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
24 enum {
25 MAX6675,
26 MAX31855,
27 MAX31855K,
28 MAX31855J,
29 MAX31855N,
30 MAX31855S,
31 MAX31855T,
32 MAX31855E,
33 MAX31855R,
34 };
35
36 static const char maxim_tc_types[] = {
37 'K', '?', 'K', 'J', 'N', 'S', 'T', 'E', 'R'
38 };
39
40 static 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
58 static 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
93 static const unsigned long max31855_scan_masks[] = {0x3, 0};
94
95 struct 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
105 static 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
121 struct 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
maxim_thermocouple_read(struct maxim_thermocouple_data * data,struct iio_chan_spec const * chan,int * val)129 static 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
maxim_thermocouple_trigger_handler(int irq,void * private)163 static 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
maxim_thermocouple_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)181 static 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
222 static const struct iio_info maxim_thermocouple_info = {
223 .read_raw = maxim_thermocouple_read_raw,
224 };
225
maxim_thermocouple_probe(struct spi_device * spi)226 static 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
264 static 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 };
276 MODULE_DEVICE_TABLE(spi, maxim_thermocouple_id);
277
278 static 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 };
290 MODULE_DEVICE_TABLE(of, maxim_thermocouple_of_match);
291
292 static 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 };
300 module_spi_driver(maxim_thermocouple_driver);
301
302 MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
303 MODULE_DESCRIPTION("Maxim thermocouple sensors");
304 MODULE_LICENSE("GPL");
305