mode(indio_dev);
197 if (ret)
198 return ret;
199
200 ret = maxim_thermocouple_read(data, chan, val);
201 iio_device_release_direct_mode(indio_dev);
202
203 if (!ret)
204 return IIO_VAL_INT;
205
206 break;
207 case IIO_CHAN_INFO_SCALE:
208 switch (chan->channel2) {
209 case IIO_MOD_TEMP_AMBIENT:
210 *val = 62;
211 *val2 = 500000; /* 1000 * 0.0625 */
212 ret = IIO_VAL_INT_PLUS_MICRO;
213 break;
214 default:
215 *val = 250; /* 1000 * 0.25 */
216 ret = IIO_VAL_INT;
217 }
218 break;
219 case IIO_CHAN_INFO_THERMOCOUPLE_TYPE:
220 *val = data->tc_type;
221 ret = IIO_VAL_CHAR;
222 break;
223 }
224
225 return ret;
226 }
227
228 static const struct iio_info maxim_thermocouple_info = {
229 .read_raw = maxim_thermocouple_read_raw,
230 };
231
maxim_thermocouple_probe(struct spi_device * spi)232 static int maxim_thermocouple_probe(struct spi_device *spi)
233 {
234 const struct spi_device_id *id = spi_get_device_id(spi);
235 struct iio_dev *indio_dev;
236 struct maxim_thermocouple_data *data;
237 const int chip_type = (id->driver_data == MAX6675) ? MAX6675 : MAX31855;
238 const struct maxim_thermocouple_chip *chip =
239 &maxim_thermocouple_chips[chip_type];
240 int ret;
241
242 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
243 if (!indio_dev)
244 return -ENOMEM;
245
246 indio_dev->info = &maxim_thermocouple_info;
247 indio_dev->name = MAXIM_THERMOCOUPLE_DRV_NAME;
248 indio_dev->channels = chip->channels;
249 indio_dev->available_scan_masks = chip->scan_masks;
250 indio_dev->num_channels = chip->num_channels;
251 indio_dev->modes = INDIO_DIRECT_MODE;
252
253 data = iio_priv(indio_dev);
254 data->spi = spi;
255 data->chip = chip;
256 data->tc_type = maxim_tc_types[id->driver_data];
257
258 ret = devm_iio_triggered_buffer_setup(&spi->dev,
259 indio_dev, NULL,
260 maxim_thermocouple_trigger_handler, NULL);
261 if (ret)
262 return ret;
263
264 if (id->driver_data == MAX31855)
265 dev_warn(&spi->dev, "generic max31855 ID is deprecated\nplease use more specific part type");
266
267 return devm_iio_device_register(&spi->dev, indio_dev);
268 }
269
270 static const struct spi_device_id maxim_thermocouple_id[] = {
271 {"max6675", MAX6675},
272 {"max31855", MAX31855},
273 {"max31855k", MAX31855K},
274 {"max31855j", MAX31855J},
275 {"max31855n", MAX31855N},
276 {"max31855s", MAX31855S},
277 {"max31855t", MAX31855T},
278 {"max31855e", MAX31855E},
279 {"max31855r", MAX31855R},
280 {},
281 };
282 MODULE_DEVICE_TABLE(spi, maxim_thermocouple_id);
283
284 static const struct of_device_id maxim_thermocouple_of_match[] = {
285 { .compatible = "maxim,max6675" },
286 { .compatible = "maxim,max31855" },
287 { .compatible = "maxim,max31855k" },
288 { .compatible = "maxim,max31855j" },
289 { .compatible = "maxim,max31855n" },
290 { .compatible = "maxim,max31855s" },
291 { .compatible = "maxim,max31855t" },
292 { .compatible = "maxim,max31855e" },
293 { .compatible = "maxim,max31855r" },
294 { },
295 };
296 MODULE_DEVICE_TABLE(of, maxim_thermocouple_of_match);
297
298 static struct spi_driver maxim_thermocouple_driver = {
299 .driver = {
300 .name = MAXIM_THERMOCOUPLE_DRV_NAME,
301 .of_match_table = maxim_thermocouple_of_match,
302 },
303 .probe = maxim_thermocouple_probe,
304 .id_table = maxim_thermocouple_id,
305 };
306 module_spi_driver(maxim_thermocouple_driver);
307
308 MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
309 MODULE_DESCRIPTION("Maxim thermocouple sensors");
310 MODULE_LICENSE("GPL");
311